CN115508668A - Fault line selection analysis method based on single-phase asymmetry - Google Patents
Fault line selection analysis method based on single-phase asymmetry Download PDFInfo
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Abstract
The invention discloses a single-phase asymmetric fault line selection analysis method, which can effectively reduce the probability of arcing of a ground fault by configuring a single-phase isolation transformer, thereby reducing or even eliminating the probability of fire caused by the ground fault, and can efficiently and sensitively identify the ground fault by constructing a high-sensitivity ground fault identification criterion based on zero-sequence voltage mutation, so that a worker can timely process the ground fault, thereby reducing or even eliminating the probability of fire caused by the ground fault.
Description
Technical Field
The invention relates to the technical field of power distribution network fault identification, in particular to a fault line selection analysis method based on single-phase asymmetry.
Background
A large number of low-density population areas exist in Sanzhou-one cities such as Sichuan sweet, ara, liang, panzhihua and the like, the coverage rate of forest and grassland is high, and the environmental meteorological conditions are severe. Partial 10kV distribution lines or branch lines in the areas penetrate through grassland forests to supply power to remote residential settlement points, the distribution capacity is usually extremely small and ranges from dozens of kilowatts to hundreds of kilowatts, meanwhile, the intrinsic safety level of equipment is poor, operation and maintenance are extremely difficult, and the risk of mountain fire caused by faults is extremely high. The emergency shutdown risk avoidance of the lines under severe meteorological conditions is an effective mountain fire prevention measure adopted in recent years, but obviously causes the deterioration of the power supply reliability of the areas, and the complaint rate of related units is high.
To close this conflict, companies have studied the use of small distributed photovoltaics to supply these decentralized loads, but on the one hand, they require a large investment, each power supply point being calculated on the order of 30kW, requiring an investment of more than 20 ten thousand yuan; on the other hand, the capability of electronic equipment to resist high cold and high altitude is not fully verified, and daily operation and emergency treatment after failure of photovoltaic and energy storage equipment in remote areas are not mentioned at all. It is understood that in 2014, 3 million photovoltaic systems for more users are installed in Tibet region, and in 2019, large-scale replacement is required. More critically, these regions have in fact constructed medium voltage distribution systems, and changing to distributed photovoltaic power supply means a significant investment waste.
Therefore, the existing power grid resources are utilized, the power supply reliability requirement can be met through the flexible adjustment of the power distribution mode and the network structure, the risk of mountain fire caused by faults of the power grid resources can be reduced as far as possible, and the method is a research of important practical significance of machines and tools. Various operating condition characteristics such as rural distribution network load level, overhead distribution are fully considered, and the characteristic that the operating conditions of rural distribution network lines present low load and seasonal alternative change is not easy to find. Further, for analysis and investigation of low-load rural areas with high mountain fire risk, incomplete statistics shows that the recorded multiple earth faults are mainly (A, C-phase) side-phase earth faults in the early stage. Aiming at such key areas, how to effectively reduce, even to a certain extent, the situation of worsening and developing of the grounding arc fault caused by external lapped power lines due to uncontrollable factors such as strong wind, rainstorm and the like of the side phase is controlled, and for example, high-risk mountain fire such as high-coverage vegetation, forest grassland and the like with favorable combustion conditions, the three-phase voltage level of the power distribution network needs to be optimized according to the side phase arcing requirement, the distribution of the phase voltage is adjusted, the favorable conditions of arcing are controlled, and the probability of grounding arcing is reduced.
Disclosure of Invention
The application aims to provide a fault line selection analysis method based on single-phase asymmetry, and the problems that in the prior art, a fire disaster is caused due to the fact that an earth fault is arcing and the earth fault is not monitored in time are solved.
The invention is realized by the following technical scheme:
a fault line selection analysis method based on single-phase asymmetry comprises the following steps:
the method comprises the steps of obtaining the wiring modes of a main transformer at a transformer station side and a transformer area at a load side in a power distribution network, and determining the wiring mode of a single-phase isolation transformer to be configured based on the wiring modes of the main transformer and the transformer area;
acquiring capacitance current corresponding to each feeder line in a power distribution network, and performing subnet segmentation based on the capacitance current to obtain a plurality of subnets;
adjusting taps of secondary windings in the single-phase isolation transformers, and configuring the single-phase isolation transformers for each sub-network according to the wiring mode of the single-phase isolation transformers to be configured to obtain the sub-networks after the single-phase isolation transformers are configured;
and constructing a high-sensitivity ground fault identification criterion based on zero sequence voltage mutation, and performing fault line selection based on the high-sensitivity ground fault identification criterion to determine the sub-network with the fault.
In a possible embodiment, obtaining the wiring manner of the main transformer at the substation side and the platform transformer at the load side in the power distribution network includes:
the method comprises the steps that a connection group of a main transformer on the transformer substation side is obtained to be a first connection group or a second connection group, wherein the first connection group represents that a primary winding of the main transformer is Yn-shaped connection and a secondary winding of the main transformer is Y-shaped connection; the second wiring group represents that a primary winding of the main transformer is Yn-shaped wiring and a secondary winding of the main transformer is delta-shaped wiring;
the method comprises the steps that a connection group of a load side platform area transformer is obtained to be a third connection group or a fourth connection group, wherein the third connection group represents that a primary winding of the platform area transformer is a Y-shaped connection and a secondary winding of the platform area transformer is a Yn-shaped connection; and the fourth wiring group represents that the primary winding of the transformer in the transformer area is delta-shaped wiring and the secondary winding is Yn wiring.
In a possible embodiment, determining the connection mode of the single-phase isolation transformer to be configured based on the connection modes of the main transformer and the platform transformer includes:
when a secondary winding of a main transformer is in Y-shaped connection and a primary winding of a transformer in a transformer area is in Y-shaped connection, determining that the primary winding of the single-phase isolation transformer is in Y-shaped connection and the secondary winding is in Y-shaped connection;
when a secondary winding of a main transformer is in Y-shaped connection and a primary winding of a transformer in a transformer area is in delta-shaped connection, determining that the primary winding of the single-phase isolation transformer is in Y-shaped connection and the secondary winding is in delta-shaped connection;
when a secondary winding of a main transformer is in delta connection and a primary winding of a transformer in a transformer area is in Y connection, determining that the primary winding of the single-phase isolation transformer is in delta connection and the secondary winding is in Y connection;
when the secondary winding of the main transformer is delta-shaped connection and the primary winding of the transformer in the transformer area is delta-shaped connection, the primary winding of the single-phase isolation transformer is determined to be delta-shaped connection and the secondary winding is determined to be delta-shaped connection.
In a possible implementation manner, obtaining a capacitance current corresponding to each feeder line in the power distribution network includes:
wherein ,
representing electricity of a feederThe total length of the cable line corresponds to,
representing the capacitive current corresponding to the cabling of the feeder,
representing the capacitive current corresponding to the overhead line of the feeder,
indicating the total length, I, of the overhead line of the feeder C Representing the total capacitive current for the feed line.
In a possible implementation, the subnet division is performed based on the capacitance current to obtain a plurality of subnets, including:
constructing a subnet division optimization module according to the capacitance current on each feeder line;
and traversing all the subnet partition schemes based on the subnet partition optimization model, and determining the final subnet partition scheme to obtain a plurality of subnets.
In a possible implementation manner, the subnet partition optimization model is:
wherein ,L_TISO Representing the total number of sub-networks, i.e. the total number of three-phase isolating transformers, C sum (L_T ISO ) Represents the total cost of setting up a three-phase isolation transformer,
respectively representing the sum of the capacitive currents of at least one of the feeders in the N sub-networks,
representing the threshold of the capacitive current.
In one possible embodiment, adjusting the tap of the secondary winding in the single-phase isolation transformer comprises:
the critical voltage conditions for constructing the secondary winding in the single-phase isolation transformer are as follows:
wherein ,Uborder Representing the phase voltage, U, of the distribution network arc_ignite Represents that the grounding arc is controlled to be the critical distribution network phase voltage U under the non-arcing mode F_ISO Representing the voltage, U, of the primary winding in a single-phase isolating transformer S_ISO Representing the voltage, T, of the secondary winding in a single-phase isolating transformer ratio Indicating control U border Phase voltage which is not arcing and needs to be met when the power distribution network operates normally is met;
and adjusting taps of the secondary winding in the single-phase isolation transformer according to the critical voltage condition.
In a possible embodiment, adjusting a tap of a secondary winding in a single-phase isolation transformer, and configuring a single-phase isolation transformer for each sub-network according to a connection mode of the single-phase isolation transformer to be configured to obtain the sub-network configured with the single-phase isolation transformer, includes:
adjusting a tap of a secondary winding in the single-phase isolation transformer;
and determining that the primary winding of the single-phase isolation transformer is connected with the secondary winding in the main transformer and that the secondary winding with the tap adjusted in the single-phase isolation transformer is connected with the primary winding of the transformer area according to the wiring mode of the single-phase isolation transformer to be configured and the tap of the secondary winding, and connecting the single-phase isolation transformer with the transformer area through a feeder line to obtain a sub-network configured with the single-phase isolation transformer.
In one possible implementation, the high-sensitivity ground fault identification criterion based on the zero-sequence voltage mutation is constructed as follows:
wherein ,u00 Represents the system voltage symmetry, u 00 ＝(C B -0.5C A -0.5C C )/(C A +C B +C C )，C A Representing the equivalent capacitance parameter, C, of the capacitive circuit charged with respect to earth of the system A B Representing the equivalent capacitance parameter, C, of the system B in relation to the earth-charged capacitive circuit C Capacitance equivalent parameter, U, representing the system C with respect to the earth charging capacitance circuit β Representing an intermediate variable, U β ＝0.6667|U AB |，|U AB I represents the modulus of the line voltage, g 0 Representing the single-phase ground conductance of the system, w represents the angular frequency, C ∑ Representing the sum of capacitances to earth, j representing the imaginary operator, g f Representing the conductivity form of the transition resistance, d g Represents the damping rate of the system under the influence of the transition resistance, d 0 Which represents the initial damping rate of the system,
represents the zero sequence voltage phasor of the system before the fault occurs,
the zero sequence voltage phasor after the fault is shown,
indicating the zero sequence voltage sudden change phasor before and after the fault,
and representing the amplitude of the abrupt zero sequence voltage phasor.
In a possible implementation manner, performing fault line selection based on the high-sensitivity ground fault identification criterion, and determining a subnet with a fault, includes:
obtaining zero sequence voltage sudden change phasor before and after fault according to real-time parameters of the sub-network
And the amplitude of the sudden change zero sequence voltage phasor
Judging whether zero sequence voltage sudden change phasor before and after fault exists
The amplitude value of the zero sequence voltage phasor is larger than a set first threshold value or is suddenly changed
And if the number of the sub-networks is larger than the set first threshold value, judging that the corresponding sub-network has the ground fault, otherwise, judging that the corresponding sub-network has no ground fault.
The application provides a fault route selection analysis method based on single-phase asymmetry, through configuration single-phase isolation transformer, can effectively reduce the probability that earth fault arcing, thereby reduce or even eliminate the probability that leads to the conflagration to through constructing the high sensitive earth fault identification criterion based on zero sequence voltage sudden change, can high-efficiently sensitively discern earth fault, so that the staff can in time handle earth fault, thereby reduce or even eliminate the probability that leads to the conflagration by earth fault.
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In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings that are required in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and that those skilled in the art may also derive other related drawings based on these drawings without inventive effort. In the drawings:
fig. 1 is a flowchart of a fault line selection analysis method based on single-phase asymmetry according to an embodiment of the present application.
Fig. 2 is an equivalent block diagram of a power distribution network based on single-phase transformer isolation according to an embodiment of the present application.
Fig. 3 is a schematic structural diagram of a fault line selection analysis apparatus based on single-phase asymmetry according to an embodiment of the present application.
Fig. 4 is a schematic structural diagram of a fault line selection analysis device based on single-phase asymmetry according to an embodiment of the present application.
Reference numbers and corresponding part names in the drawings:
21-wiring mode determination module, 22-subnet partition module, 23-configuration module, 24-line selection module, 31-memory, 32-processor and 33-bus.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.
Example 1
As shown in fig. 1, a fault line selection analysis method based on single-phase asymmetry includes:
s11, obtaining the wiring modes of a main transformer at a transformer station side and a transformer area at a load side in the power distribution network, and determining the wiring mode of the single-phase isolation transformer to be configured based on the wiring modes of the main transformer and the transformer area.
After the wiring mode of the single-phase isolation transformer is determined, the main transformer and the transformer area transformer can be connected through the single-phase isolation transformer, and therefore arcing generated by ground faults is effectively restrained.
S12, obtaining the capacitance current corresponding to each 10kV feeder line in the power distribution network, and carrying out subnet segmentation based on the capacitance current to obtain a plurality of subnets.
S13, adjusting taps of secondary windings in the single-phase isolation transformers, and configuring the single-phase isolation transformers for each sub-network according to the wiring mode of the single-phase isolation transformers to be configured so as to achieve a single-phase asymmetric structure and obtain the sub-networks with the single-phase isolation transformers.
And guiding the adjustment and control of the joint of the secondary winding under the guidance of a non-arcing target.
S14, constructing a high-sensitivity ground fault identification criterion based on zero sequence voltage mutation, performing fault line selection based on the high-sensitivity ground fault identification criterion, and determining a sub-network with a fault.
In a possible implementation mode, the technical scheme of the single-phase transformer isolation based on zero sequence blocking is that a single-phase isolation transformer which is isolated with the same voltage class, namely 10kV/10kV, but has a non-communicated zero sequence loop is adopted on a 10kV feeder line of a power distribution network for the first time. Obtain the wiring mode of the main transformer of transformer substation side and the platform district transformer of load side in the distribution network, include:
the method comprises the steps of obtaining a first connection group or a second connection group of a main transformer on the transformer station side, wherein the first connection group represents that a primary winding of the main transformer is Yn-shaped connection and a secondary winding of the main transformer is Y-shaped connection. The second connection group represents that the primary winding of the main transformer is Yn-shaped connection and the secondary winding is delta-shaped connection.
And obtaining a third connection group or a fourth connection group as the connection group of the load side platform area transformer, wherein the third connection group represents that the primary winding of the platform area transformer is Y-shaped connection and the secondary winding is Yn-shaped connection. And the fourth wiring group represents that the primary winding of the transformer in the transformer area is delta-shaped wiring and the secondary winding is Yn wiring.
In a possible embodiment, determining the connection mode of the single-phase isolation transformer to be configured based on the connection modes of the main transformer and the platform transformer includes:
when the secondary winding of the main transformer is in Y-shaped connection and the primary winding of the transformer in the transformer area is in Y-shaped connection, the primary winding of the single-phase isolation transformer is determined to be in Y-shaped connection and the secondary winding of the single-phase isolation transformer is determined to be in Y-shaped connection.
When the secondary winding of the main transformer is in Y-shaped connection and the primary winding of the transformer in the transformer area is in delta-shaped connection, the primary winding of the single-phase isolation transformer is determined to be in Y-shaped connection and the secondary winding of the single-phase isolation transformer is determined to be in delta-shaped connection.
When the secondary winding of the main transformer is in delta connection and the primary winding of the transformer in the transformer area is in Y connection, the primary winding of the single-phase isolation transformer is determined to be in delta connection and the secondary winding of the single-phase isolation transformer is determined to be in Y connection.
When the secondary winding of the main transformer is in delta connection and the primary winding of the transformer in the transformer area is in delta connection, the primary winding of the single-phase isolation transformer is determined to be in delta connection and the secondary winding of the single-phase isolation transformer is determined to be in delta connection.
In a possible implementation manner, acquiring a capacitance current corresponding to each 10kV feeder in the power distribution network includes:
wherein ,
representing the total length of the corresponding cable run of the 10kV feeder,
representing the capacitance current corresponding to the cable line of the 10kV feeder,
represents the capacitance current corresponding to the overhead line of the 10kV feeder,
total length, I, corresponding to an overhead line representing a 10kV feeder C Representing the total capacitive current for a 10kV feeder.
In a possible implementation manner, a technical solution of optimal subnet partition considering a fault current suppression effect is provided, and the subnet partition is performed based on a capacitance current to obtain a plurality of subnets, including:
and constructing a subnet division optimization module according to the capacitance current on each 10kV feeder line.
And traversing all the subnet partition schemes based on the subnet partition optimization model, and determining the final subnet partition scheme to obtain a plurality of subnets.
In a possible implementation manner, the subnet partition target is set according to the operation requirement of the distribution network or the fault current suppression effect. According to the requirement of the actual distribution network operation, particularly the lines in remote areas of the three-state one-city area in Sichuan, a subnet division mode is set, the set of each divided sub-feeder line does not exceed 3A, and the condition is relatively easy to achieve, because the lines in the three-state one-city area are mainly overhead lines, each feeder line generally does not exceed 50km, and the length of cables is generally concentrated at the outgoing line of a transformer substation; secondly, the sub-feeder network completely separated into the sum of the number of the independent sub-feeders is also possible, but the corresponding cost is relatively high. Thus, the subnet partition optimization model may be:
wherein ,L_TISO Representing the total number of sub-networks, i.e. the total number of three-phase isolating transformers, C sum (L_T ISO ) Represents the total cost of placing a three-phase isolation transformer,
respectively representing the sum of the capacitance currents of at least one 10kV feeder in the N sub-networks,
representing the threshold of the capacitive current.
In one possible embodiment, adjusting the tap of the secondary winding in the single-phase isolation transformer comprises:
according to the conditions and requirements of grounding arcing, the power supply radius and the power supply capacity of a comprehensive line and the power supply requirements of users, a system single-phase asymmetric operation structure which is in accordance with A, C side phase and middle phase voltage differentiation is constructed, the three-phase voltage level of the power distribution network is optimized, and the distribution among phases is adjusted. According to the condition of grounding arcing, a method for adjusting the tap of the secondary winding of the single-phase transformer corresponding to the critical voltage can be established, and the condition of the critical voltage for establishing the secondary winding in the single-phase isolation transformer is as follows:
wherein ,Uborder Representing the phase voltage, U, of the distribution network arc_ignite Represents the critical distribution network phase voltage U under the mode that the grounding arc is controlled to be not arcing F_ISO Representing the voltage, U, of the primary winding in a single-phase isolating transformer S_ISO Representing the voltage, T, of the secondary winding in a single-phase isolating transformer ratio Indicating control U border And phase voltages which are not arcing and need to be met during normal operation of the power distribution network are met.
And adjusting a tap of a secondary winding in the single-phase isolation transformer according to the critical voltage condition.
In a possible embodiment, adjusting a tap of a secondary winding in a single-phase isolation transformer, and configuring a single-phase isolation transformer for each sub-network according to a connection mode of the single-phase isolation transformer to be configured, to obtain a sub-network configured with the single-phase isolation transformer, includes:
and adjusting a tap of a secondary winding in the single-phase isolation transformer.
According to the wiring mode of the single-phase isolation transformer to be configured and the tap of the secondary winding, the connection of the primary winding of the single-phase isolation transformer and the secondary winding in the main transformer is determined, the connection of the secondary winding with the tap adjusted in the single-phase isolation transformer and the primary winding of the transformer area is determined, the single-phase isolation transformer is connected with the transformer area through a 10kV feeder line, and the sub-network with the single-phase isolation transformer is obtained.
As shown in fig. 2, an equivalent block diagram of the distribution network after the single-phase isolation transformer is configured is provided, and the distribution network is isolated by the single-phase isolation transformer and then connected to the transformer of the transformer area.
In a possible implementation mode, according to a single-phase asymmetric operation technology of preorder single-phase transformer isolation, further comparing ground fault line selection criteria constructed based on a first-half wave method, a phase asymmetry method and other related methods, and after analyzing fault characteristics corresponding to the back of each criterion, providing a line selection criterion based on zero-sequence voltage mutation, wherein the most practical and relatively sensitive criterion adopted by the criterion is zero-sequence voltage phasor amplitude values before and after the mutation. The high-sensitivity ground fault identification criterion based on the zero-sequence voltage mutation is constructed as follows:
wherein ,u00 Represents the system voltage symmetry, u 00 ＝(C B -0.5C A -0.5C C )/(C A +C B +C C )，C A Representing the equivalent capacitance parameter, C, of the capacitive circuit charged with respect to earth of the system A B Representing the equivalent capacitance parameter, C, of the system B in relation to the earth-charged capacitive circuit C Capacitance equivalent parameter, U, representing the system C with respect to the earth charging capacitance circuit β Representing an intermediate variable, U β ＝0.6667|U AB |，|U AB I represents the modulus of the line voltage, g 0 Representing the single-phase ground conductance of the system, w represents the angular frequency, C ∑ Representing the sum of capacitances to ground, j representing the imaginary operator, g f Representing the conductivity form of the transition resistance, d g Representing the damping rate of the system under the influence of the transition resistance, d 0 Which represents the initial damping rate of the system,
represents the zero sequence voltage phasor of the system before the fault occurs,
the zero sequence voltage phasor after the fault is shown,
indicating the zero sequence voltage sudden change phasor before and after the fault,
and representing the amplitude of the abrupt zero sequence voltage phasor.
In a possible implementation manner, performing fault line selection based on a high-sensitivity ground fault identification criterion, and determining a sub-network with a fault, includes:
obtaining zero sequence voltage sudden change phasor before and after fault according to real-time parameters of the sub-network
And the amplitude of the sudden change zero sequence voltage phasor
Judging whether zero sequence voltage sudden change phasor before and after fault exists
The amplitude value of the zero sequence voltage phasor is larger than a set first threshold value or is suddenly changed
And if the number of the sub-networks is larger than the set first threshold value, judging that the corresponding sub-network has the ground fault, otherwise, judging that the corresponding sub-network has no ground fault.
The application provides a fault route selection analysis method based on single-phase asymmetry, through configuration single-phase isolation transformer, can effectively reduce the probability that earth fault arcing, thereby reduce or even eliminate the probability that leads to the conflagration to through constructing the high sensitive earth fault identification criterion based on zero sequence voltage sudden change, can high-efficiently sensitively discern earth fault, so that the staff can in time handle earth fault, thereby reduce or even eliminate the probability that leads to the conflagration by earth fault.
The line selection method provided by the invention is a zero sequence blocking-based single-phase transformer isolation general scheme, considers a sub-network segmentation optimal technical scheme of a fault current suppression effect, a non-arcing target-guided secondary winding joint adjustment technology, and a high-sensitivity ground fault identification criterion based on zero sequence voltage mutation, namely four forward and backward dependence progressive single-phase asymmetric operation technologies and a new line selection criterion, optimizes the voltage distribution of the middle-voltage side phase of the power distribution network, displays the fault characteristics under the ground fault, constructs a novel starting and line selection technology in accordance with the background of the ground line selection according to the forward and backward dependence progressive single-phase asymmetric operation technology and the new line selection criterion, enhances the technical problem of the traditional 'old and difficult' of the high-resistance ground fault under the single-phase ground fault, highly promotes the line selection technology by a higher level, promotes the development of the ground fault identification technology of the power distribution network, has stronger suppression effect on the prevention of secondary disasters caused by the ground fault, and has strong production support effect on the production of the first line.
And (3) simulating the power distribution network added with the single-phase isolation transformer, and obtaining a simulation result shown in the table 1.
TABLE 1 three-phase voltage and three-phase current effective values before and after isolation based on single-phase isolation transformer
As can be seen from table 1, although the introduction of the single-phase isolation transformer may reduce the three-phase power supply capability of the system (approximately 1/3), it may reduce the side-to-ground voltage on the basis of effectively isolating the zero-sequence current, and even by adjusting the transformation ratio of the isolation transformer, the occurrence of the ground fault arcing may be further suppressed.
In addition, for the performance of the proposed line selection criterion, the invention also performs the ground fault experiment under different fault resistances, and the result is depicted in table 2.
TABLE 2 Single-phase earth fault test under different transition resistances, sensitivity performance effect of the criterion
From table 2 it can be seen that: compared with the traditional mode, the single-phase asymmetric operation system and the line selection method based on single-phase transformer isolation can effectively show fault characteristics, the zero-sequence voltage break variable is basically and averagely increased to about 1.7 times, the rule is kept unchanged along with the higher transition resistance, the high-transition-resistance earth fault with the same difficulty is obvious, and the single-phase asymmetric operation technology and the accompanying earth fault line selection criterion have better line selection capability and can better accord with the requirements of practical engineering application.
Example 2
As shown in fig. 3, the present embodiment provides a fault line selection analysis apparatus based on single-phase asymmetry, which includes a connection mode determining module 21, a subnet dividing module 22, a configuration module 23, and a line selection module 24.
The connection mode determining module 21 is configured to obtain connection modes of a main transformer on a substation side and a transformer substation on a load side in the power distribution network, and determine a connection mode of a single-phase isolation transformer to be configured based on the connection modes of the main transformer and the transformer substation.
The subnet dividing module 22 is configured to obtain capacitance currents corresponding to each feeder in the power distribution network, and divide a subnet based on the capacitance currents to obtain a plurality of subnets.
The configuration module 23 is configured to adjust a tap of a secondary winding in the single-phase isolation transformer, and configure the single-phase isolation transformer for each sub-network according to a connection mode of the single-phase isolation transformer to be configured, so as to obtain the sub-network configured with the single-phase isolation transformer.
The line selection module 24 is configured to construct a high-sensitivity ground fault identification criterion based on zero-sequence voltage abrupt change, perform fault line selection based on the high-sensitivity ground fault identification criterion, and determine a sub-network with a fault.
The fault line selection analysis apparatus based on single-phase asymmetry according to this embodiment may implement the method technical solution described in embodiment 1, and the principle and the beneficial effect thereof are similar, and are not described herein again.
Example 3
As shown in fig. 4, the present embodiment provides a fault line selection analysis device based on single-phase asymmetry, which includes a memory 31 and a processor 32, and the memory 31 and the processor 32 are connected to each other through a bus 33.
The memory 31 stores computer-executable instructions.
For example, the Memory may include, but is not limited to, a Random Access Memory (RAM), a Read Only Memory (ROM), a Flash Memory (Flash Memory), a First In First Out (FIFO), a First In Last Out (FILO), and/or a First In Last Out (FILO); in particular, the processor may include one or more processing cores, such as a 4-core processor, an 8-core processor, and so on. The processor may be implemented in at least one hardware form of a DSP (Digital Signal Processing), an FPGA (Field Programmable Gate Array), and a PLA (Programmable Logic Array), and may also include a main processor and a coprocessor, where the main processor is a processor for Processing data in an awake state and is also referred to as a Central Processing Unit (CPU); a coprocessor is a low power processor for processing data in a standby state.
In some embodiments, the processor may be integrated with a GPU (Graphics Processing Unit) which is responsible for rendering and drawing contents required to be displayed on the display screen, for example, the processor may not be limited to a processor adopting a model STM32F105 series microprocessor, a Reduced Instruction Set Computer (RISC) microprocessor, an X86 or other architecture processor or an embedded neural Network Processor (NPU); the transceiver may be, but is not limited to, a wireless fidelity (WIFI) wireless transceiver, a bluetooth wireless transceiver, a General Packet Radio Service (GPRS) wireless transceiver, a ZigBee wireless transceiver (ieee802.15.4 standard-based low power local area network protocol), a 3G transceiver, a 4G transceiver, and/or a 5G transceiver, etc. In addition, the device may also include, but is not limited to, a power module, a display screen, and other necessary components.
Example 4
The present embodiment provides a computer-readable storage medium, in which computer-executable instructions are stored, and when the computer-executable instructions are executed by a processor, the computer-readable storage medium is used for implementing a fault line selection analysis method based on single-phase asymmetry according to embodiment 1.
Example 5
Embodiments of the present application may also provide a computer program product, which includes a computer program, and when the computer program is executed by a processor, the method for analyzing a fault route selection based on single-phase asymmetry is implemented as described in embodiment 1.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A fault line selection analysis method based on single-phase asymmetry is characterized by comprising the following steps:
the method comprises the steps of obtaining the wiring modes of a main transformer at a transformer station side and a transformer area at a load side in a power distribution network, and determining the wiring mode of a single-phase isolation transformer to be configured based on the wiring modes of the main transformer and the transformer area;
acquiring capacitance current corresponding to each feeder line in a power distribution network, and performing subnet segmentation based on the capacitance current to obtain a plurality of subnets;
adjusting taps of secondary windings in the single-phase isolation transformers, and configuring the single-phase isolation transformers for each sub-network according to the wiring mode of the single-phase isolation transformers to be configured to obtain the sub-networks after the single-phase isolation transformers are configured;
and constructing a high-sensitivity ground fault identification criterion based on zero sequence voltage mutation, and performing fault line selection based on the high-sensitivity ground fault identification criterion to determine the sub-network with the fault.
2. The single-phase asymmetry-based fault line selection analysis method according to claim 1, wherein obtaining the connection modes of a main transformer on a substation side and a transformer in a load side in a power distribution network comprises:
the method comprises the steps that a connection group of a main transformer on the transformer substation side is obtained to be a first connection group or a second connection group, wherein the first connection group represents that a primary winding of the main transformer is Yn-shaped connection and a secondary winding of the main transformer is Y-shaped connection; the second wiring group represents that a primary winding of the main transformer is Yn-shaped wiring and a secondary winding of the main transformer is delta-shaped wiring;
the method comprises the steps that a connection group of a load side platform area transformer is obtained to be a third connection group or a fourth connection group, wherein the third connection group represents that a primary winding of the platform area transformer is a Y-shaped connection and a secondary winding of the platform area transformer is a Yn-shaped connection; and the fourth wiring group represents that the primary winding of the transformer in the transformer area is delta-shaped wiring and the secondary winding is Yn wiring.
3. The single-phase asymmetry-based fault line selection analysis method according to claim 2, wherein determining the connection mode of the single-phase isolation transformer to be configured based on the connection modes of the main transformer and the transformer in the transformer area comprises:
when a secondary winding of a main transformer is in Y-shaped connection and a primary winding of a transformer in a transformer area is in Y-shaped connection, determining that the primary winding of the single-phase isolation transformer is in Y-shaped connection and the secondary winding is in Y-shaped connection;
when a secondary winding of a main transformer is in Y-shaped connection and a primary winding of a transformer in a transformer area is in delta-shaped connection, determining that the primary winding of the single-phase isolation transformer is in Y-shaped connection and the secondary winding is in delta-shaped connection;
when a secondary winding of a main transformer is in delta connection and a primary winding of a transformer in a transformer area is in Y connection, determining that the primary winding of the single-phase isolation transformer is in delta connection and the secondary winding is in Y connection;
when the secondary winding of the main transformer is delta-shaped connection and the primary winding of the transformer in the transformer area is delta-shaped connection, the primary winding of the single-phase isolation transformer is determined to be delta-shaped connection and the secondary winding is determined to be delta-shaped connection.
4. The single-phase asymmetry-based fault line selection analysis method according to claim 1, wherein obtaining capacitance currents corresponding to each feeder line in the power distribution network comprises:
wherein ,
indicating the total length of the corresponding cabling of the feeder,
representing the capacitive current corresponding to the cabling of the feeder,
representing the capacitive current corresponding to the overhead line of the feeder,
indicating the total length, I, of the overhead line of the feeder C Representing the total capacitive current for the feed line.
5. The single-phase asymmetry-based fault line selection analysis method of claim 4, wherein performing subnet segmentation based on the capacitive current to obtain a plurality of subnets comprises:
constructing a subnet division optimization module according to the capacitance current on each feeder line;
and traversing all the subnet partition schemes based on the subnet partition optimization model, and determining the final subnet partition scheme to obtain a plurality of subnets.
6. The single-phase asymmetry-based fault line selection analysis method according to claim 5, wherein the subnet partition optimization model is:
wherein ,L_TISO Representing the total number of sub-networks, i.e. the total number of three-phase isolating transformers, C sum (L_T ISO ) Represents the total cost of placing a three-phase isolation transformer,
respectively representing the sum of the capacitive currents of at least one of the feeders in the N sub-networks,
representing the threshold of the capacitive current.
7. The method for analyzing the fault line selection based on the single-phase asymmetry, according to claim 6, wherein the adjusting the taps of the secondary winding in the single-phase isolation transformer comprises:
the critical voltage conditions for constructing the secondary winding in the single-phase isolation transformer are as follows:
wherein ,Uborder Representing the phase voltage, U, of the distribution network arc_ignite Represents that the grounding arc is controlled to be the critical distribution network phase voltage U under the non-arcing mode F_ISO Representing the voltage, U, of the primary winding in a single-phase isolating transformer S_ISO Representing the voltage, T, of the secondary winding in a single-phase isolating transformer ratio Indicating control U border Phase voltage which is not subjected to arcing and needs to be met during normal operation of the power distribution network is met;
and adjusting a tap of a secondary winding in the single-phase isolation transformer according to the critical voltage condition.
8. The single-phase asymmetry-based fault line selection analysis method according to any one of claims 1 to 7, wherein adjusting taps of secondary windings in a single-phase isolation transformer, and configuring the single-phase isolation transformer for each sub-network according to a connection mode of the single-phase isolation transformer to be configured to obtain the sub-network configured with the single-phase isolation transformer, comprises:
adjusting a tap of a secondary winding in the single-phase isolation transformer;
and determining that a primary winding of the single-phase isolation transformer is connected with a secondary winding in the main transformer and that a secondary winding with a tap adjusted in the single-phase isolation transformer is connected with a primary winding of the transformer area according to the wiring mode of the single-phase isolation transformer to be configured and the tap of the secondary winding, and connecting the single-phase isolation transformer with the transformer area through a feeder line to obtain a sub-network configured with the single-phase isolation transformer.
9. The single-phase asymmetry-based fault line selection analysis method as claimed in claim 8, wherein the high-sensitivity earth fault identification criterion based on the zero-sequence voltage mutation is constructed as follows:
wherein ,u00 Represents the system voltage symmetry, u 00 ＝(C B -0.5C A -0.5C C )/(C A +C B +C C )，C A Representing the equivalent capacitance parameter, C, of the capacitive circuit charged with respect to earth of the system A B Representing the equivalent capacitance parameter, C, of the system B in relation to the earth-charged capacitive circuit C Capacitance equivalent parameter, U, representing the system C with respect to the earth-charged capacitive circuit β Representing an intermediate variable, U β ＝0.6667|U AB |，|U AB I represents the modulus of the line voltage, g 0 Representing the single-phase ground conductance of the system, w represents the angular frequency, C ∑ Representing the sum of capacitances to earth, j representing the imaginary operator, g f Representing transitionsCharacterization of the conductivity form of the resistance, d g Representing the damping rate of the system under the influence of the transition resistance, d 0 Which represents the initial damping rate of the system,
represents the zero sequence voltage phasor of the system before the fault occurs,
the zero sequence voltage phasor after the fault is shown,
indicating the zero sequence voltage sudden change phasor before and after the fault,
and representing the amplitude of the abrupt zero sequence voltage phasor.
10. The single-phase asymmetry-based fault line selection analysis method according to claim 9, wherein performing fault line selection based on the high-sensitivity ground fault identification criterion to determine a faulty subnet comprises:
obtaining zero sequence voltage sudden change phasor before and after fault according to real-time parameters of the sub-network
And the amplitude of the sudden change zero sequence voltage phasor
Judging whether zero sequence voltage sudden change phasor before and after fault exists
The amplitude value of the zero sequence voltage phasor is larger than a set first threshold value or is suddenly changed
And if the number of the sub-networks is larger than the set first threshold value, judging that the corresponding sub-network has the ground fault, otherwise, judging that the corresponding sub-network has no ground fault.
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