High-resistance grounding fault detection method based on voltage and current sequence components

Abstract

The invention discloses a high-resistance grounding fault detection method based on voltage and current sequence components, and relates to the field of power system fault detection, and the method comprises the steps: obtaining voltage and current sequence component data, analyzing and summarizing a sequence component measurement model, measuring the voltage and current sequence component data, and obtaining a sequence component measurement result. Obtaining fault feature data, analyzing and summarizing a fault criterion model, and obtaining a fault judgment result; and a fault detection result is obtained by combining the sequence component measurement result and the fault judgment result, and high-resistance grounding fault detection is completed. According to the method, the starting criterion considering the system imbalance and the fault component is introduced, so that the reliability of fault detection is improved; by analyzing the phase difference, the single-end feeder line fault and the double-end feeder line fault are accurately distinguished, and accurate judgment of the fault type is achieved; in combination with sequence component measurement and a fault criterion model, a fault is quickly positioned, and an instruction of cutting off a fault feeder is sent out in time.

Description

Technical Field

[0001] The invention relates to the field of power system fault detection, in particular to a high-resistance grounding fault detection method based on voltage and current sequence components. Background Art

[0002] In the power system, a high-resistance ground fault refers to a situation where, when a ground fault occurs in power equipment, the ground resistance at the fault point is large, resulting in a small fault current and making it difficult to be detected by conventional protection devices. The occurrence of a high-resistance ground fault will not only affect the reliability of power supply, but may also cause equipment damage and even endanger personal safety. Therefore, how to effectively detect and locate a high-resistance ground fault is an important issue in power system protection.

[0003] Traditional ground fault detection methods mainly rely on the magnitude and direction of the current. However, for high-resistance ground faults, these traditional methods are often difficult to work due to the small fault current, which can easily lead to missed detection or misjudgment of faults. In recent years, with the development of signal processing technology and power electronics technology, fault detection methods based on voltage and current sequence components have gradually attracted attention. This method can more accurately detect and locate the fault point in the case of high-resistance ground faults by analyzing the sequence components of voltage and current, especially the zero-sequence, positive-sequence and negative-sequence components.

[0004] The detection method based on voltage and current sequence components has the characteristics of high sensitivity and high accuracy, which can overcome the shortcomings of traditional methods in high-resistance grounding fault detection. However, the existing methods and systems still have some problems in practical applications, such as insufficient anti-interference ability and high computational complexity. Therefore, a high-resistance grounding fault detection method based on voltage and current sequence components is proposed to improve the accuracy and reliability of fault detection and avoid possible misjudgment and missed judgment in traditional methods. Summary of the invention

[0005] In view of the problems of insufficient anti-interference ability, missed fault detection or misjudgment and high calculation complexity in the existing high-resistance grounding fault detection method, the present invention is proposed.

[0006] Therefore, the problem to be solved by the present invention is how to more effectively detect and locate high-resistance grounding faults in a power system, thereby improving the accuracy and reliability of fault detection.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] In a first aspect, an embodiment of the present invention provides a high-resistance grounding fault detection method based on voltage and current sequence components, which includes obtaining voltage and current sequence component data of a distribution network system, analyzing and summarizing a sequence component measurement model, measuring the voltage and current sequence component data through the sequence component measurement model, and obtaining a sequence component measurement result; obtaining fault characteristic data of the distribution network system, analyzing and summarizing a fault judgment model, judging the fault characteristic data through the fault judgment model, and obtaining a fault judgment result; combining the sequence component measurement result and the fault judgment result to obtain a fault detection result, and completing high-resistance grounding fault detection based on voltage and current sequence components.

[0009] As a preferred solution of the high-resistance grounding fault detection method based on voltage and current sequence components described in the present invention, wherein: the voltage and current sequence component data include positive sequence components, negative sequence components and zero sequence components of three-phase voltage and current; the fault characteristic data include fault components and system imbalance; the fault components include bus positive sequence voltage fault components and feeder positive sequence current fault components; the fault criterion model includes startup criterion and fault feeder criterion.

[0010] As a preferred solution of the high-resistance grounding fault detection method based on voltage and current sequence components of the present invention, the fault criterion model includes the following steps: calculating the starting criterion R of each feeder in the distribution network according to the system imbalance and the fault component, and judging whether the starting criterion R is satisfied, and determining the suspected fault feeder; for the suspected fault feeder, analyzing the phase difference between the bus positive sequence voltage fault component and the feeder positive sequence current fault component Formulate a fault feeder criterion and determine whether the fault feeder criterion is met; determine the fault location and issue an instruction to cut off the fault feeder based on the start criterion R and the determination result of the fault feeder criterion.

[0011] As a preferred solution of the high-resistance grounding fault detection method based on voltage and current sequence components of the present invention, the calculation formula of the starting criterion R is as follows:

[0012]

[0013] Among them, R is the starting criterion, R set is the preset start criterion threshold, F n is the system imbalance index, F i is the fault component index, where

[0014]

[0015] Among them, ΔI0 is the effective value of the zero-sequence current fault component of the feeder, ΔI1 is the effective value of the negative-sequence current fault component of the feeder, ΔI2 is the effective value of the positive-sequence current fault component of the feeder, I0 is the effective value of the zero-sequence current of the feeder, I1 is the effective value of the negative-sequence current of the feeder, and I2 is the effective value of the positive-sequence current of the feeder.

[0016] As a preferred solution of the high-resistance grounding fault detection method based on voltage and current sequence components of the present invention, it also includes: when the starting criterion R value is less than or equal to the preset starting criterion threshold R set When the startup criterion R value is greater than the preset startup criterion threshold R set When , a high-resistance grounding fault occurs in the system, and it is determined to be a suspected faulty feeder, and a faulty feeder criterion check is performed; the faulty feeder criterion check includes, for a single-ended feeder fault, if the phase difference between the busbar positive sequence voltage fault component and the feeder positive sequence current fault component is The suspected fault feeder is determined to be a fault feeder and the fault feeder is directly cut off; if the phase difference between the bus positive sequence voltage fault component and the feeder positive sequence current fault component is Then exclude this suspected faulty feeder and check the next suspected faulty feeder; for a double-terminal feeder fault, if the phase difference between the busbar positive sequence voltage fault component and the feeder positive sequence current fault component is and The suspected faulty feeder is determined to be a faulty feeder, and the faulty line is removed through communication coordination, and a tripping command is sent to the circuit breaker, waiting for the circuit breaker action feedback signal, and recording the fault information; if the phase difference between the busbar positive sequence voltage fault component and the feeder positive sequence current fault component is and If the suspected faulty feeder is eliminated, the next suspected faulty feeder is checked. If the suspected faulty feeders of the single-end feeder fault and the double-end feeder fault are eliminated, it is determined to be a false alarm, and the preset start judgment threshold R is adjusted. set , and continue to monitor data from the distribution network system.

[0017] As a preferred solution of the high-resistance grounding fault detection method based on voltage and current sequence components of the present invention, wherein: the sequence component measurement model is based on the three-phase voltage and current measured values ​​to calculate the three-sequence components, and the fault component is calculated based on the three-sequence components. The specific operation includes the following steps: based on the three-phase voltage and current measured values, the three-sequence components are calculated, and the specific formula is as follows:

[0018]

[0020] α=e j120 °

[0021] in, is the positive sequence component, is the negative sequence component, is the zero sequence component, F a is the measured value of phase a voltage or current, F b is the measured value of phase b voltage or current, F c is the measured value of phase c voltage or current, and α is the rotation operator.

[0022] According to the three-sequence components, the voltage and current positive sequence fault components are calculated; the phase information of the voltage and current positive sequence fault components is extracted by discrete Fourier transform DFT, and the phase difference between the bus positive sequence voltage fault component and the feeder positive sequence current fault component is calculated.

[0023] As a preferred solution of the high-resistance grounding fault detection method based on voltage and current sequence components of the present invention, the three-sequence components include positive sequence components, negative sequence components and zero sequence components; the calculation formula of the voltage and current positive sequence fault component is as follows:

[0024]

[0025] Among them, F a ' is the positive sequence component before the fault, F b ' is the negative sequence component before the fault, F c ' is the zero sequence component before the fault, is the positive sequence component of phase a fault, is the negative sequence component of phase a fault, It is the zero-sequence component of phase a fault.

[0026] In the second aspect, an embodiment of the present invention provides a high-resistance grounding fault detection system based on voltage and current sequence components, which includes: a sequence component measurement module, used to obtain voltage and current sequence component data of the distribution network system, analyze and summarize the sequence component measurement model, measure the voltage and current sequence component data through the sequence component measurement model, and obtain sequence component measurement results; a fault judgment module, used to obtain fault characteristic data of the distribution network system, analyze and summarize the fault judgment model, judge the fault characteristic data through the fault judgment model, and obtain a fault judgment result; a detection module, used to combine the sequence component measurement result and the fault judgment result to obtain a fault detection result, and complete high-resistance grounding fault detection based on voltage and current sequence components.

[0027] In a third aspect, an embodiment of the present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, wherein: when the computer program instructions are executed by the processor, the steps of the high-resistance grounding fault detection method based on voltage and current sequence components as described in the first aspect of the present invention are implemented.

[0028] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program instructions are executed by a processor, the steps of the high-resistance grounding fault detection method based on voltage and current sequence components as described in the first aspect of the present invention are implemented.

[0029] The beneficial effects of the present invention are as follows: the present invention accurately captures the characteristics of high-resistance faults by analyzing the sequence components of three-phase voltage and current, effectively overcoming the limitations of traditional overcurrent protection in detecting small current faults; introduces a startup criterion that considers system imbalance and fault components, improves the reliability of fault detection, and reduces false alarms and missed alarms; by analyzing the phase difference between the bus positive-sequence voltage fault component and the feeder positive-sequence current fault component, it is possible to accurately distinguish between single-end and double-end feeder faults and achieve accurate determination of the fault type; combines sequence component measurement and fault criterion model to form a complete fault detection process, which can not only quickly locate the fault, but also promptly issue an instruction to cut off the faulty feeder, greatly improving the operating safety and reliability of the distribution network system. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0031] Figure 1 This is a flow chart of a high-resistance grounding fault detection method based on voltage and current sequence components in Example 1.

[0032] Figure 2 This is the IEEE 33-node model of the high-resistance grounding fault detection method based on voltage and current sequence components in Example 2.

[0033] Figure 3 This is the 0-0.1s single-phase short-circuit voltage and current positive sequence component of the high-resistance grounding fault detection method based on voltage and current sequence components in Example 2.

[0034] Figure 4 This is the single-phase short-circuit voltage and current positive sequence fault component of the high-resistance grounding fault detection method based on voltage and current sequence components in Example 2.

[0035] Figure 5 Embodiment 2 is a two-phase short circuit 0-0.1s voltage and current positive sequence component of a high-resistance grounding fault detection method based on voltage and current sequence components.

[0036] Figure 6 Embodiment 2 is a two-phase short-circuit voltage and current positive sequence fault component of a high-resistance grounding fault detection method based on voltage and current sequence components.

[0037] Figure 7 Embodiment 2 is a three-phase short circuit 0-0.1s voltage and current positive sequence component of a high-resistance grounding fault detection method based on voltage and current sequence components.

[0038] Figure 8 Embodiment 2 is a three-phase short-circuit voltage and current positive sequence fault component of a high-resistance grounding fault detection method based on voltage and current sequence components. DETAILED DESCRIPTION

[0039] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0040] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0041] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0042] Example 1

[0043] Reference Figure 1 , which is the first embodiment of the present invention, provides a high-resistance grounding fault detection method based on voltage and current sequence components, including:

[0044] S1: Obtain the voltage and current sequence component data of the distribution network system, analyze and summarize the sequence component measurement model, measure the voltage and current sequence component data through the sequence component measurement model, and obtain the sequence component measurement results.

[0045] Furthermore, the voltage and current sequence component data include positive sequence components, negative sequence components and zero sequence components of the three-phase voltage and current; the sequence component measurement model is to calculate the three-sequence components based on the three-phase voltage and current measured values, and calculate the fault component based on the three-sequence components. The specific operation includes the following steps: based on the three-phase voltage and current measured values, calculate the three-sequence components, the specific formula is as follows:

[0046]

[0048] α=e j120 °

[0049] in, is the positive sequence component, is the negative sequence component, is the zero sequence component, F a is the measured value of phase a voltage or current, F b is the measured value of phase b voltage or current, F c is the measured value of phase c voltage or current, and α is the rotation operator.

[0050] Specifically, the positive sequence fault component of voltage and current is calculated based on the three sequence components; the phase information of the positive sequence fault component of voltage and current is extracted by discrete Fourier transform DFT, and the phase difference between the bus positive sequence voltage fault component and the feeder positive sequence current fault component is calculated.

[0051] It should be noted that the three-sequence components include positive-sequence component, negative-sequence component and zero-sequence component.

[0052] Furthermore, the fault characteristic data includes fault components and system imbalance; the calculation formula of the voltage and current positive sequence fault components is as follows:

[0053]

[0054] Among them, F a ' is the positive sequence component before the fault, F b ' is the negative sequence component before the fault, F c ' is the zero sequence component before the fault, is the positive sequence component of phase a fault, is the negative sequence component of phase a fault, is the zero-sequence component of phase a fault.

[0055] It should be noted that by analyzing the sequence components of voltage and current, high-resistance grounding faults can be detected and located more accurately, because the sequence components can more clearly reflect the voltage and current characteristics under the fault state and effectively reduce the interference of other factors. When a high-resistance grounding fault occurs in the distribution network, the short-circuit current is often lower than the threshold of the traditional overcurrent protection, making it difficult for conventional protection devices to detect and clear the fault. If the short-circuit fault is not eliminated in time, more serious consequences may occur. In order to solve this problem, this paper analyzes the fault component characteristics of the distribution network when a high-resistance grounding fault occurs, and proposes a fault criterion based on the phase difference between the busbar positive sequence voltage fault component and the positive sequence current fault component of each feeder connected to it, which is suitable for the detection of high-resistance grounding faults in the distribution network. At the same time, in order to solve various problems caused by system imbalance in the process of high-resistance grounding fault detection, corresponding fault detection start criteria are formulated. On this basis, a high-resistance grounding fault detection method based on the fault component principle is formed.

[0056] S2: Obtain fault characteristic data of the distribution network system, analyze and summarize the fault judgment model, judge the fault characteristic data through the fault judgment model, and obtain the fault judgment result.

[0057] It should be noted that the sequence component is mainly affected by the load, and the presence of single-phase load, especially in the branch feeder, causes most distribution network systems to be unbalanced. Due to this imbalance, the negative sequence component will also exist during the normal operation of the distribution network, which may cause the erroneous operation of the fault detection scheme based on the sequence component principle. When a high-resistance fault occurs in the distribution network, the current and voltage characteristics before and after the fault do not change significantly, and the fault current does not significantly exceed the rated load current, which further reduces the reliability of the fault start-up criterion based on the sequence component principle. In order to solve these problems, the fault component is introduced into the formulation of the start-up criterion, and the corresponding start-up criterion is proposed to improve the accuracy and reliability of fault detection.

[0058] Specifically, the fault components include the bus positive sequence voltage fault component and the feeder positive sequence current fault component; the fault criterion model includes the following steps: according to the system imbalance and the fault component, the starting criterion R of each feeder in the distribution network is calculated, and whether the starting criterion R is satisfied is determined to determine the suspected fault feeder; for the suspected fault feeder, the phase difference between the bus positive sequence voltage fault component and the feeder positive sequence current fault component is analyzed. Formulate fault feeder criterion and determine whether the fault feeder criterion is met; determine the fault location and issue an instruction to cut off the fault feeder based on the judgment result of the start criterion R and the fault feeder criterion.

[0059] Furthermore, the calculation formula of the start criterion R is as follows:

[0060]

[0061] Among them, R is the starting criterion, R set is the preset start criterion threshold, F n is the system imbalance index, F i is the fault component index, where

[0062]

[0063] Among them, ΔI0 is the effective value of the zero-sequence current fault component of the feeder, ΔI1 is the effective value of the negative-sequence current fault component of the feeder, ΔI2 is the effective value of the positive-sequence current fault component of the feeder, I0 is the effective value of the zero-sequence current of the feeder, I1 is the effective value of the negative-sequence current of the feeder, and I2 is the effective value of the positive-sequence current of the feeder.

[0064] It should be noted that in the distribution network, due to the inherent imbalance, F nThe value of F is usually not zero. Under normal circumstances, the system imbalance is small, usually less than 20%. However, when a low-resistance fault occurs in the distribution network system, F n The value of F n The change of can effectively distinguish the unbalanced state and low resistance fault state of the system. When a high resistance fault occurs, the values ​​of the zero sequence component and negative sequence component of the system may not exceed the values ​​during normal operation. In order to improve the reliability of the starting criterion R, the fault component F i The introduction criterion is formulated. This startup criterion reflects the change relationship of the sequence component from the normal operating state to the fault state, and is less sensitive to network imbalance, so it can be effectively used for the detection of high-resistance faults. In addition, in the actual distribution network, although there may be a situation where the system is fault-free but the load changes, since the changes in the three-phase load usually occur synchronously, no additional negative sequence components and zero sequence components are introduced, so the startup criterion will not cause false start.

[0065] S3: The fault detection result is obtained by combining the sequence component measurement result and the fault judgment result, and the high-resistance grounding fault detection based on the voltage and current sequence components is completed.

[0066] Specifically, when the start criterion R value is less than or equal to the preset start criterion threshold R set When the startup criterion R value is greater than the preset startup criterion threshold R set When a high-resistance grounding fault occurs in the system, it is determined to be a suspected faulty feeder, and a faulty feeder judgment check is performed.

[0067] Furthermore, the fault feeder criterion check includes, for a single-ended feeder fault, if the phase difference between the busbar positive sequence voltage fault component and the feeder positive sequence current fault component is The suspected fault feeder is determined to be a fault feeder and the fault feeder is directly cut off; if the phase difference between the bus positive sequence voltage fault component and the feeder positive sequence current fault component is Then exclude this suspected faulty feeder and check the next suspected faulty feeder; for a double-terminal feeder fault, if the phase difference between the busbar positive sequence voltage fault component and the feeder positive sequence current fault component is and The suspected faulty feeder is determined to be a faulty feeder, and the faulty line is removed through communication coordination, and a tripping command is sent to the circuit breaker, waiting for the circuit breaker action feedback signal, and recording the fault information; if the phase difference between the busbar positive sequence voltage fault component and the feeder positive sequence current fault component is and Then eliminate this suspected faulty feeder and check the next suspected faulty feeder.

[0068] Furthermore, if the suspected faulty feeders of the single-end feeder fault and the double-end feeder fault have been eliminated, it is determined to be a false alarm, and the preset start criterion threshold R is adjusted. set , and continue to monitor data from the distribution network system.

[0069] It should be noted that in the process of fault location and fault feeder removal, based on the above criteria and fault detection process, it can be seen that a lot of redundancy is introduced in the derivation of the fault criteria. The fault detection criterion is not a fixed value, but a phase interval. In order to accurately locate the fault line, after calculating the phase difference of the positive sequence fault component of the feeder voltage and current, it is necessary to compare the phase difference with the fault detection criterion. The comparison result is expressed as a logical value of yes or no. Therefore, in the process of fault location and fault removal, only these logical values ​​need to be transmitted, and even if there is a communication delay, it will not affect the accuracy of fault location. For the location and removal of double-ended feeders, specific conditions must be met, so it needs to be achieved through communication. and For the positioning and removal of single-ended feeders, only the corresponding conditions need to be met, and there is no need to compare with other phase difference information, so no communication is required. In addition, only the phasor measurement information of feeders connected to the same bus needs to be synchronized, and the phasor measurement information between different buses does not need to be synchronized.

[0070] Furthermore, the present embodiment also provides a high-resistance grounding fault detection system based on voltage and current sequence components, including: a sequence component measurement module, used to obtain voltage and current sequence component data of the distribution network system, analyze and summarize the sequence component measurement model, measure the voltage and current sequence component data through the sequence component measurement model, and obtain the sequence component measurement results; a fault judgment module, used to obtain fault characteristic data of the distribution network system, analyze and summarize the fault judgment model, judge the fault characteristic data through the fault judgment model, and obtain the fault judgment result; a detection module, used to combine the sequence component measurement result and the fault judgment result to obtain the fault detection result, and complete the high-resistance grounding fault detection based on voltage and current sequence components.

[0071] This embodiment also provides a computer device, which is applicable to the case of a high-resistance grounding fault detection method based on voltage and current sequence components, including a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the high-resistance grounding fault detection method based on voltage and current sequence components proposed in the above embodiment.

[0072] The computer device may be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covering the display screen, or a key, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse, etc.

[0073] The present embodiment also provides a storage medium having a computer program stored thereon, which implements the following steps when executed by a processor: obtaining voltage and current sequence component data of a distribution network system, analyzing and summarizing a sequence component measurement model, measuring the voltage and current sequence component data through the sequence component measurement model, and obtaining a sequence component measurement result; obtaining fault characteristic data of the distribution network system, analyzing and summarizing a fault judgment model, judging the fault characteristic data through the fault judgment model, and obtaining a fault judgment result; combining the sequence component measurement result and the fault judgment result to obtain a fault detection result, and completing high-resistance grounding fault detection based on voltage and current sequence components.

[0074] In summary, the present invention accurately captures the characteristics of high-resistance faults by analyzing the sequence components of three-phase voltage and current, effectively overcoming the limitations of traditional overcurrent protection in detecting small current faults; introduces a startup criterion that considers system imbalance and fault components to improve the reliability of fault detection and reduce false alarms and missed alarms; by analyzing the phase difference between the bus positive-sequence voltage fault component and the feeder positive-sequence current fault component, it can accurately distinguish between single-end and double-end feeder faults and achieve accurate determination of the fault type; combines sequence component measurement and fault criterion model to form a complete fault detection process, which can not only quickly locate the fault, but also promptly issue an instruction to cut off the faulty feeder, greatly improving the operating safety and reliability of the distribution network system.

[0075] Example 2

[0076] Reference Figure 2 to Figure 8 , which is the second embodiment of the present invention, provides a high-resistance grounding fault detection method based on voltage and current sequence components. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0077] Specifically, Figure 2 As shown, the present invention builds an IEEE 33-node model. Specifically, the IEEE 33-node model is a standard model in power system modeling and simulation. This model consists of 33 nodes and 32 branches, wherein each node represents an electrical device in the power system, such as a transformer, a generator or a distributor, and each branch represents a section of a cable or a transmission line in the power system.

[0078] Furthermore, the IEEE 33-node model mainly consists of three parts: generator, transformer and load. The generator is the power source of the power system and is responsible for providing electricity; the transformer is used to convert the voltage from one voltage level to another to meet the needs of the system; the load represents the electrical equipment in the power system, such as lamps and household appliances. When simulating the power system, the output power of the generator, the transformation ratio of the transformer and the current parameters of the load can be adjusted to simulate different distribution network system operations, thereby analyzing and optimizing the behavior of the distribution network system.

[0079] Furthermore, the IEEE33 node model is widely used in the design and research of power systems because it can accurately simulate the operating characteristics of various types of equipment in the power system. In the IEEE 33 node fault simulation, the low resistance is set to 0.01Ω, the high resistance is set to 2kΩ, the arc suppression coil resistance is set to 500+j1000Ω, the setting multiple m is 5, the simulation time is 0.2 seconds, and the fault time is 0.1 seconds.

[0080] Specifically, in fault simulation, by analyzing the voltage and current positive sequence components under different short circuit types, the judgment criteria of high resistance ground fault can be verified. Figure 3 and Figure 4 As shown, it can be observed that when there is no short circuit, the positive sequence components of voltage and current are large, and the phase difference is between 0-90 degrees. However, when high resistance grounding occurs, the amplitudes of positive sequence voltage and positive sequence current decrease significantly, which are 0.3V and 0.4A respectively. At the same time, the phase difference increases significantly. At this time, the phase difference between the positive sequence voltage fault component and the positive sequence current fault component is 11ms, that is, 198°, which meets the criterion of high resistance fault.

[0081] Furthermore, when two phases are short-circuited, Figure 5 and Figure 6 As shown, it can be seen that under normal conditions, the positive sequence components of the voltage and current are still large, and the phase difference is between 0 and 90 degrees. When a high-resistance grounding fault occurs, the amplitudes of the positive sequence voltage and current decrease to 0.4V and 0.8A respectively, but the phase difference increases significantly to 11.2ms, or 201°, which also meets the criteria for a high-resistance fault.

[0082] Furthermore, in the case of a three-phase short circuit, Figure 7 and Figure 8 As shown, it can be seen that the positive sequence components of voltage and current in the waveform are large under normal conditions, and the phase difference is between 0 and 90 degrees. When a high-resistance grounding fault occurs, the amplitudes of the positive sequence voltage and current drop to 0.6V and 1.3A respectively, but the phase difference increases significantly to 11.4ms, or 205°, which also meets the criteria for a high-resistance fault.

[0083] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A high-resistance grounding fault detection method based on voltage and current sequence components, characterized in that: include, Acquire voltage and current sequence component data of the distribution network system, analyze and summarize a sequence component measurement model, measure the voltage and current sequence component data using the sequence component measurement model, and obtain a sequence component measurement result; Acquire fault characteristic data of the distribution network system, analyze and summarize a fault judgment model, judge the fault characteristic data by the fault judgment model, and obtain a fault judgment result; The fault detection result is obtained by combining the sequence component measurement result and the fault judgment result, and the high-resistance grounding fault detection based on the voltage and current sequence components is completed.

2. The high-resistance grounding fault detection method based on voltage and current sequence components according to claim 1 is characterized in that: The voltage and current sequence component data include positive sequence components, negative sequence components and zero sequence components of three-phase voltage and current; the fault characteristic data include fault components and system imbalance; the fault components include bus positive sequence voltage fault components and feeder positive sequence current fault components; the fault judgment model includes startup judgment criteria and fault feeder judgment criteria.

3. The high-resistance grounding fault detection method based on voltage and current sequence components according to claim 2, characterized in that: The construction process of the fault criterion model includes the following steps: Calculate the start-up criterion R of each feeder in the distribution network according to the system imbalance and the fault component, and determine whether the start-up criterion R is met to determine the suspected fault feeder; For the suspected faulty feeder, the phase difference between the bus positive sequence voltage fault component and the feeder positive sequence current fault component is analyzed. Formulate a fault feeder criterion, and determine whether the fault feeder criterion is met; According to the judgment results of the starting criterion R and the fault feeder criterion, the fault location is determined and an instruction to cut off the faulty feeder is issued.

4. The high-resistance grounding fault detection method based on voltage and current sequence components as claimed in claim 3 is characterized in that: The calculation formula of the start criterion R is as follows: Among them, R is the starting criterion, R set is the preset start criterion threshold, F n is the system imbalance index, F i is the fault component index, where Among them, ΔI0 is the effective value of the zero-sequence current fault component of the feeder, ΔI1 is the effective value of the negative-sequence current fault component of the feeder, ΔI2 is the effective value of the positive-sequence current fault component of the feeder, I0 is the effective value of the zero-sequence current of the feeder, I1 is the effective value of the negative-sequence current of the feeder, and I2 is the effective value of the positive-sequence current of the feeder.

5. The high-resistance grounding fault detection method based on voltage and current sequence components according to claim 4 is characterized in that: Also includes, When the start criterion R value is less than or equal to the preset start criterion threshold R set When , the system operates normally and continues to monitor the data of the distribution network system; When the start criterion R value is greater than the preset start criterion threshold R set When the system has a high-resistance grounding fault, it is determined to be a suspected faulty feeder, and the faulty feeder judgment check is performed; The fault feeder criterion check includes: For a single-ended feeder fault, if the phase difference between the busbar positive sequence voltage fault component and the feeder positive sequence current fault component is The suspected fault feeder is determined to be a fault feeder and the fault feeder is directly cut off; if the phase difference between the bus positive sequence voltage fault component and the feeder positive sequence current fault component is Then eliminate this suspected faulty feeder and check the next suspected faulty feeder; For a double-terminal feeder fault, if the phase difference between the busbar positive sequence voltage fault component and the feeder positive sequence current fault component is and The suspected faulty feeder is determined to be a faulty feeder, and the faulty line is removed through communication coordination, and a tripping command is sent to the circuit breaker, waiting for the circuit breaker action feedback signal, and recording the fault information; if the phase difference between the busbar positive sequence voltage fault component and the feeder positive sequence current fault component is and Then eliminate this suspected faulty feeder and check the next suspected faulty feeder; If the suspected faulty feeders of single-end feeder fault and double-end feeder fault have been eliminated, it is judged as a false alarm and the preset start judgment threshold R is adjusted. set , and continue to monitor data from the distribution network system.

6. The high-resistance grounding fault detection method based on voltage and current sequence components according to claim 1, characterized in that: The sequence component measurement model calculates three-sequence components based on the measured values ​​of three-phase voltage and current, and calculates the fault component based on the three-sequence components. The specific operation includes the following steps: Based on the measured values ​​of three-phase voltage and current, the three-sequence components are calculated. The specific formula is as follows: α＝e j120 ° in, is the positive sequence component, is the negative sequence component, is the zero sequence component, F a is the measured value of phase a voltage or current, F b is the measured value of phase b voltage or current, F c is the measured value of phase c voltage or current, α is the rotation operator; Calculating the voltage and current positive sequence fault components according to the three sequence components; The phase information of the voltage and current positive sequence fault component is extracted by discrete Fourier transform DFT, and the phase difference between the bus positive sequence voltage fault component and the feeder positive sequence current fault component is calculated.

7. The high-resistance grounding fault detection method based on voltage and current sequence components according to claim 6, characterized in that: The three-sequence components include positive-sequence component, negative-sequence component and zero-sequence component; the calculation formula of the voltage and current positive-sequence fault component is as follows: Among them, F a ' is the positive sequence component before the fault, F b ' is the negative sequence component before the fault, F c ' is the zero sequence component before the fault, is the positive sequence component of phase a fault, is the negative sequence component of phase a fault, is the zero-sequence component of phase a fault.

8. A high-resistance grounding fault detection system based on voltage and current sequence components, based on the high-resistance grounding fault detection method based on voltage and current sequence components according to any one of claims 1 to 7, characterized in that: include, A sequence component measurement module is used to obtain voltage and current sequence component data of the distribution network system, analyze and summarize a sequence component measurement model, measure the voltage and current sequence component data through the sequence component measurement model, and obtain a sequence component measurement result; A fault judgment module is used to obtain fault characteristic data of the distribution network system, analyze and summarize a fault judgment model, judge the fault characteristic data through the fault judgment model, and obtain a fault judgment result; The detection module is used to obtain a fault detection result by combining the sequence component measurement result and the fault judgment result, and complete the high-resistance grounding fault detection based on the voltage and current sequence components.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the high-resistance grounding fault detection method based on voltage and current sequence components according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the high-resistance grounding fault detection method based on voltage and current sequence components according to any one of claims 1 to 7 are implemented.

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