A phase selection method based on a new zero sequence directional element and a new zero sequence current double polarization criterion

Abstract

The application discloses a phase selection method based on a new zero sequence direction element and a new zero sequence current bipolarization criterion, and comprises the following steps: calculating zero sequence voltage and zero sequence current according to three-phase voltage vectors and three-phase current vectors at a protection installation point; calculating zero sequence compensation voltage, ground compensation voltage and phase-to-phase compensation voltage according to the zero sequence voltage, the zero sequence current and preset high-resistance distance protection setting values; determining a fault direction of the protection installation point according to the zero sequence voltage, the zero sequence current and a preset new zero sequence direction element criterion; in the case that the fault direction is a positive direction fault, determining a fault phase according to the three-phase current vectors and a preset sequence current absolute value phase selection element criterion; and determining a phase selection result according to the fault phase, the zero sequence compensation voltage, the ground compensation voltage, the phase-to-phase compensation voltage, a ground fault criterion based on a compensation voltage amplitude of a healthy phase, a zero sequence current phase selection criterion of phase compensation voltage polarization and a zero sequence current phase selection criterion of phase-to-phase compensation voltage polarization.

Description

Technical Field

[0001] This invention relates to the field of relay protection technology, and more specifically, to a phase selection method based on a novel zero-sequence direction element and a novel zero-sequence current dual-polarization criterion. Background Technology

[0002] As one of the fundamental components of relay protection, the phase selection element's operating performance is crucial for fault phase identification in distance protection. Traditional phase selection elements select the faulty phase after the protection has determined the fault to be within the designated zone. Currently, the phase selection elements widely used in engineering are typically current sequence component phase selection elements, which have advantages such as clear physical meaning and high phase selection sensitivity, and can accurately select phases for various types of ground faults. However, under high transition resistance ground fault conditions, traditional distance relays have poor sensitivity and cannot reliably determine whether the fault is inside or outside the zone. Traditional phase selection elements cannot accurately select the phase when the fault within the zone is unknown. If the zero-sequence reactance criterion, which has higher sensitivity, is used for fault identification, the faulty phase must first be selected for the zero-sequence reactance criterion to be effective. Therefore, how to reliably select the phase under high transition resistance fault conditions when the fault within or outside the zone is unknown remains a problem to be solved. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a phase selection method based on a novel zero-sequence direction element and a novel zero-sequence current dual-polarization criterion.

[0004] According to one aspect of the present invention, a phase selection method based on a novel zero-sequence direction element and a novel zero-sequence current dual-polarization criterion is provided, comprising:

[0005] Calculate the zero-sequence voltage and zero-sequence current based on the obtained three-phase voltage vector and three-phase current vector at the protection installation point;

[0006] Calculate the zero-sequence compensation voltage, grounding compensation voltage, and phase-to-phase compensation voltage based on the zero-sequence voltage, zero-sequence current, and preset high-resistance distance protection settings.

[0007] The fault direction at the protection installation point is determined based on the zero-sequence voltage, zero-sequence current, and the preset criteria of the new zero-sequence direction element.

[0008] In the case of a fault in the positive direction, the faulty phase is determined based on the three-phase current vector and the preset sequence current absolute value phase selection element criterion.

[0009] The phase selection result is determined based on the fault phase, zero-sequence compensation voltage, grounding compensation voltage, phase-to-phase compensation voltage, and preset grounding fault criteria based on the amplitude of the healthy phase compensation voltage, zero-sequence current phase selection criteria based on phase compensation voltage polarization, and zero-sequence current phase selection criteria based on phase-to-phase compensation voltage polarization.

[0010] Optionally, zero-sequence voltage and zero-sequence current The calculation formula is:

[0011]

[0012] In the formula, These are the three-phase voltage and current phasors at the protection installation point, respectively. Optionally, a preset high-resistance distance protection setting value Z is provided. set The expression is:

[0013] Z set =KZ l

[0014] In the formula, Z1 is the positive sequence impedance of the entire line of this level, and K is the reliability coefficient;

[0015] Zero-sequence compensation voltage The calculation formula is:

[0016]

[0017] Optionally, grounding compensation voltage and interphase compensation voltage The calculation formula is:

[0018]

[0019] In the formula, k = (z0 - z1) / 3z1 is the zero-sequence compensation coefficient of this line. These are the voltage and current phasors for each phase, respectively. These are the voltage and current phasors for each phase, respectively, with the superscript ' indicating the compensation amount.

[0020] Optionally, the expression for the novel zero-sequence direction element criterion is:

[0021]

[0022] In the formula, Z L This is the positive sequence impedance of the entire length of the line at this level; It is the zero-sequence voltage; The zero-sequence voltage is k0 = (Z0 - Z1) / 3Z1, where Z0 and Z1 are the zero-sequence compensation coefficients, respectively, and the zero-sequence impedance and positive-sequence impedance per unit length of the line. If the new zero-sequence directional element criterion is met, it is considered a positive-direction fault and enters the phase selection element discrimination logic; otherwise, it is considered a reverse-direction fault and the phase selection element and zero-sequence protection are blocked.

[0023] Optionally, the expression for the sequence current absolute value phase selection element criterion is:

[0024]

[0025] In the formula, The positive sequence current phasor is based on this phase. The positive-sequence current amplitude was removed for the corresponding phase. The phase with the largest fault is identified as the faulty phase. These are the phasors of the current in each phase.

[0026] Optionally, the phase selection result is determined based on the fault phase, zero-sequence compensation voltage, grounding compensation voltage, phase-to-phase compensation voltage, and preset grounding fault criteria based on the amplitude of the healthy phase compensation voltage, zero-sequence current phase selection criteria based on phase compensation voltage polarization, and zero-sequence current phase selection criteria based on phase-to-phase compensation voltage polarization, including:

[0027] Determine whether the faulty phase meets the ground fault criterion based on the amplitude of the healthy phase compensation voltage, the zero-sequence current phase selection criterion based on the phase compensation voltage polarization, and the zero-sequence current phase selection criterion based on the phase-to-phase compensation voltage polarization based on the zero-sequence compensation voltage, the ground compensation voltage, and the phase-to-phase compensation voltage polarization.

[0028] When any one of the faulty phases A, B, or C simultaneously satisfies the ground fault criterion based on the amplitude of the healthy phase compensation voltage, the zero-sequence current phase selection criterion based on the phase compensation voltage polarization, and the zero-sequence current phase selection criterion based on the inter-phase compensation voltage polarization, the phase is determined as the selected phase.

[0029] Optionally, the expression for the ground fault criterion based on the amplitude of the healthy phase compensation voltage is:

[0030]

[0031] In the formula, The inter-phase compensation voltage between the two phases of the non-faulty phase; m>0.87; U LL This is the rated line voltage.

[0032] Optionally, the expression for the phase selection criterion of zero-sequence current in phase-compensated voltage polarization is:

[0033]

[0034] in,

[0035]

[0036] In the formula, This is the grounding compensation voltage; γ1 to γ3 are the zero-sequence currents, and γ1 to γ3 are the operating boundary angles of the zero-sequence current phase selection criterion for inter-phase compensation voltage polarization.

[0037] The expression for the phase selection criterion of zero-sequence current in phase-to-phase compensation voltage polarization is:

[0038]

[0039] In the formula, This is the phase-to-phase compensation voltage.

[0040] According to another aspect of the present invention, a phase selection device based on a novel zero-sequence direction element and a novel zero-sequence current dual-polarization criterion is provided, comprising:

[0041] The first calculation module is used to calculate the zero-sequence voltage and zero-sequence current based on the three-phase voltage vector and three-phase current vector at the protection installation point.

[0042] The second calculation module is used to calculate the zero-sequence compensation voltage, grounding compensation voltage, and phase-to-phase compensation voltage based on the zero-sequence voltage, zero-sequence current, and preset high-resistance distance protection settings.

[0043] The first determining module is used to determine the fault direction of the protection installation point based on the zero-sequence voltage, zero-sequence current, and the preset new zero-sequence direction element criterion.

[0044] The second determining module is used to determine the faulty phase based on 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.

[0045] The third determination module is used to determine the phase selection result based on the fault phase, zero-sequence compensation voltage, grounding compensation voltage, phase-to-phase compensation voltage, and preset grounding fault criteria based on the amplitude of the healthy phase compensation voltage, zero-sequence current phase selection criteria based on phase compensation voltage polarization, and zero-sequence current phase selection criteria based on phase-to-phase compensation voltage polarization.

[0046] According to another aspect of the present invention, a computer-readable storage medium is provided, the storage medium storing a computer program for performing the methods described in any of the above aspects of the present invention.

[0047] According to another aspect of the present invention, an electronic device is provided, the electronic device comprising: a processor; a memory for storing executable instructions of the processor; the processor being configured to read the executable instructions from the memory and execute the instructions to implement the method described in any of the preceding aspects of the present invention.

[0048] Therefore, based on the unique fault characteristics of fault phase compensation voltage, healthy phase compensation voltage, and zero-sequence current, this invention proposes a phase selection principle with dual polarization of zero-sequence current. This principle can reliably select a single-phase ground fault phase within the fault zone when the transition resistance is no greater than 500Ω (500kV), improving the reliability of the phase selection element under ground faults with large transition resistance. This also solves the technical problem that existing phase selection elements with sequence current have difficulty selecting high-resistance ground fault phases. Attached Figure Description

[0049] Exemplary embodiments of the present invention can be more fully understood by referring to the following figures:

[0050] Figure 1 This is a schematic flowchart of a phase selection method based on a novel zero-sequence direction element and a novel zero-sequence current dual-polarization criterion provided in an exemplary embodiment of the present invention.

[0051] Figure 2 This is a schematic diagram of the phase selection algorithm logic provided in an exemplary embodiment of the present invention;

[0052] Figure 3 This is a schematic diagram of a simulation verification power grid platform provided in an exemplary embodiment of the present invention;

[0053] Figure 4 This is a schematic diagram of the phase selection device based on a novel zero-sequence direction element and a novel zero-sequence current dual-polarization criterion provided in an exemplary embodiment of the present invention;

[0054] Figure 5 This is the structure of an electronic device provided in an exemplary embodiment of the present invention. Detailed Implementation

[0055] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It is obvious that the described embodiments are merely some embodiments of the present invention, and not all embodiments of the present invention, and it should be understood that the present invention is not limited to the exemplary embodiments described herein.

[0056] It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention.

[0057] Those skilled in the art will understand that the terms "first," "second," etc., in the embodiments of the present invention are only used to distinguish different steps, devices, or modules, and do not represent any specific technical meaning, nor do they indicate a necessary logical order between them.

[0058] It should also be understood that in the embodiments of the present invention, "multiple" can refer to two or more, and "at least one" can refer to one, two or more.

[0059] 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 defined or given contrary instructions in the context.

[0060] Furthermore, the term "and / or" in this invention is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this invention generally indicates that the preceding and following related objects have an "or" relationship.

[0061] It should also be understood that the description of the various embodiments in this invention emphasizes the differences between the various embodiments, and the similarities or similarities can be referred to each other. For the sake of brevity, they will not be described in detail.

[0062] At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn according to actual scale.

[0063] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0064] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0065] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0066] The embodiments of this invention can be applied to electronic devices such as terminal devices, computer systems, and servers, and can operate together with a wide range of other general-purpose or special-purpose computing system environments or configurations. Well-known examples of terminal devices, computing systems, environments, and / or configurations suitable for use with electronic devices such as terminal devices, computer systems, and servers 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 PCs, minicomputer systems, mainframe computer systems, and distributed cloud computing environments including any of the above systems, etc.

[0067] Electronic devices such as terminal devices, computer systems, and servers can be described in the general context of computer system executable instructions (such as program modules) executed by a computer system. Typically, 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 distributed cloud computing environments, where tasks are executed by remote processing devices linked through communication networks. In distributed cloud computing environments, program modules can reside on local or remote computing system storage media, including storage devices.

[0068] Exemplary methods

[0069] Figure 1 This is a schematic flowchart illustrating a phase selection method based on a novel zero-sequence direction element and a novel zero-sequence current dual-polarization criterion provided in an exemplary embodiment of the present invention. This embodiment can be applied to electronic devices, such as… Figure 1 As shown, the phase selection method 100 based on a novel zero-sequence direction element and a novel zero-sequence current dual-polarization criterion includes the following steps:

[0070] Step 101: Calculate the zero-sequence voltage and zero-sequence current based on the obtained three-phase voltage vector and three-phase current vector at the protection installation point;

[0071] Step 102: Calculate the zero-sequence compensation voltage, grounding compensation voltage, and phase-to-phase compensation voltage based on the zero-sequence voltage, zero-sequence current, and the preset high-resistance distance protection setting.

[0072] Step 103: Determine the fault direction of the protection installation point based on the zero-sequence voltage, zero-sequence current, and the preset new zero-sequence direction element criteria;

[0073] Step 104: In the case of a fault in the positive direction, determine the faulty phase based on the three-phase current vector and the preset sequence current absolute value phase selection element criterion.

[0074] Step 105: Determine the phase selection result based on the fault phase, zero-sequence compensation voltage, grounding compensation voltage, phase-to-phase compensation voltage, and preset grounding fault criteria based on the amplitude of the healthy phase compensation voltage, zero-sequence current phase selection criteria based on phase compensation voltage polarization, and zero-sequence current phase selection criteria based on phase-to-phase compensation voltage polarization.

[0075] Specifically, addressing the problem that existing phase selection elements with high-resistance ground faults are difficult to select, this invention proposes a phase selection principle with dual polarization of zero-sequence current, based on the unique fault characteristics of the fault phase compensation voltage, the healthy phase compensation voltage, and the zero-sequence current. This principle can reliably select a single-phase ground fault phase within the fault zone when the transition resistance is no greater than 500Ω (500kV), improving the reliability of the phase selection element during ground faults with high transition resistance. This invention proposes a phase selection method based on a novel zero-sequence directional element and a novel zero-sequence current dual polarization criterion. The specific implementation of the method is as follows:

[0076] (1) Data preparation

[0077] Obtain the three-phase voltage and current phasors at the protection installation point Calculate zero-sequence voltage and zero-sequence current

[0078]

[0079] Set the high-impedance distance protection setting:

[0080] Z set =KZ l (1.2)

[0081] In the formula, Z1 is the positive sequence impedance of the entire length of the line at this level, and K is the reliability coefficient, which reflects the range of protection for the lower-level lines.

[0082] Calculate the zero-sequence compensation voltage:

[0083]

[0084] Calculate the grounding compensation voltage and the phase-to-phase compensation voltage:

[0085]

[0086] In the formula, k = (z0 - z1) / 3z1 is the zero-sequence compensation coefficient of this line. These are the grounding compensation voltage and the phase-to-phase compensation voltage, respectively. These are the voltage and current phasors for each phase, respectively. These are the voltage and current phasors for each phase, respectively, with the superscript ' indicating the compensation amount.

[0087] (2)Reference Figure 2 As shown, the main criteria consist of:

[0088] 1) Novel zero-sequence orientation element (criterion 1):

[0089] The new zero-sequence directional element is responsible for determining the fault direction. For faults in the opposite direction, the phase selection element and zero-sequence protection are blocked. When criterion 1 is met, it is regarded as a fault in the positive direction, and the phase selection element discrimination logic is entered:

[0090]

[0091] In the formula, Z L This is the positive sequence impedance of the entire length of the line at this level.

[0092] 2) Sequence current absolute value phase selection element (criterion 2):

[0093] The absolute value sequence current phase selection element determines the fault phase based on the phase relationship of each sequence current in different types of short-circuit faults, and then enters the corresponding phase zero-sequence current dual-polarization phase selection discrimination logic.

[0094]

[0095] In the formula, The positive sequence current phasor is based on this phase. The positive-sequence current amplitude was removed for the corresponding phase. The phase with the largest fault is identified as the faulty phase.

[0096] 3) Ground fault criterion based on the amplitude of the compensated voltage of the healthy phase:

[0097] When the absolute value of the sequence current phase selection element selects phase A, the actual fault may be AN, ABN, or BCN. Here, we first rule out ABN faults. A ground fault criterion based on the amplitude of the healthy phase compensation voltage is set (criterion 3). Only if this criterion is met is the zero-sequence current dual-polarization phase selection discrimination stage allowed.

[0098]

[0099] In the formula, m>0.87.

[0100] 4) Zero-sequence current dual-polarization phase selection scheme:

[0101] Design a phase selection criterion for zero-sequence current in phase-compensated voltage polarization (criterion 4):

[0102]

[0103] Design a phase selection criterion for zero-sequence current with phase-to-phase voltage polarization compensation (criterion 5):

[0104]

[0105] In criterion 4, the selection of α and β is determined by the following formula:

[0106]

[0107] When any one of A, B, or C is the same, and criteria 3 to 5 are satisfied, the phase selection can be confirmed as successful.

[0108] In one embodiment of the present invention, in order to verify the effectiveness of the zero-sequence direction element and phase selection method proposed herein, in the appendix... Figure 3 The system shown simulates different types of ground faults inside and outside the simulation zone. The simulation system parameters and settings are shown in Table 1, and the results of each criterion are recorded in Tables 1-3.

[0109] Table 1 Simulation System Parameters and Fixed Values

[0110]

[0111] Table 2. Results of Discrimination of Novel Zero-Sequence Direction Components for Forward / Reverse Faults.

[0112]

[0113]

[0114] As can be seen from Table 2, the zero-sequence directional element proposed in this patent has strong tolerance to transition and can accurately distinguish the fault direction under various types of ground short-circuit faults.

[0115] Table 3. Results of various criteria for judging short-circuit faults at point F2 AN in the area with different transition resistances.

[0116]

[0117] Note: Zero-sequence direction "1" represents the positive direction, and "2" represents the negative direction.

[0118] Table 4 Results of Criteria for Short-Circuit Faults at Point F3 ABN Outside Zone with Different Transition Resistances

[0119]

[0120] Note: A phase selection result of "0" indicates phase selection failure.

[0121] Table 5 Results of various criteria for short-circuit faults at point F3 outside the zone via different transition resistances in BCN.

[0122]

[0123] Note: A phase selection result of "0" indicates phase selection failure.

[0124] As can be seen from Tables 2-5, the proposed ground fault criterion based on the amplitude of the healthy phase compensation voltage and the zero-sequence current dual-polarization phase selection scheme can accurately identify the fault phase of a single-phase ground fault in the zone under the high resistance fault condition of 500Ω transition resistance, and reliably distinguish between phase-to-phase ground faults outside the zone, thus improving the selectivity of the existing distance protection in the case of ground short-circuit faults with large transition resistance.

[0125] Therefore, based on the unique fault characteristics of fault phase compensation voltage, healthy phase compensation voltage, and zero-sequence current, this invention proposes a phase selection principle with dual polarization of zero-sequence current. This principle can reliably select a single-phase ground fault phase within the fault zone when the transition resistance is no greater than 500Ω (500kV), improving the reliability of the phase selection element under ground faults with large transition resistance. This also solves the technical problem that existing phase selection elements with sequence current have difficulty selecting high-resistance ground fault phases.

[0126] Exemplary device

[0127] Figure 4 This is a schematic diagram of a phase selection device based on a novel zero-sequence direction element and a novel zero-sequence current dual-polarization criterion, provided in an exemplary embodiment of the present invention. Figure 4 As shown, the device 400 includes:

[0128] The first calculation module 410 is used to calculate the zero-sequence voltage and zero-sequence current based on the three-phase voltage vector and three-phase current vector at the protection installation point.

[0129] The second calculation module 420 is used to calculate the zero-sequence compensation voltage, grounding compensation voltage and phase-to-phase compensation voltage based on the zero-sequence voltage, zero-sequence current and preset high-resistance distance protection settings.

[0130] The first determining module 430 is used to determine the fault direction of the protection installation point based on the zero-sequence voltage, zero-sequence current and the preset new zero-sequence direction element criterion.

[0131] The second determining module 440 is used to determine the fault phase based on 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.

[0132] The third determining module 450 is used to determine the phase selection result based on the fault phase, zero-sequence compensation voltage, grounding compensation voltage, phase-to-phase compensation voltage, and preset grounding fault criteria based on the amplitude of healthy phase compensation voltage, zero-sequence current phase selection criteria based on phase compensation voltage polarization, and zero-sequence current phase selection criteria based on phase-to-phase compensation voltage polarization.

[0133] Optionally, zero-sequence voltage and zero-sequence current The calculation formula is:

[0134]

[0135] In the formula, These are the three-phase voltage and current phasors at the protection installation point, respectively. Optionally, a preset high-resistance distance protection setting value Z is provided. set The expression is:

[0136] Zset =KZ l

[0137] In the formula, Z1 is the positive sequence impedance of the entire line of this level, and K is the reliability coefficient;

[0138] Zero-sequence compensation voltage The calculation formula is:

[0139]

[0140] Optionally, grounding compensation voltage and interphase compensation voltage The calculation formula is:

[0141]

[0142] In the formula, k = (z0 - z1) / 3z1 is the zero-sequence compensation coefficient of this line. These are the voltage and current phasors for each phase, respectively. These are the voltage and current phasors for each phase, respectively, with the superscript ' indicating the compensation amount.

[0143] Optionally, the expression for the novel zero-sequence direction element criterion is:

[0144]

[0145] In the formula, Z L This is the positive sequence impedance of the entire length of the line at this level; It is the zero-sequence voltage; The zero-sequence voltage is k0 = (Z0 - Z1) / 3Z1, where Z0 and Z1 are the zero-sequence compensation coefficients, respectively, and the zero-sequence impedance and positive-sequence impedance per unit length of the line. If the new zero-sequence directional element criterion is met, it is considered a positive-direction fault and enters the phase selection element discrimination logic; otherwise, it is considered a reverse-direction fault and the phase selection element and zero-sequence protection are blocked.

[0146] Optionally, the expression for the sequence current absolute value phase selection element criterion is:

[0147]

[0148] In the formula, The positive sequence current phasor is based on this phase. The positive-sequence current amplitude was removed for the corresponding phase. The phase with the largest fault is identified as the faulty phase. These are the phasors of the current in each phase.

[0149] Optionally, the third determining module 450 includes:

[0150] The judgment submodule is used to determine whether the faulty phase meets the ground fault criterion based on the amplitude of the healthy phase compensation voltage, the zero-sequence current phase selection criterion based on the phase compensation voltage polarization, and the zero-sequence current phase selection criterion based on the phase compensation voltage polarization, based on the zero-sequence compensation voltage, the ground compensation voltage, and the phase-to-phase compensation voltage.

[0151] The determination submodule is used to determine the phase as the phase selection result when any one of the faulty phases A, B, or C simultaneously meets the ground fault criterion based on the amplitude of the healthy phase compensation voltage, the phase selection criterion based on the zero-sequence current of the phase compensation voltage polarization, and the phase selection criterion based on the zero-sequence current of the inter-phase compensation voltage polarization.

[0152] Optionally, the expression for the ground fault criterion based on the amplitude of the healthy phase compensation voltage is:

[0153]

[0154] In the formula, The inter-phase compensation voltage between the two phases of the non-faulty phase; m>0.87; U LL This is the rated line voltage.

[0155] Optionally, the expression for the phase selection criterion of zero-sequence current in phase-compensated voltage polarization is:

[0156]

[0157] in,

[0158]

[0159] In the formula, This is the grounding compensation voltage; γ1 to γ3 are the zero-sequence currents, and γ1 to γ3 are the operating boundary angles of the zero-sequence current phase selection criterion for inter-phase compensation voltage polarization.

[0160] The expression for the phase selection criterion of zero-sequence current in phase-to-phase compensation voltage polarization is:

[0161]

[0162] In the formula, This is the phase-to-phase compensation voltage.

[0163] Exemplary electronic devices

[0164] Figure 5 This is the structure of an electronic device provided in an exemplary embodiment of the present invention. For example... Figure 5 As shown, the electronic device 50 includes one or more processors 51 and memory 52.

[0165] The processor 51 may be a central processing unit (CPU) or other form of processing unit with data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions.

[0166] 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. 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 execute 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, these components being interconnected via a bus system and / or other forms of connection mechanisms (not shown).

[0167] In addition, the input device 53 may also include, for example, a keyboard, a mouse, etc.

[0168] The output device 54 can output various information to the outside. The output device 54 may include, for example, a display, a speaker, a printer, and a communication network and its connected remote output devices, etc.

[0169] Of course, for the sake of simplicity, Figure 5 Only some of the components of this electronic device relevant to the present invention are shown, omitting components such as buses, input / output interfaces, etc. In addition, the electronic device may include any other suitable components depending on the specific application.

[0170] Exemplary computer program products and computer-readable storage media

[0171] In addition to the methods and apparatus described above, embodiments of the present invention may also be computer program products, which include computer program instructions that, when executed by a processor, cause the processor to perform the steps of the methods according to various embodiments of the present invention described in the "Exemplary Methods" section above.

[0172] The computer program product can be written in any combination of one or more programming languages ​​to perform the operations of the embodiments of the present invention. The programming languages ​​include object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computing device, partially on the user's computing device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0173] Furthermore, embodiments of the present invention may also be computer-readable storage media storing computer program instructions thereon, which, when executed by a processor, cause the processor to perform the steps of the methods according to various embodiments of the present invention described in the "Exemplary Methods" section above.

[0174] The computer-readable storage medium may be any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or any combination thereof. More specific examples (a non-exhaustive list) of readable storage media include: an electrical connection having one or more wires, a portable disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof.

[0175] The basic principles of the present invention have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in the present invention are merely examples and not limitations, and should not be considered as essential features of each embodiment of the present invention. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the present invention to the necessity of employing the aforementioned specific details.

[0176] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For system embodiments, since they largely correspond to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0177] The block diagrams of devices, systems, devices, and systems involved in this invention are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, systems, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0178] The methods and systems of the present invention may be implemented in many ways. For example, they may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above-described order of steps for the methods is for illustrative purposes only, and the steps of the methods of the present invention are not limited to the order specifically described above unless otherwise specifically stated. Furthermore, in some embodiments, the present invention may also be implemented as a program recorded on a recording medium, the program comprising machine-readable instructions for implementing the methods according to the present invention. Thus, the present invention also covers recording media storing programs for performing the methods according to the present invention.

[0179] It should also be noted that in the systems, apparatus, and methods of the present invention, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered equivalents of the present invention. The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the invention. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of the invention. Therefore, the invention is not intended to be limited to the aspects shown herein, but rather to be carried out within the widest scope consistent with the principles and novel features disclosed herein.

[0180] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of the invention to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A phase selection method based on a novel zero-sequence direction element and a novel zero-sequence current dual-polarization criterion, characterized in that, include: Calculate the zero-sequence voltage and zero-sequence current based on the obtained three-phase voltage vector and three-phase current vector at the protection installation point; Calculate the zero-sequence compensation voltage, grounding compensation voltage, and phase-to-phase compensation voltage based on the zero-sequence voltage, the zero-sequence current, and the preset high-resistance distance protection setting. The fault direction of the protection installation point is determined based on the zero-sequence voltage, the zero-sequence current, and the preset new zero-sequence direction element criterion. In the case of a positive fault, the faulty phase is determined based on the three-phase current vector and the preset sequence current absolute value phase selection element criterion. The phase selection result is determined based on the fault phase, the zero-sequence compensation voltage, the grounding compensation voltage, the phase-to-phase compensation voltage, and the preset grounding fault criterion based on the amplitude of the healthy phase compensation voltage, the zero-sequence current phase selection criterion based on the polarization of the phase compensation voltage, and the zero-sequence current phase selection criterion based on the polarization of the phase-to-phase compensation voltage. The zero-sequence compensation voltage The calculation formula is: In the formula, It is the zero-sequence voltage. It is the zero-sequence current; Z set The preset high-resistance distance protection setting is used; The grounding compensation voltage and interphase compensation voltage The calculation formula is: In the formula, k =(z0-z1) / 3z1 is the zero-sequence compensation coefficient for this line. , These are the voltage and current phasors for each phase, respectively. , These are the voltage and current phasors for each phase, with the superscript ' indicating the compensation amount; The expression for the novel zero-sequence direction element criterion is as follows: In the formula, Z L This is the positive sequence impedance of the entire length of the line at this level; It is the zero-sequence voltage; It is the zero-sequence voltage; k 0 = ( Z 0- Z 1) / 3 Z 1 represents the zero-order compensation coefficient. Z 0、 Z 1 represents the zero-sequence impedance and positive-sequence impedance per unit length of the line. If the new zero-sequence directional element criterion is met, it is considered a positive-direction fault and enters the phase selection element discrimination logic. Otherwise, it is considered a reverse-direction fault and the phase selection element and zero-sequence protection are blocked. The expression for the sequence current absolute value phase selection element criterion is as follows: In the formula, The positive sequence current phasor is based on this phase. The positive-sequence current amplitude was removed for the corresponding phase. The phase with the largest fault is identified as the faulty phase. These are the phasors of the current in each phase; The expression for the ground fault criterion based on the amplitude of the healthy phase compensation voltage is as follows: In the formula, This is the inter-phase compensation voltage between the two phases of the non-faulty phase; m >0.87; U LL This is the rated line voltage; The expression for the zero-sequence current phase selection criterion of the phase compensation voltage polarization is as follows: in, In the formula, This is the grounding compensation voltage; It is the zero-sequence current. The operating boundary angle of the phase selection criterion for zero-sequence current in phase-to-phase voltage polarization compensation; The expression for the zero-sequence current phase selection criterion of the interphase compensation voltage polarization is as follows: In the formula, This is the phase-to-phase compensation voltage.

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, These are the three-phase voltage and current phasors at the protection installation point, respectively.

3. The method according to claim 1, characterized in that, The preset high-resistance distance protection setting value Z set The expression is: In the formula, Z 1 represents the positive sequence impedance of the entire length of this level of line. This is the reliability coefficient.

4. The method according to claim 1, characterized in that, Based on the faulty phase, the zero-sequence compensation voltage, the grounding compensation voltage, the phase-to-phase compensation voltage, and preset grounding fault criteria based on the amplitude of the healthy phase compensation voltage, zero-sequence current phase selection criteria based on phase compensation voltage polarization, and zero-sequence current phase selection criteria based on phase-to-phase compensation voltage polarization, the phase selection result is determined, including: Based on the zero-sequence compensation voltage, the grounding compensation voltage, and the phase-to-phase compensation voltage, determine whether the faulty phase meets the grounding fault criterion based on the amplitude of the healthy phase compensation voltage, the zero-sequence current phase selection criterion based on the phase compensation voltage polarization, and the zero-sequence current phase selection criterion based on the phase-to-phase compensation voltage polarization; When any one of the faulty phases A, B, or C simultaneously satisfies the ground fault criterion based on the amplitude of the healthy phase compensation voltage, the zero-sequence current phase selection criterion of the phase compensation voltage polarization, and the zero-sequence current phase selection criterion of the inter-phase compensation voltage polarization, the phase is determined as the selected phase.

5. A phase selection device based on a novel zero-sequence direction element and a novel zero-sequence current dual-polarization criterion, used to implement the method described in any one of claims 1-4, characterized in that, include: The first calculation module is used to calculate the zero-sequence voltage and zero-sequence current based on the three-phase voltage vector and three-phase current vector at the protection installation point. The second calculation module is used to calculate the zero-sequence compensation voltage, the grounding compensation voltage, and the phase-to-phase compensation voltage based on the zero-sequence voltage, the zero-sequence current, and the preset high-resistance distance protection setting. The first determining module is used to determine the fault direction of the protection installation point based on the zero-sequence voltage, the zero-sequence current, and a preset new zero-sequence direction element criterion. The second determining module is used to determine the fault phase based on 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. The third determining module is used to determine the phase selection result based on the fault phase, the zero-sequence compensation voltage, the grounding compensation voltage, the phase-to-phase compensation voltage, and preset grounding fault criteria based on the amplitude of the healthy phase compensation voltage, zero-sequence current phase selection criteria based on phase compensation voltage polarization, and zero-sequence current phase selection criteria based on phase-to-phase compensation voltage polarization.

6. The apparatus according to claim 5, characterized in that, The zero-sequence voltage and the zero-sequence current The calculation formula is: In the formula, These are the three-phase voltage and current phasors at the protection installation point, respectively.

7. The apparatus according to claim 5, characterized in that, The preset high-resistance distance protection setting value Z set The expression is: In the formula, Z 1 represents the positive sequence impedance of the entire length of this level of line. This is the reliability coefficient.

8. The apparatus according to claim 5, characterized in that, Based on the faulty phase, the zero-sequence compensation voltage, the grounding compensation voltage, the phase-to-phase compensation voltage, and preset grounding fault criteria based on the amplitude of the healthy phase compensation voltage, zero-sequence current phase selection criteria based on phase compensation voltage polarization, and zero-sequence current phase selection criteria based on phase-to-phase compensation voltage polarization, the phase selection result is determined, including: Based on the zero-sequence compensation voltage, the grounding compensation voltage, and the phase-to-phase compensation voltage, determine whether the faulty phase meets the grounding fault criterion based on the amplitude of the healthy phase compensation voltage, the zero-sequence current phase selection criterion based on the phase compensation voltage polarization, and the zero-sequence current phase selection criterion based on the phase-to-phase compensation voltage polarization; When any one of the faulty phases A, B, or C simultaneously satisfies the ground fault criterion based on the amplitude of the healthy phase compensation voltage, the zero-sequence current phase selection criterion of the phase compensation voltage polarization, and the zero-sequence current phase selection criterion of the inter-phase compensation voltage polarization, the phase is determined as the selected phase.

9. A computer-readable storage medium, characterized in that, The storage medium stores a computer program for performing the method described in any one of claims 1-4.

10. An electronic device, characterized in that, The electronic device includes: processor; Memory used to store the processor's executable instructions; 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 claims 1-4.

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