Fault positioning method and device of power distribution network, storage medium and electronic equipment

Abstract

The invention provides a fault positioning method and device for a power distribution network, a storage medium and electronic equipment, and the method comprises the steps: obtaining the zero-sequence voltage of a bus of the power distribution network, and determining a fault occurrence moment according to the zero-sequence voltage of the bus; obtaining the zero-sequence current of each measurement node on the feeder line of the power distribution network, and determining the fundamental frequency zero-sequence current corresponding to each measurement node according to the fault occurrence time and the zero-sequence current of each measurement node; calculating to obtain a similarity matrix according to the fundamental frequency zero sequence current of the measurement node at the head end of each feeder line; and according to the similarity matrix, determining the fault type of the power distribution network, including a bus fault or a feeder fault, and when the fault type is the feeder fault, determining the fault position according to the fundamental frequency zero sequence current of each measurement node on the fault feeder. According to the method, the fault position can be accurately positioned in a plurality of grounding systems, the anti-interference capability is relatively high, the adaptability to a low sampling rate is relatively good, and meanwhile, the economic cost can be greatly reduced.

Description

Technical Field

[0001] The present application relates to the field of distribution network protection and automation technology, and in particular to a distribution network fault location method, a distribution network fault location device, a computer-readable storage medium, and an electronic device. Background Art

[0002] Distribution networks are responsible for the crucial task of delivering electricity from substations to end users. Because they are directly related to the quality and safety of user power supply, their operational reliability and stability are of great concern. With society's increasing reliance on electricity supply, especially in the context of the ever-expanding scale of smart grids and new energy access, fault location in distribution networks has become a key topic in power system research. Single-phase grounding faults, in particular, are the most common form of fault in distribution networks. If not located and addressed promptly, they can lead to power outages, equipment damage, and even widespread grid failures. Therefore, researching efficient and reliable fault location technologies will not only help improve the automation level of distribution networks, but also significantly reduce power outage duration and mitigate the economic losses caused by faults.

[0003] Existing distribution network fault location technologies have made some progress, including signal injection, traveling wave, and transient methods. However, with the increasing complexity of distribution network structures, such as the widespread use of multi-branch lines, the increase in hybrid line structures, and the large-scale integration of distributed power sources such as photovoltaics, these traditional methods have low accuracy and high costs, and are no longer able to meet the needs of practical applications. Summary of the Invention

[0004] The main purpose of this application is to provide a distribution network fault location method, a distribution network fault location device, a computer-readable storage medium and an electronic device, so as to at least solve the problem that the existing distribution network fault location technology has low accuracy and high cost, resulting in low power system operation efficiency and poor stability.

[0005] To achieve the above-mentioned objectives, according to one aspect of the present application, a fault location method for a distribution network is provided, comprising: obtaining a bus zero-sequence voltage of the distribution network, and determining a fault occurrence time based on the bus zero-sequence voltage; obtaining a zero-sequence current of each measurement node on a feeder of the distribution network, and determining a fundamental frequency zero-sequence current corresponding to each measurement node based on the fault occurrence time and the zero-sequence current of each measurement node; calculating a similarity matrix based on the fundamental frequency zero-sequence current of the measurement node at the head end of each feeder; determining a fault type of the distribution network based on the similarity matrix, the fault type being a bus fault or a feeder fault, wherein, when the fault type of the distribution network is a feeder fault, the fault location is determined based on the fundamental frequency zero-sequence current of each measurement node on the fault feeder.

[0006] Optionally, determining the fault occurrence time according to the bus zero-sequence voltage includes: obtaining the fault judgment condition U0(t)>K1U P , where U0(t) is the bus zero-sequence voltage at time t, K1 is the proportional coefficient, and U P is the phase voltage of the distribution network; when the bus zero sequence voltage does not meet the fault judgment condition U0(t)>K1U P In the case where the current moment is determined to be a non-fault occurrence moment; when the bus zero-sequence voltage satisfies the fault judgment condition U0(t)>K1U P In the case of, the current time is determined to be the time when the fault occurs.

[0007] Optionally, when the distribution network is a low-resistance grounding system, K1 is 0.01; when the distribution network is a neutral point ungrounded and resonant grounding system, K1 is 0.05.

[0008] Optionally, based on the time when the fault occurs and the zero-sequence current of each measuring node, the fundamental frequency zero-sequence current corresponding to each measuring node is determined, including: using fast Fourier transform to filter the zero-sequence current of each measuring node to obtain the fundamental frequency signal of each measuring node; according to the time when the fault occurs, the fundamental frequency signal is clipped to obtain the fundamental frequency zero-sequence current one cycle after the time when the fault occurs.

[0009] Optionally, the distribution network has n feeders, and a similarity matrix is ​​calculated based on the fundamental frequency zero-sequence current of the measurement node at the head end of each feeder, including: determining the fundamental frequency zero-sequence current of the measurement node at the head end of each feeder as the head end fundamental frequency zero-sequence current of each feeder; determining the cosine similarity of the head end fundamental frequency zero-sequence current of any two feeders to obtain multiple cosine similarities; and determining the similarity matrix based on all the cosine similarities. Among them, ρ m,n is the cosine similarity between the mth feeder and the nth feeder, ρ n,m is the cosine similarity between the nth feeder and the mth feeder.

[0010] Optionally, determining the fault type of the distribution network according to the similarity matrix includes: calculating the sum of the elements of each row in the similarity matrix, and comparing the sizes of all the sums to obtain the maximum value P k and the next largest value Py, where Pk is the sum of the elements in the kth row and Py is the sum of the elements in the yth row; obtain the busbar fault judgment formula Among them, ρ k,i is the value of the i-th element in the k-th row, ρ m,iis the value of the i-th element in the m-th row, K2 is the sensitivity coefficient; when the bus fault judgment formula holds true, the fault type of the distribution network is determined to be the bus fault; when the bus fault judgment formula does not hold true, the fault type of the distribution network is determined to be the feeder fault, and the faulty feeder is determined to be the k-th feeder.

[0011] Optionally, the fault type is the feeder fault. After determining the fault type of the distribution network according to the similarity matrix, the method further comprises: calculating the waveform similarity of the zero-sequence current of any two adjacent measurement nodes on the fault feeder by cosine similarity; comparing all the waveform similarities to obtain the minimum similarity; and when the minimum similarity satisfies ρ min <K3, the fault location is determined to be between the two adjacent measurement nodes corresponding to the minimum similarity, where ρ min is the minimum similarity, K3 is the positioning sensitivity coefficient; when the minimum similarity satisfies ρ min When K is greater than or equal to K3, it is determined that the fault location is located at the end of the fault feeder.

[0012] According to another aspect of the present application, a fault locating device for a distribution network is provided, comprising: a first acquisition unit, configured to acquire a bus zero-sequence voltage of the distribution network, and determine a fault occurrence time based on the bus zero-sequence voltage; a second acquisition unit, configured to acquire a zero-sequence current of each measurement node on a feeder of the distribution network, and determine a fundamental frequency zero-sequence current corresponding to each measurement node based on the fault occurrence time and the zero-sequence current of each measurement node; a calculation unit, configured to calculate a similarity matrix based on the fundamental frequency zero-sequence current of the measurement node at the head end of each feeder; and a determination unit, configured to determine a fault type of the distribution network based on the similarity matrix, the fault type being a bus fault or a feeder fault, wherein, when the fault type of the distribution network is a feeder fault, the fault location is determined based on the fundamental frequency zero-sequence current of each measurement node on the faulty feeder.

[0013] According to another aspect of the present application, a computer-readable storage medium is provided, wherein the computer-readable storage medium includes a stored program, wherein when the program is run, the device where the computer-readable storage medium is located is controlled to execute any one of the distribution network fault location methods.

[0014] According to another aspect of the present application, an electronic device is provided, comprising: one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs include a method for executing any one of the distribution network fault location methods.

[0015] Applying the technical solution of the present application, the above-mentioned distribution network fault location method first obtains the bus zero-sequence voltage of the distribution network and determines the time of fault occurrence based on the bus zero-sequence voltage; then obtains the zero-sequence current of each measurement node on the feeder of the distribution network, and determines the fundamental frequency zero-sequence current corresponding to each measurement node based on the time of fault occurrence and the zero-sequence current of each measurement node; then, based on the fundamental frequency zero-sequence current of the measurement node at the head end of each feeder, a similarity matrix is ​​calculated; finally, based on the similarity matrix, the fault type of the distribution network is determined, and the fault type is either a bus fault or a feeder fault. Specifically, when the fault type of the distribution network is a feeder fault, the fault location is determined based on the fundamental frequency zero-sequence current of each measurement node on the fault feeder. This method can adapt to distribution networks with different grounding methods, especially in low-current grounding systems. It can withstand higher transition resistance and still ensure high positioning accuracy under high-resistance faults; it can still complete fault location under complex working conditions, and has good immunity to noise interference, time-varying transition resistance, small fault initial phase angle, unbalanced load, and access to distributed power sources; it has low requirements for sampling rate and can operate at a low sampling rate of 1200Hz. Compared with technologies such as traveling wave method that rely on high sampling rate, it greatly reduces the system's requirements for sampling equipment, making the equipment design simpler and more economical, and solving the problems of low accuracy and high cost of existing distribution network fault location technology, resulting in low power system operation efficiency and poor stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings that constitute part of this application are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation on this application. In the drawings:

[0017] Figure 1 A hardware structure block diagram of a mobile terminal for executing a fault location method for a distribution network provided in an embodiment of the present application is shown;

[0018] Figure 2 A schematic diagram of a flow chart of a method for locating a fault in a distribution network according to an embodiment of the present application is shown;

[0019] Figure 3 A schematic diagram of a fault location process according to an embodiment of the present application is shown;

[0020] Figure 4 A schematic structural diagram of a simulation model of a 10 kV distribution network provided according to an embodiment of the present application is shown;

[0021] Figure 5 A schematic diagram of a flow chart of another method for locating a fault in a distribution network provided according to an embodiment of the present application is shown;

[0022] Figure 6 A structural block diagram of a fault location device for a distribution network provided according to an embodiment of the present application is shown.

[0023] The above drawings include the following reference numerals:

[0024] 102. Processor; 104. Memory; 106. Transmission device; 108. Input / output device. DETAILED DESCRIPTION

[0025] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0026] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.

[0027] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0028] As introduced in the background technology, with the increasing complexity of the distribution network structure, such as the widespread application of multi-branch lines, the increase in hybrid line structures, and the large-scale access of distributed power sources such as photovoltaics, traditional fault location technologies, such as signal injection method, traveling wave method, transient method, etc., face many challenges in practical applications. In order to solve the problems of low accuracy and high cost of existing distribution network fault location technology, which lead to low operating efficiency and poor stability of the power system, the embodiments of the present application provide a distribution network fault location method, a distribution network fault location device, a computer-readable storage medium and an electronic device.

[0029] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0030] The method embodiments provided in the embodiments of the present application can be executed in a mobile terminal, a computer terminal or a similar computing device. Taking running on a mobile terminal as an example, Figure 1 FIG. 1 is a hardware structure block diagram of a mobile terminal for a method for locating a fault in a distribution network according to an embodiment of the present invention. Figure 1 As shown, the mobile terminal may include one or more ( Figure 1 Only one is shown) a processor 102 (the processor 102 may include but is not limited to a microprocessor MCU or a programmable logic device FPGA and other processing devices) and a memory 104 for storing data, wherein the mobile terminal may also include a transmission device 106 and an input and output device 108 for communication functions. It will be understood by those skilled in the art that Figure 1 The structure shown is only for illustration and does not limit the structure of the mobile terminal. Figure 1 More or fewer components than shown, or with Figure 1 Different configurations shown.

[0031] The memory 104 can be used to store computer programs, such as software programs and modules of application software, such as the computer program corresponding to the method for fault location in a power distribution network according to an embodiment of the present invention. The processor 102 executes the computer program stored in the memory 104 to execute various functional applications and data processing, thereby implementing the above-described method. The memory 104 may include high-speed random access memory (RAM) and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some examples, the memory 104 may further include memory remotely located from the processor 102, and such remote memory may be connected to the mobile terminal via a network. Examples of such networks include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof. The transmission device 106 is used to receive or transmit data via a network. Specific examples of such networks may include a wireless network provided by the mobile terminal's telecommunications provider. In one example, the transmission device 106 includes a network interface controller (NIC), which can be connected to other network devices via a base station to enable communication with the Internet. In one example, the transmission device 106 may be a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0032] In this embodiment, a method for locating a fault in a distribution network that runs on a mobile terminal, a computer terminal, or a similar computing device is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0033] Figure 2 FIG. 1 is a flow chart of a method for locating a fault in a distribution network according to an embodiment of the present application. Figure 2 As shown, the method includes the following steps:

[0034] Step S201, obtaining the bus zero-sequence voltage of the distribution network, and determining the fault occurrence time according to the bus zero-sequence voltage;

[0035] Specifically, by extracting the busbar zero-sequence voltage, the fault occurrence time can be efficiently determined according to the fault judgment conditions, thereby improving the fault recovery speed and reducing the power outage time.

[0036] The method of determining the fault occurrence time according to the above bus zero-sequence voltage includes the following steps:

[0037] Step S2011, obtain the fault judgment condition U0(t)>K1U P , where U0(t) is the zero-sequence voltage of the busbar at time t, K1 is the proportional coefficient, and U P is the phase voltage of the above distribution network;

[0038] Step S2012: When the zero-sequence voltage of the bus does not satisfy the fault judgment condition U0(t)>K1U P In the case of , determining the current time as a non-fault occurrence time;

[0039] Step S2013: When the zero-sequence voltage of the busbar satisfies the fault judgment condition U0(t)>K1U P In the case of , the current time is determined to be the time when the above-mentioned fault occurs.

[0040] Specifically, the fault judgment conditions can be used to quickly identify the time and location of distribution network faults, helping to improve fault handling efficiency while ensuring system safety and reliability. When the bus voltage meets the above fault judgment conditions, the fault occurrence time is recorded as t0.

[0041] Wherein, when the above-mentioned distribution network is a low-resistance grounding system, K1 is 0.01; when the above-mentioned distribution network is a neutral point ungrounded and resonant grounding system, K1 is 0.05.

[0042] Specifically, in fault judgment conditions, the proportionality factor K1 is a weighting factor used to quantify and adjust specific variables or indicators. By adjusting, amplifying, or minimizing the impact of specific factors, it enables a more accurate and reasonable fault judgment. The proportionality factor K1 has different values ​​for distribution networks with different grounding methods, such as ungrounded neutral systems, resonant grounding systems, and low-resistance grounding systems.

[0043] Step S202: obtaining the zero-sequence current of each measurement node on the feeder of the distribution network, and determining the fundamental frequency zero-sequence current corresponding to each measurement node according to the fault occurrence time and the zero-sequence current of each measurement node;

[0044] Specifically, by filtering the fundamental frequency component and cutting it to one cycle after the fault, the fundamental frequency zero-sequence current of each measurement node is obtained, which can timely detect faults, evaluate load imbalances, and provide effective data support for the stable operation of the distribution network.

[0045] The method of determining the fundamental frequency zero-sequence current corresponding to each of the measurement nodes according to the fault occurrence time and the zero-sequence current of each of the measurement nodes includes the following steps:

[0046] Step S2021, filtering the zero-sequence current of each of the measurement nodes using a fast Fourier transform to obtain a fundamental frequency signal of each of the measurement nodes;

[0047] Step S2022: According to the time when the fault occurs, the fundamental frequency signal is clipped to obtain the fundamental frequency zero-sequence current of one cycle after the time when the fault occurs.

[0048] Specifically, the fast Fourier transform method can accurately distinguish between fundamental frequency and harmonic components and effectively filter out high-frequency noise, providing more accurate and reliable measurement results, thereby improving the operating efficiency and stability of the power system and ensuring power supply reliability.

[0049] Step S203, calculating a similarity matrix based on the fundamental frequency zero-sequence current of the measurement node at the head end of each of the feeders;

[0050] Specifically, by extracting the zero-sequence current waveform and calculating the similarity, high-precision and low-cost positioning of the fault feeder and fault interval can be achieved. This is suitable for complex distribution networks with multiple branches and photovoltaic power sources, and helps to achieve automated operation of the distribution network.

[0051] The distribution network has n feeders, and a similarity matrix is ​​calculated based on the fundamental frequency zero-sequence current of the measurement node at the head end of each feeder, including the following steps:

[0052] Step S2031, determining the fundamental frequency zero-sequence current of the measurement node at the head end of each of the feeders as the head end fundamental frequency zero-sequence current of each of the feeders;

[0053] Step S2032, determining the cosine similarity of the fundamental frequency zero-sequence currents at the head ends of any two of the feeders, and obtaining a plurality of cosine similarities;

[0054] Step S2033: Determine the similarity matrix based on all the cosine similarities. Among them, ρ m,n is the cosine similarity between the mth feeder and the nth feeder, ρ n,m is the cosine similarity between the nth feeder and the mth feeder.

[0055] Specifically, the cosine similarity used can be used to measure the degree of similarity between vectors in direction, and is not affected by the size of the vector and has good noise immunity. The calculation formula of cosine similarity is: Where, ρ X,Y is the cosine similarity, X and Y are arrays (vectors) of length n. X,Y The closer the value is to 1, the more positively correlated X and Y are. X,Y When the value of is 0, it means that X and Y are independent of each other, ρ X,Y The closer the value is to -1, the more negatively correlated X and Y are.

[0056] The cosine similarity of the zero-sequence current at both ends of the fault section of the distribution network with different grounding methods is different: for the neutral point ungrounded system, the cosine similarity of the zero-sequence current at both ends of the fault section is close to -1; for the low-resistance grounding system, the cosine similarity of the zero-sequence current at both ends of the fault section is close to 0; for the resonant grounding system, the cosine similarity between the zero-sequence current of the first cycle after the fault at both ends of the fault section is generally less than 0.5, thereby achieving the normalization of the single-phase grounding fault characteristics of different grounding systems.

[0057] Step S204: Determine the fault type of the distribution network based on the similarity matrix, where the fault type is a busbar fault or a feeder fault. When the fault type of the distribution network is a feeder fault, determine the fault location based on the fundamental frequency zero-sequence current of each of the measurement nodes on the fault feeder.

[0058] Specifically, if a busbar fault is identified, fault location is not necessary. If a feeder fault is identified, the fault interval is determined by comparing the similarity of the fundamental frequency zero-sequence currents of adjacent nodes on the feeder. This approach adapts to distribution networks with different grounding methods and ensures high location accuracy. Furthermore, the system has low requirements for sampling equipment and is economical.

[0059] In one embodiment, Figure 3 As shown in the figure, the specific fault location process includes: first, using the busbar zero-sequence voltage to detect the time of fault occurrence, obtaining the zero-sequence current data of one cycle after the fault occurrence time for each measurement node, and then using FFT filtering to obtain the fundamental frequency zero-sequence current data of each measurement node; using the waveform similarity between the first measurement nodes of each feeder to complete the fault line selection, determine whether the fault line is the busbar, and if so, output the fault location result; if it is not a busbar fault, determine whether the fault line contains a branch branch, if so, use "fault line selection" to complete the fault branch line selection, and then locate the fault section; if not, use the similarity of adjacent measurement nodes on the feeder to complete the general fault section location, and finally output the result.

[0060] Determining the fault type of the distribution network according to the similarity matrix includes the following steps:

[0061] Step S301: Calculate the sum of the elements in each row of the similarity matrix and compare all the sums to obtain the maximum value P. k and the next largest value Py, where Pk is the sum of the above elements in the k-th row, and Py is the sum of the above elements in the y-th row;

[0062] Step S302: Obtain busbar fault judgment formula Among them, ρ k,i is the value of the i-th element in the k-th row, ρ m,i is the value of the i-th element in the m-th row, K2 is the sensitivity coefficient;

[0063] Step S303: if the above bus fault judgment formula is satisfied, determining that the fault type of the above distribution network is the above bus fault;

[0064] Step S304: When the busbar fault judgment formula is not satisfied, the fault type of the distribution network is determined to be the feeder fault, and the faulty feeder is determined to be the kth feeder.

[0065] Specifically, the busbar fault judgment formula can be used to determine whether the fault is located on the busbar or the feeder, more accurately locating the fault type, thereby improving fault recovery speed and reducing power outage duration. The sensitivity coefficient K2 is usually set to 0.02.

[0066] Wherein, the fault type is the feeder fault. After determining the fault type of the distribution network according to the similarity matrix, the method further includes the following steps:

[0067] Step S401, calculating the waveform similarity of the zero-sequence current of any two adjacent measurement nodes on the fault feeder by cosine similarity;

[0068] Step S402, comparing all the waveform similarities to obtain the minimum similarity;

[0069] Step S403: When the minimum similarity satisfies ρ min <K3, the fault location is determined to be between the two adjacent measurement nodes corresponding to the minimum similarity, where ρ min is the above minimum similarity, K3 is the positioning sensitivity coefficient;

[0070] Step S404: When the minimum similarity satisfies ρ min When K is greater than or equal to K3, it is determined that the fault location is located at the end of the fault feeder.

[0071] Specifically, when it is determined that the fault is located on the feeder, the fault section can be specifically located based on the above steps, improving the fault location method under complex working conditions, and having good immunity to noise interference, time-varying transition resistance, small fault initial phase angle, unbalanced load, and access to distributed power sources.

[0072] When the fault is located on a feeder, the waveform similarity of the zero-sequence currents at adjacent measurement nodes on the feeder is first calculated using cosine similarity. The minimum value is obtained by traversing all similarities and compared with the location sensitivity coefficient K3. For an ungrounded neutral point system, K3 is -0.8; for a low-resistance grounded system, K3 is 0.2; and for a resonant grounded system, K3 is 0.7.

[0073] In one embodiment, a simulation model of a 10kV distribution network is established, such as Figure 4 As shown in Figure 1, six typical fault cases are set up to test the fault location effect. Table 1 gives the relevant parameters of the six typical fault cases.

[0074] Table 1. Typical fault case parameters

[0075] Case Fault line Fault section Fault location classification 1 busbar busbar Busbar fault 2 Feeder 2 3-4 General feeder fault 3 Main Line 3 5-6 Trunk failure 4 Branch 3 13-14 Branch line failure 5 Feeder 4 10-11 Cable junction fault 6 Feeder 4 End of line Hybrid line end fault

[0076] A phase A ground fault with a transition resistance of 10Ω or 1000Ω occurs in an ungrounded neutral point system, a low-resistance grounded system, and a resonant grounded system, respectively. The corresponding characteristic correlation coefficients are shown in Table 2.

[0077] Table 2. Characteristic correlation coefficients of low-resistance and high-resistance faults in different grounding systems

[0078]

[0079] Among them, case 1 is a busbar fault, ρ 1-16All are greater than 0.98, and according to the above bus fault judgment formula, it can be judged as a bus fault; Cases 2-5 are all faults on the line section, and the characteristic correlation coefficients are all less than the corresponding positioning sensitivity coefficient K3 (-0.8, 0.2, 0.7), respectively, and are judged as section faults; Case 6 is a line end fault, ρ 9-12 Both are close to 1, greater than the location sensitivity coefficient, indicating a terminal fault. This shows that this method has good tolerance for high-resistance faults, and can tolerate transition resistances of 5kΩ and 1kΩ in low-current grounding systems and low-resistance grounding systems, respectively.

[0080] In another example, based on the above example, a time-varying transition resistor was added. 5% Gaussian white noise was added to the current at each measurement node. The initial fault phase angle was changed from 85° to 5°. The three-phase symmetrical load was changed to an asymmetric load with a 30% imbalance. Cases 1 to 6 faults were sequentially set, and the fault section location results under complex operating conditions were obtained, as shown in Table 3. The results demonstrate that this method has good noise immunity and can identify fault sections under conditions of high, time-varying transition resistors, small fault angles, and unbalanced loads.

[0081] Table 3. Fault interval location results under complex working conditions

[0082]

[0083] In another embodiment, Figure 4 Based on the distribution network shown in the figure, 1000kVA photovoltaic power sources are set up upstream and downstream of the fault point respectively. The fault location results when photovoltaic power is connected at different positions are obtained, as shown in Table 4. The results show that this method is less affected by a single large-capacity photovoltaic power source and has strong anti-interference performance.

[0084] Table 4. Positioning results when connected to photovoltaics at different locations

[0085] Case Access upstream Access downstream Access to a healthy line 1 / / busbar 2 3-4 3-4 3-4 3 5-6 5-6 5-6 4 13-14 13-14 13-14 5 10-11 10-11 10-11 6 End of 12 / End of 12

[0086] The above-mentioned distribution network fault location method of the present application first obtains the bus zero-sequence voltage of the distribution network and determines the time of fault occurrence based on the bus zero-sequence voltage; then obtains the zero-sequence current of each measurement node on the feeder of the distribution network, and determines the fundamental frequency zero-sequence current corresponding to each measurement node based on the time of fault occurrence and the zero-sequence current of each measurement node; then, a similarity matrix is ​​calculated based on the fundamental frequency zero-sequence current of the measurement node at the head end of each feeder; finally, based on the similarity matrix, the fault type of the distribution network is determined, and the fault type is either a bus fault or a feeder fault. Specifically, when the fault type of the distribution network is a feeder fault, the fault location is determined based on the fundamental frequency zero-sequence current of each measurement node on the fault feeder. This method can adapt to distribution networks with different grounding methods, especially in low-current grounding systems. It can withstand higher transition resistance and still ensure high positioning accuracy under high-resistance faults; it can still complete fault location under complex working conditions, and has good immunity to noise interference, time-varying transition resistance, small fault initial phase angle, unbalanced load, and access to distributed power sources; it has low requirements for sampling rate and can operate at a low sampling rate of 1200Hz. Compared with technologies such as traveling wave method that rely on high sampling rate, it greatly reduces the system's requirements for sampling equipment, making the equipment design simpler and more economical, and solving the problems of low accuracy and high cost of existing distribution network fault location technology, resulting in low power system operation efficiency and poor stability.

[0087] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the implementation process of the fault location method for the distribution network of the present application will be described in detail below with reference to specific embodiments.

[0088] This embodiment relates to a specific method for locating a fault in a distribution network. Figure 5 As shown, the following steps are included:

[0089] Step S1: Obtain the bus zero-sequence voltage and determine the fault occurrence time;

[0090] Step S2: extracting the zero-sequence current waveform of the fundamental frequency of each measurement node after the fault, and calculating the similarity matrix;

[0091] Step S3: comparing the similarity of the zero-sequence currents at the head ends of the feeders to determine the faulty feeder;

[0092] Step S4: further locate the fault section using the similarity of the zero-sequence currents of the section nodes.

[0093] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0094] The embodiments of the present application also provide a fault location device for a distribution network. It should be noted that the fault location device for a distribution network in the embodiments of the present application can be used to execute the fault location method for a distribution network provided in the embodiments of the present application. The device is used to implement the above-mentioned embodiments and preferred implementation methods, and the details that have been described will not be repeated here. As used below, the term "module" can be a combination of software and / or hardware that implements a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware, is also possible and conceivable.

[0095] The following introduces the fault location device for the distribution network provided in the embodiments of the present application.

[0096] Figure 6 Schematic diagram of a fault location device for a distribution network according to an embodiment of the present application. Figure 6 As shown, the device includes: a first acquisition unit 10, a second acquisition unit 20, a calculation unit 30 and a determination unit 40, the first acquisition unit 10 is used to obtain the bus zero-sequence voltage of the distribution network, and determine the fault occurrence time according to the above bus zero-sequence voltage; the second acquisition unit 20 is used to obtain the zero-sequence current of each measurement node on the feeder of the distribution network, and determine the fundamental frequency zero-sequence current corresponding to each measurement node according to the above fault occurrence time and the zero-sequence current of each measurement node; the calculation unit 30 is used to calculate the similarity matrix according to the fundamental frequency zero-sequence current of the measurement node at the head end of each feeder; the determination unit 40 is used to determine the fault type of the distribution network according to the similarity matrix, the fault type being a bus fault or a feeder fault, wherein, when the fault type of the distribution network is the feeder fault, the fault location is determined according to the fundamental frequency zero-sequence current of each measurement node on the fault feeder.

[0097] The above-mentioned distribution network fault location device of the present application includes: a first acquisition unit, a second acquisition unit, a calculation unit and a determination unit, the first acquisition unit is used to obtain the bus zero-sequence voltage of the distribution network, and determine the time of fault occurrence based on the bus zero-sequence voltage; the second acquisition unit is used to obtain the zero-sequence current of each measurement node on the feeder of the distribution network, and determine the fundamental frequency zero-sequence current corresponding to each measurement node based on the time of fault occurrence and the zero-sequence current of each measurement node; the calculation unit is used to calculate the similarity matrix based on the fundamental frequency zero-sequence current of the measurement node at the head end of each feeder; the determination unit is used to determine the fault type of the distribution network based on the similarity matrix, and the fault type is a bus fault or a feeder fault, wherein, when the fault type of the distribution network is a feeder fault, the fault location is determined based on the fundamental frequency zero-sequence current of each measurement node on the fault feeder. The device is suitable for distribution networks with different grounding methods, especially in low-current grounding systems. It can withstand higher transition resistance and still ensure high positioning accuracy under high-resistance faults; it can still complete fault positioning under complex working conditions, and has good immunity to noise interference, time-varying transition resistance, small fault initial phase angle, unbalanced load, and access to distributed power sources; it has low requirements for sampling rate and can operate at a low sampling rate of 1200Hz. Compared with technologies such as traveling wave method that rely on high sampling rate, it greatly reduces the system's requirements for sampling equipment, making the equipment design simpler and more economical, and solving the problems of low accuracy and high cost of existing distribution network fault positioning technology, resulting in low power system operation efficiency and poor stability.

[0098] In some embodiments, the first acquisition unit includes a first acquisition module, a second acquisition module and a third acquisition module. The first acquisition module is used to obtain the fault judgment condition U0(t)>K1U P , where U0(t) is the zero-sequence voltage of the busbar at time t, K1 is the proportional coefficient, and U P The second acquisition module is used for the above bus zero sequence voltage does not meet the above fault judgment condition U0 (t) > K1U P In the case of, determining the current moment as the non-fault occurrence moment; the third acquisition module is used to determine the current moment as the non-fault occurrence moment when the bus zero sequence voltage satisfies the above fault judgment condition U0(t)>K1U P In this case, the current time is determined to be the time when the above fault occurred. This helps improve the efficiency of fault handling and at the same time ensure the security and reliability of the system.

[0099] In some examples, when the distribution network is a low-resistance grounded system, K1 is set to 0.01 by the first acquisition module; when the distribution network is an ungrounded neutral point or resonant grounded system, K1 is set to 0.05. The proportionality coefficient K1 is a weighting factor used to quantify and adjust specific variables or indicators. By adjusting, amplifying, or reducing the impact of specific factors, a more accurate and reasonable assessment of the fault condition can be achieved.

[0100] In some instances, the second acquisition unit includes a fourth acquisition module and a fifth acquisition module. The fourth acquisition module is configured to filter the zero-sequence current at each measurement node using a fast Fourier transform (FFT) to obtain a fundamental frequency signal at each measurement node. The fifth acquisition module is configured to clip the fundamental frequency signal based on the time of the fault occurrence to obtain the fundamental frequency zero-sequence current one cycle after the time of the fault occurrence. The FFT method can accurately distinguish between fundamental frequency and harmonic components and effectively filter out high-frequency noise, providing more accurate and reliable measurement results, thereby improving the operating efficiency and stability of the power system and ensuring power supply reliability.

[0101] In some examples, the calculation unit includes a first calculation module, a second calculation module, and a third calculation module. The first calculation module is used to determine the fundamental frequency zero-sequence current of the measurement node at the head end of each of the above-mentioned feeders as the head end fundamental frequency zero-sequence current of each of the above-mentioned feeders; the second calculation module is used to determine the cosine similarity of the head end fundamental frequency zero-sequence current of any two of the above-mentioned feeders to obtain multiple cosine similarities; the third calculation module is used to determine the above-mentioned similarity matrix based on all the above-mentioned cosine similarities. Among them, ρ m,n is the cosine similarity between the mth feeder and the nth feeder, ρ n,m is the cosine similarity between the nth feeder and the mth feeder. The cosine similarity used can be used to measure the similarity between vectors in direction, and is not affected by the size of the vector and has good noise immunity.

[0102] In some examples, the determination unit includes a first determination module, a second determination module, a third determination module, and a fourth determination module. The first determination module is used to calculate the sum of the elements of each row in the similarity matrix and compare the sizes of all the above sums to obtain the maximum value P k and the next largest value Py, where Pk is the sum of the above elements in the kth row, and Py is the sum of the above elements in the yth row; the second determination module is used to obtain the bus fault judgment formula Among them, ρ k,i is the value of the i-th element in the k-th row, ρ m,iThe third determination module is used to determine, if the bus fault determination formula holds true, that the distribution network fault type is the bus fault. The fourth determination module is used to determine, if the bus fault determination formula does not hold true, that the distribution network fault type is the feeder fault, and to identify the faulty feeder as the kth feeder. This allows for more accurate fault location, thereby improving fault recovery speed and reducing power outage duration.

[0103] In some examples, the determination unit further includes a fifth determination module, a sixth determination module, a seventh determination module, and an eighth determination module. The fifth determination module is used to calculate the waveform similarity of the zero-sequence current of any two adjacent measurement nodes on the fault feeder by cosine similarity; the sixth determination module is used to compare all the waveform similarities to obtain the minimum similarity; the seventh determination module is used to determine the waveform similarity when the minimum similarity satisfies ρ min <K3, the fault location is determined to be between the two adjacent measurement nodes corresponding to the minimum similarity, where ρ min is the above minimum similarity, K3 is the positioning sensitivity coefficient; the eighth determination module is used to determine the minimum similarity when the above minimum similarity satisfies ρ min In the case of K3 or higher, the fault location is determined to be at the end of the fault feeder. This can specifically locate the fault section and improve the fault location method under complex working conditions.

[0104] The above-mentioned distribution network fault location device includes a processor and a memory. The above-mentioned first acquisition unit and the like are stored as program units in the memory. The processor executes the program units stored in the memory to implement the corresponding functions. The above-mentioned modules are all located in the same processor; alternatively, the above-mentioned modules can be located in different processors in any combination.

[0105] The processor contains a core, which retrieves the corresponding program unit from memory. One or more cores can be configured, and adjusting the core parameters can address the low accuracy and high cost of existing distribution network fault location technology, which leads to low power system efficiency and poor stability.

[0106] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0107] An embodiment of the present invention provides a computer-readable storage medium, which includes a stored program. When the program is executed, the device where the computer-readable storage medium is located is controlled to execute the method for locating the fault in the distribution network.

[0108] Specifically, the fault location method of the distribution network includes:

[0109] Step S201, obtaining the bus zero-sequence voltage of the distribution network, and determining the fault occurrence time according to the bus zero-sequence voltage;

[0110] Specifically, by extracting the busbar zero-sequence voltage, the fault occurrence time can be efficiently determined according to the fault judgment conditions, thereby improving the fault recovery speed and reducing the power outage time.

[0111] Step S202: obtaining the zero-sequence current of each measurement node on the feeder of the distribution network, and determining the fundamental frequency zero-sequence current corresponding to each measurement node according to the fault occurrence time and the zero-sequence current of each measurement node;

[0112] Specifically, by filtering the fundamental frequency component and cutting it to one cycle after the fault, the fundamental frequency zero-sequence current of each measurement node is obtained, which can timely detect faults, evaluate load imbalances, and provide effective data support for the stable operation of the distribution network.

[0113] Step S203, calculating a similarity matrix based on the fundamental frequency zero-sequence current of the measurement node at the head end of each of the feeders;

[0114] Specifically, by extracting the zero-sequence current waveform and calculating the similarity, high-precision and low-cost positioning of the fault feeder and fault interval can be achieved. This is suitable for complex distribution networks with multiple branches and photovoltaic power sources, and helps to achieve automated operation of the distribution network.

[0115] Step S204: Determine the fault type of the distribution network based on the similarity matrix, where the fault type is a busbar fault or a feeder fault. When the fault type of the distribution network is a feeder fault, determine the fault location based on the fundamental frequency zero-sequence current of each of the measurement nodes on the fault feeder.

[0116] Specifically, if a busbar fault is identified, fault location is not necessary. If a feeder fault is identified, the fault interval is determined by comparing the similarity of the fundamental frequency zero-sequence currents of adjacent nodes on the feeder. This approach adapts to distribution networks with different grounding methods and ensures high location accuracy. Furthermore, the system has low requirements for sampling equipment and is economical.

[0117] Optionally, determining the fault occurrence time according to the above bus zero-sequence voltage includes: obtaining the fault judgment condition U0(t)>K1U P , where U0(t) is the zero-sequence voltage of the busbar at time t, K1 is the proportional coefficient, and U Pis the phase voltage of the distribution network; when the zero-sequence voltage of the bus does not meet the above fault judgment condition U0(t)>K1U P In the case of, the current moment is determined to be the non-fault occurrence moment; when the above bus zero sequence voltage satisfies the above fault judgment condition U0(t)>K1U P In the case of , the current time is determined to be the time when the above-mentioned fault occurs.

[0118] Optionally, when the distribution network is a low-resistance grounding system, K1 is 0.01; when the distribution network is a neutral point ungrounded and resonant grounding system, K1 is 0.05.

[0119] Optionally, based on the above-mentioned fault occurrence time and the zero-sequence current of each of the above-mentioned measurement nodes, the fundamental frequency zero-sequence current corresponding to each of the above-mentioned measurement nodes is determined, including: using fast Fourier transform to filter the zero-sequence current of each of the above-mentioned measurement nodes to obtain the fundamental frequency signal of each of the above-mentioned measurement nodes; based on the above-mentioned fault occurrence time, the above-mentioned fundamental frequency signal is clipped to obtain the above-mentioned fundamental frequency zero-sequence current one cycle after the above-mentioned fault occurrence time.

[0120] Optionally, the distribution network has n feeders, and a similarity matrix is ​​calculated based on the fundamental frequency zero-sequence current of the measurement node at the head end of each feeder, including: determining the fundamental frequency zero-sequence current of the measurement node at the head end of each feeder as the head end fundamental frequency zero-sequence current of each feeder; determining the cosine similarity of the head end fundamental frequency zero-sequence current of any two feeders to obtain multiple cosine similarities; and determining the similarity matrix based on all the cosine similarities. Among them, ρ m,n is the cosine similarity between the mth feeder and the nth feeder, ρ n,m is the cosine similarity between the nth feeder and the mth feeder.

[0121] Optionally, determining the fault type of the distribution network according to the similarity matrix includes: calculating the sum of the elements in each row of the similarity matrix, and comparing the sizes of all the sums to obtain the maximum value P k and the next largest value Py, where Pk is the sum of the above elements in row k, and Py is the sum of the above elements in row y; obtain the busbar fault judgment formula Among them, ρ k,i is the value of the i-th element in the k-th row, ρ m,i is the value of the i-th element in the m-th row, K2 is the sensitivity coefficient; when the above bus fault judgment formula holds true, the fault type of the above distribution network is determined to be the above bus fault; when the above bus fault judgment formula does not hold true, the fault type of the above distribution network is determined to be the above feeder fault, and the above faulty feeder is determined to be the k-th feeder.

[0122] Optionally, the fault type is the feeder fault. After determining the fault type of the distribution network according to the similarity matrix, the method further comprises: calculating the waveform similarity of the zero-sequence current of any two adjacent measurement nodes on the fault feeder by cosine similarity; comparing all the waveform similarities to obtain the minimum similarity; and when the minimum similarity satisfies ρ min <K3, the fault location is determined to be between the two adjacent measurement nodes corresponding to the minimum similarity, where ρ min is the above minimum similarity, K3 is the positioning sensitivity coefficient; when the above minimum similarity satisfies ρ min When K is greater than or equal to K3, it is determined that the fault location is located at the end of the fault feeder.

[0123] An embodiment of the present invention provides a processor, which is used to run a program, wherein the program executes the fault location method of the power distribution network when running.

[0124] Specifically, the fault location method of the distribution network includes:

[0125] Step S201, obtaining the bus zero-sequence voltage of the distribution network, and determining the fault occurrence time according to the bus zero-sequence voltage;

[0126] Specifically, by extracting the busbar zero-sequence voltage, the fault occurrence time can be efficiently determined according to the fault judgment conditions, thereby improving the fault recovery speed and reducing the power outage time.

[0127] Step S202: obtaining the zero-sequence current of each measurement node on the feeder of the distribution network, and determining the fundamental frequency zero-sequence current corresponding to each measurement node according to the fault occurrence time and the zero-sequence current of each measurement node;

[0128] Specifically, by filtering the fundamental frequency component and cutting it to one cycle after the fault, the fundamental frequency zero-sequence current of each measurement node is obtained, which can timely detect faults, evaluate load imbalances, and provide effective data support for the stable operation of the distribution network.

[0129] Step S203, calculating a similarity matrix based on the fundamental frequency zero-sequence current of the measurement node at the head end of each of the feeders;

[0130] Specifically, by extracting the zero-sequence current waveform and calculating the similarity, high-precision and low-cost positioning of the fault feeder and fault interval can be achieved. This is suitable for complex distribution networks with multiple branches and photovoltaic power sources, and helps to achieve automated operation of the distribution network.

[0131] Step S204: Determine the fault type of the distribution network based on the similarity matrix, where the fault type is a busbar fault or a feeder fault. When the fault type of the distribution network is a feeder fault, determine the fault location based on the fundamental frequency zero-sequence current of each of the measurement nodes on the fault feeder.

[0132] Specifically, if a busbar fault is identified, fault location is not necessary. If a feeder fault is identified, the fault interval is determined by comparing the similarity of the fundamental frequency zero-sequence currents of adjacent nodes on the feeder. This approach adapts to distribution networks with different grounding methods and ensures high location accuracy. Furthermore, the system has low requirements for sampling equipment and is economical.

[0133] An embodiment of the present invention provides a device, comprising a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, at least the following steps are performed:

[0134] Step S201, obtaining the bus zero-sequence voltage of the distribution network, and determining the fault occurrence time according to the bus zero-sequence voltage;

[0135] Specifically, by extracting the busbar zero-sequence voltage, the fault occurrence time can be efficiently determined according to the fault judgment conditions, thereby improving the fault recovery speed and reducing the power outage time.

[0136] Step S202: obtaining the zero-sequence current of each measurement node on the feeder of the distribution network, and determining the fundamental frequency zero-sequence current corresponding to each measurement node according to the fault occurrence time and the zero-sequence current of each measurement node;

[0137] Specifically, by filtering the fundamental frequency component and cutting it to one cycle after the fault, the fundamental frequency zero-sequence current of each measurement node is obtained, which can timely detect faults, evaluate load imbalances, and provide effective data support for the stable operation of the distribution network.

[0138] Step S203, calculating a similarity matrix based on the fundamental frequency zero-sequence current of the measurement node at the head end of each of the feeders;

[0139] Specifically, by extracting the zero-sequence current waveform and calculating the similarity, high-precision and low-cost positioning of the fault feeder and fault interval can be achieved. This is suitable for complex distribution networks with multiple branches and photovoltaic power sources, and helps to achieve automated operation of the distribution network.

[0140] Step S204: Determine the fault type of the distribution network based on the similarity matrix, where the fault type is a busbar fault or a feeder fault. When the fault type of the distribution network is a feeder fault, determine the fault location based on the fundamental frequency zero-sequence current of each of the measurement nodes on the fault feeder.

[0141] Specifically, if a busbar fault is identified, fault location is not necessary. If a feeder fault is identified, the fault interval is determined by comparing the similarity of the fundamental frequency zero-sequence currents of adjacent nodes on the feeder. This approach adapts to distribution networks with different grounding methods and ensures high location accuracy. Furthermore, the system has low requirements for sampling equipment and is economical.

[0142] The devices in this article can be servers, PCs, PADs, mobile phones, etc.

[0143] The present application also provides a computer program product, which, when executed on a data processing device, is adapted to execute a program for initializing at least the following method steps:

[0144] Step S201, obtaining the bus zero-sequence voltage of the distribution network, and determining the fault occurrence time according to the bus zero-sequence voltage;

[0145] Specifically, by extracting the busbar zero-sequence voltage, the fault occurrence time can be efficiently determined according to the fault judgment conditions, thereby improving the fault recovery speed and reducing the power outage time.

[0146] Step S202: obtaining the zero-sequence current of each measurement node on the feeder of the distribution network, and determining the fundamental frequency zero-sequence current corresponding to each measurement node according to the fault occurrence time and the zero-sequence current of each measurement node;

[0147] Specifically, by filtering the fundamental frequency component and cutting it to one cycle after the fault, the fundamental frequency zero-sequence current of each measurement node is obtained, which can timely detect faults, evaluate load imbalances, and provide effective data support for the stable operation of the distribution network.

[0148] Step S203, calculating a similarity matrix based on the fundamental frequency zero-sequence current of the measurement node at the head end of each of the feeders;

[0149] Specifically, by extracting the zero-sequence current waveform and calculating the similarity, high-precision and low-cost positioning of the fault feeder and fault interval can be achieved. This is suitable for complex distribution networks with multiple branches and photovoltaic power sources, and helps to achieve automated operation of the distribution network.

[0150] Step S204: Determine the fault type of the distribution network based on the similarity matrix, where the fault type is a busbar fault or a feeder fault. When the fault type of the distribution network is a feeder fault, determine the fault location based on the fundamental frequency zero-sequence current of each of the measurement nodes on the fault feeder.

[0151] Specifically, if a busbar fault is identified, fault location is not necessary. If a feeder fault is identified, the fault interval is determined by comparing the similarity of the fundamental frequency zero-sequence currents of adjacent nodes on the feeder. This approach adapts to distribution networks with different grounding methods and ensures high location accuracy. Furthermore, the system has low requirements for sampling equipment and is economical.

[0152] Obviously, those skilled in the art will appreciate that the various modules or steps of the present invention described above can be implemented using a general-purpose computing device, can be centralized on a single computing device, or can be distributed across a network of multiple computing devices. They can be implemented using program code executable by the computing device, and thus, can be stored in a storage device and executed by the computing device. In some cases, the steps shown or described herein can be performed in a different order than that shown, or can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0153] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0154] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0155] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1The function specified in one or more boxes.

[0156] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0157] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0158] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0159] Computer-readable media includes permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices, or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transitory media such as modulated data signals and carrier waves.

[0160] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0161] From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

[0162] 1) The fault location method of the above-mentioned distribution network of the present application first obtains the bus zero-sequence voltage of the distribution network and determines the time of fault occurrence based on the bus zero-sequence voltage; then obtains the zero-sequence current of each measurement node on the feeder of the distribution network, and determines the fundamental frequency zero-sequence current corresponding to each measurement node based on the time of fault occurrence and the zero-sequence current of each measurement node; then, based on the fundamental frequency zero-sequence current of the measurement node at the head end of each feeder, a similarity matrix is ​​calculated; finally, based on the similarity matrix, the fault type of the distribution network is determined, and the fault type is either a bus fault or a feeder fault. When the fault type of the distribution network is a feeder fault, the fault location is determined based on the fundamental frequency zero-sequence current of each measurement node on the fault feeder. This method can adapt to distribution networks with different grounding methods, especially in low-current grounding systems. It can withstand higher transition resistance and still ensure high positioning accuracy under high-resistance faults; it can still complete fault location under complex working conditions, and has good immunity to noise interference, time-varying transition resistance, small fault initial phase angle, unbalanced load, and access to distributed power sources; it has low requirements for sampling rate and can operate at a low sampling rate of 1200Hz. Compared with technologies such as traveling wave method that rely on high sampling rate, it greatly reduces the system's requirements for sampling equipment, making the equipment design simpler and more economical, and solving the problems of low accuracy and high cost of existing distribution network fault location technology, resulting in low power system operation efficiency and poor stability.

[0163] 2) The fault location device of the distribution network mentioned above in the present application includes: a first acquisition unit, a second acquisition unit, a calculation unit and a determination unit. The first acquisition unit is used to obtain the bus zero-sequence voltage of the distribution network and determine the time when the fault occurs based on the bus zero-sequence voltage; the second acquisition unit is used to obtain the zero-sequence current of each measurement node on the feeder of the distribution network, and determine the fundamental frequency zero-sequence current corresponding to each measurement node based on the time when the fault occurs and the zero-sequence current of each measurement node; the calculation unit is used to calculate the similarity matrix based on the fundamental frequency zero-sequence current of the measurement node at the head end of each feeder; the determination unit is used to determine the fault type of the distribution network based on the similarity matrix, and the fault type is a bus fault or a feeder fault. When the fault type of the distribution network is a feeder fault, the fault location is determined based on the fundamental frequency zero-sequence current of each measurement node on the fault feeder. The device is suitable for distribution networks with different grounding methods, especially in low-current grounding systems. It can withstand higher transition resistance and still ensure high positioning accuracy under high-resistance faults; it can still complete fault positioning under complex working conditions, and has good immunity to noise interference, time-varying transition resistance, small fault initial phase angle, unbalanced load, and access to distributed power sources; it has low requirements for sampling rate and can operate at a low sampling rate of 1200Hz. Compared with technologies such as traveling wave method that rely on high sampling rate, it greatly reduces the system's requirements for sampling equipment, making the equipment design simpler and more economical, and solving the problems of low accuracy and high cost of existing distribution network fault positioning technology, resulting in low power system operation efficiency and poor stability.

[0164] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for locating a fault in a distribution network, characterized in that: include: Obtaining a bus zero-sequence voltage of the distribution network, and determining a fault occurrence time according to the bus zero-sequence voltage; Obtaining the zero-sequence current of each measurement node on the feeder of the distribution network, and determining the fundamental frequency zero-sequence current corresponding to each measurement node according to the fault occurrence time and the zero-sequence current of each measurement node; A similarity matrix is ​​calculated based on the fundamental frequency zero-sequence current of the measurement node at the head end of each feeder; The fault type of the distribution network is determined according to the similarity matrix, and the fault type is a bus fault or a feeder fault. When the fault type of the distribution network is a feeder fault, the fault location is determined according to the fundamental frequency zero-sequence current of each measurement node on the fault feeder.

2. The method according to claim 1, characterized in that Determining the fault occurrence time according to the bus zero-sequence voltage includes: Obtain fault judgment condition U0(t)>K1U P , where U0(t) is the bus zero-sequence voltage at time t, K1 is the proportionality coefficient, and U P is the phase voltage of the distribution network; When the bus zero-sequence voltage does not satisfy the fault judgment condition U0(t)>K1U P In the case of , the current time is determined to be a non-fault occurrence time; When the bus zero-sequence voltage satisfies the fault judgment condition U0(t)>K1U P In the case of a fault, the current time is determined to be the time when the fault occurs.

3. The method according to claim 2, characterized in that When the distribution network is a low-resistance grounding system, K1 is 0.

01. When the distribution network is a neutral point ungrounded and resonant grounding system, K1 is 0.

05.

4. The method according to claim 1, characterized in that Determining the fundamental frequency zero-sequence current corresponding to each of the measurement nodes according to the fault occurrence time and the zero-sequence current of each of the measurement nodes includes: Using fast Fourier transform to filter the zero-sequence current of each measurement node to obtain the baseband signal of each measurement node; The baseband signal is clipped according to the fault occurrence time to obtain the baseband zero-sequence current of one cycle after the fault occurrence time.

5. The method according to claim 1, characterized in that The distribution network has n feeders, and a similarity matrix is ​​calculated based on the fundamental frequency zero-sequence current of the measurement node at the head end of each feeder, including: Determine the fundamental frequency zero-sequence current of the measurement node at the head end of each feeder as the head end fundamental frequency zero-sequence current of each feeder; Determine the cosine similarity of the fundamental frequency zero-sequence current at the head end of any two of the feeders to obtain multiple cosine similarities; According to all the cosine similarities, the similarity matrix is ​​determined Among them, ρ m,n is the cosine similarity between the mth feeder and the nth feeder, ρ n,m is the cosine similarity between the nth feeder and the mth feeder.

6. The method according to claim 1, characterized in that Determining the fault type of the distribution network according to the similarity matrix includes: Calculate the sum of the elements in each row of the similarity matrix, and compare the sizes of all the sums to obtain the maximum value P k and the next largest value Py, where Pk is the sum of the elements in the k-th row, and Py is the sum of the elements in the y-th row; Obtain bus fault judgment formula Among them, ρ k,i is the value of the i-th element in the k-th row, ρ m,i is the value of the i-th element in the m-th row, K2 is the sensitivity coefficient; In the case where the bus fault judgment formula is established, determining that the fault type of the distribution network is the bus fault; When the bus fault judgment formula is not valid, the fault type of the distribution network is determined to be the feeder fault, and the faulty feeder is determined to be the kth feeder.

7. The method according to claim 1, characterized in that The fault type is the feeder fault, and after determining the fault type of the distribution network according to the similarity matrix, the method further includes: Calculating the waveform similarity of the zero-sequence current of any two adjacent measurement nodes on the fault feeder by cosine similarity; Comparing all the waveform similarities to obtain the minimum similarity; When the minimum similarity satisfies ρ min <K3, it is determined that the fault location is located between two adjacent measurement nodes corresponding to the minimum similarity, where ρ min is the minimum similarity, K3 is the positioning sensitivity coefficient; When the minimum similarity satisfies ρ min ≥K3, it is determined that the fault position is located at the end of the fault feeder.

8. A fault location device for a distribution network, characterized in that: include: A first acquisition unit, used to acquire a bus zero-sequence voltage of the distribution network, and determine a fault occurrence time according to the bus zero-sequence voltage; A second acquisition unit is used to acquire the zero-sequence current of each measurement node on the feeder of the distribution network, and determine the fundamental frequency zero-sequence current corresponding to each measurement node according to the fault occurrence time and the zero-sequence current of each measurement node; A calculation unit, configured to calculate a similarity matrix according to the fundamental frequency zero-sequence current of the measurement node at the head end of each feeder; A determination unit is used to determine the fault type of the distribution network according to the similarity matrix, wherein the fault type is a bus fault or a feeder fault, wherein, when the fault type of the distribution network is the feeder fault, the fault location is determined according to the fundamental frequency zero-sequence current of each measurement node on the fault feeder.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored program, wherein when the program is executed, the device where the computer-readable storage medium is located is controlled to execute the method for locating a fault in a distribution network according to any one of claims 1 to 7.

10. An electronic device, characterized in that: include: One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by the one or more processors, and the one or more programs include a method for executing a fault location method for a distribution network as described in any one of claims 1 to 7.

Images