A method for determining fault phase and fault distance during single-phase grounding fault

Abstract

The present invention discloses a method for determining the fault phase and fault distance during a single-phase grounding fault, and relates to the technical field of distribution network fault location. The method comprises: injecting a common-mode detection signal into the distribution network using a power electronic device; collecting and calculating the current phasor, voltage phasor, zero-sequence voltage phasor, and zero-sequence current phasor at the head end of the fault line after the common-mode detection signal is injected; calculating the differential admittance amplitude of each phase based on the current phasor, voltage phasor, zero-sequence voltage phasor, and zero-sequence current phasor; determining the fault phase; obtaining the fundamental frequency zero-sequence voltage at the head end of the line and the fault phase voltage phasor of the fault phase, calculating the upper limit of the ground fault transition resistance, and determining the ground fault transition resistance range; and calculating the fault distance based on the current phasor, voltage phasor, zero-sequence voltage phasor, zero-sequence current phasor, and the ground fault transition resistance range. The present invention can improve the accuracy of phase selection and distance measurement for single-phase grounding faults in distribution networks.

Description

Technical Field

[0001] The present application relates to the technical field of distribution network fault location, and in particular to a method for determining a fault phase and a fault distance during a single-phase grounding fault. Background Art

[0002] The distribution network, a crucial component of the power system, directly supplies power to consumers. Its safe and stable operation is crucial for ensuring power quality and socioeconomic activities. my country's distribution network primarily utilizes an ungrounded neutral point or arc suppression coil-grounded system. Due to the wide coverage of its lines and complex operating environment, distribution network faults are frequent, with single-phase grounding faults accounting for over 80% of these faults. With advances in power electronics technology, some researchers have proposed leveraging existing power electronics to inject signals into the distribution network's neutral point and analyze the response characteristics to achieve arc suppression and fault location. For arc suppression, only by accurately identifying the faulty phase can the arc suppression device perform targeted arc suppression operations on that phase. For fault location, once the faulty phase is determined, the location system can determine the distance based on that phase's specific electrical characteristics. Therefore, rapid and accurate identification of the faulty phase is a crucial foundation and prerequisite for achieving arc suppression and fault location. When a single-phase grounding fault occurs in a distribution network, rapid detection and precise fault location facilitate timely fault resolution, power restoration, and improved power supply reliability.

[0003] The distribution network, a crucial component of the power system, directly supplies power to consumers. Its safe and stable operation is crucial for ensuring power quality and socioeconomic activities. my country's distribution network primarily utilizes an ungrounded neutral point or arc suppression coil-grounded system. Due to the wide coverage of its lines and complex operating environment, distribution network faults are frequent, with single-phase grounding faults accounting for over 80% of these faults. With advances in power electronics technology, some researchers have proposed leveraging existing power electronics to inject signals into the distribution network's neutral point and analyze the response characteristics to achieve arc suppression and fault location. For arc suppression, only by accurately identifying the faulty phase can the arc suppression device perform targeted arc suppression operations on that phase. For fault location, once the faulty phase is determined, the location system can determine the distance based on that phase's specific electrical characteristics. Therefore, rapid and accurate identification of the faulty phase is a crucial foundation and prerequisite for achieving arc suppression and fault location. When a single-phase grounding fault occurs in a distribution network, rapid detection and precise fault location facilitate timely fault resolution, power restoration, and improved power supply reliability.

[0004] Therefore, in the prior art, when determining the fault phase and the fault distance, the accuracy of determining the fault phase and the fault distance is poor due to external interference. Summary of the Invention

[0005] Based on this, it is necessary to provide a method for determining the fault phase and fault distance during a single-phase grounding fault in order to address the above technical issues.

[0006] This manual adopts the following technical solutions:

[0007] This specification provides a method for determining the fault phase and fault distance during a single-phase grounding fault, including:

[0008] Using power electronics to inject common-mode probing signals into the distribution network;

[0009] Collect and calculate the current phasor, voltage phasor, zero-sequence voltage phasor and zero-sequence current phasor at the head end of the fault line after injecting the common-mode detection signal;

[0010] The differential admittance amplitude of each phase is obtained by calculation based on the current phasor, voltage phasor, zero-sequence voltage phasor and zero-sequence current phasor;

[0011] The phase corresponding to the minimum differential admittance amplitude among the differential admittance amplitudes of each phase is taken as the first phase, and whether the ratio of the second differential admittance amplitude of the second phase to the third differential admittance amplitude of the third phase satisfies a preset ratio interval is determined; if so, the first phase is determined as the fault phase;

[0012] Obtain the fundamental frequency line head-end zero-sequence voltage and the fault phase voltage phasor of the fault phase, calculate the upper limit of the ground fault transition resistance, and determine the ground fault transition resistance range;

[0013] The fault distance is calculated based on the current phasor, voltage phasor, zero-sequence voltage phasor, zero-sequence current phasor and the ground fault transition resistance range.

[0014] Optionally, a power electronic device is used to inject a common-mode detection signal into the distribution network, specifically including:

[0015] injecting a common-mode detection signal into the distribution network according to an injection strategy using a power electronic device;

[0016] Among them, the injection strategy includes constant voltage strategy and constant current injection strategy;

[0017] The frequency of the common-mode detection signal is less than the carrier frequency of the power electronic equipment, the upper frequency band limit of the measuring equipment, and the upper frequency band limit of the line π model. The injection duration of the common-mode detection signal is not less than the stabilization time of the common-mode detection signal and is greater than the data window duration of the ranging algorithm.

[0018] The injection voltage amplitude of the constant voltage strategy is less than 10% of the rated voltage, and the injection current of the constant current injection strategy is less than 10% of the rated current.

[0019] Optionally, the differential admittance amplitude of each phase is calculated based on the current phasor, voltage phasor, zero-sequence voltage phasor, and zero-sequence current phasor, using the following formula:

[0020] ;

[0021] Among them, DIFA, DIFB and DIFC represent the differential admittance amplitude of phase A, phase B and phase C respectively. 、 and represents the current phasor, 、 and represents the voltage phasor, Represents the zero-sequence voltage phasor.

[0022] Optionally, the preset ratio interval is:

[0023] ;

[0024] in, is the second differential admittance amplitude, is the third differential admittance amplitude, and are the upper and lower limits of the ratio of the differential admittance amplitudes, respectively.

[0025] Optionally, the upper limit calculation formula of the ground fault transition resistance is:

[0026] ;

[0027] in, 、 Respectively represent the total admittance of the three-phase lines A, B and C to the ground, 、 、 , Indicates the total capacitance of the three-phase lines A, B, and C to the ground. Indicates the neutral point to ground admittance, for an ungrounded system =0, represents the neutral point fundamental frequency steady-state voltage, represents the fundamental frequency steady-state voltage of the fault phase, Indicates the upper limit of the ground fault transition resistance, represents the imaginary unit, represents the angular frequency;

[0028] The ground fault transition resistance range is:

[0029] ;

[0030] in, is the ground fault transition resistance.

[0031] Optionally, the fault distance calculation formula is:

[0032] ;

[0033] in, and are the fault phase voltage and current at the line head end, and are the zero-sequence voltage and current at the line head end, 、 and are the positive sequence resistance, inductance and capacitance per unit length of the line, 、 、 are the zero-sequence resistance, inductance and capacitance per unit length of the line, is the distance from the line head end to the fault point, is the fault point transition resistance, zero sequence current compensation coefficient , , zero-sequence voltage compensation coefficient , represents the function of the fault distance, Indicates the zero-sequence voltage at the fault point, Indicates the zero-sequence voltage at the end of the line, Indicates the current value flowing through the series branch of phase A upstream of the fault point. Indicates the zero-sequence current upstream of the fault point, represents the imaginary unit, represents the angular frequency, Indicates the total length of the line.

[0034] This specification provides a device for determining the fault phase and fault distance during a single-phase grounding fault, including:

[0035] A signal injection module is specifically used to inject a common-mode detection signal into the distribution network using a power electronic device;

[0036] The data calculation module is specifically used to collect and calculate the current phasor, voltage phasor, zero-sequence voltage phasor and zero-sequence current phasor at the head end of the fault line after the common-mode detection signal is injected; and the differential admittance amplitude of each phase is calculated based on the current phasor, voltage phasor, zero-sequence voltage phasor and zero-sequence current phasor;

[0037] a fault phase determination module, specifically configured to determine the phase corresponding to the minimum differential admittance amplitude among the differential admittance amplitudes of each phase as the first phase, and determine whether the ratio of the second differential admittance amplitude of the second phase to the third differential admittance amplitude of the third phase satisfies a preset ratio interval; if so, determine the first phase as the fault phase;

[0038] The fault distance determination module is specifically used to obtain the zero-sequence voltage at the head end of the line at the fundamental frequency and the fault phase voltage phasor of the fault phase, calculate the upper limit of the ground fault transition resistance, and determine the range of the ground fault transition resistance; based on the current phasor, voltage phasor, zero-sequence voltage phasor, zero-sequence current phasor and the range of the ground fault transition resistance, the fault distance is calculated.

[0039] This specification provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the method for determining the fault phase and fault distance during a single-phase grounding fault is implemented.

[0040] This specification provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the method for determining the fault phase and fault distance during a single-phase grounding fault is implemented.

[0041] At least one of the above technical solutions adopted in this specification can achieve the following beneficial effects:

[0042] In the method for determining the fault phase and fault distance during a single-phase grounding fault provided in this specification, a power electronic device is used to inject a common-mode detection signal into the neutral point of the distribution network, and the injected detection signal is used to perform fault phase selection and distance measurement.

[0043] The present invention combines the high controllability of existing power electronic equipment, injects common-mode detection signals into the distribution network, enhances fault characteristics, overcomes the influence of transition resistance, and improves the accuracy of phase selection and distance measurement for single-phase grounding faults in the distribution network. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0045] Figure 1 This is a flow chart of a method for determining the fault phase and fault distance during a single-phase grounding fault provided in this specification;

[0046] Figure 2 A schematic diagram of a simulation experiment to verify the method of the present invention;

[0047] Figure 3 This is a schematic diagram of a device for determining the fault phase and fault distance during a single-phase grounding fault provided in this manual;

[0048] Figure 4 This is a schematic diagram of a computer device that implements a method for determining the fault phase and fault distance during a single-phase grounding fault provided in this specification. DETAILED DESCRIPTION

[0049] To make the purpose, technical solutions, and advantages of this specification more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the specific embodiments of this specification and the corresponding drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0050] In the distribution network system, the system zero-sequence voltage increases after a single-phase grounding fault occurs in the distribution network, significantly deviating from the normal value. The corresponding startup criterion is shown in the formula:

[0051] ;

[0052] Where: Generally, it is 10% of the system rated voltage; The power frequency steady-state zero-sequence voltage at the neutral point of the distribution network The absolute value of the sampling points, The power frequency steady-state zero-sequence voltage at the neutral point of the distribution network The absolute value of the sampling points.

[0053] For example, under normal circumstances, zero-sequence voltage is like the surface of calm water, with minimal fluctuations (e.g., 0.05 kV). When a leakage event occurs, the voltage suddenly spikes to 1.2 kV, 1.3 kV, and 1.4 kV (exceeding 1 kV at three consecutive points), prompting the system to immediately trigger an alarm and disconnect the faulty line. However, interference can occur. For example, the voltage might occasionally jump to 1.1 kV, only to return to 0.2 kV at the next point. The system ignores this fluctuation and does not generate an error. Therefore, only after three consecutive voltage spikes are the voltage abnormalities confirmed to be a true leakage event, prompting a prompt power outage to protect the equipment. This approach avoids misdiagnosis while enabling rapid response to actual faults.

[0054] The following describes in detail the technical solutions provided by various embodiments of the present application in conjunction with the accompanying drawings.

[0055] Figure 1 This is a flow chart of a method for determining the fault phase and fault distance during a single-phase grounding fault in this specification, which specifically includes the following steps:

[0056] S101: Use a power electronic device to inject a common-mode detection signal into a distribution network.

[0057] In this embodiment, a power electronic device is used to inject a common-mode detection signal into the power distribution network, specifically including:

[0058] Use power electronic devices to inject common-mode detection signals into the distribution network according to the injection strategy; the injection strategy includes a constant voltage strategy and a constant current injection strategy; the frequency of the common-mode detection signal is lower than the carrier frequency of the power electronic equipment, the upper limit of the frequency band of the measuring equipment and the upper limit of the applicable frequency band of the line π model; the injection duration of the common-mode detection signal is not less than the stabilization time of the common-mode detection signal and is longer than the data window duration of the ranging algorithm; the injection voltage amplitude of the constant voltage strategy is less than 10% of the rated voltage, and the injection current of the constant current injection strategy is less than 10% of the rated current.

[0059] Based on this, in one or more embodiments of this specification, the execution entity can be a hardware device or system with multimodal data collection, processing and analysis capabilities, including servers, edge computing devices, etc.

[0060] The server mentioned in this specification can be a server set up on a business platform, or a device such as a desktop computer or a laptop computer that can execute the solution of this specification. For the sake of convenience, the following description will only take the server as the execution subject.

[0061] For example, a common-mode detection signal can be injected into the distribution network using power electronic devices, specifically into the neutral point of the distribution network. The neutral point in a distribution network refers to the common point of a star connection in a three-phase AC power system. It is typically connected to the ground using various electrical connections (grounded or ungrounded) to achieve voltage balancing and fault control. It is a core parameter for the safe operation of the power grid, directly affecting system insulation levels, overvoltage suppression, relay protection logic, and power supply reliability.

[0062] Optionally, the upper limit of the frequency of the injected non-industrial frequency signal shall not exceed the smaller value of the carrier frequency of the power electronic equipment, the upper limit of the frequency band of the measuring equipment, and the upper limit of the applicable frequency band of the line π model; avoid the industrial frequency harmonic band; the injected voltage amplitude shall not exceed 10% of the rated voltage during constant voltage injection, and shall not exceed 10% of the rated current during constant current injection; the duration of the injected signal shall ensure that the injected signal is stable and shall be greater than the data window duration required by the ranging algorithm.

[0063] The data window duration of the distance measurement algorithm refers to the data window duration for determining the fault distance.

[0064] S102: Collect and calculate the current phasor, voltage phasor, zero-sequence voltage phasor, and zero-sequence current phasor at the head end of the fault line after the common-mode detection signal is injected.

[0065] Exemplarily, the head end of the fault line is a section of the fault line in the distribution network after the common mode detection signal is injected, and the current phasor, voltage phasor, zero-sequence voltage phasor and zero-sequence current phasor of the common mode signal are collected and calculated.

[0066] A common-mode probe signal is a common-mode voltage or current signal with controllable frequency and amplitude, artificially injected into the distribution network via power electronic devices. Common-mode signals refer to the voltage / current components of all phases with respect to ground, either naturally present in the distribution network or induced by the probe signal. Fault detection is achieved by analyzing the disturbance response in the common-mode signal.

[0067] Among them, the current phasor can be expressed as 、 and , the voltage phasor can be expressed as 、 and , the zero-sequence voltage phasor and the zero-sequence current phasor can be expressed as and .

[0068] S103: Calculate the differential admittance amplitude of each phase according to the current phasor, the voltage phasor, the zero-sequence voltage phasor, and the zero-sequence current phasor.

[0069] In this embodiment, the differential admittance amplitude of each phase is calculated based on the current phasor, voltage phasor, zero-sequence voltage phasor, and zero-sequence current phasor, using the following formula:

[0070] ;

[0071] Among them, DIFA, DIFB and DIFC represent the differential admittance amplitude of phase A, phase B and phase C respectively. 、 and represents the current phasor, 、 and represents the voltage phasor, Represents the zero-sequence voltage phasor.

[0072] S104: The phase corresponding to the minimum differential admittance amplitude among the differential admittance amplitudes of each phase is taken as the first phase, and it is determined whether the ratio of the second differential admittance amplitude of the second phase to the third differential admittance amplitude of the third phase meets a preset ratio range. If so, the first phase is determined to be the fault phase.

[0073] In this embodiment, the preset ratio interval is:

[0074] ;

[0075] in, is the second differential admittance amplitude, is the third differential admittance amplitude, and are the upper and lower limits of the ratio of the differential admittance amplitudes, respectively.

[0076] For example, during the fault phase determination process, a zero-sequence signal is injected, resulting in equal voltage and current in the non-fault phase. Furthermore, after the injection, the voltage and current at the two non-fault phase terminals should be equal, resulting in the differential admittance amplitude of the fault phase being equal to 0. Furthermore, the stored historical data shows a corresponding proportional relationship between the differential admittance amplitudes of the fault phases. Therefore, a preset proportional interval can be determined based on the ratio of the differential admittance amplitudes of the two non-fault phases in the historical data to determine the differential admittance amplitude ratio relationship satisfied by the non-fault phase.

[0077] Optionally, during the fault phase determination process, the first differential admittance amplitude of the first phase satisfies the following formula:

[0078] ;

[0079] Among them, DIFA, DIFB and DIFC represent the differential admittance amplitude of phase A, phase B and phase C respectively. is the first differential admittance amplitude;

[0080] S105: Obtain the fundamental frequency line head-end zero-sequence voltage and the fault phase voltage phasor of the fault phase, calculate the upper limit value of the ground fault transition resistance, and determine the ground fault transition resistance range.

[0081] In this embodiment, the calculation formula for the upper limit of the ground fault transition resistance is:

[0082] ;

[0083] in, 、 Respectively represent the total admittance of the three-phase lines A, B and C to the ground, 、 、 , Indicates the total capacitance of the three-phase lines A, B, and C to the ground. Indicates the neutral point to ground admittance, for an ungrounded system =0, represents the neutral point fundamental frequency steady-state voltage, represents the fundamental frequency steady-state voltage of the fault phase, Indicates the upper limit of the ground fault transition resistance, represents the imaginary unit, represents the angular frequency;

[0084] The ground fault transition resistance range is:

[0085] ;

[0086] in, is the ground fault transition resistance.

[0087] S106: Calculate the fault distance based on the current phasor, the voltage phasor, the zero-sequence voltage phasor, the zero-sequence current phasor, and the ground fault transition resistance range.

[0088] In this embodiment, the fault distance calculation formula is:

[0089] ;

[0090] in, and are the fault phase voltage and current at the line head end, and are the zero-sequence voltage and current at the line head end, 、 and are the positive sequence resistance, inductance and capacitance per unit length of the line, 、 、 are the zero-sequence resistance, inductance and capacitance per unit length of the line, is the distance from the line head end to the fault point, is the fault point transition resistance, zero sequence current compensation coefficient , , zero-sequence voltage compensation coefficient , represents the function of the fault distance, Indicates the zero-sequence voltage at the fault point, Indicates the zero-sequence voltage at the end of the line, Indicates the current value flowing through the series branch of phase A upstream of the fault point. Indicates the zero-sequence current upstream of the fault point, represents the imaginary unit, represents the angular frequency, Indicates the total length of the line.

[0091] In this embodiment, when solving the fault distance calculation formula, from Decrease to 0 Ω, and substitute each Value, characteristic frequency electrical quantity at the head end of the line. When the imaginary part of is closest to 0, The real part of is the fault distance, corresponding to This is the true value of the transition resistance. As shown in the following formula:

[0092] ;

[0093] in, Indicates the total length of the line. Express satisfaction The nth solution of express The set of all solutions of Indicates the i The imaginary part of a solution, express p The real part of is the fault distance.

[0094] Optionally, in this embodiment, a simulation analysis can be performed based on a single-phase grounding fault model of a 10 kV neutral point ungrounded distribution network using electromagnetic transient simulation software PSCAD / EMTDC as an example to verify the correctness and accuracy of the present invention.

[0095] like Figure 2 As shown, Figure 2 Schematic diagram of the simulation experiment to verify the method of the present invention. Figure 2 In the simulation model of the distribution network, the load of each feeder is set to 1 MV·A. L A phase A ground fault occurs 4 km from the busbar. Point M in the diagram is the electrical measurement point at the line's headend. Table 1 shows the cable parameters in the simulation diagram.

[0096] Table 1 Cable parameters

[0097]

[0098] exist Figure 2 In the schematic diagram of the simulation experiment shown, the power electronic device is controlled to inject a current signal with a frequency of 575 Hz and an injection current amplitude of 20 A at the neutral point, and the method of the present invention is executed. L 2 load simulation, and obtain the voltage and current data of 575 Hz at the M end of the line after the fault. The phase selection and distance measurement results are shown in Tables 2 and 3. Table 2 is a summary table of phase selection results under different fault conditions, and Table 3 is a summary table of distance measurement results under different fault conditions.

[0099] Table 2 Summary of phase selection results under different fault conditions

[0100]

[0101] According to Table 2, the method for determining the fault phase and fault distance during a single-phase grounding fault and the grounding fault phase selection method proposed in the present invention are accurate and effective.

[0102] Table 3 Summary of ranging results under different fault conditions

[0103]

[0104] The ranging results in Table 3 show that the maximum relative error is 0.21% and the maximum absolute error is 24.8 m, respectively. The range measurement is highly accurate and unaffected by transition resistance and load.

[0105] based on Figure 1 The method for determining the fault phase and fault distance during a single-phase grounding fault shown in the figure combines the high controllability of existing power electronic equipment to inject a common-mode detection signal into the distribution network, enhance the fault characteristics, overcome the influence of transition resistance, and improve the accuracy of phase selection and distance measurement for single-phase grounding faults in the distribution network.

[0106] When applying the method for determining the fault phase and fault distance in the case of a single-phase ground fault provided in this manual, it is not necessary to use Figure 1 The steps are executed in the order shown. The specific execution order of the steps can be determined according to needs and this manual does not limit this.

[0107] The above is a method for determining the fault phase and fault distance during a single-phase grounding fault provided by one or more embodiments of this specification. Based on the same idea, this specification also provides a corresponding device for determining the fault phase and fault distance during a single-phase grounding fault, such as Figure 3 shown.

[0108] Figure 3 The schematic diagram of a device for determining the fault phase and fault distance during a single-phase grounding fault provided in this specification includes:

[0109] A signal injection module is specifically used to inject a common-mode detection signal into the distribution network using a power electronic device;

[0110] The data calculation module is specifically used to collect and calculate the current phasor, voltage phasor, zero-sequence voltage phasor and zero-sequence current phasor at the head end of the fault line after the common-mode detection signal is injected; and the differential admittance amplitude of each phase is calculated based on the current phasor, voltage phasor, zero-sequence voltage phasor and zero-sequence current phasor;

[0111] a fault phase determination module, specifically configured to determine the phase corresponding to the minimum differential admittance amplitude among the differential admittance amplitudes of each phase as the first phase, and determine whether the ratio of the second differential admittance amplitude of the second phase to the third differential admittance amplitude of the third phase satisfies a preset ratio interval; if so, determine the first phase as the fault phase;

[0112] The fault distance determination module is specifically used to obtain the zero-sequence voltage at the head end of the line at the fundamental frequency and the fault phase voltage phasor of the fault phase, calculate the upper limit of the ground fault transition resistance, and determine the range of the ground fault transition resistance; based on the current phasor, voltage phasor, zero-sequence voltage phasor, zero-sequence current phasor and the range of the ground fault transition resistance, the fault distance is calculated.

[0113] The specific limitations of the device for determining the fault phase and fault distance during a single-phase ground fault can be found in the limitations of the method for determining the fault phase and fault distance during a single-phase ground fault described above and will not be further elaborated here. Each module within the device for determining the fault phase and fault distance during a single-phase ground fault can be implemented in whole or in part via software, hardware, or a combination thereof. Each of these modules can be embedded in or independent of a processor within a computer device in hardware form, or stored in a computer device memory in software form, allowing the processor to call and execute the corresponding operations of each module.

[0114] This specification also provides a computer-readable storage medium, which stores a computer program that can be used to execute the above Figure 1 A method for determining the fault phase and fault distance during a single-phase grounding fault is provided.

[0115] This manual also provides Figure 4 The structural diagram of the computer equipment shown in FIG. Figure 4 At the hardware level, the computer device includes a processor, an internal bus, a network interface, a memory, and a non-volatile memory. Of course, it may also include other hardware required for the business. The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs it to achieve the above Figure 1 A method for determining the fault phase and fault distance during a single-phase grounding fault is provided.

[0116] Those skilled in the art will appreciate that all or part of the processes in the above-described method embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the above-described method embodiments. Any reference to memory, storage, database, or other media used in the embodiments provided herein may include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory, or optical storage. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0117] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A method for determining the fault phase and fault distance during a single-phase grounding fault, characterized in that: include: Using power electronics to inject common-mode probing signals into the distribution network; Collect and calculate the current phasor, voltage phasor and zero-sequence voltage and current phasor at the head end of the fault line after injecting the common-mode detection signal; Calculating the differential admittance amplitude of each phase according to the current phasor, the voltage phasor and the zero-sequence voltage and current phasor; The phase corresponding to the minimum differential admittance amplitude among the differential admittance amplitudes of the phases is taken as the first phase, and whether the ratio of the second differential admittance amplitude of the second phase to the third differential admittance amplitude of the third phase satisfies a preset ratio interval is determined; if so, the first phase is determined as the fault phase; Obtaining the fundamental frequency line head-end zero-sequence voltage and the fault phase voltage phasor of the fault phase, calculating the upper limit value of the ground fault transition resistance, and determining the ground fault transition resistance range; Calculating a fault distance based on the current phasor, the voltage phasor, the zero-sequence voltage and current phasor, and the ground fault transition resistance range; The preset ratio interval is: in, is the second differential admittance amplitude, is the third differential admittance amplitude, and are the upper and lower limits of the ratio of the differential admittance amplitudes, respectively; The calculation formula for the upper limit of the ground fault transition resistance is: in, 、 Respectively represent the total admittance of the three-phase lines A, B and C to the ground, 、 、 , Indicates the total capacitance of the three-phase lines A, B, and C to the ground. Indicates the neutral point to ground admittance, for an ungrounded system =0, represents the neutral point fundamental frequency steady-state voltage, represents the fundamental frequency steady-state voltage of the fault phase, Indicates the upper limit of the ground fault transition resistance, represents the imaginary unit, represents the angular frequency; The ground fault transition resistance range is: in, is the ground fault transition resistance; The fault distance calculation formula is: in, and are the fault phase voltage and current at the line head end, and are the zero-sequence voltage and current at the line head end, 、 and are the positive sequence resistance, inductance and capacitance per unit length of the line, 、 、 is the zero-sequence resistance, inductance and capacitance per unit length of the line, is the distance from the line head end to the fault point, is the fault point transition resistance, zero sequence current compensation coefficient , , zero-sequence voltage compensation coefficient , represents the function of the fault distance, Indicates the zero-sequence voltage at the fault point, Indicates the zero-sequence voltage at the end of the line, Indicates the current value flowing through the series branch of phase A upstream of the fault point. Indicates the zero-sequence current upstream of the fault point, represents the imaginary unit, represents the angular frequency, Indicates the total length of the line.

2. The method for determining the fault phase and fault distance during a single-phase grounding fault according to claim 1, wherein: The method of injecting a common-mode detection signal into the power distribution network using a power electronic device specifically includes: injecting a common-mode detection signal into the distribution network according to an injection strategy using a power electronic device; Wherein, the injection strategy includes a constant voltage strategy and a constant current injection strategy; The frequency of the common-mode detection signal is less than the carrier frequency of the power electronic device, the upper limit of the frequency band of the measuring device, and the upper limit of the applicable frequency band of the line π model. The injection duration of the common-mode detection signal is not less than the stabilization time of the common-mode detection signal and is greater than the data window duration of the ranging algorithm. The injection voltage amplitude of the constant voltage strategy is less than Rated voltage, the injection current of the constant current injection strategy is less than Rated current.

3. The method for determining the fault phase and fault distance during a single-phase grounding fault according to claim 1, wherein: The differential admittance amplitude of each phase is calculated based on the current phasor, the voltage phasor and the zero-sequence voltage and current phasor, and the formula used is: Among them, DIFA, DIFB and DIFC represent the differential admittance amplitude of phase A, phase B and phase C respectively. 、 and represents the current phasor, 、 and represents the voltage phasor, and Represents the zero-sequence voltage and current phasor.

4. A device for determining the fault phase and fault distance during a single-phase grounding fault, characterized in that: include: A signal injection module is specifically used to inject a common-mode detection signal into the distribution network using a power electronic device; A data calculation module is specifically used to collect and calculate the current phasor, voltage phasor and zero-sequence voltage and current phasor at the head end of the fault line after the common-mode detection signal is injected; and to obtain the differential admittance amplitude of each phase based on the current phasor, the voltage phasor and the zero-sequence voltage and current phasor; a fault phase determination module, specifically configured to determine the phase corresponding to the minimum differential admittance amplitude among the differential admittance amplitudes of the phases as the first phase, and determine whether the ratio of the second differential admittance amplitude of the second phase to the third differential admittance amplitude of the third phase satisfies a preset ratio interval; if so, determine the first phase as the fault phase; A fault distance determination module is specifically configured to obtain the zero-sequence voltage at the line head end of the fundamental frequency and the fault phase voltage phasor of the fault phase, calculate the upper limit of the ground fault transition resistance, and determine the ground fault transition resistance range; and calculate the fault distance based on the current phasor, voltage phasor, zero-sequence voltage and current phasor, and the ground fault transition resistance range; The preset ratio interval is: in, is the second differential admittance amplitude, is the third differential admittance amplitude, and are the upper and lower limits of the ratio of the differential admittance amplitudes, respectively; The calculation formula for the upper limit of the ground fault transition resistance is: in, 、 Respectively represent the total admittance of the three-phase lines A, B and C to the ground, 、 、 , Indicates the total capacitance of the three-phase lines A, B, and C to the ground. Indicates the neutral point to ground admittance, for an ungrounded system =0, represents the neutral point fundamental frequency steady-state voltage, represents the fundamental frequency steady-state voltage of the fault phase, Indicates the upper limit of the ground fault transition resistance, represents the imaginary unit, represents the angular frequency; The ground fault transition resistance range is: in, is the ground fault transition resistance; The fault distance calculation formula is: in, and are the fault phase voltage and current at the line head end, and are the zero-sequence voltage and current at the line head end, 、 and are the positive sequence resistance, inductance and capacitance per unit length of the line, 、 、 is the zero-sequence resistance, inductance and capacitance per unit length of the line, is the distance from the line head end to the fault point, is the fault point transition resistance, zero sequence current compensation coefficient , , zero-sequence voltage compensation coefficient , represents the function of the fault distance, Indicates the zero-sequence voltage at the fault point, Indicates the zero-sequence voltage at the end of the line, Indicates the current value flowing through the series branch of phase A upstream of the fault point. Indicates the zero-sequence current upstream of the fault point, represents the imaginary unit, represents the angular frequency, Indicates the total length of the line.

5. A computer-readable storage medium, characterized in that The storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 3 is implemented.

6. A computer device, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method according to any one of claims 1 to 3 is implemented.

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