Method and system for memory voltage polarization phase comparison distance protection action execution

Abstract

The invention discloses a memory voltage polarization phase comparison type distance protection action execution method and system, and belongs to the technical field of power systems and automation thereof. The method comprises the steps of obtaining three-phase voltage data at a protection installation point after a fault occurs in a protected line in a power system, and obtaining a basic variable according to the three-phase voltage data; according to the basic variable, based on a preset discrimination formula, determining whether the protected line enters a phase comparison type distance protection logic of memory voltage polarization; if the protected line enters the phase comparison type distance protection logic of memory voltage polarization, determining a judgment result of inter-phase compensation voltage before and after the fault based on the basic variable; and inputting a memory voltage polarization characteristic correction link to the protection line based on the judgment result, and adjusting correction parameters in the memory voltage polarization characteristic correction link so as to enable the action of memory voltage polarization ratio phase distance protection to be correctly executed. The problem of distance protection maloperation caused by the fact that the memory positive sequence voltage and the real-time fault current are basically in the same phase is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems and automation thereof, and more particularly to a method and system for executing a phase-type distance protection action by memorizing a voltage polarization ratio. Background Art

[0002] Flexible DC transmission technology based on modular multilevel converters (MMCs) has been widely used in large-scale renewable energy transmission and grid-connected projects in recent years because it does not have commutation failure problems, has four-quadrant operation capabilities, does not require large-capacity reactive power support, and has flexible DC networking capabilities. It can effectively meet the frequency and voltage support requirements of renewable energy such as wind power and photovoltaics.

[0003] Phase-comparison distance protection based on positive-sequence voltage polarization has become the mainstream backup protection for AC transmission lines due to its operational characteristics, lack of dead zones, and simple implementation of judgment criteria. However, when a three-phase short-circuit fault occurs in an AC system, the system's positive-sequence voltage drops significantly, and the polarization quantity loses its reference value, rendering the phase-comparison distance protection based on positive-sequence voltage polarization ineffective. Therefore, when the system voltage drops significantly, a memory voltage is required as a reference. However, due to the regulation characteristics of flexible direct current (FDC) and renewable energy sources, the converter's equivalent internal potential is no longer constant after a fault, and the memory voltage also loses its reference value. Actual engineering simulation analysis and on-site fault recordings have shown that the memory voltage polarization phase-comparison distance protection currently used by mainstream protection manufacturers lacks reliability in scenarios where renewable energy and FDC are introduced. Summary of the Invention

[0004] In response to the above problems, the present invention proposes a method for memorizing the correct action of voltage polarization phase ratio distance protection, comprising:

[0005] Obtaining three-phase voltage data at a protection installation point after a protected line fault occurs in the power system, and obtaining basic variables based on the three-phase voltage data;

[0006] According to the basic variables and based on a preset judgment formula, it is judged whether the protected line enters the phase comparison distance protection logic of the memory voltage polarization;

[0007] If the protected line enters the phase-comparison distance protection logic with memory voltage polarization, the judgment result of the phase-to-phase compensation voltage before and after the fault is determined based on the basic variables;

[0008] Based on the discrimination result, a memory voltage polarization characteristic correction link is added to the protection circuit, and correction parameters are adjusted in the memory voltage polarization characteristic correction link to ensure that the memory voltage polarization phase-to-phase distance protection is correctly executed. Optional three-phase voltage data includes:

[0009] After the protected line fails, the three-phase voltage and current phasors of the sampling point at the protection installation point, as well as the three-phase voltage and current phasors of the sampling point two cycles ago.

[0010] Optional, basic variables, including:

[0011] The positive sequence voltage and current corresponding to the three-phase voltage and current phasors, and the positive sequence voltage and current corresponding to the three-phase voltage and current phasors two weeks ago at the sampling point.

[0012] Optionally, a preset discriminant formula is as follows:

[0013]

[0014] in, is the positive sequence voltage phasor of the faulty special phase (taking phase A as an example), U N is the rated voltage of the line.

[0015] Optionally, based on the basic variables, intermediate variables are determined, and based on the intermediate variables, a judgment result of the phase compensation voltage before and after the fault is determined, wherein the intermediate variables include: the positive sequence power factor angle of the sampling point, the positive sequence power factor angle of two cycles before the fault, and the equivalent positive sequence power factor angle mutation amount;

[0016] The calculation formula of the positive sequence power factor angle is as follows:

[0017]

[0018] The calculation formula for the two-wave front positive sequence power factor angle is as follows:

[0019]

[0020] The calculation formula of the equivalent positive sequence power factor angle mutation is as follows:

[0021]

[0022] Among them, PF 1m is the positive sequence power factor angle, PF 1m|0| is the positive sequence power factor angle of two cycles ahead, ΔPF1 1.m is the equivalent positive sequence power factor angular mutation, is the measured voltage phasor of the fault phase 2 cycles before the fault, Measure the current phasor at the sampling point before the fault occurs. is the measured voltage phasor 2 cycles before the B phase fault, is the measured voltage phasor 2 cycles before the C phase fault, is the positive sequence voltage phasor of the faulty special phase 2 cycles before the fault, It is the positive sequence current phasor of the faulty special phase 2 cycles before the fault.

[0023] Optional, the discrimination result includes: the original discrimination result of the phase-comparison distance protection of the memory voltage polarization, and the discrimination formula is as follows:

[0024]

[0025] Among them, μ is the original judgment result of phase-comparison distance protection of memory voltage polarization, is the BC phase compensation voltage, It is the BC phase compensation voltage 2 cycles before the fault.

[0026] Optionally, based on the discrimination result, a memory voltage polarization characteristic correction link is added to the protection circuit, including:

[0027] When the original judgment result μ of the phase-to-phase distance protection of the memory voltage polarization in the judgment result falls on the action boundary, and the equivalent positive sequence power factor angle mutation ΔPF1 1m Indicates that when the fault of the protected circuit is in the reverse direction, a memory voltage polarization characteristic correction link is input to the protection circuit;

[0028] Among them, the correction parameters of the memory voltage polarization characteristic correction link include: the corrected line memory voltage and the memory positive sequence voltage correction angle;

[0029] Among them, the corrected line memory voltage is as follows:

[0030]

[0031] Among them, the memory positive sequence voltage correction angle is as follows:

[0032]

[0033] Among them, μ is the original judgment result of phase-to-phase distance protection of memory voltage polarization, ΔPF1 1.m is the equivalent positive sequence power factor angular mutation, is the corrected line memory voltage, To perform a counterclockwise rotation angle θ operation on the line memory voltage phasor.

[0034] In another aspect, the present invention further provides a system for memorizing the correct operation of voltage polarization ratio phase distance protection, comprising:

[0035] A data acquisition unit is used to obtain three-phase voltage data at a protection installation point after a protected line fails in the power system, and obtain basic variables based on the three-phase voltage data;

[0036] A first judging unit is configured to judge whether the protected line enters a phase-comparison distance protection logic with memory voltage polarization according to the basic variables and a preset judging formula;

[0037] A second discrimination unit is configured to determine, based on the basic variables, a discrimination result of the phase-to-phase compensation voltage before and after the fault, after the protected line enters the phase-to-phase distance protection logic with memory voltage polarization;

[0038] The protection unit is configured to, based on the discrimination result, input a memory voltage polarization characteristic correction link to the protection circuit and adjust correction parameters in the memory voltage polarization characteristic correction link to ensure that the memory voltage polarization phase-to-phase distance protection is correctly executed. Optionally, the three-phase voltage data includes:

[0039] After the protected line fails, the three-phase voltage and current phasors of the sampling point at the protection installation point, as well as the three-phase voltage and current phasors of the sampling point two cycles ago.

[0040] Optional, basic variables, including:

[0041] The positive sequence voltage and current corresponding to the three-phase voltage and current phasors, and the positive sequence voltage and current corresponding to the three-phase voltage and current phasors two weeks ago at the sampling point.

[0042] Optionally, a preset discriminant formula is as follows:

[0043]

[0044] in, is the positive sequence voltage phasor of the faulty special phase (taking phase A as an example), U N is the rated voltage of the line.

[0045] Optionally, based on the basic variables, intermediate variables are determined, and based on the intermediate variables, a judgment result of the phase compensation voltage before and after the fault is determined, wherein the intermediate variables include: the positive sequence power factor angle of the sampling point, the positive sequence power factor angle of two cycles before the fault, and the equivalent positive sequence power factor angle mutation amount;

[0046] The calculation formula of the positive sequence power factor angle is as follows:

[0047]

[0048] The calculation formula for the two-wave front positive sequence power factor angle is as follows:

[0049]

[0050] The calculation formula of the equivalent positive sequence power factor angle mutation is as follows:

[0051]

[0052] Among them, PF 1m is the positive sequence power factor angle, PF 1m|0| is the positive sequence power factor angle of two cycles ahead, ΔPF1 1.m is the equivalent positive sequence power factor angular mutation, is the measured voltage phasor of the fault phase 2 cycles before the fault, Measure the current phasor at the sampling point before the fault occurs. is the measured voltage phasor 2 cycles before the B phase fault, is the measured voltage phasor 2 cycles before the C phase fault, is the positive sequence voltage phasor of the faulty special phase 2 cycles before the fault, It is the positive sequence current phasor of the faulty special phase 2 cycles before the fault.

[0053] Optional, the discrimination result includes: the original discrimination result of the phase-comparison distance protection of the memory voltage polarization, and the discrimination formula is as follows:

[0054]

[0055] Among them, μ is the original judgment result of phase-comparison distance protection of memory voltage polarization, is the BC phase compensation voltage, It is the BC phase compensation voltage 2 cycles before the fault.

[0056] Optionally, based on the discrimination result, a memory voltage polarization characteristic correction link is added to the protection circuit, including:

[0057] When the original judgment result μ of the phase-to-phase distance protection of the memory voltage polarization in the judgment result falls on the action boundary, and the equivalent positive sequence power factor angle mutation ΔPF1 1m Indicates that when the fault of the protected circuit is in the reverse direction, a memory voltage polarization characteristic correction link is input to the protection circuit;

[0058] Among them, the correction parameters of the memory voltage polarization characteristic correction link include: the corrected line memory voltage and the memory positive sequence voltage correction angle;

[0059] Among them, the corrected line memory voltage is as follows:

[0060]

[0061] Among them, the memory positive sequence voltage correction angle is as follows:

[0062]

[0063] Among them, μ is the original judgment result of phase-to-phase distance protection of memory voltage polarization, ΔPF11.m is the equivalent positive sequence power factor angular mutation, is the corrected line memory voltage, To perform a counterclockwise rotation angle θ operation on the line memory voltage phasor.

[0064] In yet another aspect, the present invention further provides a computing device comprising: one or more processors;

[0065] a processor for executing one or more programs;

[0066] When the one or more programs are executed by the one or more processors, the above-described method is implemented.

[0067] In another aspect, the present invention further provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed, the method described above is implemented.

[0068] Compared with the prior art, the present invention has the following beneficial effects:

[0069] The present invention provides a method for correctly operating a memory voltage polarization phase-comparison distance protection, comprising: obtaining three-phase voltage data at a protection installation point after a protected line in a power system fails, obtaining basic variables based on the three-phase voltage data; judging whether the protected line enters the memory voltage polarization phase-comparison distance protection logic based on the basic variables and a preset discrimination formula; if the protected line enters the memory voltage polarization phase-comparison distance protection logic, determining a discrimination result of the phase-to-phase compensation voltage before and after the fault based on the basic variables; and, based on the discrimination result, applying a memory voltage polarization characteristic correction link to the protection line, and adjusting correction parameters in the memory voltage polarization characteristic correction link to correctly execute the memory voltage polarization phase-comparison distance protection. The present invention solves the problem of misoperation of distance protection caused by the memorized positive sequence voltage and the real-time fault current being substantially in phase, thereby improving the reliability of backup protection for near-zone AC lines in flexible direct current / new energy access systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 is a flow chart of an embodiment of the method of the present invention;

[0071] Figure 2 A topology diagram of a flexible direct current / new energy access alternating current system according to an embodiment of the method of the present invention;

[0072] Figure 3 This is a schematic diagram of voltage and current measurement for the AB phase short circuit to ABC three-phase short circuit protection outside the F5 zone of the method embodiment of the present invention;

[0073] Figure 4A schematic diagram of a malfunction of a phase-comparison distance protection with existing memory voltage polarization according to an embodiment of the method of the present invention;

[0074] Figure 5 ΔPF1 on the system side of the embodiment of the method of the present invention 1m Schematic diagram of the changes;

[0075] Figure 6 This is a schematic diagram of the operation of the phase-to-phase distance protection according to the improved solution of the method embodiment of the present invention;

[0076] Figure 7 It is a structural diagram of the system of the present invention. DETAILED DESCRIPTION

[0077] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to provide a thorough and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments shown in the accompanying drawings is not intended to limit the present invention. In the accompanying drawings, identical elements are denoted by the same reference numerals.

[0078] Unless otherwise specified, the terms used herein (including technical terms) have the meanings commonly understood by those skilled in the art. In addition, it is understood that terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0079] Example 1:

[0080] The present invention proposes a method for memorizing the correct action of voltage polarization phase ratio distance protection, such as Figure 1 Shown, including:

[0081] Step 1: Obtain three-phase voltage data at a protection installation point after a protected line fault occurs in the power system, and obtain basic variables based on the three-phase voltage data;

[0082] Step 2: judging whether the protected line enters the phase-comparison distance protection logic of memory voltage polarization based on the basic variables and a preset judgment formula;

[0083] Step 3: If the protected line enters the phase-comparison distance protection logic with memory voltage polarization, the judgment result of the phase compensation voltage before and after the fault is determined based on the basic variables;

[0084] Step 4: Based on the discrimination result, a memory voltage polarization characteristic correction link is added to the protection circuit, and correction parameters are adjusted in the memory voltage polarization characteristic correction link to ensure that the memory voltage polarization phase-to-phase distance protection is correctly executed. The three-phase voltage data includes:

[0085] After the protected line fails, the three-phase voltage and current phasors of the sampling point at the protection installation point, as well as the three-phase voltage and current phasors of the sampling point two cycles ago.

[0086] Among them, the basic variables include:

[0087] The positive sequence voltage and current corresponding to the three-phase voltage and current phasors, and the positive sequence voltage and current corresponding to the three-phase voltage and current phasors two weeks ago at the sampling point.

[0088] Among them, the preset discriminant formula is as follows:

[0089]

[0090] in, is the positive sequence voltage phasor of the faulty special phase (taking phase A as an example), U N is the rated voltage of the line.

[0091] Wherein, based on the basic variables, intermediate variables are determined, and based on the intermediate variables, the judgment result of the phase compensation voltage before and after the fault is determined, the intermediate variables include: the positive sequence power factor angle of the sampling point, the positive sequence power factor angle of two cycles before the fault, and the equivalent positive sequence power factor angle mutation amount;

[0092] The calculation formula of the positive sequence power factor angle is as follows:

[0093]

[0094] The calculation formula for the two-wave front positive sequence power factor angle is as follows:

[0095]

[0096] The calculation formula of the equivalent positive sequence power factor angle mutation is as follows:

[0097]

[0098] Among them, PF 1m is the positive sequence power factor angle, PF 1m|0| is the positive sequence power factor angle of two-wave front, ΔPF1 1.m is the equivalent positive sequence power factor angular mutation, is the measured voltage phasor of the fault phase 2 cycles before the fault, Measure the current phasor at the sampling point before the fault occurs. is the measured voltage phasor 2 cycles before the B phase fault, is the measured voltage phasor 2 cycles before the C phase fault, is the positive sequence voltage phasor of the faulty special phase 2 cycles before the fault, It is the positive sequence current phasor of the faulty special phase 2 cycles before the fault.

[0099] The discrimination result includes: the original discrimination result of the phase-comparison distance protection of the memory voltage polarization, and the discrimination formula is as follows:

[0100]

[0101] Among them, μ is the original judgment result of phase-comparison distance protection of memory voltage polarization, is the BC phase compensation voltage, It is the BC phase compensation voltage 2 cycles before the fault.

[0102] Wherein, based on the discrimination result, a memory voltage polarization characteristic correction link is added to the protection circuit, including:

[0103] When the original judgment result μ of the phase-to-phase distance protection of the memory voltage polarization in the judgment result falls on the action boundary, and the equivalent positive sequence power factor angle mutation ΔPF1 1m Indicates that when the fault of the protected circuit is in the reverse direction, a memory voltage polarization characteristic correction link is input to the protection circuit;

[0104] Among them, the correction parameters of the memory voltage polarization characteristic correction link include: the corrected line memory voltage and the memory positive sequence voltage correction angle;

[0105] Among them, the corrected line memory voltage is as follows:

[0106]

[0107] Among them, the memory positive sequence voltage correction angle is as follows:

[0108]

[0109] Among them, μ is the original judgment result of phase-to-phase distance protection of memory voltage polarization, ΔPF1 1.m is the equivalent positive sequence power factor angular mutation, is the corrected line memory voltage, To perform a counterclockwise rotation angle θ operation on the line memory voltage phasor.

[0110] The present invention will be further described below with reference to specific implementation cases:

[0111] First, obtain the three-phase voltage and current phasors at the protection installation point of the protected line And the three-phase voltage and current phasors of two wave fronts The subscript |0| represents the two cycles before the current sampling point;

[0112] The following analysis is based on the phase-to-phase distance protection of the memory voltage polarization between phases BC on the system side (m side). The same applies to phases CA and AB. First, calculate the positive sequence voltage and positive sequence current

[0113]

[0114] Then calculate the memorized positive sequence voltage and current two cycles ago

[0115]

[0116] Where, is the rotation factor, and the subscript |0| represents the memory of the first two cycles.

[0117] Determine whether the positive sequence voltage amplitude after a fault enters the phase comparison distance protection logic of the memory voltage polarization:

[0118]

[0119] When equation (3) is satisfied, the protection enters the phase-comparison distance protection logic with memory voltage polarization.

[0120] Since the positive sequence voltage is too low, the phase-to-phase voltage memory is used. and real-time positive sequence current Calculate the positive sequence power factor angle PF of the current sampling point after the fault 1m :

[0121]

[0122] Calculate the positive sequence power factor angle PF for two cycles ahead 1m|0| :

[0123]

[0124] Calculate the equivalent positive sequence power factor angle mutation ΔPF1 1m :

[0125]

[0126] The original judgment result of the phase-comparison distance protection with memory voltage polarization is:

[0127]

[0128] The improved criterion for phase-comparison distance protection with memory voltage polarization is:

[0129]

[0130] Where U com To compensate voltage, BC phase distance protection:

[0131]

[0132] Where Z set It is the line positive sequence impedance corresponding to the protection range.

[0133] This is the corrected line memory voltage:

[0134]

[0135] Where θ is the memory positive sequence voltage correction angle. The selection of θ angle depends on the original phase comparison judgment result μ and the calculation of the positive sequence power factor angle mutation ΔPF1. 1m :

[0136]

[0137] For flexible DC and new energy access systems that use a unity power factor control strategy after a fault, when a three-phase fault occurs on the busbar on the nearby AC line system side, the converter still maintains the original phase output without sudden change, resulting in the memory voltage and the real-time positive sequence current being basically in phase, which may cause the phase-comparison distance protection on the system side to malfunction due to the polarization of the memory voltage. The judgment results μ and ΔPF1 of the original phase comparison criterion are used to determine the phase-comparison distance protection. 1m The inverter control characteristics can be inverted. When μ falls on the action boundary and ΔPF1 1m When the fault is in the reverse direction, the memory voltage polarization characteristic correction link is put into use, as shown in equations (10) to (11), which can effectively solve the problem of incorrect operation of the phase-comparison distance protection due to memory voltage polarization.

[0138] The effectiveness of the proposed scheme is verified by taking the actual positive sequence voltage polarization phase comparison distance protection misoperation case of a photovoltaic AC transmission system in a western province as an example. Figure 2 As shown, the photovoltaic station adopts the fixed unity power factor control strategy and the negative sequence suppression control strategy. The fault occurrence time is 40ms. The fault point is at F5. The fault type is the AB interphase short circuit fault at F5 turning into ABC three-phase short circuit fault. The action results of the existing memory voltage polarization phase-to-phase distance protection and the action characteristics of the improved scheme are plotted as shown in Figure 3-Figure 6 shown.

[0139] Depend on Figure 3It can be seen that after the fault, the system voltage drops severely, entering the phase-comparison distance protection link of memory voltage polarization, and the photovoltaic inverter suppresses the negative sequence current, which deteriorates the performance of the distance protection operation. Figure 4 It can be seen that after the fault turns into a three-phase short circuit fault, the phase-comparison distance protection malfunctions due to the polarization of the memory voltage between phases AB at about 68ms, and the phase-comparison angle is about 94°, entering the action zone. Figure 5 It can be seen that the system side ΔPF1 1m After 60ms, it drops rapidly to about 0, and Equation (11) is satisfied. The angle θ is adjusted adaptively. In Equation (10), the action area is equivalently moved up by 15°, as shown in Figure 6 As shown in the figure, the false operation of the phase-to-phase distance protection due to the memory voltage polarization is effectively avoided, and the reliability of the protection is improved.

[0140] Example 2:

[0141] The present invention also proposes a system 200 for memorizing the correct action of voltage polarization ratio phase distance protection, such as Figure 7 Shown, including:

[0142] The data acquisition unit 201 is used to obtain three-phase voltage data at a protection installation point after a protected line fails in the power system, and obtain basic variables based on the three-phase voltage data;

[0143] A first determination unit 202 is configured to determine whether the protected line enters a phase-comparison distance protection logic with memory voltage polarization according to the basic variables and a preset determination formula;

[0144] The second determination unit 203 is configured to determine the determination result of the phase-to-phase compensation voltage before and after the fault based on the basic variables after the protected line enters the phase-to-phase distance protection logic with memory voltage polarization;

[0145] The protection unit 204 is configured to, based on the discrimination result, apply a memory voltage polarization characteristic correction link to the protection circuit and adjust correction parameters in the memory voltage polarization characteristic correction link to ensure that the memory voltage polarization phase-to-phase distance protection is correctly executed. The three-phase voltage data includes:

[0146] After the protected line fails, the three-phase voltage and current phasors of the sampling point at the protection installation point, as well as the three-phase voltage and current phasors of the sampling point two cycles ago.

[0147] Among them, the basic variables include:

[0148] The positive sequence voltage and current corresponding to the three-phase voltage and current phasors, and the positive sequence voltage and current corresponding to the three-phase voltage and current phasors two weeks ago at the sampling point.

[0149] Among them, the preset discriminant formula is as follows:

[0150]

[0151] in, is the positive sequence voltage phasor of the faulty special phase (taking phase A as an example), U N is the rated voltage of the line.

[0152] Wherein, based on the basic variables, intermediate variables are determined, and based on the intermediate variables, the judgment result of the phase compensation voltage before and after the fault is determined, the intermediate variables include: the positive sequence power factor angle of the sampling point, the positive sequence power factor angle of two cycles before the fault, and the equivalent positive sequence power factor angle mutation amount;

[0153] The calculation formula of the positive sequence power factor angle is as follows:

[0154]

[0155] The calculation formula for the two-wave front positive sequence power factor angle is as follows:

[0156]

[0157] The calculation formula of the equivalent positive sequence power factor angle mutation is as follows:

[0158]

[0159] Among them, PF 1m is the positive sequence power factor angle, PF 1m|0| is the positive sequence power factor angle of two-wave front, ΔPF1 1.m is the equivalent positive sequence power factor angular mutation, is the measured voltage phasor of the fault phase 2 cycles before the fault, Measure the current phasor at the sampling point before the fault occurs. is the measured voltage phasor 2 cycles before the B phase fault, is the measured voltage phasor 2 cycles before the C phase fault, is the positive sequence voltage phasor of the faulty special phase 2 cycles before the fault, is the positive sequence current phasor of the faulty special phase 2 cycles before the fault. The discrimination result includes: the original discrimination result of the phase-comparison distance protection with memory voltage polarization, and the discrimination formula is as follows:

[0160]

[0161] Among them, μ is the original judgment result of phase-comparison distance protection of memory voltage polarization, is the BC phase compensation voltage, It is the BC phase compensation voltage 2 cycles before the fault.

[0162] Wherein, based on the discrimination result, a memory voltage polarization characteristic correction link is added to the protection circuit, including:

[0163] When the original judgment result μ of the phase-to-phase distance protection of the memory voltage polarization in the judgment result falls on the action boundary, and the equivalent positive sequence power factor angle mutation ΔPF1 1m Indicates that when the fault of the protected circuit is in the reverse direction, a memory voltage polarization characteristic correction link is input to the protection circuit;

[0164] Among them, the correction parameters of the memory voltage polarization characteristic correction link include: the corrected line memory voltage and the memory positive sequence voltage correction angle;

[0165] Among them, the corrected line memory voltage is as follows:

[0166]

[0167] Among them, the memory positive sequence voltage correction angle is as follows:

[0168]

[0169] Among them, μ is the original judgment result of phase-to-phase distance protection of memory voltage polarization, ΔPF1 1.m is the equivalent positive sequence power factor angular mutation, is the corrected line memory voltage, To perform a counterclockwise rotation angle θ operation on the line memory voltage phasor.

[0170] The present invention introduces equivalent positive-sequence power factor angle mutation information into the phase comparison criterion, and utilizes the significant difference between the smaller equivalent positive-sequence power factor angle mutation amount and the larger equivalent positive-sequence power factor angle mutation amount on the system side caused by the control characteristics of the flexible DC converter with fault in the area, to adaptively correct the phase angle of the polarization voltage in the phase comparison criterion, thereby solving the problem of false operation of distance protection caused by the memorized positive-sequence voltage and the real-time fault current being basically in phase, and improving the reliability of backup protection of AC lines in the vicinity of the flexible DC / new energy access system.

[0171] Example 3:

[0172] Based on the same inventive concept, the present invention also provides a computer device, which includes a processor and a memory, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc., which are the computing core and control core of the terminal, which is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding functions, so as to implement the steps of the method in the above embodiment.

[0173] Example 4:

[0174] Based on the same inventive concept, the present invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device for storing programs and data. It can be understood that the computer-readable storage medium here can include both built-in storage media in the computer device and, of course, extended storage media supported by the computer device. The computer-readable storage medium provides a storage space that stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space. These instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of the method in the above embodiment.

[0175] It will be understood by those skilled in the art that the embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of the present invention may be implemented in various computer languages, for example, the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0176] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0177] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0178] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0179] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0180] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for executing a memorized voltage polarization phase ratio distance protection action, characterized in that: include: Obtaining three-phase voltage data at a protection installation point after a protected line fault occurs in the power system, and obtaining basic variables based on the three-phase voltage data; According to the basic variables and based on a preset judgment formula, it is judged whether the protected line enters the phase comparison distance protection logic of the memory voltage polarization; If the protected line enters the phase-comparison distance protection logic with memory voltage polarization, the judgment result of the phase-to-phase compensation voltage before and after the fault is determined based on the basic variables; Based on the discrimination result, a memory voltage polarization characteristic correction link is added to the protection circuit, and correction parameters are adjusted in the memory voltage polarization characteristic correction link to ensure that the memory voltage polarization phase-to-phase distance protection is correctly executed.

2. The method according to claim 1, characterized in that The three-phase voltage data includes: After the protected line fails, the three-phase voltage and current phasors of the sampling point at the protection installation point, as well as the three-phase voltage and current phasors of the sampling point two cycles ago.

3. The method according to claim 1, characterized in that The basic variables include: The positive sequence voltage and current corresponding to the three-phase voltage and current phasors, and the positive sequence voltage and current corresponding to the three-phase voltage and current phasors two weeks ago at the sampling point.

4. The method according to claim 1, wherein The preset discriminant formula is as follows: in, is the positive sequence voltage phasor of the faulty special phase, U N is the rated voltage of the line.

5. The method according to claim 1, wherein Based on the basic variables, intermediate variables are determined, and based on the intermediate variables, a judgment result of the interphase compensation voltage before and after the fault is determined, wherein the intermediate variables include: a positive-sequence power factor angle at the sampling point, a positive-sequence power factor angle two cycles ahead, and a mutation amount of the equivalent positive-sequence power factor angle; The calculation formula of the positive sequence power factor angle is as follows: The calculation formula for the two-wave front positive sequence power factor angle is as follows: The calculation formula of the equivalent positive sequence power factor angle mutation is as follows: Among them, PF 1m is the positive sequence power factor angle, PF 1m|0| is the positive sequence power factor angle of two-wave front, ΔPF1 1.m is the equivalent positive sequence power factor angular mutation, is the measured voltage phasor of the fault phase 2 cycles before the fault, Measure the current phasor at the sampling point before the fault occurs. is the measured voltage phasor 2 cycles before the B phase fault, is the measured voltage phasor 2 cycles before the C phase fault, is the positive sequence voltage phasor of the faulty special phase 2 cycles before the fault, It is the positive sequence current phasor of the faulty special phase 2 cycles before the fault.

6. The method according to claim 1, characterized in that The discrimination result includes: the original discrimination result of the phase-comparison distance protection of the memory voltage polarization, and the discrimination formula is as follows: Among them, μ is the original judgment result of phase-comparison distance protection of memory voltage polarization, is the BC phase compensation voltage, It is the BC phase compensation voltage 2 cycles before the fault.

7. The method according to claim 1, characterized in that Based on the discrimination result, a memory voltage polarization characteristic correction link is added to the protection circuit, including: When the original judgment result μ of the phase-to-phase distance protection of the memory voltage polarization in the judgment result falls on the action boundary, and the equivalent positive sequence power factor angle mutation ΔPF1 1m Indicates that when the fault of the protected circuit is in the reverse direction, a memory voltage polarization characteristic correction link is input to the protection circuit; Among them, the correction parameters of the memory voltage polarization characteristic correction link include: the corrected line memory voltage and the memory positive sequence voltage correction angle; Among them, the corrected line memory voltage is as follows: Among them, the memory positive sequence voltage correction angle is as follows: Among them, μ is the original judgment result of phase-to-phase distance protection of memory voltage polarization, ΔPF1 1.m is the equivalent positive sequence power factor angular mutation, is the corrected line memory voltage, To perform a counterclockwise rotation angle θ operation on the line memory voltage phasor.

8. A system for memorizing voltage polarization phase ratio distance protection action execution, characterized in that: include: A data acquisition unit is used to obtain three-phase voltage data at a protection installation point after a protected line fails in the power system, and obtain basic variables based on the three-phase voltage data; A first judging unit is configured to judge whether the protected line enters a phase-comparison distance protection logic with memory voltage polarization according to the basic variables and a preset judging formula; A second discrimination unit is configured to determine, based on the basic variables, a discrimination result of the phase-to-phase compensation voltage before and after the fault, after the protected line enters the phase-to-phase distance protection logic with memory voltage polarization; The protection unit is used to input a memory voltage polarization characteristic correction link into the protection circuit based on the discrimination result, and adjust correction parameters in the memory voltage polarization characteristic correction link to ensure that the memory voltage polarization phase-to-phase distance protection is correctly executed.

9. The system according to claim 8, characterized in that The three-phase voltage data includes: After the protected line fails, the three-phase voltage and current phasors of the sampling point at the protection installation point, as well as the three-phase voltage and current phasors of the sampling point two cycles ago.

10. The system according to claim 8, wherein: The basic variables include: The positive sequence voltage and current corresponding to the three-phase voltage and current phasors, and the positive sequence voltage and current corresponding to the three-phase voltage and current phasors two weeks ago at the sampling point.

11. The system according to claim 8, wherein: The preset discriminant formula is as follows: in, is the positive sequence voltage phasor of the faulty special phase (taking phase A as an example), U N is the rated voltage of the line.

12. The system according to claim 8, wherein: Based on the basic variables, intermediate variables are determined, and based on the intermediate variables, a judgment result of the interphase compensation voltage before and after the fault is determined, wherein the intermediate variables include: a positive-sequence power factor angle at the sampling point, a positive-sequence power factor angle two cycles ahead, and a mutation amount of the equivalent positive-sequence power factor angle; The calculation formula of the positive sequence power factor angle is as follows: The calculation formula for the two-wave front positive sequence power factor angle is as follows: The calculation formula of the equivalent positive sequence power factor angle mutation is as follows: Among them, PF 1m is the positive sequence power factor angle, PF 1m|0| is the positive sequence power factor angle of two cycles ahead, ΔPF1 1.m is the equivalent positive sequence power factor angular mutation, is the measured voltage phasor of the fault phase 2 cycles before the fault, Measure the current phasor at the sampling point before the fault occurs. is the measured voltage phasor 2 cycles before the B phase fault, is the measured voltage phasor 2 cycles before the C phase fault, is the positive sequence voltage phasor of the faulty special phase 2 cycles before the fault, It is the positive sequence current phasor of the faulty special phase 2 cycles before the fault.

13. The system according to claim 8, wherein: The discrimination result includes: the original discrimination result of the phase-comparison distance protection of the memory voltage polarization, and the discrimination formula is as follows: Among them, μ is the original judgment result of phase-comparison distance protection of memory voltage polarization, for, for.

14. The system according to claim 8, wherein: Based on the discrimination result, a memory voltage polarization characteristic correction link is added to the protection circuit, including: When the original judgment result μ of the phase-to-phase distance protection of the memory voltage polarization in the judgment result falls on the action boundary, and the equivalent positive sequence power factor angle mutation ΔPF1 1m Indicates that when the fault of the protected circuit is in the reverse direction, a memory voltage polarization characteristic correction link is input to the protection circuit; Among them, the correction parameters of the memory voltage polarization characteristic correction link include: the corrected line memory voltage and the memory positive sequence voltage correction angle; Among them, the corrected line memory voltage is as follows: Among them, the memory positive sequence voltage correction angle is as follows: Among them, μ is the original judgment result of phase-to-phase distance protection of memory voltage polarization, ΔPF1 1.m is the equivalent positive sequence power factor angular mutation, is the corrected line memory voltage, To perform a counterclockwise rotation angle θ operation on the line memory voltage phasor.

15. A computer device, characterized in that: include: one or more processors; a processor for executing one or more programs; When the one or more programs are executed by the one or more processors, the method according to any one of claims 1 to 7 is implemented.

16. A computer-readable storage medium, characterized in that A computer program is stored thereon, and when the computer program is executed, the method according to any one of claims 1 to 7 is implemented.

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