CN114924161A

CN114924161A - Method and system for analyzing insulation situation of power distribution system

Info

Publication number: CN114924161A
Application number: CN202210402309.8A
Authority: CN
Inventors: 刘红文; 聂鼎; 柴晨超; 赵现平; 张春丽; 杨金东; 李月梅; 杨莉; 闫永梅
Original assignee: Electric Power Research Institute of Yunnan Power Grid Co Ltd
Current assignee: Electric Power Research Institute of Yunnan Power Grid Co Ltd
Priority date: 2022-04-18
Filing date: 2022-04-18
Publication date: 2022-08-19

Abstract

The embodiment of the invention discloses a method and a system for analyzing the insulation situation of a power distribution system, wherein the method comprises the following steps: injecting a broadband voltage into the power distribution system at different output frequencies; acquiring operating parameters of a power distribution system; determining a first insulation state of the distribution line according to the broadband voltage and the broadband zero-sequence current of the line; determining the ground fault state of the distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current; determining a second insulation state of the bus based on the three-phase bus pulse voltage and the three-phase bus power frequency voltage; determining a third insulation state of the low-voltage winding of the transformer based on the secondary side three-phase broadband current and the broadband voltage of the transformer; and outputting the operation and maintenance strategy based on each insulation state. By the method, the insulation state of the power distribution network can be monitored on line, the insulation situation of the power distribution system can be comprehensively evaluated, a solution is provided for the transition from preemptive maintenance to active operation and maintenance of the power distribution system, and the operation and maintenance efficiency, accuracy and power supply reliability are improved.

Description

Method and system for analyzing insulation situation of power distribution system

Technical Field

The invention relates to the technical field of power systems, in particular to a method and a system for analyzing the insulation situation of a power distribution system.

Background

Insulation faults are the most common major form of fault during operation of electrical power systems. Different from a power transmission network, a distribution line is low in erection height and is very easily influenced by a channel environment, and insulation faults occur. At the beginning of the insulation fault of the distribution line, the system voltage, current and the like have no obvious changes and are difficult to detect, and the insulation fault point is continuously developed, so that the insulation performance is continuously reduced, and finally, a single-phase earth fault, an interphase short-circuit fault and the like can be caused. The most fundamental solution to the problem of frequent insulation faults of the distribution lines is to effectively operate and maintain the distribution lines, and through efficient operation and maintenance, the insulation hidden dangers can be effectively checked, so that the occurrence probability of the insulation faults of the distribution lines is greatly reduced. However, the distribution line has high operation and maintenance difficulty, hidden dangers are difficult to find, the blind comprehensive operation and maintenance efficiency is low, and extremely high labor cost and time cost are required. In actual work, the operation and maintenance work of the distribution line appears 'to rush (repair) for maintenance', operation and maintenance personnel are tired of dealing with various faults, and the efficiency is extremely low. How to achieve accurate operation and maintenance and high-efficiency operation and maintenance is a problem which troubles operation and maintenance personnel of a power distribution system.

The bus switch cabinet is an important operation device of a power distribution system, once the switch cabinet has an insulation fault, an interphase short circuit is easily caused, and the safe operation of a main transformer is threatened, so that the insulation monitoring of the switch cabinet is very necessary. And the switch cabinet is strictly closed, so that the switch cabinet is difficult to observe and maintain.

The transformer is a key device in the power system, and the safety and the stability of the power system are seriously influenced by sudden failure of the transformer in the operation process, thereby causing great asset loss and large-area power failure. Transformer related accidents indicate that insulation damage is one of the major causes of accidents. In operation the transformer is inevitably subjected to short circuit current surges and the windings will be subjected to large, non-uniform axial and radial electrodynamic forces. When a weak link exists in the internal mechanical structure of the winding, the winding deformation is inevitably generated due to the cumulative effect of short-circuit electric shock. Including axial and radial dimensional changes, body displacement, turn-to-turn shorts and winding distortions, bulging, etc. After the transformer winding is deformed, the insulation capability is reduced, and if the transformer winding cannot be found in time, accidents such as burst damage, insulation breakdown and the like can be caused by continuous operation.

The problems are the common problems in the power distribution system, cover the main equipment, lines and the like of the power distribution system, and can be uniformly summarized into the insulation monitoring problem of the power system. There is a need for a convenient, economical and effective method for timely on-line monitoring of the above problems.

Disclosure of Invention

The invention mainly aims to provide a method and a system for analyzing the insulation situation of a power distribution system, which can solve the problem that the prior art lacks a method for effectively monitoring the power distribution system on line.

In order to achieve the above object, a first aspect of the present invention provides a method for analyzing an insulation situation of a power distribution system, the method including:

injecting a broadband voltage into the power distribution system at different output frequencies;

acquiring operation parameters of the power distribution system, wherein the operation parameters at least comprise line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero sequence current and transformer secondary side three-phase broadband current;

determining a first insulation state of the distribution line according to the broadband voltage and the line broadband zero sequence current; determining the ground fault state of the distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current; determining a second insulation state of the bus based on the three-phase bus pulse voltage and the three-phase bus power frequency voltage; determining a third insulation state of the low-voltage winding of the transformer based on the secondary side three-phase broadband current and the broadband voltage of the transformer;

and outputting a line operation and maintenance strategy, a bus operation and maintenance strategy and a transformer operation and maintenance strategy based on the first insulation state, the ground fault state, the second insulation state and the third insulation state.

In one possible implementation manner, the determining the first insulation state of the distribution line according to the wideband voltage and the line wideband zero-sequence current includes:

determining a first angle difference between the line broadband zero-sequence current and the broadband voltage of each line under different output frequencies according to the broadband voltage and the line broadband zero-sequence current under different output frequencies;

determining a first dielectric spectrum of each distribution line under different output frequencies by using the first angle difference and tangent value algorithm;

and when the distribution line with the first dielectric spectrum at the current moment being larger than the first dielectric spectrum at the previous moment under the same output frequency exists, determining that the first insulation state of the distribution line is a line insulation fault.

In a feasible implementation manner, the determining the ground fault state of the distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current includes:

determining whether the distribution line has a line ground fault or not according to the power frequency zero sequence current of the line;

and if the distribution line has a line ground fault, determining the fault type and the ground fault state of the distribution line according to the magnitude of the secondary side power frequency current of the transformer, wherein the fault type comprises an interphase short-circuit fault or a single-phase short-circuit fault.

In a possible implementation manner, the determining the second insulation state of the bus based on the three-phase bus pulse voltage and the three-phase bus power frequency voltage includes:

and when the ratio of the amplitude of the three-phase bus pulse voltage of each bus switch cabinet to the three-phase bus power frequency voltage is greater than or equal to a preset multiple threshold value, and the phase of the three-phase bus pulse voltage of each bus switch cabinet is greater than a preset phase threshold value, determining that the second insulation state of the bus is a bus insulation fault, wherein the preset phase threshold value is based on the phase setting of the three-phase bus power frequency voltage of each bus switch cabinet.

In one possible implementation manner, the determining a third insulation state of the low-voltage winding of the transformer based on the three-phase broadband current and the broadband voltage at the secondary side of the transformer includes:

determining a second angle difference between the broadband voltage under different frequencies and the broadband current of the secondary side of the transformer of each phase of the transformer by using the broadband current of the secondary side of the transformer and the broadband voltages under different frequencies;

determining a second dielectric spectrum of each phase of the transformer under different frequencies by utilizing the second angle difference and tangent value algorithm;

determining a third insulation state of the low voltage winding of the transformer based on the second dielectric spectrum of each phase of the transformer at the respective output frequency.

In one possible implementation, the determining a third insulation state of the low-voltage winding of the transformer according to the second dielectric spectrum of each phase of the transformer at the respective output frequency includes:

determining a first transformer reference dielectric spectrum of each phase of a transformer at different output frequencies when the distribution system is in normal operation;

and if the second dielectric spectrum with the same phase is larger than the first transformer reference dielectric spectrum under the same output frequency, determining that the third insulation state of the transformer low-voltage winding is the insulation fault of the transformer low-voltage winding.

In a possible implementation, the determining, by using the first angle difference and tangent value algorithm, a first dielectric spectrum of each distribution line at different output frequencies further includes:

determining line reference dielectric spectra at different output frequencies of the power distribution system during normal operation;

determining a line dielectric spectrum correlation coefficient by using the first dielectric spectrum of each distribution line under different output frequencies and the line reference dielectric spectrum, wherein the line dielectric spectrum correlation coefficient is obtained on the basis of a curve of the first dielectric spectrum changing along with different output frequencies and a curve of the line reference dielectric spectrum changing along with different output frequencies;

and if the dielectric spectrum correlation coefficient of any one distribution line is smaller than a first preset correlation coefficient threshold value, determining that the first insulation state of the distribution line is a line insulation fault.

In one possible implementation, the transformer includes a primary side and a secondary side, the primary side includes a high voltage winding side or a medium voltage winding side, the secondary side includes a low voltage winding side or a medium voltage winding side, and the wideband voltage is injected from the primary side, and then the third insulation state of the transformer low voltage winding is determined based on the transformer secondary side three-phase wideband current and the wideband voltage, and the method further includes:

determining a third angle difference between the broadband voltage of the secondary side under different frequencies and the broadband current of the secondary side of the transformer by using the broadband current of the secondary side of the transformer and the broadband voltages under different frequencies;

determining a third dielectric spectrum between each phase of the secondary side and the primary side of the transformer under different frequencies by using the third angle difference and the tangent value algorithm;

determining a second transformer reference dielectric spectrum between each phase of the primary side and the secondary side under different output frequencies when the power distribution system operates normally;

determining a transformer dielectric spectrum correlation coefficient between the secondary side of the transformer and each phase of the primary side according to the third dielectric spectrum and the second transformer reference dielectric spectrum at each output frequency, the transformer dielectric spectrum correlation coefficient being obtained based on a curve of the in-phase third dielectric spectrum of the secondary side and the primary side varying with different output frequencies and a curve of the second transformer reference dielectric spectrum varying with different output frequencies;

and if the correlation coefficient of the dielectric spectrum of the transformer of any phase is smaller than a second preset correlation coefficient threshold value, determining that the third insulation state of the low-voltage winding of the transformer is the insulation fault of the low-voltage winding of the transformer.

In one possible implementation, outputting a line operation and maintenance strategy based on the first insulation state includes:

performing statistical analysis on a first insulation state of the distribution line to determine a first insulation failure condition of the distribution line, wherein the first insulation state comprises a line insulation fault;

when the first insulation failure condition is a distribution line with the insulation failure times within a preset first time length being more than or equal to a preset first time threshold, outputting a first line operation and maintenance strategy, wherein the first line operation and maintenance strategy comprises suggesting strengthening line patrol and searching for a failure position;

when the first insulation failure condition is a distribution line with the insulation failure frequency within a preset second time length being greater than or equal to a preset second frequency threshold value, outputting a second line operation and maintenance strategy, wherein the second line operation and maintenance strategy comprises a proposal of strengthening line patrol and line channel cleaning; the preset first time length is less than a preset second time length, and the preset second time threshold is greater than the preset first time threshold;

when the first insulation failure condition is a distribution line with the insulation failure frequency within a preset third time length being greater than or equal to a preset third time threshold value, outputting a third line operation and maintenance strategy, wherein the third line operation and maintenance strategy comprises a proposal of carrying out line conductor insulation treatment; the preset second time length is smaller than the preset third time length, and the preset third time threshold is larger than the preset second time threshold.

In one possible implementation manner, outputting a bus operation and maintenance strategy based on the second insulation state includes:

performing statistical analysis on a second insulation state of a bus of the power distribution system, and determining a second insulation fault condition of the bus, wherein the second insulation state comprises a bus insulation fault;

and when the second insulation fault condition is that a bus insulation fault exists, outputting a bus operation and maintenance strategy, wherein the bus operation and maintenance strategy comprises suggesting power failure to check the fault condition and carry out first-aid repair.

In one possible implementation, outputting a transformer operation and maintenance strategy based on the third insulation state includes:

and when the third insulation state of the transformer is insulation fault of the low-voltage winding of the transformer, outputting a transformer operation and maintenance strategy, wherein the transformer operation and maintenance strategy comprises the recommendation of power failure for transformer maintenance.

In one possible implementation, outputting a line operation and maintenance policy based on the ground fault condition includes:

performing statistical analysis on the ground fault state of the distribution line to determine the ground fault condition of the distribution line;

when the ground fault condition is a distribution line with the number of times of line ground faults existing within a preset fourth time period being greater than or equal to a preset first time threshold and the duration of each line ground fault being less than or equal to a preset first time threshold, outputting a fourth line operation and maintenance strategy, wherein the fourth line operation and maintenance strategy is that intermittent ground faults occur to the distribution line, and suggesting line channel cleaning;

when the ground fault condition is a distribution line with the number of times of line ground faults within a preset fourth time period being greater than or equal to a preset first time threshold and the duration of the line ground faults each time being less than or equal to a preset second time threshold, outputting a fifth line operation and maintenance strategy, wherein the fifth line operation and maintenance strategy is to perform foreign body touch on the distribution line and suggest to perform line channel cleaning and inspection; the preset second time threshold is greater than the preset first time threshold;

when the ground fault condition is a distribution line with the number of times of line ground faults within a preset fourth time period being greater than or equal to a preset first time threshold and the duration of each line ground fault being less than or equal to a preset third time threshold, outputting a sixth line operation and maintenance strategy, wherein the sixth line operation and maintenance strategy is that line continuous single-phase ground faults occur on the distribution line, and the line conductor insulation is recommended to be strengthened; the preset third time threshold is greater than the preset second time threshold.

In order to achieve the above object, a second aspect of the present invention provides an insulation situation analysis system for a power distribution system, the insulation situation analysis system comprising:

a signal injection module: for injecting a broadband voltage at different output frequencies into the power distribution system;

a parameter monitoring module: the system comprises a power distribution system, a power source, a transformer, a three-phase bus pulse voltage, a line broadband zero-sequence current and a transformer, wherein the power distribution system is used for acquiring operation parameters of the power distribution system, and the operation parameters at least comprise a line power frequency zero-sequence current, a transformer secondary side power frequency current, a three-phase bus power frequency voltage, a three-phase bus pulse voltage, a line broadband zero-sequence current and a transformer secondary side three-phase broadband current;

a line analysis module: the first insulation state of the distribution line is determined according to the broadband voltage and the line broadband zero-sequence current; determining the ground fault state of the distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current;

a bus analysis module: the second insulation state of the bus is determined based on the three-phase bus pulse voltage and the three-phase bus power frequency voltage;

the transformer analysis module: the device comprises a first insulation state, a second insulation state and a third insulation state, wherein the first insulation state is used for determining a first insulation state of a low-voltage winding of the transformer based on a three-phase broadband current and a broadband voltage of a secondary side of the transformer;

the operation and maintenance strategy output module: and the output module is used for outputting a line operation and maintenance strategy, a bus operation and maintenance strategy and a transformer operation and maintenance strategy based on the first insulation state, the ground fault state, the second insulation state and the third insulation state.

To achieve the above object, a third aspect of the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps as shown in the first aspect and any possible implementation manner.

To achieve the above object, a fourth aspect of the present invention provides a computer device, which includes a memory and a processor, wherein the memory stores a computer program, and the computer program, when executed by the processor, causes the processor to execute the steps shown in the first aspect and any possible implementation manner.

The embodiment of the invention has the following beneficial effects:

the invention provides a method for analyzing the insulation situation of a power distribution system, which comprises the following steps: injecting a broadband voltage into the power distribution system at different output frequencies; acquiring operation parameters of a power distribution system, wherein the operation parameters at least comprise line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero sequence current and transformer secondary side three-phase broadband current; determining a first insulation state of the distribution line according to the broadband voltage and the broadband zero-sequence current of the line; determining the ground fault state of the distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current; determining a second insulation state of the bus based on the three-phase bus pulse voltage and the three-phase bus power frequency voltage; determining a third insulation state of the low-voltage winding of the transformer based on the secondary side three-phase broadband current and the broadband voltage of the transformer; and outputting a line operation and maintenance strategy, a bus operation and maintenance strategy and a transformer operation and maintenance strategy based on the first insulation state, the ground fault state, the second insulation state and the third insulation state. By the method, the insulation states of the bus, the distribution line and the transformer can be monitored on line, the insulation situation of the power distribution system can be comprehensively evaluated, operation and maintenance early warning and suggestions are given, a technical solution is provided for the power distribution system from preemptive maintenance to active operation and maintenance, accurate operation and maintenance of the power distribution system are achieved, and operation and maintenance efficiency, accuracy and power supply reliability are improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

Wherein:

fig. 1 is a flowchart of an insulation situation analysis method for a power distribution system according to an embodiment of the present invention;

FIG. 2 is another flowchart of a method for analyzing an insulation situation of a power distribution system according to an embodiment of the present invention;

FIG. 3 is a flowchart illustrating a method for analyzing an insulation situation of a power distribution system according to an embodiment of the present invention;

FIG. 4 is a flowchart of a method for analyzing an insulation situation of a power distribution system according to an embodiment of the present invention;

fig. 5 is a flowchart illustrating a method for analyzing an insulation situation of a power distribution system according to another embodiment of the present invention;

fig. 6 is a block diagram of an insulation situation analysis system of a power distribution system according to an embodiment of the present invention;

fig. 7 is a block diagram of a computer device according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, fig. 1 is a flowchart illustrating an insulation situation analyzing method for a power distribution system according to an embodiment of the present invention; the method as shown in fig. 1 may comprise the steps of:

101. injecting broadband voltage to the power distribution system at different output frequencies;

it should be noted that the present invention may be executed by a control device with control analysis capability, and further, the control device may be a distribution system insulation state analysis system in a distribution system, or may be executed directly by the distribution system, which is not limited herein, and this embodiment is described by taking an application to a distribution system insulation state analysis system as an example. Further, first, injecting a frequency sweep signal into the power distribution system, and injecting a broadband voltage into the power distribution system at different output frequencies to achieve the injection of the frequency sweep signal, where the injection of the broadband voltage may be achieved by controlling a voltage source, and the voltage source may be a broadband voltage source. Illustratively, the output frequency may vary between 0.001Hz-1 MHz.

102. Acquiring operation parameters of the power distribution system, wherein the operation parameters at least comprise line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero sequence current and transformer secondary side three-phase broadband current;

furthermore, the operation parameters of the power distribution system are obtained, the operation parameters refer to the electrical parameters of each electrical element when the power distribution system operates, the operating parameters include, but are not limited to, line power frequency zero sequence current, transformer secondary side power frequency current, three phase bus power frequency voltage, three phase bus pulse voltage, line wide frequency zero sequence current, transformer secondary side three phase wide frequency current, zero sequence power frequency voltage, line zero sequence power frequency current, transformer secondary side three phase power frequency current, and line zero sequence wide frequency current, among others, for example, can monitor distribution system's operating parameter through setting up the signal acquisition device that corresponds, for example the sensor, utilize signal acquisition device, specifically can include power frequency volume monitoring and wide band voltage and wide band current monitoring to distribution system, wherein, power frequency volume monitoring can include: three-phase bus power frequency voltage, zero sequence power frequency voltage, line zero sequence power frequency current and transformer secondary side three-phase power frequency current; broadband voltage and broadband current monitoring includes: three-phase bus pulse voltage monitoring, transformer secondary side three-phase broadband current monitoring and line zero sequence broadband current monitoring.

103. Determining a first insulation state of the distribution line according to the broadband voltage and the line broadband zero-sequence current; determining the ground fault state of the distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current; determining a second insulation state of the bus based on the three-phase bus pulse voltage and the three-phase bus power frequency voltage; determining a third insulation state of the low-voltage winding of the transformer based on the secondary side three-phase broadband current and the broadband voltage of the transformer;

it can be understood that after obtaining the above operation parameters, the operation states of the electrical elements of the power distribution system can be evaluated and analyzed through step 103, in this embodiment, the operation states of the distribution line, the bus and the transformer in the power distribution system are evaluated and analyzed respectively, and specifically, the first insulation state of the distribution line is determined through the wideband voltage and the line wideband zero-sequence current; determining the ground fault state of the distribution line through the line power frequency zero sequence current and the transformer secondary side power frequency current; determining a second insulation state of the bus through the three-phase bus pulse voltage and the three-phase bus power frequency voltage; and determining a third insulation state of the low-voltage winding of the transformer through the three-phase broadband current and the broadband voltage of the secondary side of the transformer. The first insulation state indicates the insulation condition of the distribution line, and the first insulation state comprises line insulation fault or line insulation normal; the ground fault state indicates the ground fault condition of the distribution line, and the ground fault state comprises a line ground fault or a line ungrounded fault; the second insulation state indicates the insulation condition of the bus, and the second insulation state comprises bus insulation failure or normal bus insulation; the third insulation state indicates an insulation condition of the transformer, and the third insulation state includes a transformer insulation fault or a transformer insulation normal.

104. And outputting a line operation and maintenance strategy, a bus operation and maintenance strategy and a transformer operation and maintenance strategy based on the first insulation state, the ground fault state, the second insulation state and the third insulation state.

It should be noted that after the operation states of the electrical elements in the power distribution system are obtained, the operation and maintenance strategy may be output according to the operation states, that is, after the first insulation state of the distribution line is obtained, the line operation and maintenance strategy may be output based on the first insulation state; after the ground fault state of the distribution line is obtained, a line operation and maintenance strategy can be output based on the ground fault state; after the second insulation state of the bus is obtained, a bus operation and maintenance strategy can be output based on the second insulation state; after the third insulation state of the transformer is obtained, the operation and maintenance strategy of the transformer can be output based on the third insulation state. Further, the operation and maintenance strategy is used to indicate a maintenance strategy for the operation state of the electrical component, and in this embodiment, the line operation and maintenance strategy, the bus operation and maintenance strategy, and the transformer operation and maintenance strategy may be respectively output based on the first insulation state, the ground fault state, the second insulation state, and the third insulation state.

The invention provides a method for analyzing the insulation situation of a power distribution system, which comprises the following steps: injecting a broadband voltage into the power distribution system at different output frequencies; acquiring operation parameters of a power distribution system, wherein the operation parameters at least comprise line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero sequence current and transformer secondary side three-phase broadband current; determining a first insulation state of the distribution line according to the broadband voltage and the broadband zero-sequence current of the line; determining the ground fault state of the distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current; determining a second insulation state of the bus based on the three-phase bus pulse voltage and the three-phase bus power frequency voltage; determining a third insulation state of the low-voltage winding of the transformer based on the secondary side three-phase broadband current and the broadband voltage of the transformer; and outputting a line operation and maintenance strategy, a bus operation and maintenance strategy and a transformer operation and maintenance strategy based on the first insulation state, the ground fault state, the second insulation state and the third insulation state. By the method, the insulation states of the bus, the distribution line and the transformer can be monitored on line, the insulation situation of the distribution system can be comprehensively evaluated, operation and maintenance early warning, suggestions and the like are given, a technical solution is provided for the transformation from emergency maintenance to active operation and maintenance of the distribution system, the accurate operation and maintenance of the distribution system is realized, and the operation and maintenance efficiency, the accuracy and the power supply reliability are improved.

Referring to fig. 2, fig. 2 is another flowchart of a method for analyzing an insulation situation of a power distribution system according to an embodiment of the present invention, where the method shown in fig. 2 is an analysis of a power distribution line, and the method shown in fig. 2 may include the following steps:

201. injecting a broadband voltage into the power distribution system at different output frequencies;

202. acquiring operation parameters of the power distribution system, wherein the operation parameters at least comprise line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero sequence current and transformer secondary side three-phase broadband current;

it should be noted that steps 201 and 202 are similar to steps 101 and 102 shown in fig. 1, and for avoiding repetition, details are not repeated here, and reference may be specifically made to the contents of steps 101 and 102 shown in fig. 1.

203. Determining a first angle difference between the line broadband zero-sequence current and the broadband voltage of each line under different output frequencies according to the broadband voltage and the line broadband zero-sequence current under different output frequencies;

in this embodiment, the insulation state of the distribution line is evaluated and analyzed according to the dielectric loss value of each line, and therefore, a first angle difference between the line broadband zero-sequence current and the broadband voltage of each line at different output frequencies needs to be determined according to the broadband voltage and the line broadband zero-sequence current at different output frequencies, where the first angle difference represents a phase difference between the line broadband zero-sequence current and the broadband voltage. And obtaining the dielectric loss value of each line by using the first angle difference.

204. Determining a first dielectric spectrum of each distribution line under different output frequencies by using the first angle difference and tangent value algorithm;

further, a first dielectric spectrum of each distribution line under different output frequencies is determined by using a first angle difference and tangent value algorithm, wherein the first dielectric spectrum is a tangent value corresponding to the first angle difference, the tangent value can be used for representing the zero sequence loss degree of the distribution lines, and the tangent value can be used as the dielectric loss value of each line.

Steps 201, 202, 203 and 204 are illustrated: firstly, in step 201, a sinusoidal voltage with an output frequency of n and an amplitude of m is applied to a neutral point of a power distribution system to obtain broadband voltages at different output frequencies; further, step 203 is executed according to the system zero sequence voltage (wideband voltage) and the line zero sequence current (line wideband zero sequence current) obtained in step 202, and in step 203, under the output frequency n, the phase difference σ between the system zero sequence voltage and the line zero sequence current is obtained _n The phase difference Δ δ is calculated by step 204 _n The tangent value of (A) is calculated to obtain a first dielectric spectrum (line node loss value), wherein the tangent value can be referred toThe following formula is calculated: tan (900-. DELTA.delta.) _n ) Wherein n represents the number of the output frequency for distinguishing different output frequencies, further, the step s gradually changes the output frequency applied to the system neutral point, the amplitude is kept as s, and the steps 202 and 204 are executed in a loop to obtain the dielectric spectrum of each line under different output frequencies, wherein the variation range of the output frequency can be 0.1 Hz-1MHz, and the amplitude m can be 0-0.5 kV.

205. When a distribution line with a first dielectric spectrum at the current moment being larger than that at the previous moment under the same output frequency exists, determining that the first insulation state of the distribution line is a line insulation fault;

it should be noted that, the sizes of the first dielectric spectrums before and after the fault at the same frequency point of the lines are different, and therefore, the first insulation state of the distribution line is determined by comparing the sizes of the first dielectric spectrums before and after the fault at the same frequency point of each line, and then the first dielectric spectrum after the fault is in an increasing trend than the first dielectric spectrum before the fault.

In a possible implementation manner, the step 204 may be further followed by determining the first insulation state through a correlation coefficient between the first dielectric spectrums, and then the step 204 may further be followed by a 1-A3:

a1, determining the line reference dielectric spectrum at different output frequencies when the power distribution system normally operates;

in this embodiment, when the power distribution system normally operates, the broadband voltage is injected into the power distribution system at different output frequencies, and the broadband voltage and the line broadband zero-sequence current when the power distribution system normally operates are used to obtain the line reference dielectric spectrum at different output frequencies when the power distribution system normally operates, so that the line reference dielectric spectrum at different output frequencies when the power distribution system normally operates can be further determined, and the line reference dielectric spectrum is used as a reference standard for evaluating the insulation state of the line.

A2, determining a line dielectric spectrum correlation coefficient by using the first dielectric spectrum of each distribution line under different output frequencies and the line reference dielectric spectrum, wherein the line dielectric spectrum correlation coefficient is obtained based on a curve of the first dielectric spectrum changing with different output frequencies and a curve of the line reference dielectric spectrum changing with different output frequencies;

further, a line dielectric spectrum correlation coefficient is calculated through the obtained line reference dielectric spectrum and the first dielectric spectrum, wherein a curve of the first dielectric spectrum changing with different output frequencies and a curve of the line reference dielectric spectrum changing with different output frequencies can be obtained through different output frequencies, and further, the line dielectric spectrum correlation coefficient is used for representing the correlation degree of the curve of the first dielectric spectrum changing with different output frequencies and the curve of the line reference dielectric spectrum changing with different output frequencies.

Illustratively, the correlation coefficient of the line dielectric spectrum can be obtained by the following equation:

wherein, the first and the second end of the pipe are connected with each other,

x may represent a first dielectric spectrum, y a line reference dielectric spectrum, i represents a certain frequency point, i ∈ n, n is a set of different frequency points, x may include the first dielectric spectrum of each phase of the power distribution line, and similarly, the first dielectric spectrum may include the line reference dielectric spectrum of each phase of the power distribution line, and the line dielectric spectrum correlation coefficient is used to represent a correlation degree of a curve of the first dielectric spectrum varying with different output frequencies and a curve of the line reference dielectric spectrum varying with different output frequencies, where the correlation coefficient is 1 if the two curves are completely correlated, and is 0 if the correlation coefficient is completely uncorrelated.

A3, if the correlation coefficient of the dielectric spectrum of any one distribution line is smaller than a first preset correlation coefficient threshold value, determining that the first insulation state of the distribution line is a line insulation fault.

It can be understood that, when the dielectric spectrum correlation degree is smaller, it can be said that the difference between the first dielectric spectrum and the reference dielectric spectrum of the line in normal operation is larger, and therefore, if the dielectric spectrum correlation coefficient of any one of the distribution lines is smaller than the first preset correlation coefficient threshold value, the first insulation state of the distribution line is determined to be a line insulation fault. Further, by taking the first preset correlation coefficient threshold value as 0.5, for example, in steps a1-A3, a dielectric spectrum of each line at an output frequency of 0.1Hz to 1MHz is obtained through calculation when the system normally operates, and the dielectric spectrum is marked as a reference dielectric spectrum (line reference dielectric spectrum); continuously calculating the dielectric spectrum (first dielectric spectrum) of each line with the output frequency of 0.1 Hz-1MHz in real time; and further calculating a correlation coefficient (line dielectric spectrum correlation coefficient) between a real-time dielectric spectrum (first dielectric spectrum) of each line at the output frequency of 0.1 Hz-1MHz and a reference dielectric spectrum (line dielectric spectrum correlation coefficient) of each line at the output frequency of 0.1 Hz-1MHz, and if the correlation coefficient of the first dielectric spectrum and the reference dielectric spectrum is less than 0.5, considering that the line has insulation reduction, namely the first insulation state of the power distribution line is a line insulation fault.

206. Performing statistical analysis on a first insulation state of the distribution line, and determining a first insulation fault condition of the distribution line, wherein the first insulation state comprises a line insulation fault;

in this embodiment, data recording is also performed, and the recording content includes, but is not limited to, information of the first insulation state of the distribution line, such as the line name and the occurrence time of the insulation drop. Therefore, when the operation and maintenance strategy is output, the first insulation fault condition of the distribution line can be determined through carrying out statistical analysis on the first insulation state of the distribution line, and the operation and maintenance strategy is output through the fault condition, wherein the first insulation state at least comprises the line insulation fault.

207. When the first insulation failure condition is a distribution line with the insulation failure times within a preset first time length being more than or equal to a preset first time threshold, outputting a first line operation and maintenance strategy, wherein the first line operation and maintenance strategy comprises suggesting strengthening line patrol and searching for a failure position;

208. when the first insulation failure condition is a distribution line with the insulation failure frequency within a preset second time length being greater than or equal to a preset second frequency threshold value, outputting a second line operation and maintenance strategy, wherein the second line operation and maintenance strategy comprises a proposal of strengthening line patrol and line channel cleaning; the preset first time length is less than a preset second time length, and the preset second time threshold is greater than the preset first time threshold;

209. when the first insulation fault condition is a distribution line with the insulation fault frequency within a preset third time length being greater than or equal to a preset third frequency threshold value, outputting a third line operation and maintenance strategy, wherein the third line operation and maintenance strategy comprises a proposal of carrying out insulation treatment on a line lead; the preset second time length is smaller than the preset third time length, and the preset third time threshold is larger than the preset second time threshold.

It should be noted that, in step 207-: 1) if insulation faults occur more than 10 times in 1 week of a certain line, the line inspection is recommended to be strengthened, and the fault position is searched; 2) if insulation faults of a certain line occur more than 50 times in 1 month, the line patrol is recommended to be strengthened, and the line channel is cleaned. 3) If more than 500 insulation faults occur in a certain line in one year, the insulation treatment of the line conductor is recommended.

The invention provides a method for analyzing the insulation situation of a power distribution system, which comprises the following steps: injecting broadband voltage to the power distribution system at different output frequencies; acquiring operation parameters of a power distribution system, wherein the operation parameters at least comprise line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero sequence current and transformer secondary side three-phase broadband current; determining a first insulation state of the distribution line according to the broadband voltage and the broadband zero-sequence current of the line; and outputting the line operation and maintenance strategy based on the first insulation state. The method can be used for monitoring the insulation state of the distribution line on line, giving operation and maintenance early warning, suggestions and the like, and monitoring the insulation state of the distribution line on line in a mode, such as evaluating and analyzing dielectric spectrum and dielectric spectrum correlation coefficients, so that the accuracy and credibility of a detection result are improved, a technical solution is provided for the transition from preemptive maintenance to active operation and maintenance of the distribution system, the accurate operation and maintenance of the distribution system is realized, and the operation and maintenance efficiency, accuracy and power supply reliability are improved.

Referring to fig. 3, fig. 3 is a flowchart illustrating a method for analyzing an insulation situation of a power distribution system according to another embodiment of the present invention; the method shown in fig. 3 is an analysis of a distribution line, and the method shown in fig. 3 may include:

301. injecting broadband voltage to the power distribution system at different output frequencies;

302. acquiring operation parameters of the power distribution system, wherein the operation parameters at least comprise line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero sequence current and transformer secondary side three-phase broadband current;

it should be noted that steps 301 and 302 are similar to steps 201 and 202 shown in fig. 2, and for avoiding repetition, details are not repeated here, and reference may be specifically made to the contents of steps 201 and 202 shown in fig. 2.

303. Determining whether the distribution line has a line ground fault according to the power frequency zero sequence current of the line;

304. if the distribution line has a line ground fault, determining a fault type and a ground fault state of the distribution line according to the magnitude of secondary side power frequency current of a transformer, wherein the fault type comprises an interphase short-circuit fault or a single-phase short-circuit fault;

it should be noted that whether a single-phase ground fault occurs in the system can be judged according to the system power frequency three-phase voltage, the power frequency zero-sequence voltage and the line power frequency zero-sequence current, specifically, whether a line ground fault exists in the distribution line is determined according to the size of the line power frequency zero-sequence current, if the line ground fault exists in the distribution line, the fault type and the ground fault state of the distribution line are determined according to the size of the transformer secondary side power frequency current, wherein the fault type includes an inter-phase short-circuit fault or a single-phase short-circuit fault.

305. Performing statistical analysis on the ground fault state of the distribution line to determine the ground fault condition of the distribution line;

further, in this embodiment, the data recording may further include recording a line name, a fault time, and a fault point current of the ground fault; and recording the line name, the single-phase earth fault frequency, the duration, the phase-to-phase fault frequency, the earth fault resistance and the fault current of each line. Therefore, when the operation and maintenance strategy is output, the grounding fault condition of the distribution line can be determined by performing statistical analysis on the grounding fault condition of the distribution line, and the operation and maintenance strategy is output through the grounding fault condition.

306. When the ground fault condition is a distribution line with the number of times of line ground faults within a preset fourth time period being greater than or equal to a preset first time threshold value and the duration of the line ground faults each time being less than or equal to a preset first time threshold value, outputting a fourth line operation and maintenance strategy, wherein the fourth line operation and maintenance strategy is that intermittent ground faults occur on the distribution line, and suggesting line channel cleaning;

307. when the ground fault condition is a distribution line with the number of times of line ground faults within a preset fourth time period being greater than or equal to a preset first time threshold value and the duration of the line ground faults each time being less than or equal to a preset second time threshold value, outputting a fifth line operation and maintenance strategy, wherein the fifth line operation and maintenance strategy is that foreign object touch occurs on the distribution line, and advising to carry out line channel cleaning and inspection; the preset second time threshold is greater than the preset first time threshold;

308. when the ground fault condition is a distribution line with the number of times of line ground faults within a preset fourth time period being greater than or equal to a preset first time threshold and the duration of each line ground fault being less than or equal to a preset third time threshold, outputting a sixth line operation and maintenance strategy, wherein the sixth line operation and maintenance strategy is that line continuous single-phase ground faults occur on the distribution line, and the line conductor insulation is recommended to be strengthened; the preset third time threshold is greater than the preset second time threshold.

It should be noted that, in step 306, after performing statistical analysis on the ground fault state, the step 308 includes outputting the line operation and maintenance policy under different ground fault conditions, where the preset first time threshold, the preset second time threshold, and the preset third time threshold are sequentially increased, illustratively, the preset fourth time is one minute, the preset first time threshold is 1s, the preset second time threshold is 1s to 10s, and the preset third time threshold is more than 10s, and the preset first time threshold is 3 times or more, then statistically analyzing the ground fault condition of the line, and outputting an operation and maintenance recommendation: 1) if the line has single-phase earth fault with 3 times or more within 1s within 1 minute, considering that the line has intermittent earth fault, and recommending line channel cleaning; 2) if the line has a single-phase earth fault with the duration of 1-10 s, the line is considered to have a foreign object touch, the line channel cleaning is recommended to be carried out, and the line insulator, the lightning arrester, the bird nest, the small animal invasion and the like are checked; 3) if the line has single-phase earth fault for more than 10s, the line continuous single-phase earth fault is considered to occur, and the insulation of the line conductor is recommended to be strengthened.

The invention provides a method for analyzing the insulation situation of a power distribution system, which comprises the following steps: injecting broadband voltage to the power distribution system at different output frequencies; acquiring operation parameters of a power distribution system, wherein the operation parameters at least comprise line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero sequence current and transformer secondary side three-phase broadband current; determining the ground fault state of the distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current; and outputting a line operation and maintenance strategy based on the ground fault state. By the method, the ground fault state of the distribution line can be monitored on line, operation and maintenance early warning, suggestions and the like are given, a technical solution is provided for the power distribution system to change from preemptive maintenance to active operation and maintenance, accurate operation and maintenance of the power distribution system are realized, and operation and maintenance efficiency, accuracy and power supply reliability are improved.

Referring to fig. 4, fig. 4 is a flowchart illustrating a method for analyzing an insulation situation of a power distribution system according to an embodiment of the present invention, where the method shown in fig. 4 is used for evaluating and analyzing a bus of the power distribution system, and the method shown in fig. 4 may include:

401. injecting a broadband voltage into the power distribution system at different output frequencies;

402. acquiring operation parameters of the power distribution system, wherein the operation parameters at least comprise line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero sequence current and transformer secondary side three-phase broadband current;

it should be noted that steps 401 and 402 are similar to steps 101 and 102 shown in fig. 1, and for avoiding repetition, details are not repeated here, and reference may be specifically made to the contents of steps 101 and 102 shown in fig. 1.

403. When the ratio of the amplitude of the three-phase bus pulse voltage of each bus switch cabinet to the three-phase bus power frequency voltage is greater than or equal to a preset multiple threshold value, and the phase of the three-phase bus pulse voltage of each bus switch cabinet is greater than a preset phase threshold value, determining that the second insulation state of the bus is a bus insulation fault, wherein the preset phase threshold value is set based on the phase of the three-phase bus power frequency voltage of each bus switch cabinet;

in this embodiment, the second insulation state of the bus is determined by analyzing each bus switch cabinet, specifically, when the ratio of the amplitude of the three-phase bus pulse voltage of each bus switch cabinet to the three-phase bus power frequency voltage is greater than or equal to a preset multiple threshold value, and the phase of the three-phase bus pulse voltage of each bus switch cabinet is greater than a preset phase threshold value, it is determined that the second insulation state of the bus is a bus insulation fault, and the preset phase threshold value is set based on the phase of the three-phase bus power frequency voltage of each bus switch cabinet, that is, when the amplitude of the three-phase bus pulse voltage of the bus switch cabinet exceeds the preset multiple threshold value of the background threshold value, it is determined that the bus insulation fault occurs in the outlet cabinet, and the bus insulation fault is indicated. Illustratively, detecting that the pulse voltage amplitude of each bus switch cabinet exceeds 1.5 times of a background threshold value, and considering that the outlet cabinet has a bus insulation fault; and judging which switch cabinet the bus insulation fault occurs in by adopting an amplitude comparison method.

Illustratively, the second insulation state may also be determined by: detecting whether the pulse voltage amplitude of each bus switch cabinet exceeds a threshold value, wherein the threshold value is 0.1% -50% of the nominal voltage of the system; checking whether the phase of the pulse voltage is in the range of pi-pi/4-pi + pi/4 or-pi/4 of the phase power frequency voltage; and if pulse voltages meeting the conditions S901 and S902 exist in 2-100 continuous power frequency periods of the outgoing line cabinet of a certain line, determining that the outgoing line cabinet has a bus insulation fault.

404. Performing statistical analysis on a second insulation state of a bus of the power distribution system, and determining a second insulation fault condition of the bus, wherein the second insulation state comprises a bus insulation fault;

in this embodiment, the position and the occurrence time of the bus insulation fault are also recorded, so that the bus insulation fault of the bus of the power distribution system in the second insulation state can be statistically analyzed, and the second insulation fault condition of the bus is determined.

405. And when the second insulation fault condition is that a bus insulation fault exists, outputting a bus operation and maintenance strategy, wherein the bus operation and maintenance strategy comprises suggesting power failure to check the fault condition and carry out first-aid repair.

The invention provides a method for analyzing the insulation situation of a power distribution system, which comprises the following steps: injecting a broadband voltage into the power distribution system at different output frequencies; acquiring operation parameters of a power distribution system, wherein the operation parameters at least comprise line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero sequence current and transformer secondary side three-phase broadband current; determining a second insulation state of the bus based on the three-phase bus pulse voltage and the three-phase bus power frequency voltage; and outputting the bus operation and maintenance strategy based on the second insulation state. By the method, the insulation state of the bus can be monitored on line, operation and maintenance early warning, suggestions and the like are given, a technical solution is provided for the power distribution system to change from preemptive maintenance to active operation and maintenance, the power distribution system is accurately operated and maintained, and the operation and maintenance efficiency, accuracy and power supply reliability are improved.

Referring to fig. 5, fig. 5 is another two flow charts of an insulation situation analysis method for a power distribution system according to an embodiment of the present invention; the method shown in fig. 5 is an analysis of a transformer, and the method shown in fig. 5 may include:

501. injecting broadband voltage to the power distribution system at different output frequencies;

502. acquiring operation parameters of the power distribution system, wherein the operation parameters at least comprise line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero sequence current and transformer secondary side three-phase broadband current;

503. Determining a second angle difference between the broadband voltage under different frequencies and the broadband current of the secondary side of the transformer of each phase of the transformer by using the broadband current of the secondary side of the transformer and the broadband voltage under different frequencies;

504. determining a second dielectric spectrum of each phase of the transformer under different frequencies by utilizing the second angle difference and tangent value algorithm;

illustratively, the steps 501-504 may refer to the following example: sinusoidal voltage with frequency n and amplitude m is coupled to three phases of a first side winding of a main transformer through a step 501, phase difference between second side current of the main transformer with three phases of frequency n and sinusoidal voltage with output frequency n is calculated through a step 503 according to the three-phase current of a second side winding of the main transformer obtained through the step 502; calculating a residual angle of the phase difference between the current and the voltage and calculating a tangent value of the residual angle as a three-phase dielectric loss value of the winding at the first side to the second side of the main transformer with the frequency n through step 504; gradually changing the frequency of the output sinusoidal voltage by step length s, keeping the amplitude value as m, and circularly executing 501-504 to obtain a third dielectric spectrum of 0.1 Hz-1MHz of the first side to the second side windings of the three phases of the main transformer;

505. determining a third insulation state of the low-voltage winding of the transformer based on the second dielectric spectrum of each phase of the transformer at the respective output frequency;

it will be appreciated that the second dielectric spectrum described above is based on the variation of dielectric loss with output frequency, and therefore the third insulation state of the low voltage winding of the transformer can be determined from the second dielectric spectrum of each phase of the transformer at the respective output frequency.

Illustratively, step 505 may include B1-B2:

b1, determining the first transformer reference dielectric spectrum of each phase of the transformer under different output frequencies when the power distribution system operates normally;

and B2, if the second dielectric spectrum in the same phase is larger than the first transformer reference dielectric spectrum under the same output frequency, determining that the third insulation state of the transformer low-voltage winding is a transformer low-voltage winding insulation fault.

Illustratively, the dielectric spectrum of the low-voltage winding of the main transformer in the normal state (such as when the main transformer is put into operation) at the output frequency of 0.1 Hz-1MHz is respectively calculated and used as the first transformer reference dielectric spectrum (reference dielectric spectrum) of each phase. The third insulation state of the low-voltage winding of the transformer can be determined by the size relationship of the in-phase second dielectric spectrum and the first transformer reference dielectric spectrum under the same output frequency. Specifically, if the same-phase second dielectric spectrum is larger than the first transformer reference dielectric spectrum under the same output frequency, determining that the third insulation state of the transformer low-voltage winding is an insulation fault of the transformer low-voltage winding; and if the same-phase second dielectric spectrum is equal to the first transformer reference dielectric spectrum under the same output frequency, determining that the third insulation state of the transformer low-voltage winding is normal.

In a possible implementation manner, the insulation state of the transformer may be further determined by a correlation coefficient of a dielectric spectrum, where the transformer includes a primary side and a secondary side, the primary side includes a high voltage winding side or a medium voltage winding side, and the secondary side includes a low voltage winding side or a medium voltage winding side, and further, a wideband voltage is injected from the primary side, and then the third insulation state of the low voltage winding of the transformer is determined based on a three-phase wideband current and the wideband voltage of the secondary side of the transformer, and the method further includes:

c1, determining a third angle difference between the secondary side broadband voltage and the secondary side broadband current of the transformer under different frequencies by using the secondary side broadband current of the transformer and the broadband voltages under different frequencies;

c2, determining a third dielectric spectrum between each phase of the secondary side and the primary side of the transformer under different frequencies by utilizing the third angle difference and the tangent value algorithm;

further, the following examples can be referred to in step 501-504: wherein, through step 501, a sinusoidal voltage with frequency n and amplitude m is coupled to the x phase of the primary side winding of the primary transformer, through the x phase current of the secondary side winding of the primary transformer obtained in step 502, further, step C1 calculates the phase difference between the secondary side current of the primary transformer with frequency n and the sinusoidal voltage (broadband voltage) with output frequency n of the x phase, step C2 calculates the residual angle of the phase difference between the current and the voltage and calculates the tangent value of the residual angle as the dielectric loss value of the x phase of the primary side winding to the secondary side winding of the primary transformer with frequency n; changing the frequency of the output sinusoidal voltage step by step 501 with a step s, keeping the amplitude as m, and circularly executing 502, C1 and C2 to obtain a dielectric spectrum of 0.1 Hz-1MHz of a winding of a first side and a second side of an x-phase of the main transformer; and (3) processing the other two phases in steps 501, 502, C1 and C2 to obtain a third dielectric spectrum of 0.1Hz to 1MHz of the first side winding to the second side winding of the three phases of the main transformer. Exemplary third dielectric spectra of the first side-to-second side winding include a third dielectric spectrum of the low voltage winding to the medium voltage winding, a third dielectric spectrum of the low voltage winding to the high voltage winding, and a third dielectric spectrum of the medium voltage winding to the high voltage winding.

C3, determining a second transformer reference dielectric spectrum between each phase of the secondary side and the primary side under different output frequencies when the power distribution system operates normally;

illustratively, when the power distribution system is in normal operation (such as when the main transformer is put into operation), the 0.1 Hz-1MHz dielectric spectrums of the low-voltage winding to the medium-voltage winding, the low-voltage winding to the high-voltage winding, and the medium-voltage winding to the high-voltage winding of the main transformer are obtained by performing the loop processes 502, C1, and C2, respectively, as reference dielectric spectrums (second transformer reference dielectric spectrums) of the low-voltage winding to the medium-voltage winding, the low-voltage winding to the high-voltage winding, and the medium-voltage winding to the high-voltage winding.

C4, determining transformer dielectric spectrum correlation coefficients between the secondary side of the transformer and the phases of the primary side according to the third dielectric spectrum and the second transformer reference dielectric spectrum at the respective output frequencies, the transformer dielectric spectrum correlation coefficients being obtained based on a curve of the third dielectric spectrum of the secondary side and the primary side in phase varying with different output frequencies and a curve of the second transformer reference dielectric spectrum varying with different output frequencies;

further, similarity coefficients of 0.1 Hz-1MHz dielectric spectrums of the low-voltage winding pair medium-voltage winding, the low-voltage winding pair high-voltage winding and the medium-voltage winding pair high-voltage winding and respective reference dielectric spectrums are calculated respectively. Determining a transformer dielectric spectrum correlation coefficient between the secondary side of the transformer and each phase of the primary side according to the third dielectric spectrum of each phase of the low-voltage winding pair medium-voltage winding at each output frequency and the second transformer reference dielectric spectrum of each phase of the low-voltage winding pair medium-voltage winding at each output frequency, and determining a transformer dielectric spectrum correlation coefficient between the secondary side of the transformer and each phase of the primary side according to the third dielectric spectrum of each phase of the low-voltage winding pair high-voltage winding at each output frequency and the second transformer reference dielectric spectrum of each phase of the low-voltage winding pair high-voltage winding; and determining a transformer dielectric spectrum correlation coefficient between each phase of the secondary side and the primary side of the transformer according to the third dielectric spectrum of each phase of the high-voltage winding by the medium-voltage winding under each output frequency and the second transformer reference dielectric spectrum of each phase of the high-voltage winding by the medium-voltage winding, wherein the transformer dielectric spectrum correlation coefficient also needs to be calculated by an in-phase dielectric spectrum.

It should be noted thatThe calculation method of the coefficient of linearity can also refer to the correlation coefficient of the line dielectric spectrum, and then the formula r _xy Where x may also represent the third dielectric spectrum for each phase of the transformer and y represents the reference dielectric spectrum for each phase, the correlation coefficient of the transformer dielectric spectrum is used to represent the degree of correlation between the curve of the third dielectric spectrum with different output frequencies and the curve of the reference dielectric spectrum with different output frequencies, where the correlation coefficient is 1 if the two curves are completely correlated and 0 if the two curves are not completely correlated.

And C5, if the correlation coefficient of the dielectric spectrum of the transformer of any phase is smaller than a second preset correlation coefficient threshold value, determining that the third insulation state of the transformer low-voltage winding is a transformer low-voltage winding insulation fault.

For example, the second predetermined correlation coefficient threshold may be 0.5, and if the correlation coefficient of the dielectric spectrum of the transformer is less than 0.5, the transformer is considered to have an insulation fault, and if the correlation coefficient of the dielectric spectrum of the transformer is greater than or equal to 0.5, the transformer is considered to have a normal insulation.

506. And when the third insulation state of the transformer is the insulation fault of the low-voltage winding of the transformer, outputting a transformer operation and maintenance strategy, wherein the transformer operation and maintenance strategy comprises the suggestion of power failure for transformer maintenance.

And further, when the third insulation state of the transformer is insulation fault of the low-voltage winding of the transformer, the operation and maintenance strategy of the transformer is output to suggest power failure to overhaul the transformer.

It should be noted that, the operation and maintenance strategy may configure an output priority according to the influence of each operation and maintenance strategy on the current operating state of the power distribution system, and output the operation and maintenance strategy according to the output priority, or set a priority order directly from the operation and maintenance operation suggested in the operation and maintenance strategy, which is not limited herein, so that emergency fault priority prompting and priority processing may be implemented.

The invention provides a method for analyzing the insulation situation of a power distribution system, which comprises the following steps: injecting broadband voltage to the power distribution system at different output frequencies; acquiring operation parameters of a power distribution system, wherein the operation parameters at least comprise line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero sequence current and transformer secondary side three-phase broadband current; determining a third insulation state of the low-voltage winding of the transformer based on the secondary side three-phase broadband current and the broadband voltage of the transformer; and outputting the operation and maintenance strategy of the transformer based on the third insulation state. The method can be used for monitoring the insulation state of the transformer on line, giving operation and maintenance early warning, suggestions and the like, judging the insulation state of the transformer through the dielectric spectrums of all phases of the transformer and the correlation coefficients of the dielectric spectrums, and being beneficial to improving the detection accuracy, providing a technical solution for the transition from preemptive maintenance to active operation and maintenance of the power distribution system, realizing the accurate operation and maintenance of the power distribution system, and improving the operation and maintenance efficiency, accuracy and power supply reliability.

In conclusion, the invention has the advantages that: (1) the system insulation is completely monitored on line, and the timeliness is strong; (2) the monitoring range covers the main equipment of the power distribution system: the main transformer, the switch cabinet and the line are subjected to comprehensive insulation on-line monitoring, and the monitoring range is wide; (3) the sensitivity is high, early discovery and early management of the potential insulation hazard of the main transformer and the line are realized, and the potential insulation hazard can be effectively prevented from developing into a major fault. (4) The comprehensive operation and maintenance suggestion is provided, the current 'emergency maintenance' situation of the power distribution system is broken, the accurate and efficient operation and maintenance of the power distribution system are realized, the reliability and the safety of the power distribution system are improved, and the operation and maintenance cost of the system is effectively reduced.

Referring to fig. 6, fig. 6 is a block diagram of an insulation situation analysis system of a power distribution system according to an embodiment of the present invention; as shown in fig. 6, the insulation situation analysis system of the power distribution system includes:

the signal injection module 601: for injecting a broadband voltage at different output frequencies into the power distribution system;

the parameter monitoring module 602: the system comprises a power distribution system, a power source, a transformer, a power source, a transformer, a power source and the like, and is used for obtaining operation parameters of the power distribution system, wherein the operation parameters at least comprise line power frequency zero sequence current, secondary side power frequency current, three-phase bus power voltage, three-phase bus pulse voltage, line broadband zero sequence current, and secondary side broadband three-phase broadband current of the transformer;

the line analysis module 603: the first insulation state of the distribution line is determined according to the broadband voltage and the line broadband zero sequence current; determining the ground fault state of the distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current;

bus analysis module 604: the second insulation state of the bus is determined based on the three-phase bus pulse voltage and the three-phase bus power frequency voltage;

transformer analysis module 605: the device comprises a first insulation state, a second insulation state and a third insulation state, wherein the first insulation state is used for determining a first insulation state of a low-voltage winding of the transformer based on a three-phase broadband current and a broadband voltage of a secondary side of the transformer;

the operation and maintenance policy output module 606: and the output module is used for outputting a line operation and maintenance strategy, a bus operation and maintenance strategy and a transformer operation and maintenance strategy based on the first insulation state, the ground fault state, the second insulation state and the third insulation state.

The invention provides an insulation situation analysis system of a power distribution system, which comprises: a signal injection module: for injecting a broadband voltage at different output frequencies into a power distribution system; a parameter monitoring module: the system is used for obtaining operation parameters of a power distribution system, wherein the operation parameters at least comprise line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero sequence current and transformer secondary side three-phase broadband current; a line analysis module: the first insulation state of the distribution line is determined according to the broadband voltage and the broadband zero-sequence current of the line; determining the ground fault state of the distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current; a bus analysis module: the second insulation state of the bus is determined based on the three-phase bus pulse voltage and the three-phase bus power frequency voltage; the transformer analysis module: the device comprises a first insulation state, a second insulation state and a third insulation state, wherein the first insulation state is used for determining a first insulation state of a low-voltage winding of the transformer based on a three-phase broadband current and a broadband voltage of a secondary side of the transformer; operation and maintenance strategy output module: and the output circuit, the bus and the transformer are used for outputting a circuit operation and maintenance strategy, a bus operation and maintenance strategy and a transformer operation and maintenance strategy based on the first insulation state, the ground fault state, the second insulation state and the third insulation state. Through the system, the insulation states of the bus, the distribution line and the transformer can be monitored on line, the insulation situation of the distribution system is comprehensively evaluated, operation and maintenance early warning, suggestions and the like are given, a technical solution is provided for the transformation from emergency maintenance to active operation and maintenance of the distribution system, the accurate operation and maintenance of the distribution system is realized, and the operation and maintenance efficiency, the accuracy and the power supply reliability are improved.

FIG. 7 is a diagram illustrating an internal structure of a computer device in one embodiment. The computer device may specifically be a terminal, and may also be a server. As shown in fig. 7, the computer device includes a processor, a memory, and a network interface connected by a system bus. Wherein the memory includes a non-volatile storage medium and an internal memory. The non-volatile storage medium of the computer device stores an operating system and may also store a computer program which, when executed by the processor, causes the processor to carry out the above method. The internal memory may also have a computer program stored thereon, which, when executed by the processor, causes the processor to perform the method described above. It will be appreciated by those skilled in the art that the configuration shown in fig. 7 is a block diagram of only a portion of the configuration associated with the present application, and is not intended to limit the computing device to which the present application may be applied, and that a particular computing device may include more or fewer components than shown, or may combine certain components, or have a different arrangement of components.

In an embodiment, a computer device is proposed, comprising a memory and a processor, the memory storing a computer program which, when executed by the processor, causes the processor to perform the steps of the method as shown in fig. 1, 2, 3, 4 and 5.

In an embodiment, a computer-readable storage medium is proposed, on which a computer program is stored which, when executed by a processor, causes the processor to carry out the steps of the method as shown in fig. 1, 2, 3, 4 and 5.

It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a non-volatile computer-readable storage medium, and can include the processes of the embodiments of the methods described above when the program is executed. Any reference to memory, storage, database, or other medium used in the embodiments provided herein may include non-volatile and/or volatile memory, among others. Non-volatile memory can include read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus Direct RAM (RDRAM), direct bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present application. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A method for analyzing an insulation situation of a power distribution system, the method comprising:

injecting broadband voltage to the power distribution system at different output frequencies;

determining a first insulation state of the distribution line according to the broadband voltage and the line broadband zero-sequence current; determining the ground fault state of the distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current; determining a second insulation state of the bus based on the three-phase bus pulse voltage and the three-phase bus power frequency voltage; determining a third insulation state of the low-voltage winding of the transformer based on the secondary side three-phase broadband current and the broadband voltage of the transformer;

2. The method of claim 1, wherein determining the first insulation state of the distribution line according to the wideband voltage and the line wideband zero sequence current comprises:

and when a distribution line with the first dielectric spectrum of the current moment larger than that of the previous moment under the same output frequency exists, determining that the first insulation state of the distribution line is a line insulation fault.

3. The method of claim 1, wherein the determining the ground fault state of the distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current comprises:

determining whether the distribution line has a line ground fault according to the power frequency zero sequence current of the line;

4. The method of claim 1, wherein determining the second insulation state of the bus based on the three-phase bus pulse voltage and the three-phase bus line frequency voltage comprises:

5. The method of claim 1, wherein determining a third insulation state of the low-voltage winding of the transformer based on the broadband voltage and the broadband current of the secondary side of the transformer comprises:

determining a second angle difference between the broadband voltage under different frequencies and the broadband current of the secondary side of the transformer of each phase of the transformer by using the broadband current of the secondary side of the transformer and the broadband voltage under different frequencies;

determining a third insulation state of the low voltage winding of the transformer based on the second dielectric spectrum for each phase of the transformer at the respective output frequency.

6. The method of claim 5, wherein said determining a third insulation state of a low voltage winding of said transformer based on a second dielectric spectrum of each phase of said transformer at a respective output frequency comprises:

determining a first transformer reference dielectric spectrum of each phase of a transformer at different output frequencies when the power distribution system operates normally;

7. The method of claim 2, wherein determining the first dielectric spectrum for each distribution line at different output frequencies using the first angle difference and tangent algorithm further comprises:

determining line reference dielectric spectrums under different output frequencies when the power distribution system operates normally;

8. The method of claim 1, wherein the transformer comprises a primary side and a secondary side, the primary side comprising a high voltage winding side or a medium voltage winding side, the secondary side comprising a low voltage winding side or a medium voltage winding side, and the wideband voltage is injected from the primary side, and wherein determining the third insulation state of the transformer low voltage winding based on the transformer secondary side three-phase wideband current and the wideband voltage further comprises:

determining transformer dielectric spectrum correlation coefficients between the secondary side of the transformer and the phases of the primary side according to the third dielectric spectrum and the second transformer reference dielectric spectrum at the respective output frequencies, wherein the transformer dielectric spectrum correlation coefficients are obtained based on a curve of the in-phase third dielectric spectrum of the secondary side and the primary side varying with different output frequencies and a curve of the second transformer reference dielectric spectrum varying with different output frequencies;

and if the correlation coefficient of the dielectric spectrum of the transformer of any phase is smaller than a second preset correlation coefficient threshold value, determining that the third insulation state of the transformer low-voltage winding is the insulation fault of the transformer low-voltage winding.

9. The method of claim 1, wherein outputting a line operation and maintenance strategy based on the first insulation state comprises:

when the first insulation failure condition is the distribution line with the insulation failure times within a preset first time length being more than or equal to a preset first time threshold value, outputting a first line operation and maintenance strategy, wherein the first line operation and maintenance strategy comprises the steps of recommending strengthening line inspection and searching for a failure position;

when the first insulation failure condition is the distribution line with the insulation failure frequency within the preset second time length being more than or equal to the preset second time threshold value, outputting a second line operation and maintenance strategy, wherein the second line operation and maintenance strategy comprises the steps of recommending and strengthening line patrol, and clearing a line channel; the preset first time length is less than a preset second time length, and the preset second time threshold is greater than the preset first time threshold;

10. The method of claim 1, wherein outputting a bus operation and maintenance strategy based on the second insulation state comprises:

11. The method of claim 1, wherein outputting a transformer operation and maintenance strategy based on the third insulation state comprises:

and when the third insulation state of the transformer is the insulation fault of the low-voltage winding of the transformer, outputting a transformer operation and maintenance strategy, wherein the transformer operation and maintenance strategy comprises the suggestion of power failure for transformer maintenance.

12. The method of claim 1, wherein outputting a line operation and maintenance strategy based on the ground fault condition comprises:

when the ground fault condition is a distribution line with the number of times of line ground faults within a preset fourth time period being greater than or equal to a preset first time threshold value and the duration of the line ground faults each time being less than or equal to a preset first time threshold value, outputting a fourth line operation and maintenance strategy, wherein the fourth line operation and maintenance strategy is that intermittent ground faults occur on the distribution line, and suggesting line channel cleaning;

when the ground fault condition is a distribution line with the number of times of line ground faults within a preset fourth time period being greater than or equal to a preset first time threshold value and the duration of the line ground faults each time being less than or equal to a preset third time threshold value, outputting a sixth line operation and maintenance strategy, wherein the sixth line operation and maintenance strategy is that line continuous single-phase ground faults occur on the distribution line, and suggesting that line lead insulation is strengthened; the preset third time threshold is greater than the preset second time threshold.

13. An electrical distribution system insulation posture analysis system, the electrical distribution system insulation posture analysis system comprising:

a signal injection module: for injecting a broadband voltage at different output frequencies into a power distribution system;

a bus analysis module: the system comprises a bus, a first insulation state, a second insulation state and a control circuit, wherein the bus is used for determining the first insulation state of the bus based on three-phase bus pulse voltage and three-phase bus power frequency voltage;

operation and maintenance strategy output module: and the output module is used for outputting a line operation and maintenance strategy, a bus operation and maintenance strategy and a transformer operation and maintenance strategy based on the first insulation state, the ground fault state, the second insulation state and the third insulation state.