CN111025085A - Single-phase fault phase selection method, device, equipment and medium based on line voltage increase - Google Patents

Single-phase fault phase selection method, device, equipment and medium based on line voltage increase Download PDF

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CN111025085A
CN111025085A CN201911322459.2A CN201911322459A CN111025085A CN 111025085 A CN111025085 A CN 111025085A CN 201911322459 A CN201911322459 A CN 201911322459A CN 111025085 A CN111025085 A CN 111025085A
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phase
fault
bus
voltage
line voltage
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CN111025085B (en
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刘文泽
谭炜豪
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South China University of Technology SCUT
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08—Locating faults in cables, transmission lines, or networks
    • G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
    • G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08—Locating faults in cables, transmission lines, or networks
    • G01R31/088—Aspects of digital computing

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Abstract

The invention discloses a single-phase fault phase selection method, a single-phase fault phase selection device, single-phase fault phase selection equipment and a single-phase fault phase selection medium based on line voltage increase, wherein the method comprises the following steps: collecting the three-phase voltage and the line voltage of a bus of a transformer substation; calculating the zero sequence voltage of the bus according to the three-phase voltage of the bus; judging whether a single-phase earth fault exists or not according to the three-phase voltage and the zero-sequence voltage of the bus at the current moment; if so, extracting the three-phase line voltage of the bus before the fault; calculating the amplitude increase amount of the line voltage according to the three-phase line voltage of the bus at the current moment and the three-phase line voltage of the bus before the fault; sequencing the increasing amounts of the line voltage amplitude from large to small to sequentially obtain a maximum value of the increasing amount, a middle value of the increasing amount and a minimum value of the increasing amount; generating an algorithm criterion according to the maximum value, the intermediate value and the minimum value of the increment; and selecting a fault phase from the three phases according to the result of the algorithm criterion. The invention considers the unbalance amount of the ungrounded neutral point power distribution system before the fault, and has higher phase selection accuracy in the actual fault.

Description

Single-phase fault phase selection method, device, equipment and medium based on line voltage increase
Technical Field
The invention relates to a single-phase fault phase selection method, a single-phase fault phase selection device, single-phase fault phase selection equipment and a single-phase fault phase selection medium based on line voltage increase, and belongs to the field of fault phase selection of 10kV power distribution networks.
Background
Compared with the mode that the neutral point is grounded through an arc suppression coil and the neutral point is grounded through a small resistor, the neutral point ungrounded system has great advantages in the aspects of power supply reliability and the like, but still has the problems of intermittent overvoltage of an electric arc, low accuracy of phase selection and line selection and the like. The adoption of active intervention type arc extinction technologies such as 'arc extinction cabinet' not only transfers the current of a fault point through bus grounding, plays a good role in fault arc extinction, but also provides a premise for active line selection. Therefore, if the correct phase selection can be ensured, the active intervention type arc extinction can greatly ensure the power supply reliability and the personal safety.
However, the above method strictly requires accurate phase selection, and correct fault phase selection provides a basis for subsequent fault line selection and the like. If the phase selection cannot be performed correctly, not only the line selection cannot be performed successfully, but also more serious faults such as interphase short circuit and the like can be caused. Therefore, further research and solution are needed to provide a phase selection method with higher phase selection accuracy. In addition, the actual operating environment is usually three-phase asymmetric, and how to accurately select the phase and the line under the condition of considering the unbalance of the system is also a problem to be considered. In addition, the fault types in the power distribution network are various, including metallic direct earth faults, arc grounding faults and the like, transient characteristics and duration time existing in different fault type systems are different, and arc extinction can be carried out as soon as possible after faults are required according to the consideration of personal safety and equipment safety, so that the phase selection speed needs to be improved on the premise of ensuring correct phase selection. Because the construction scale of the power distribution network is large, and a large amount of investment is needed for modifying or newly adding detection equipment, the phase selection accuracy rate can be improved on the premise of the current detection equipment.
Disclosure of Invention
In view of the above, the present invention provides a line voltage increase-based single-phase fault phase selection method, device, equipment, and medium, which can quickly and accurately determine a fault phase by collecting voltage information before a fault and comparing the voltage information after the fault after a single-phase ground fault occurs in an ungrounded neutral power distribution system, can still ensure correct phase selection when the ungrounded neutral power distribution system is unbalanced, provide a guarantee for personal safety, and help subsequent fault line selection operations.
A first object of the present invention is to provide a single-phase fault phase selection method based on the amount of line voltage increase.
A second object of the present invention is to provide a single-phase fault phase selection device based on the amount of increase in line voltage.
It is a third object of the invention to provide a computer apparatus.
It is a fourth object of the present invention to provide a storage medium.
The first purpose of the invention can be achieved by adopting the following technical scheme:
a single-phase fault phase selection method based on line voltage increase amount is applied to a neutral point ungrounded power distribution system, and the method comprises the following steps:
collecting the three-phase voltage and the line voltage of a bus of a transformer substation;
calculating the zero sequence voltage of the bus according to the three-phase voltage of the bus;
judging whether a single-phase earth fault exists or not according to the three-phase voltage and the zero-sequence voltage of the bus at the current moment;
if the single-phase earth fault exists, extracting the three-phase line voltage of the bus before the fault;
calculating the amplitude increase amount of the line voltage according to the three-phase line voltage of the bus at the current moment and the three-phase line voltage of the bus before the fault;
sequencing the increasing amounts of the line voltage amplitude from large to small to sequentially obtain a maximum value of the increasing amount, a middle value of the increasing amount and a minimum value of the increasing amount;
generating an algorithm criterion according to the maximum value, the intermediate value and the minimum value of the increment;
and selecting a fault phase from the three phases according to the result of the algorithm criterion.
Further, the method further comprises:
enqueuing the fault phase selection result to a queue;
judging whether the current counting variable is less than 4 fs(iv) f; wherein f issIs the sampling frequency, f is the voltage frequency;
if the current counting variable is less than 4 fsAnd/f, adding one to the current counting variable as the next counting variable, returning to the current three-phase line voltage of the bus and the three-phase line voltage of the bus before the fault,calculating the increase of the amplitude of the line voltage, and executing subsequent operation;
if the current counting variable is greater than or equal to 4 fsIf yes, judging whether the fault phase selection results in the queue are consistent;
if the fault phase selection results are consistent, outputting a fault phase selection result;
if the fault phase selection results are inconsistent, calculating to obtain a new fault phase selection result according to the three-phase voltage of the bus at the next moment and the three-phase line voltage of the bus before the fault;
and enqueuing the new fault phase selection result to a queue, dequeuing the head element in the queue, and returning to judge whether the fault phase selection results in the queue are consistent.
Further, the selecting a fault phase of the three phases according to the result of the algorithm criterion specifically includes:
judging whether the result of the algorithm criterion is true;
if the result of the algorithm criterion is true, the initial phase corresponding to the minimum value of the increment is a fault phase;
and if the result of the algorithm criterion is false, the final phase corresponding to the maximum value of the increment is the fault phase.
Further, the algorithm criterion is as follows:
flag＝[(ΔUmid-ΔUmin)-(ΔUmax-ΔUmid)]>0
wherein, Delta Umax、ΔUmidAnd Δ UminMaximum increase, intermediate increase, and minimum increase, respectively.
Further, the determining whether a single-phase ground fault exists according to the three-phase voltage and the zero-sequence voltage of the bus at the current moment specifically includes:
if zero sequence voltage is generated and negative sequence voltage is not generated, judging that single-phase earth fault exists;
if no zero sequence voltage or negative sequence voltage is generated, judging that no single-phase earth fault exists.
Further, the bus zero sequence voltage is calculated according to the bus three-phase voltage, as follows:
U0＝Ua+Ub+Uc
wherein, U0For bus zero sequence voltage, Ua、UbAnd UcIs the three-phase voltage of the bus.
The second purpose of the invention can be achieved by adopting the following technical scheme:
a single-phase fault phase selection apparatus based on line voltage increase for use in an ungrounded neutral power distribution system, the apparatus comprising:
the acquisition module is used for acquiring the three-phase voltage and the line voltage of a bus of the transformer substation;
the first calculation module is used for calculating the zero sequence voltage of the bus according to the three-phase voltage of the bus;
the first judgment module is used for judging whether a single-phase earth fault exists or not according to the three-phase voltage and the zero-sequence voltage of the bus at the current moment;
the extraction module is used for extracting the three-phase line voltage of the bus before the fault if the single-phase earth fault exists;
the second calculation module is used for calculating the amplitude increase amount of the line voltage according to the three-phase line voltage of the bus at the current moment and the three-phase line voltage of the bus before the fault;
the sequencing module is used for sequencing the increasing quantity of the line voltage amplitude from large to small to sequentially obtain a maximum value of the increasing quantity, a middle value of the increasing quantity and a minimum value of the increasing quantity;
the generating module is used for generating an algorithm criterion according to the maximum value of the increment, the intermediate value of the increment and the minimum value of the increment;
and the first phase selection module is used for selecting a fault phase in the three phases according to the result of the algorithm criterion.
Further, the apparatus further comprises:
the enqueue module is used for enqueuing the fault phase selection result to a queue;
a second judging module for judging whether the current counting variable is less than 4 fs(iv) f; wherein f issIs the sampling frequency, f is the voltage frequency;
a first returning module for returning the current counting variable to the current counting variable if the current counting variable is less than 4 fsIf yes, adding one to the current counting variable to serve as the next counting variable, returning to the step of calculating the increase of the amplitude of the line voltage according to the three-phase line voltage of the bus at the current moment and the three-phase line voltage of the bus before the fault, and executing subsequent operation;
a third judging module for judging if the current counting variable is greater than or equal to 4 fsIf yes, judging whether the fault phase selection results in the queue are consistent;
the output module is used for outputting a fault phase selection result if the fault phase selection results are consistent;
the second phase selection module is used for calculating to obtain a new fault phase selection result according to the three-phase voltage of the bus at the next moment and the three-phase line voltage of the bus before the fault if the fault phase selection results are inconsistent;
and the second returning module is used for enqueuing the new fault phase selection result to the queue, dequeuing the head element in the queue, and returning to judge whether the fault phase selection results in the queue are consistent.
The third purpose of the invention can be achieved by adopting the following technical scheme:
a computer device comprises a processor and a memory for storing a program executable by the processor, wherein the processor executes the program stored in the memory to realize the single-phase fault phase selection method.
The fourth purpose of the invention can be achieved by adopting the following technical scheme:
a storage medium stores a program which, when executed by a processor, implements the above-described single-phase fault phase selection method.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention considers that the calculation precision of the amplitude is higher than that of the phase angle, the phase angle change characteristic is reflected to the amplitude change through the regular relation between the amplitude and the phase angle, the phase selection is determined by acquiring the line voltage amplitude before and after the fault and comparing the increase of the line voltage amplitude, and the increase of the line voltage amplitude is used as the phase selection basis, so that the accuracy of the phase selection can be improved while the current detection equipment is not modified or updated.
2. Compared with the prior art that transient information caused by faults is prevented from influencing fault phase selection results by setting constant longer time delay, the method adopts short time delay and then circularly judges in a queue mode, can quickly select phases when low-resistance grounding faults occur, can output fault phase selection results when the transient information cannot influence the fault phase selection results when high-resistance grounding faults occur, can accelerate phase selection speed while ensuring phase selection accuracy, and greatly ensures personal safety.
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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 description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
Fig. 1 is a flowchart of a single-phase fault phase selection method based on the amount of line voltage increase according to embodiment 1 of the present invention.
Fig. 2 is a flowchart of determining whether a single-phase ground fault exists according to embodiment 1 of the present invention.
Fig. 3 is a block diagram showing a configuration of a single-phase fault phase selection apparatus according to embodiment 2 of the present invention.
Fig. 4 is a block diagram of a phase selection module according to embodiment 2 of the present invention.
Fig. 5 is a block diagram of a computer device according to embodiment 3 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer and more complete, the technical solutions in the embodiments of the present invention will be described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments, and all other embodiments obtained by a person of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the protection scope of the present invention.
Example 1:
the embodiment provides a single-phase fault phase selection method based on line voltage increase, which is applied to a neutral point ungrounded distribution system, wherein before the system starts to work, the neutral point ungrounded distribution system is in a stable normal working state, and no fault occurs in three cycles after the device is connected; the phase selection conditions of the method are set as follows: the voltage information before the fault is required to be three-phase voltage only containing unbalance of a neutral point ungrounded power distribution system; the voltage information after the fault needs to be a steady-state quantity, and cannot contain a transient quantity.
As shown in fig. 1, the single-phase fault phase selection method of the present embodiment includes the following steps:
and S1, collecting the three-phase voltage and the line voltage of the bus of the transformer substation.
Obtaining the three-phase voltage of the bus of the transformer substation and the line voltage in an acquisition mode, and recording the three-phase voltage of the bus, wherein the three-phase voltage of the bus is Ua、UbAnd UcThe bus three-phase line voltage is Uab、UbcAnd Uca。
S2, calculating the zero sequence voltage of the bus according to the three-phase voltage of the bus, and the following formula is:
U0＝Ua+Ub+Uc
s3, judging whether a single-phase earth fault exists or not according to the three-phase voltage and the zero-sequence voltage of the bus at the current moment, and if yes, entering the step S4; if not, the process returns to step S1.
Wherein, according to the bus three-phase voltage and the zero sequence voltage at the present moment, it is judged whether there is a single-phase earth fault as shown in fig. 2, which specifically includes:
s301, if generating zero sequence voltage (namely U)0Not equal to 0) and no negative sequence voltage is generated, it is determined that a single-phase ground fault exists.
S302, if no zero sequence voltage or negative sequence voltage is generated, judging that no single-phase earth fault exists.
S4, extracting and storing the three-phase line voltage of the bus before the fault, namely the three-phase line voltage of the bus before the three cycles, namely Uab’、Ubc' and Uca', and initializes a count variable i to 1.
And S5, calculating the increase of the line voltage amplitude according to the three-phase voltage of the bus at the current moment and the three-phase line voltage of the bus before the fault.
The three-phase voltage of the bus at the current moment is Ua、UbAnd UcThe saved three-phase line voltage of the bus before the fault is Uab’、Ubc' and Uca', calculating the increase of the line voltage amplitude DeltaUab、ΔUbcAnd Δ UcaThe following formula:
ΔUab＝Uab-U′ab
ΔUbc＝Ubc-U′bc
ΔUca＝Uca-U′ca
if the amplitude of the line voltage is increased by a positive value, the amplitude of the line voltage is increased, and if the amplitude of the line voltage is increased by a negative value, the amplitude of the line voltage is decreased.
S6, sequencing the increasing quantities of the line voltage amplitude from large to small to obtain a maximum value of the increasing quantity, a middle value of the increasing quantity and a minimum value of the increasing quantity in sequence.
Increase the amplitude of line voltage by an amount Δ Uab、ΔUbcAnd Δ UcaComparing, and sorting from large to small in numerical value to obtain the maximum value delta U of the increase quantitymaxIncrease amount intermediate value Δ UmidAnd increase amount minimum value DeltaUmin。
S7, generating an algorithm criterion according to the maximum value, the middle value and the minimum value of the increment, wherein the algorithm criterion comprises the following steps:
flag＝[(ΔUmid-ΔUmin)-(ΔUmax-ΔUmid)]>0
s8, selecting a fault phase from the three phases according to the result of the algorithm criterion, wherein the fault phase specifically comprises the following steps:
s801, judging whether the result of the algorithm criterion flag is TRUE (TRUE), namely judging whether the algorithm criterion flag >0 is TRUE.
S802, judging the criterion flag of the algorithm>If 0 is true, indicating that the result of the algorithm criterion flag is true, the minimum increase Δ UminThe corresponding initial phase is the failure phase, and the process proceeds to step S9.
S803, if the algorithm determines the criterion flag>If 0 is not true (i.e., flag ≦ 0), indicating that the result of the algorithm criterion flag is FALSE (FALSE), the maximum increase Δ UmaxThe corresponding final phase is a failure phase, and the process proceeds to step S9.
U of bus line voltage in steps S802 to S803abFor example, a is the initial phase and b is the final phase.
S9, enqueue the fault phase selection result to a queue Qph。
S10, judging whether the current counting variable is less than 4 fs(iv) f; wherein f issIs the sampling frequency and f is the voltage frequency.
S11, if the current counting variable i is less than 4 fsIf yes, adding one to the current counting variable to serve as the next counting variable, and returning to the step S5; if the current counting variable i is greater than or equal to 4 fsAnd/f, then the flow proceeds to step S12.
The current counting variable i is initialized to 1, and the current counting variable is incremented by one as the next counting variable, i.e., i ═ i +1, and the next counting variable is 2, and iteration is continued until the current counting variable i is greater than or equal to 4 × fsAnd/f, no more counting.
S12, judging queue QphIf the phase selection result of the fault phase is consistent, the step S14 is executed; if the fault phase selection results are inconsistent, the three-phase power of the bus at the next moment is obtainedAnd calculating the voltage and the three-phase line voltage of the bus before the fault by using the calculation modes of the steps S5-S8 to obtain a new fault phase selection result, and entering the step S13.
S13, enqueue the new fault phase selection result to a queue QphQueue QphDequeues the head-of-line element in (1), and returns to step S12.
And S14, outputting a fault phase selection result, and ending phase selection.
Those skilled in the art will appreciate that all or part of the steps in the method for implementing the above embodiments may be implemented by a program to instruct associated hardware, and the corresponding program may be stored in a computer-readable storage medium.
It should be noted that although the method operations of the above-described embodiments are depicted in the drawings in a particular order, this does not require or imply that these operations must be performed in this particular order, or that all of the illustrated operations must be performed, to achieve desirable results. Rather, the depicted steps may change the order of execution. Additionally or alternatively, certain steps may be omitted, multiple steps combined into one step execution, and/or one step broken down into multiple step executions.
Example 2:
as shown in fig. 3, the present embodiment provides a single-phase fault phase selection apparatus based on line voltage increase, which is applied to a neutral point ungrounded power distribution system, and includes an acquisition module 301, a first calculation module 302, a first judgment module 303, an extraction module 304, a second calculation module 305, a sorting module 306, a generation module 307, a first phase selection module 308, an enqueue module 309, a second judgment module 310, a first return module 311, a third judgment module 312, an output module 313, a second phase selection module 314, and a second return module 315, where specific functions of each module are as follows:
the acquisition module 301 is used for acquiring the bus three-phase voltage and the line voltage of the transformer substation.
The first calculating module 302 is configured to calculate a bus zero-sequence voltage according to the bus three-phase voltage.
The first judging module 303 is configured to judge whether a single-phase ground fault exists according to the three-phase voltage and the zero-sequence voltage of the bus at the current time.
The extraction module 304 is configured to extract the three-phase line voltage of the bus before the fault if the single-phase ground fault exists.
The second calculating module 305 is configured to calculate an increase amount of the amplitude of the line voltage according to the three-phase line voltage of the bus at the current time and the three-phase line voltage of the bus before the fault.
The sorting module 306 is configured to sort the increase amounts of the line voltage amplitudes from large to small, and obtain a maximum increase amount value, an intermediate increase amount value, and a minimum increase amount value in sequence.
The generating module 307 is configured to generate an algorithm criterion according to the maximum increment, the intermediate increment, and the minimum increment.
The first phase selection module 308 is configured to select a faulty phase among the three phases according to the result of the algorithm criterion.
The enqueue module 309, configured to enqueue the phase selection result of the failed phase to the queue Qph。
The second determining module 310 is configured to determine whether the current counting variable is less than 4 × fs(iv) f; wherein f issIs the sampling frequency and f is the voltage frequency.
The first returning module 311 is configured to, if the current counting variable is less than 4 × fsAnd/f, adding one to the current counting variable to serve as the next counting variable, returning to calculate the increase of the amplitude of the line voltage according to the three-phase line voltage of the bus at the current moment and the three-phase line voltage of the bus before the fault, and executing subsequent operation.
The third determining module 312 is configured to determine if the current counting variable is greater than or equal to 4 × fsIf/f, then judge queue QphWhether the fault phase selection results in (1) are consistent.
And the output module 313 is configured to output the phase selection result of the fault phase if the phase selection results of the fault phases are consistent.
And the second phase selection module 314 is configured to, if the faulty phase selection result is inconsistent, calculate to obtain a new faulty phase selection result according to the bus three-phase voltage at the next moment and the bus three-phase line voltage before the fault.
The second returning module 315 is configured to enqueue the new fault phase selection result to the queue QphQueue QphThe head element in the queue is dequeued and returns to the judgment queue QphWhether the fault phase selection results in (1) are consistent.
Further, as shown in fig. 4, the first phase selection module 308 specifically includes:
the judging unit 3081 is used for judging whether the result of the algorithm criterion is true.
A first phase selection unit 3082 for Δ U if the result of the algorithm criterion is trueminThe corresponding starting phase is the failed phase.
A second phase selection unit 3083 for Δ U if the result of the algorithm criterion is falsemaxThe corresponding end phase is the faulted phase.
The specific implementation of each module in this embodiment may refer to embodiment 1, which is not described herein any more; it should be noted that the system provided in this embodiment is only illustrated by the division of the functional modules, and in practical applications, the functions may be distributed by different functional modules according to needs, that is, the internal structure is divided into different functional modules to complete all or part of the functions described above.
It will be understood that the terms "first," "second," and the like as used in the above-described apparatus may be used to describe various modules, but these modules are not limited by these terms. These terms are only used to distinguish one module from another. For example, the first determining module may be referred to as a second determining module, and similarly, the second splicing unit may be referred to as a first determining module, and the first determining module and the second determining module are both determining modules, but are not the same determining module, without departing from the scope of the present invention.
Example 3:
the present embodiment provides a computer apparatus, which is a computer, and as shown in fig. 5, the computer apparatus includes a processor 502, a memory, an input device 503, a display 504, and a network interface 505 that are connected by a system bus 501, the processor is configured to provide computing and controlling capabilities, the memory includes a nonvolatile storage medium 506 and an internal memory 507, the nonvolatile storage medium 506 stores an operating system, a computer program, and a database, the internal memory 507 provides an environment for the operating system and the computer program in the nonvolatile storage medium to run, and when the processor 502 executes the computer program stored in the memory, the single-phase fault phase selection method of embodiment 1 described above is implemented, as follows:
collecting the three-phase voltage and the line voltage of a bus of a transformer substation;
calculating the zero sequence voltage of the bus according to the three-phase voltage of the bus;
judging whether a single-phase earth fault exists or not according to the three-phase voltage and the zero-sequence voltage of the bus at the current moment;
if the single-phase earth fault exists, extracting the three-phase line voltage of the bus before the fault;
calculating the amplitude increase amount of the line voltage according to the three-phase line voltage of the bus at the current moment and the three-phase line voltage of the bus before the fault;
sequencing the increasing amounts of the line voltage amplitude from large to small to sequentially obtain a maximum value of the increasing amount, a middle value of the increasing amount and a minimum value of the increasing amount;
generating an algorithm criterion according to the maximum value, the intermediate value and the minimum value of the increment;
selecting a fault phase from the three phases according to the result of the algorithm criterion;
enqueuing the fault phase selection result to a queue;
judging whether the current counting variable is less than 4 fs(iv) f; wherein f issIs the sampling frequency, f is the voltage frequency;
if the current counting variable is less than 4 fsIf yes, adding one to the current counting variable to serve as the next counting variable, returning to the step of calculating the increase of the amplitude of the line voltage according to the three-phase line voltage of the bus at the current moment and the three-phase line voltage of the bus before the fault, and executing subsequent operation;
if the current counting variable is greater than or equal to 4 fsIf/f, then determine the queueWhether the fault phase selection results are consistent or not;
if the fault phase selection results are consistent, outputting a fault phase selection result;
if the fault phase selection results are inconsistent, calculating to obtain a new fault phase selection result according to the three-phase voltage of the bus at the next moment and the three-phase line voltage of the bus before the fault;
and enqueuing the new fault phase selection result to a queue, dequeuing the head element in the queue, and returning to judge whether the fault phase selection results in the queue are consistent.
Example 4:
the present embodiment provides a storage medium, which is a computer-readable storage medium, and stores a computer program, and when the computer program is executed by a processor, the single-phase fault phase selection method of the above embodiment 1 is implemented as follows:
collecting the three-phase voltage and the line voltage of a bus of a transformer substation;
calculating the zero sequence voltage of the bus according to the three-phase voltage of the bus;
judging whether a single-phase earth fault exists or not according to the three-phase voltage and the zero-sequence voltage of the bus at the current moment;
if the single-phase earth fault exists, extracting the three-phase line voltage of the bus before the fault;
calculating the amplitude increase amount of the line voltage according to the three-phase line voltage of the bus at the current moment and the three-phase line voltage of the bus before the fault;
sequencing the increasing amounts of the line voltage amplitude from large to small to sequentially obtain a maximum value of the increasing amount, a middle value of the increasing amount and a minimum value of the increasing amount;
generating an algorithm criterion according to the maximum value, the intermediate value and the minimum value of the increment;
selecting a fault phase from the three phases according to the result of the algorithm criterion;
enqueuing the fault phase selection result to a queue;
judging whether the current counting variable is less than 4 fs(iv) f; wherein f issIs the sampling frequency, f is the voltage frequency;
if the current counting variable is less than 4 fsIf yes, adding one to the current counting variable to serve as the next counting variable, returning to the step of calculating the increase of the amplitude of the line voltage according to the three-phase line voltage of the bus at the current moment and the three-phase line voltage of the bus before the fault, and executing subsequent operation;
if the current counting variable is greater than or equal to 4 fsIf yes, judging whether the fault phase selection results in the queue are consistent;
if the fault phase selection results are consistent, outputting a fault phase selection result;
if the fault phase selection results are inconsistent, calculating to obtain a new fault phase selection result according to the three-phase voltage of the bus at the next moment and the three-phase line voltage of the bus before the fault;
and enqueuing the new fault phase selection result to a queue, dequeuing the head element in the queue, and returning to judge whether the fault phase selection results in the queue are consistent.
The storage medium described in this embodiment may be a magnetic disk, an optical disk, a computer Memory, a Random Access Memory (RAM), a usb disk, a removable hard disk, or other media.
In summary, the invention considers that the calculation precision of the amplitude is higher than that of the phase angle, the phase angle change characteristic is reflected to the amplitude change through the regular relation between the amplitude and the phase angle, the phase selection is determined by collecting the line voltage amplitude before and after the fault and comparing the increase of the line voltage amplitude, and the increase of the line voltage amplitude is used as the phase selection basis, so that the accuracy of the phase selection can be improved while the current detection equipment is not modified or updated, in the actual engineering, the unbalance amount of 5% usually exists in the neutral point ungrounded distribution system; in addition, compared with the prior art that transient information caused by faults is prevented from influencing fault phase selection results by setting constant longer time delay, the method adopts the form of queue to carry out circular judgment after short time delay, not only can fast select the phase when low-resistance earth faults occur, but also can output the fault phase selection results when the transient information cannot influence the fault phase selection results when high-resistance earth faults occur, can accelerate the phase selection speed while ensuring the phase selection accuracy, and greatly ensures the personal safety.
The above description is only for the preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art can substitute or change the technical solution and the inventive concept of the present invention within the scope of the present invention.

Claims (10)

1. A single-phase fault phase selection method based on line voltage increase is applied to a neutral point ungrounded power distribution system, and is characterized by comprising the following steps:
collecting the three-phase voltage and the line voltage of a bus of a transformer substation;
calculating the zero sequence voltage of the bus according to the three-phase voltage of the bus;
judging whether a single-phase earth fault exists or not according to the three-phase voltage and the zero-sequence voltage of the bus at the current moment;
if the single-phase earth fault exists, extracting the three-phase line voltage of the bus before the fault;
calculating the amplitude increase amount of the line voltage according to the three-phase line voltage of the bus at the current moment and the three-phase line voltage of the bus before the fault;
sequencing the increasing amounts of the line voltage amplitude from large to small to sequentially obtain a maximum value of the increasing amount, a middle value of the increasing amount and a minimum value of the increasing amount;
generating an algorithm criterion according to the maximum value, the intermediate value and the minimum value of the increment;
and selecting a fault phase from the three phases according to the result of the algorithm criterion.
2. The single-phase fault phase selection method of claim 1, further comprising:
enqueuing the fault phase selection result to a queue;
judging whether the current counting variable is less than 4 fs(iv) f; wherein f issIs the sampling frequency, f is the voltage frequency;
if the current counting variable is less than 4 fsIf yes, adding one to the current counting variable to serve as the next counting variable, returning to the step of calculating the increase of the amplitude of the line voltage according to the three-phase line voltage of the bus at the current moment and the three-phase line voltage of the bus before the fault, and executing subsequent operation;
if the current counting variable is greater than or equal to 4 fsIf yes, judging whether the fault phase selection results in the queue are consistent;
if the fault phase selection results are consistent, outputting a fault phase selection result;
if the fault phase selection results are inconsistent, calculating to obtain a new fault phase selection result according to the three-phase voltage of the bus at the next moment and the three-phase line voltage of the bus before the fault;
and enqueuing the new fault phase selection result to a queue, dequeuing the head element in the queue, and returning to judge whether the fault phase selection results in the queue are consistent.
3. The single-phase fault phase selection method according to any one of claims 1-2, wherein selecting a fault phase of three phases as a result of the algorithmic criteria comprises:
judging whether the result of the algorithm criterion is true;
if the result of the algorithm criterion is true, the initial phase corresponding to the minimum value of the increment is a fault phase;
and if the result of the algorithm criterion is false, the final phase corresponding to the maximum value of the increment is the fault phase.
4. A single-phase fault phase selection method according to claim 3, characterized in that said algorithm criterion is as follows:
flag＝[(ΔUmid-ΔUmin)-(ΔUmax-ΔUmid)]>0
wherein, Delta Umax、ΔUmidAnd Δ UminMaximum increase, intermediate increase, and minimum increase, respectively.
5. The single-phase fault phase selection method according to any one of claims 1 to 2, wherein the determining whether a single-phase ground fault exists according to the three-phase voltage and the zero-sequence voltage of the bus at the current time specifically includes:
if zero sequence voltage is generated and negative sequence voltage is not generated, judging that single-phase earth fault exists;
if no zero sequence voltage or negative sequence voltage is generated, judging that no single-phase earth fault exists.
6. The single-phase fault phase selection method according to any one of claims 1-2, wherein the bus zero-sequence voltage is calculated according to the bus three-phase voltage as follows:
U0＝Ua+Ub+Uc
wherein, U0For bus zero sequence voltage, Ua、UbAnd UcIs the three-phase voltage of the bus.
7. A single-phase fault phase selection apparatus based on line voltage increase for use in an ungrounded neutral power distribution system, the apparatus comprising:
the acquisition module is used for acquiring the three-phase voltage and the line voltage of a bus of the transformer substation;
the first calculation module is used for calculating the zero sequence voltage of the bus according to the three-phase voltage of the bus;
the first judgment module is used for judging whether a single-phase earth fault exists or not according to the three-phase voltage and the zero-sequence voltage of the bus at the current moment;
the extraction module is used for extracting the three-phase line voltage of the bus before the fault if the single-phase earth fault exists;
the second calculation module is used for calculating the amplitude increase amount of the line voltage according to the three-phase line voltage of the bus at the current moment and the three-phase line voltage of the bus before the fault;
the sequencing module is used for sequencing the increasing quantity of the line voltage amplitude from large to small to sequentially obtain a maximum value of the increasing quantity, a middle value of the increasing quantity and a minimum value of the increasing quantity;
the generating module is used for generating an algorithm criterion according to the maximum value of the increment, the intermediate value of the increment and the minimum value of the increment;
and the first phase selection module is used for selecting a fault phase in the three phases according to the result of the algorithm criterion.
8. The single-phase fault phase selection apparatus of claim 7, further comprising:
the enqueue module is used for enqueuing the fault phase selection result to a queue;
a second judging module for judging whether the current counting variable is less than 4 fs(iv) f; wherein f issIs the sampling frequency, f is the voltage frequency;
a first returning module for returning the current counting variable to the current counting variable if the current counting variable is less than 4 fsIf yes, adding one to the current counting variable to serve as the next counting variable, returning to the step of calculating the increase of the amplitude of the line voltage according to the three-phase line voltage of the bus at the current moment and the three-phase line voltage of the bus before the fault, and executing subsequent operation;
a third judging module for judging if the current counting variable is greater than or equal to 4 fsIf yes, judging whether the fault phase selection results in the queue are consistent;
the output module is used for outputting a fault phase selection result if the fault phase selection results are consistent;
the second phase selection module is used for calculating to obtain a new fault phase selection result according to the three-phase voltage of the bus at the next moment and the three-phase line voltage of the bus before the fault if the fault phase selection results are inconsistent;
and the second returning module is used for enqueuing the new fault phase selection result to the queue, dequeuing the head element in the queue, and returning to judge whether the fault phase selection results in the queue are consistent.
9. A computer device comprising a processor and a memory for storing processor-executable programs, wherein the processor, when executing a program stored in the memory, implements the single-phase fault phase selection method of any one of claims 1 to 6.
10. A storage medium storing a program, wherein the program, when executed by a processor, implements the single-phase fault phase selection method of any one of claims 1 to 6.
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