Grounding distance protection method and device for coping with weak short-circuit current of power transmission line

Abstract

The invention discloses a grounding distance protection method and device for coping with weak short-circuit current of a power transmission line. The method comprises the following steps: calculating a zero-sequence voltage, a zero-sequence current, a zero-sequence compensation voltage, a grounding compensation voltage and an interphase compensation voltage according to a three-phase voltage vector, a three-phase current vector and a preset high-resistance distance protection constant value at a protection mounting point; determining the fault direction of the protection mounting point according to the zero-sequence direction element criterion; when the fault direction is a positive direction fault, determining a fault phase according to a three-phase current vector and a preset sequence current absolute value phase selection element criterion; determining a short-circuit fault type of the fault phase according to the fault phase and a preset short-circuit fault type criterion; determining a short-circuit fault position according to the short-circuit fault type, the grounding compensation voltage of the fault phase, the inter-phase voltage vector, the inter-phase current phasor and a preset short-circuit fault position criterion; and starting corresponding grounding distance relay action protection according to the short circuit fault position.

Description

Technical Field

[0001] The present invention relates to the technical field of power system transmission line protection, and more specifically, to a ground distance protection method and device for coping with weak short-circuit current of a transmission line. Background Art

[0002] When a ground short circuit fault occurs in an overhead transmission line through a large transition resistance, the voltage drop at the fault point is not obvious, and the current flowing into the fault point is relatively weak, causing the phase differential protection to be insensitive due to the small differential current, and the distance protection to be unable to operate due to the large measurement impedance and difficulty in falling into the action area, resulting in the inability to remove the fault, which has an adverse impact on the safe and stable operation of equipment and power grids. The existing polygonal characteristic impedance distance protection, variable distance protection, and positive sequence voltage polarization phase-to-phase distance protection have weak resistance to transition resistance and are insufficiently sensitive in weak short-circuit current ground short-circuit fault scenarios. It is urgent to study ground distance protection methods for weak short-circuit currents. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a grounding distance protection method and device for coping with weak short-circuit current of a transmission line.

[0004] According to one aspect of the present invention, there is provided a ground distance protection method for weak short-circuit current of a transmission line, comprising:

[0005] Calculate the zero-sequence voltage, zero-sequence current, zero-sequence compensation voltage, grounding compensation voltage and phase-to-phase compensation voltage according to the obtained three-phase voltage vector, three-phase current vector and preset high-resistance distance protection setting at the protection installation point;

[0006] Determine the fault direction of the protection installation point based on the zero-sequence voltage, zero-sequence current and the preset zero-sequence direction element criterion;

[0007] In the case where the fault direction is a positive fault, the fault phase is determined according to the three-phase current vector and the preset sequence current absolute value phase selection component criterion;

[0008] Determine the short-circuit fault type of the fault phase according to the grounding compensation voltage, phase-to-phase compensation voltage, zero-sequence current, zero-sequence voltage of the fault phase and the preset short-circuit fault type judgment criterion;

[0009] Determine the short-circuit fault location according to the short-circuit fault type, the grounding compensation voltage of the fault phase, the phase-to-phase voltage vector and the phase-to-phase current phasor, and the preset short-circuit fault location criterion;

[0010] According to the short-circuit fault location, the corresponding ground distance relay is activated for protection.

[0011] Optionally, the zero sequence voltage and zero sequence current The calculation formula is:

[0012]

[0013] In the formula, They are the three-phase voltage and current phasors at the protection installation point respectively;

[0014] Preset high resistance distance protection setting Z set The expression is:

[0015] Z set =KZ l

[0016] In the formula, Z1 is the positive sequence impedance of the entire line at this level, and K is the reliability coefficient;

[0017] Zero sequence compensation voltage The calculation formula is:

[0018]

[0019] Ground compensation voltage And phase compensation voltage The calculation formula is:

[0020]

[0021] In the formula, k = (z0-z1) / 3z1 is the zero-sequence compensation coefficient of this line, z 0、 z1 are the zero-sequence impedance and positive-sequence impedance per unit length of the line, are the voltage and current phasors of each phase, are the phase-to-phase voltage and current phasors respectively, and the superscript ' represents the compensation amount.

[0022] Optionally, the expression of the zero-sequence directional element criterion is:

[0023]

[0024] Wherein, k1 is the reliability coefficient, k0 is the zero-sequence compensation coefficient of the line; when the zero-sequence direction element criterion is met, it is determined to be a positive direction fault and enters the high-resistance distance protection pre-selection phase process; otherwise, it is determined to be a reverse direction fault and the high-resistance distance protection is locked.

[0025] Optionally, the expression of the sequence current absolute value phase selection element criterion is:

[0026]

[0027] In the formula, is the positive sequence current phasor based on the current phase, The current amplitude of the corresponding phase with the positive sequence removed is: The maximum phase is confirmed as the fault phase.

[0028] Optionally, determining the short-circuit fault type of the fault phase according to the grounding compensation voltage, the phase-to-phase compensation voltage, the zero-sequence current, the zero-sequence voltage and a preset short-circuit fault type criterion of the fault phase includes:

[0029] Determine whether the interphase compensation voltage of the fault phase meets the first short-circuit fault criterion. If so, determine whether the zero-sequence current, grounding compensation voltage and interphase compensation voltage of the fault phase meet the second short-circuit fault criterion or the third short-circuit fault criterion.

[0030] When the second short-circuit fault criterion is met, the short-circuit fault type is determined to be a fault phase high-resistance grounding short-circuit fault;

[0031] When the third short-circuit fault criterion is met, it is determined that the short-circuit fault type is a fault phase low-resistance grounding short-circuit fault.

[0032] Optionally, the first short circuit fault criterion is:

[0033]

[0034] Wherein, when the first short-circuit fault criterion is not met, the phase selection fails to lock the high-resistance distance relay;

[0035] The second short-circuit fault criterion is:

[0036]

[0037] The third short-circuit fault criterion is:

[0038]

[0039] In the formula, I set It is the zero-sequence current threshold. If the second short-circuit fault criterion and the third short-circuit fault criterion are not met, the phase selection fails and the high-resistance distance relay is locked.

[0040] Optionally, determining the short-circuit fault location according to the short-circuit fault type, the grounding compensation voltage of the fault phase, the phase-to-phase voltage vector and the phase-to-phase current phasor, and a preset short-circuit fault location criterion includes:

[0041] According to the phase-to-phase voltage vector of the fault phase, the phase compensation voltage before the fault is calculated;

[0042] According to the grounding compensation voltage of the fault phase and the phase compensation voltage before the fault, the phase compensation voltage change before and after the fault is calculated;

[0043] Calculate the characteristic angle of overload and fault according to the interphase voltage vector and interphase current phasor of the fault phase;

[0044] It is determined whether the characteristic angle, the phase compensation voltage before the fault and the change in the phase compensation voltage meet the short-circuit fault location criterion, and the short-circuit fault location is determined according to the judgment result.

[0045] Optionally, the short circuit fault location criterion includes:

[0046] Line sending end judgment criteria:

[0047]

[0048] Line receiving end judgment criteria:

[0049]

[0050] Phase-separated high-resistance ground distance relay criterion:

[0051]

[0052] Where α = 180-Z Line.1 , Z Line.1 is the line positive sequence impedance, the selection principle of γ1 is:

[0053]

[0054] In the formula, is the phase compensation voltage before the phase fault; is the phase compensation voltage change; characteristic angle is the line positive sequence impedance angle; is the ground compensation voltage.

[0055] According to another aspect of the present invention, there is provided a ground distance protection device for coping with weak short-circuit current of a transmission line, comprising:

[0056] A calculation module is used to calculate the zero-sequence voltage, zero-sequence current, zero-sequence compensation voltage, grounding compensation voltage and phase-to-phase compensation voltage according to the acquired three-phase voltage vector, three-phase current vector and preset high-resistance distance protection setting at the protection installation point;

[0057] A first determination module is used to determine the fault direction of the protection installation point according to the zero-sequence voltage, the zero-sequence current and a preset zero-sequence direction element criterion;

[0058] The second determination module is used to determine the fault phase according to the three-phase current vector and the preset sequence current absolute value phase selection component criterion when the fault direction is a positive direction fault;

[0059] A third determination module is used to determine the short-circuit fault type of the fault phase according to the grounding compensation voltage, phase-to-phase compensation voltage, zero-sequence current, zero-sequence voltage of the fault phase and a preset short-circuit fault type criterion;

[0060] A fourth determination module is used to determine the short-circuit fault location according to the short-circuit fault type, the grounding compensation voltage of the fault phase, the phase-to-phase voltage vector and the phase-to-phase current phasor, and a preset short-circuit fault location criterion;

[0061] The starting module is used to start the corresponding ground distance relay protection according to the short circuit fault location.

[0062] According to another aspect of the present invention, a computer-readable storage medium is provided, wherein the storage medium stores a computer program, and the computer program is used to execute the method described in any one of the above aspects of the present invention.

[0063] According to another aspect of the present invention, an electronic device is provided, comprising: a processor; a memory for storing instructions executable by the processor; the processor is configured to read the executable instructions from the memory and execute the instructions to implement the method described in any one of the above aspects of the present invention.

[0064] Therefore, the present invention proposes a new scheme for weak short-circuit current grounding distance protection. This scheme takes into account the advantages of distance protection selectivity and zero-sequence protection sensitivity, and can cut off high-resistance grounding short-circuit faults with zero-sequence current not less than 150A, greatly improving the performance of relay protection devices under high transition resistance weak short-circuit current grounding short-circuit faults. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0066] Figure 1 It is a flow chart of a ground distance protection method for weak short-circuit current of a power transmission line provided by an exemplary embodiment of the present invention;

[0067] Figure 2 is a flow chart of a high-ancestor distance protection algorithm provided by an exemplary embodiment of the present invention;

[0068] Figure 3 is a schematic diagram of a simulation verification platform provided by an exemplary embodiment of the present invention;

[0069] Figure 4 It is a structural schematic diagram of a ground distance protection device for coping with weak short-circuit current of a transmission line provided by an exemplary embodiment of the present invention;

[0070] Figure 5 This is a structure of an electronic device provided by an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0071] Below, the exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments of the present invention, and it should be understood that the present invention is not limited to the exemplary embodiments described here.

[0072] It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

[0073] Those skilled in the art can understand that the terms "first" and "second" in the embodiments of the present invention are only used to distinguish different steps, devices or modules, etc., and neither represent any specific technical meaning nor indicate the necessary logical order between them.

[0074] It should also be understood that, in the embodiments of the present invention, “plurality” may refer to two or more than two, and “at least one” may refer to one, two or more than two.

[0075] It should also be understood that any component, data or structure mentioned in the embodiments of the present invention can generally be understood as one or more, unless explicitly limited or otherwise indicated in the context.

[0076] In addition, the term "and / or" in the present invention is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects before and after are in an "or" relationship.

[0077] It should also be understood that the description of the various embodiments of the present invention focuses on the differences between the various embodiments, and the same or similar aspects thereof can be referenced to each other, and for the sake of brevity, they will not be described one by one.

[0078] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0079] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0080] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0081] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0082] Embodiments of the present invention can be applied to electronic devices such as terminal devices, computer systems, servers, etc., which can operate with many other general or special computing system environments or configurations. Examples of well-known terminal devices, computing systems, environments and / or configurations suitable for use with electronic devices such as terminal devices, computer systems, servers, etc. include, but are not limited to: personal computer systems, server computer systems, thin clients, thick clients, handheld or laptop devices, microprocessor-based systems, set-top boxes, programmable consumer electronics, network personal computers, small computer systems, large computer systems, and distributed cloud computing technology environments including any of the above systems, etc.

[0083] Electronic devices such as terminal devices, computer systems, servers, etc. can be described in the general context of computer system executable instructions (such as program modules) executed by computer systems. Generally, program modules can include routines, programs, object programs, components, logic, data structures, etc., which perform specific tasks or implement specific abstract data types. Computer systems / servers can be implemented in a distributed cloud computing environment, where tasks are performed by remote processing devices linked through a communication network. In a distributed cloud computing environment, program modules can be located on local or remote computing system storage media including storage devices.

[0084] Exemplary Methods

[0085] Figure 1 FIG. 1 is a flow chart of a method for ground distance protection of a power transmission line against weak short-circuit current provided by an exemplary embodiment of the present invention. This embodiment can be applied to electronic devices, such as Figure 1 As shown, the ground distance protection method 100 for weak short-circuit current of a transmission line includes the following steps:

[0086] Step 101, calculating the zero-sequence voltage, zero-sequence current, zero-sequence compensation voltage, grounding compensation voltage and phase-to-phase compensation voltage according to the acquired three-phase voltage vector, three-phase current vector and preset high-resistance distance protection setting at the protection installation point;

[0087] Step 102, determining the fault direction of the protection installation point according to the zero-sequence voltage, the zero-sequence current and a preset zero-sequence direction element criterion;

[0088] Step 103, when the fault direction is a positive fault, determine the fault phase according to the three-phase current vector and a preset sequence current absolute value phase selection component criterion;

[0089] Step 104, determining the short circuit fault type of the fault phase according to the grounding compensation voltage, phase-to-phase compensation voltage, zero-sequence current, zero-sequence voltage of the fault phase and a preset short circuit fault type criterion;

[0090] Step 105, determining the short-circuit fault location according to the short-circuit fault type, the grounding compensation voltage of the fault phase, the phase-to-phase voltage vector and the phase-to-phase current phasor, and a preset short-circuit fault location criterion;

[0091] Step 106: according to the short circuit fault position, start the corresponding ground distance relay protection.

[0092] Specifically, in view of the shortcomings of the existing differential protection and distance protection in the case of high-resistance grounding short-circuit faults, the insufficient selectivity of the staged time-limited overcurrent protection, and the difficulty in setting the zero-sequence inverse time-limited protection, a new scheme for weak short-circuit current grounding distance protection is proposed based on the unique fault characteristics of the grounding point voltage and zero-sequence current. This scheme takes into account the advantages of distance protection selectivity and zero-sequence protection sensitivity, and can cut off high-resistance grounding short-circuit faults with zero-sequence current not less than 150A, greatly improving the performance of the relay protection device under high transition resistance weak short-circuit current grounding short-circuit faults.

[0093] The present invention proposes a distance protection method for high transition resistance grounding short circuit fault, including a ratio-amplitude zero-sequence directional element based on zero-sequence compensation voltage, a high-resistance grounding fault phase selection method based on the polarization of zero-sequence reactance line and non-fault phase compensation voltage, and a ratio-phase high-resistance grounding distance protection relay based on phase compensation voltage variation. Figure 2 As shown, the specific implementation of the method is as follows:

[0094] (1) Data preparation

[0095] Get the three-phase voltage and current phasors at the protection installation point Calculate zero sequence voltage and zero sequence current

[0096]

[0097] Set the high resistance distance protection setting

[0098] Z set =KZ l (1.2)

[0099] Where Z1 is the positive sequence impedance of the entire line at this level, and K is the reliability coefficient, which reflects the scope of protecting the lower-level line.

[0100] Calculate zero-sequence compensation voltage

[0101]

[0102] Calculate the ground compensation voltage and phase compensation voltage:

[0103]

[0104] In the formula, k = (z0-z1) / 3z1 is the zero-sequence compensation coefficient of this line, They are the ground compensation voltage and the phase compensation voltage, are the voltage and current phasors of each phase, are the phase-to-phase voltage and current phasors respectively.

[0105] (2) Main criteria

[0106] 1) Zero-sequence directional element (criterion 1)

[0107] The zero-sequence directional element is responsible for determining the fault direction. For a reverse fault, the high-resistance distance protection is locked. When criterion 1 is met, it is considered a positive fault and enters the high-resistance distance protection pre-selection phase process:

[0108]

[0109] 2) The sequence current absolute value phase selection element preliminarily determines the fault phase according to the phase relationship of each sequence current of different types of short-circuit faults (criterion 2):

[0110]

[0111] In the formula, is the positive sequence current phasor based on the current phase, The positive sequence current amplitude is eliminated for the corresponding phase. The maximum phase is confirmed as the fault phase.

[0112] 3) Taking the A phase initially selected by formula (1.6) as an example, determine whether the compensation voltage amplitude between the BC phases satisfies the following formula:

[0113]

[0114] If equation (1.7) is satisfied, proceed to the next step, otherwise the phase selection fails and the high-resistance distance relay is locked.

[0115] 4) Determine whether the following formula is satisfied (criterion 3):

[0116]

[0117] If equation (1.8) is satisfied, it is determined to be a high-resistance ground short circuit fault of phase A in the zone, otherwise proceed to the next step.

[0118] 5) Determine whether the following formula is satisfied (criterion 4):

[0119]

[0120] In the formula, I setis the zero-sequence current threshold, which can be set to 1.5 kA. If equation (1.9) is satisfied, it is judged as a low-resistance ground short circuit fault of phase A in the area.

[0121] If equations (1.8) and (1.9) are not satisfied, the phase selection fails and the high-resistance distance relay is locked.

[0122] 6) High resistance distance relay

[0123] Calculate the phase compensation voltage before the fault:

[0124]

[0125] Calculate the phase compensation voltage change:

[0126]

[0127] Calculate the characteristic angle reflecting overload and fault:

[0128]

[0129] In the formula, is the line positive sequence impedance angle.

[0130] If the following criteria are met, it is identified as the line sending end (criterion 5):

[0131]

[0132] If the following criteria are met, it is identified as the receiving end of the line:

[0133]

[0134] Set up the phase-separated high-resistance ground distance relay (criterion 6):

[0135]

[0136] α=180-Z Line.1 , Z Line.1 is the line positive sequence impedance, the selection principle of γ1 is:

[0137]

[0138] When equation (1.8) - equation (1.9) is selected Mutually, The corresponding formula (1.18) satisfies, then Phase new type high resistance ground distance relay action output.

[0139] Table 1 Results of various criteria for short-circuit fault at point F2 AN in the area with different transition resistances

[0140]

[0141]

[0142] Note: Phase selection result "1" means phase A is selected

[0143] Table 2 Results of various criteria for short-circuit fault of ABN at F3 outside the area through different transition resistances

[0144]

[0145] Note: Phase selection result "0" means phase selection failed

[0146] Table 3 Results of various criteria for short-circuit fault of BCN at F3 point outside the area through different transition resistances

[0147]

[0148] Note: Phase selection result "0" means phase selection failed

[0149] In order to verify the effectiveness of the new grounding distance protection scheme for weak short-circuit current proposed in this paper, Figure 3 Different types of ground short circuit faults inside and outside the area are simulated on the system shown, and the results of various criteria are recorded as shown in Tables 1 to 3.

[0150] It can be seen from Tables 1 to 3 that the proposed new scheme for ground distance protection against weak short-circuit current can accurately identify the fault phase of single-phase ground fault in the zone under the condition of high-resistance fault with 500Ω transition resistance, and reliably distinguish the phase-to-phase ground fault outside the zone, thus improving the selectivity of the existing distance protection in the case of large transition resistance ground short-circuit fault.

[0151] Therefore, the present invention proposes a new scheme for weak short-circuit current grounding distance protection. This scheme takes into account the advantages of distance protection selectivity and zero-sequence protection sensitivity, and can cut off high-resistance grounding short-circuit faults with zero-sequence current not less than 150A, greatly improving the performance of relay protection devices under high transition resistance weak short-circuit current grounding short-circuit faults.

[0152] Exemplary Devices

[0153] Figure 4 FIG. 1 is a schematic diagram of the structure of a ground distance protection device for weak short-circuit current of a transmission line provided by an exemplary embodiment of the present invention. Figure 4 As shown, the device 400 includes:

[0154] A calculation module 410 is used to calculate the zero-sequence voltage, zero-sequence current, zero-sequence compensation voltage, grounding compensation voltage and phase-to-phase compensation voltage according to the acquired three-phase voltage vector, three-phase current vector and preset high-resistance distance protection setting at the protection installation point;

[0155] A first determination module 420, configured to determine a fault direction of a protection installation point according to a zero-sequence voltage, a zero-sequence current and a preset zero-sequence direction element criterion;

[0156] The second determination module 430 is used to determine the fault phase according to the three-phase current vector and the preset sequence current absolute value phase selection element criterion when the fault direction is a positive direction fault;

[0157] The third determination module 440 is used to determine the short circuit fault type of the fault phase according to the grounding compensation voltage, the phase-to-phase compensation voltage, the zero-sequence current, the zero-sequence voltage and the preset short circuit fault type criterion of the fault phase;

[0158] The fourth determination module 450 is used to determine the short-circuit fault location according to the short-circuit fault type, the grounding compensation voltage of the fault phase, the phase-to-phase voltage vector and the phase-to-phase current phasor, and a preset short-circuit fault location criterion;

[0159] The starting module 460 is used to start the corresponding ground distance relay protection according to the short circuit fault position.

[0160] Optionally, the zero sequence voltage and zero sequence current The calculation formula is:

[0161]

[0162] In the formula, They are the three-phase voltage and current phasors at the protection installation point respectively;

[0163] Preset high resistance distance protection setting Z set The expression is:

[0164] Z set =KZ l

[0165] In the formula, Z1 is the positive sequence impedance of the entire line at this level, and K is the reliability coefficient;

[0166] Zero sequence compensation voltage The calculation formula is:

[0167]

[0168] Ground compensation voltage And phase compensation voltage The calculation formula is:

[0169]

[0170] In the formula, k = (z0-z1) / 3z1 is the zero-sequence compensation coefficient of this line, z 0、z1 are the zero-sequence impedance and positive-sequence impedance per unit length of the line, are the voltage and current phasors of each phase, are the phase-to-phase voltage and current phasors respectively, and the superscript ' represents the compensation amount.

[0171] Optionally, the expression of the zero-sequence directional element criterion is:

[0172]

[0173] Wherein, k1 is the reliability coefficient, k0 is the zero-sequence compensation coefficient of the line; when the zero-sequence direction element criterion is met, it is determined to be a positive direction fault and enters the high-resistance distance protection pre-selection phase process; otherwise, it is determined to be a reverse direction fault and the high-resistance distance protection is locked.

[0174] Optionally, the expression of the sequence current absolute value phase selection element criterion is:

[0175]

[0176] In the formula, is the positive sequence current phasor based on the current phase, The current amplitude of the corresponding phase with the positive sequence removed is: The maximum phase is confirmed as the fault phase.

[0177] Optionally, the third determining module 440 includes:

[0178] A judgment submodule, used to judge whether the interphase compensation voltage of the fault phase meets the first short-circuit fault criterion, and if so, to judge whether the zero-sequence current, grounding compensation voltage and interphase compensation voltage of the fault phase meet the second short-circuit fault criterion or the third short-circuit fault criterion;

[0179] A first determination submodule is used to determine that the short-circuit fault type is a fault phase high-resistance grounding short-circuit fault when a second short-circuit fault criterion is met;

[0180] The second determination submodule is used to determine that the short-circuit fault type is a faulty phase low-resistance grounding short-circuit fault when the third short-circuit fault determination criterion is met.

[0181] Optionally, the first short circuit fault criterion is:

[0182]

[0183] Wherein, when the first short-circuit fault criterion is not met, the phase selection fails to lock the high-resistance distance relay;

[0184] The second short-circuit fault criterion is:

[0185]

[0186] The third short-circuit fault criterion is:

[0187]

[0188] In the formula, I set It is the zero-sequence current threshold. If the second short-circuit fault criterion and the third short-circuit fault criterion are not met, the phase selection fails and the high-resistance distance relay is locked.

[0189] Optionally, the fourth determining module 450 includes:

[0190] A first calculation submodule is used to calculate the pre-fault phase compensation voltage according to the phase-to-phase voltage vector of the faulty phase;

[0191] The second calculation submodule is used to calculate the phase compensation voltage change before and after the fault according to the grounding compensation voltage of the fault phase and the phase compensation voltage before the fault;

[0192] The third calculation submodule is used to calculate the characteristic angle reflecting overload and fault according to the phase-to-phase voltage vector and the phase-to-phase current phasor of the fault phase;

[0193] The determination submodule is used to determine whether the characteristic angle, the phase compensation voltage before the fault and the phase compensation voltage change meet the short-circuit fault location criterion, and determine the short-circuit fault location according to the judgment result.

[0194] Optionally, the short circuit fault location criterion includes:

[0195] Line sending end judgment criteria:

[0196]

[0197] Line receiving end judgment criteria:

[0198]

[0199] Phase split high resistance ground distance relay criterion:

[0200]

[0201] Where α = 180-Z Line.1 , Z Line.1 is the line positive sequence impedance, the selection principle of γ1 is:

[0202]

[0203] In the formula, is the phase compensation voltage before the phase fault; is the phase compensation voltage change; characteristic angle ΦΦ=BC,CA,AB

[0204] , is the line positive sequence impedance angle; is the ground compensation voltage.

[0205] Exemplary Electronic Devices

[0206] Figure 5 This is a structure of an electronic device provided by an exemplary embodiment of the present invention. Figure 5 As shown, the electronic device 50 includes one or more processors 51 and a memory 52 .

[0207] The processor 51 may be a central processing unit (CPU) or other forms of processing units having data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions.

[0208] The memory 52 may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, random access memory (RAM) and / or cache memory (cache), etc. The non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 51 may run the program instructions to implement the methods of the software programs of the various embodiments of the present invention described above and / or other desired functions. In one example, the electronic device may also include: an input device 53 and an output device 54, which are interconnected via a bus system and / or other forms of connection mechanisms (not shown).

[0209] In addition, the input device 53 may also include, for example, a keyboard, a mouse, etc.

[0210] The output device 54 can output various information to the outside. The output device 54 can include, for example, a display, a speaker, a printer, a communication network and a remote output device connected thereto.

[0211] Of course, to simplify, Figure 5 Only some of the components related to the present invention in the electronic device are shown, and components such as a bus, an input / output interface, etc. are omitted. In addition, the electronic device may further include any other appropriate components according to specific application conditions.

[0212] Exemplary computer program products and computer-readable storage media

[0213] In addition to the above-mentioned methods and devices, an embodiment of the present invention may also be a computer program product, which includes computer program instructions, which, when executed by a processor, enable the processor to execute the steps of the method according to various embodiments of the present invention described in the above-mentioned "Exemplary Method" section of this specification.

[0214] The computer program product may be written in any combination of one or more programming languages ​​to write program code for performing the operations of the embodiments of the present invention, including object-oriented programming languages ​​such as Java, C++, etc., and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user computing device, partially on the user device, as a separate software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0215] In addition, an embodiment of the present invention may also be a computer-readable storage medium having computer program instructions stored thereon, which, when executed by a processor, enable the processor to execute the steps of the method according to various embodiments of the present invention described in the above “Exemplary Method” section of this specification.

[0216] The computer readable storage medium can adopt any combination of one or more readable media. The readable medium can be a readable signal medium or a readable storage medium. The readable storage medium can include, for example, but is not limited to, a system, system or device of electricity, magnetism, light, electromagnetic, infrared, or semiconductor, or any combination of the above. More specific examples (non-exhaustive list) of readable storage media include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0217] The basic principle of the present invention is described above in conjunction with specific embodiments. However, it should be pointed out that the advantages, strengths, effects, etc. mentioned in the present invention are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. must be possessed by each embodiment of the present invention. In addition, the specific details disclosed above are only for the purpose of illustration and facilitation of understanding, rather than limitation, and the above details do not limit the present invention to being implemented by adopting the above specific details.

[0218] Each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system embodiment, since it basically corresponds to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0219] The block diagrams of the devices, systems, equipment, and systems involved in the present invention are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagram. As will be appreciated by those skilled in the art, these devices, systems, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open words, referring to "including but not limited to", and can be used interchangeably with them. The words "or" and "and" used here refer to the words "and / or" and can be used interchangeably with them, unless the context clearly indicates otherwise. The word "such as" used here refers to the phrase "such as but not limited to", and can be used interchangeably with it.

[0220] The method and system of the present invention may be implemented in many ways. For example, the method and system of the present invention may be implemented by software, hardware, firmware or any combination of software, hardware, firmware. The above order of steps for the method is only for illustration, and the steps of the method of the present invention are not limited to the order specifically described above, unless otherwise specifically stated. In addition, in some embodiments, the present invention may also be implemented as a program recorded in a recording medium, which includes machine-readable instructions for implementing the method according to the present invention. Thus, the present invention also covers a recording medium storing a program for executing the method according to the present invention.

[0221] It should also be noted that in the system, device and method of the present invention, each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations should be regarded as equivalent schemes of the present invention. The above description of the disclosed aspects is provided to enable any technician in the field to make or use the present invention. Various modifications to these aspects are very obvious to those skilled in the art, and the general principles defined here can be applied to other aspects without departing from the scope of the present invention. Therefore, the present invention is not intended to be limited to the aspects shown here, but in accordance with the widest range consistent with the principles and novel features disclosed here.

[0222] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present invention to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A ground distance protection method for weak short-circuit current of a transmission line, characterized in that: include: Calculate the zero-sequence voltage, zero-sequence current, zero-sequence compensation voltage, grounding compensation voltage and phase-to-phase compensation voltage according to the obtained three-phase voltage vector, three-phase current vector and preset high-resistance distance protection setting at the protection installation point; Determining the fault direction of the protection installation point according to the zero-sequence voltage, the zero-sequence current and a preset zero-sequence direction element criterion; In the case where the fault direction is a positive direction fault, the fault phase is determined according to the three-phase current vector and a preset sequence current absolute value phase selection element criterion; Determine the short-circuit fault type of the fault phase according to the grounding compensation voltage of the fault phase, the phase-to-phase compensation voltage, the zero-sequence current, the zero-sequence voltage and a preset short-circuit fault type criterion; Determine the short-circuit fault location according to the short-circuit fault type, the grounding compensation voltage of the fault phase, the phase-to-phase voltage vector and the phase-to-phase current phasor, and a preset short-circuit fault location criterion; According to the short-circuit fault position, the corresponding ground distance relay action protection is started.

2. The method according to claim 1, characterized in that The zero sequence voltage and the zero sequence current The calculation formula is: In the formula, They are the three-phase voltage and current phasors at the protection installation point respectively; The preset high-resistance distance protection setting Z set The expression is: WITH set =KZ l In the formula, Z1 is the positive sequence impedance of the entire line at this level, and K is the reliability coefficient; The zero sequence compensation voltage The calculation formula is: The ground compensation voltage And phase compensation voltage The calculation formula is: In the formula, k = (z0-z1) / 3z1 is the zero-sequence compensation coefficient of this line, z 0、 z1 are the zero-sequence impedance and positive-sequence impedance per unit length of the line, are the voltage and current phasors of each phase, are the phase-to-phase voltage and current phasors respectively, and the superscript ' represents the compensation amount.

3. The method according to claim 2, characterized in that The expression of the zero-sequence directional element criterion is: Wherein, k1 is the reliability coefficient, k0 is the zero-sequence compensation coefficient of the line; when the zero-sequence directional element criterion is met, it is determined to be a positive direction fault and enters the high-resistance distance protection pre-selection phase process; otherwise, it is determined to be a reverse direction fault and the high-resistance distance protection is locked.

4. The method according to claim 1, characterized in that: The expression of the sequence current absolute value phase selection element criterion is: In the formula, is the positive sequence current phasor based on the current phase, The current amplitude of the corresponding phase with the positive sequence removed is: The maximum phase is confirmed as the fault phase.

5. The method according to claim 2, characterized in that: Determining the short-circuit fault type of the fault phase according to the grounding compensation voltage of the fault phase, the phase-to-phase compensation voltage, the zero-sequence current, the zero-sequence voltage, and a preset short-circuit fault type criterion includes: Determine whether the interphase compensation voltage of the fault phase satisfies the first short-circuit fault criterion, and if so, determine whether the zero-sequence current, grounding compensation voltage and interphase compensation voltage of the fault phase meet the second short-circuit fault criterion or the third short-circuit fault criterion; When the second short-circuit fault criterion is met, determining that the short-circuit fault type is a fault phase high-resistance grounding short-circuit fault; When the third short-circuit fault criterion is met, it is determined that the short-circuit fault type is a faulty phase low-resistance grounding short-circuit fault.

6. The method according to claim 5, characterized in that The first short-circuit fault criterion is: Wherein, when the first short-circuit fault criterion is not met, the phase selection fails and the high-resistance distance relay is locked; The second short-circuit fault criterion is: The third short-circuit fault criterion is: In the formula, I set is the zero-sequence current threshold, wherein if the second short-circuit fault criterion and the third short-circuit fault criterion are not met, the phase selection fails and the high-resistance distance relay is locked.

7. The method according to claim 1, characterized in that Determining the short-circuit fault location according to the short-circuit fault type, the grounding compensation voltage of the fault phase, the phase-to-phase voltage vector and the phase-to-phase current phasor, and a preset short-circuit fault location criterion includes: Calculating a pre-fault phase compensation voltage according to the phase-to-phase voltage vector of the fault phase; Calculating the phase compensation voltage change before and after the fault according to the grounding compensation voltage of the fault phase and the phase compensation voltage before the fault; Calculate the characteristic angle reflecting overload and fault according to the phase-to-phase voltage vector and phase-to-phase current phasor of the fault phase; It is determined whether the characteristic angle, the phase compensation voltage before the fault and the phase compensation voltage change satisfy the short-circuit fault position criterion, and the short-circuit fault position is determined according to the determination result.

8. The method according to claim 7, characterized in that The short-circuit fault location criterion includes: Line sending end judgment criteria: Line receiving end judgment criteria: Phase-separated high-resistance ground distance relay criterion: Where α = 180-Z Line.1 , Z Line.1 is the line positive sequence impedance, the selection principle of γ1 is: In the formula, is the phase compensation voltage before the phase fault; is the phase compensation voltage change; characteristic angle is the line positive sequence impedance angle; is the ground compensation voltage.

9. A ground distance protection device for weak short-circuit current of a transmission line, characterized in that: include: A calculation module is used to calculate the zero-sequence voltage, zero-sequence current, zero-sequence compensation voltage, grounding compensation voltage and phase-to-phase compensation voltage according to the acquired three-phase voltage vector, three-phase current vector and preset high-resistance distance protection setting at the protection installation point; A first determination module, configured to determine the fault direction of the protection installation point according to the zero-sequence voltage, the zero-sequence current and a preset zero-sequence direction element criterion; A second determination module is used to determine the fault phase according to the three-phase current vector and a preset sequence current absolute value phase selection element criterion when the fault direction is a positive direction fault; A third determination module is used to determine the short-circuit fault type of the fault phase according to the grounding compensation voltage of the fault phase, the phase-to-phase compensation voltage, the zero-sequence current, the zero-sequence voltage and a preset short-circuit fault type criterion; A fourth determination module, used to determine the short-circuit fault location according to the short-circuit fault type, the grounding compensation voltage of the fault phase, the phase-to-phase voltage vector and the phase-to-phase current phasor, and a preset short-circuit fault location criterion; The starting module is used to start the corresponding ground distance relay protection according to the short circuit fault position.

10. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and the computer program is used to execute the method according to any one of claims 1 to 8.

11. An electronic device, characterized in that: The electronic device comprises: processor; a memory for storing instructions executable by the processor; The processor is used to read the executable instructions from the memory and execute the instructions to implement the method described in any one of claims 1 to 8.

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