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

Abstract

The application provides a power distribution network fault positioning method and device, a storage medium and an electronic device. The method comprises the following steps: acquiring a bus zero sequence voltage of a power distribution network, and determining a fault occurrence time according to the bus zero sequence voltage; acquiring zero sequence currents of each measurement node on a feeder of the power distribution network, and determining a fundamental frequency zero sequence current corresponding to each measurement node according to the fault occurrence time and the zero sequence currents of each measurement node; calculating a similarity matrix according to the fundamental frequency zero sequence current of the measurement node at the head end of each feeder; determining a fault type of the power distribution network according to the similarity matrix, including a bus fault or a feeder fault, wherein, in the case of the fault type being a feeder fault, a fault position is determined according to the fundamental frequency zero sequence current of each measurement node on the fault feeder. The method can accurately position the fault position in multiple grounding systems, has strong anti-interference ability, has good adaptability to low sampling rate, and can greatly reduce the economic cost.

Description

TECHNICAL FIELD

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

[0002] The power distribution network undertakes the important task of transmitting electric energy from a transformer substation to end users, and its reliability and stability are of great concern because it is directly related to the power supply quality and power safety of users. With the increasing dependence of society on power supply, especially under the background of the continuous expansion of smart grid and new energy access, the fault location problem of the power distribution network has become one of the key topics of power system research. In particular, single-phase grounding fault, as the most common form of fault in the power distribution network, if not located and handled in time, may cause power outage, equipment damage, and even large-scale power grid failure. Therefore, researching efficient and reliable fault location technology not only helps to improve the automation level of the power distribution network, but also greatly reduces the economic loss caused by power outage.

[0003] Existing power distribution network fault location technologies have made some progress, including signal injection method, traveling wave method, transient method, etc. However, with the increasing complexity of the power distribution network structure, such as the widespread use of multi-branch lines, the increase of mixed line structure, and the large-scale access of photovoltaic and other distributed power sources, the precision of these traditional methods is low and the cost is high, which cannot meet the needs of practical applications. SUMMARY

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

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a fault location method of a power distribution network is provided, comprising: acquiring a bus zero sequence voltage of the power distribution network, and determining a fault occurrence time according to the bus zero sequence voltage; acquiring a zero sequence current of each measurement node on a feeder of the power distribution network, and determining a 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 a similarity matrix according to the fundamental frequency zero sequence current of the measurement node at the head of each feeder; determining a fault type of the power distribution network according to the similarity matrix, the fault type being a bus fault or a feeder fault, wherein, in the case that the fault type of the power distribution network is the feeder fault, determining a fault location according to 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 comprises: obtaining a fault judgment condition U0(t)>K1U P , wherein U0(t) is the bus zero sequence voltage at time t, K1 is a proportional coefficient, U P is the phase voltage of the power distribution network; in the case that the bus zero sequence voltage does not satisfy the fault judgment condition U0(t)>K1U P , determining that the current time is a non-fault occurrence time; in the case that the bus zero sequence voltage satisfies the fault judgment condition U0(t)>K1U P , determining that the current time is the fault occurrence time.

[0007] Optionally, in the case that the power distribution network is a small-resistance grounding system, K1 is 0.01; in the case that the power distribution network is a neutral point ungrounded and resonance grounding system, K1 is 0.05.

[0008] Optionally, according to the fault occurrence time and the zero sequence current of each measurement node, determining the fundamental frequency zero sequence current corresponding to each measurement node comprises: filtering the zero sequence current of each measurement node by using fast Fourier transform to obtain the fundamental frequency signal of each measurement node; and cutting the fundamental frequency signal according to the fault occurrence time to obtain the fundamental frequency zero sequence current of the next cycle after the fault occurrence time.

[0009] Optionally, the power distribution network has n feeders, and a similarity matrix is calculated according to the fundamental frequency zero sequence current of the measurement node at the head end of each feeder, comprising: 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 a plurality of cosine similarities; and determining the similarity matrix according to all the cosine similarities , wherein ρ m,n is the cosine similarity of the mth feeder and the nth feeder, ρ n,m is the cosine similarity of the nth feeder and the mth feeder.

[0010] Optionally, according to the similarity matrix, determining the fault type of the power distribution network comprises: calculating the sum of each row element in the similarity matrix, and comparing the size of all the sums to obtain a maximum value P k and a second maximum value Py, wherein Pk is the sum of the kth row element, Py is the sum of the yth row element; and obtaining a bus fault judgment formula , wherein ρ k,i is the value of the kth row and ith element, ρ m,iThe value of the mth row and ith element is K2, which is a sensitivity coefficient; in a case where the bus fault judgment formula is established, it is determined that the fault type of the power distribution network is the bus fault; in a case where the bus fault judgment formula is not established, it is determined that the fault type of the power distribution network is the feeder fault, and the fault feeder is the kth feeder.

[0011] Optionally, the fault type is the feeder fault, and after the fault type of the power distribution network is determined according to the similarity matrix, the method further includes: calculating the waveform similarity of the zero sequence currents of any two adjacent measurement nodes on the fault feeder by cosine similarity; comparing all the waveform similarities to obtain a minimum similarity; in a case where the minimum similarity satisfies ρ min ≤ K3, it is determined that the fault location is between the two adjacent measurement nodes corresponding to the minimum similarity, wherein ρ min is the minimum similarity, and K3 is a positioning sensitivity coefficient; in a case where the minimum similarity satisfies ρ min ≥ K3, it is determined that the fault location is at the end of the fault feeder.

[0012] According to another aspect of the present application, a fault location device of a power distribution network is provided, which includes: a first obtaining unit configured to obtain bus zero sequence voltages of the power distribution network, and determine a fault occurrence time according to the bus zero sequence voltages; a second obtaining unit configured to obtain zero sequence currents of each measurement node on a feeder of the power distribution network, and determine a base frequency zero sequence current corresponding to each measurement node according to the fault occurrence time and the zero sequence currents of each measurement node; a calculating unit configured to calculate a similarity matrix according to the base frequency zero sequence current of a measurement node at a head end of each feeder; and a determining unit configured to determine a fault type of the power distribution network according to the similarity matrix, the fault type being a bus fault or a feeder fault, wherein in a case where the fault type of the power distribution network is the feeder fault, a fault location is determined according to the base frequency zero sequence currents of each measurement node on a fault feeder.

[0013] According to still another aspect of the present application, a computer readable storage medium is provided, which includes a stored program, wherein the program, when executed, controls a device where the computer readable storage medium is located to perform any of the fault location methods of the power distribution network.

[0014] According to yet another aspect of the present application, an electronic device is provided, which includes 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 program for performing any of the fault location methods of the power distribution network.

[0015] With the technical solution of the present application, the fault positioning method of the power distribution network first acquires the bus zero sequence voltage of the power distribution network, and determines the fault occurrence time according to the bus zero sequence voltage; then acquires the zero sequence currents of each measurement node on the feeder of the power distribution network, and determines the base frequency zero sequence currents corresponding to each measurement node according to the fault occurrence time and the zero sequence currents of each measurement node; then calculates the similarity matrix according to the base frequency zero sequence currents of the measurement node at the head of each feeder; and finally determines the fault type of the power distribution network according to the similarity matrix, wherein the fault type is a bus fault or a feeder fault, and in the case of a feeder fault of the power distribution network, the fault position is determined according to the base frequency zero sequence currents of each measurement node on the fault feeder. This method can adapt to power distribution networks with different grounding modes, especially in a small current grounding system, it can withstand a relatively high 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 anti-interference performance for noise interference, transition resistance time-varying, small fault initial phase angle, unbalanced load and connected distributed power supply; it has a lower requirement for sampling rate and can operate at a low sampling rate of 1200Hz, compared with technologies such as traveling wave method which depend on high sampling rate, greatly reducing the requirement of the system on sampling equipment, making the equipment design simpler and more economical, and solving the problems of low precision, high cost, low operation efficiency and poor stability of the existing power distribution network fault positioning technology. BRIEF DESCRIPTION OF DRAWINGS

[0016] The drawings accompanying the specification of the present application form a part thereof, serve to provide further understanding of the present application, and together with the specification explain the present application, and do not constitute an inappropriate limitation to the present application. In the drawings:

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

[0018] Figure 2 A flowchart of a fault positioning method of a power distribution network is shown according to an embodiment of the present application;

[0019] Figure 3 A flowchart of a fault position positioning is shown according to an embodiment of the present application;

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

[0021] Figure 5 A flowchart of another fault positioning method of a power distribution network is shown according to an embodiment of the present application;

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

[0023] Among them, the above-mentioned drawings include the following reference signs:

[0024] 102, processor; 104, memory; 106, transmission device; 108, input and output device. DETAILED DESCRIPTION

[0025] It should be noted that the embodiments and features in the present application can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0026] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0027] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily limit to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

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

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

[0030] The methods and embodiments provided in this application can be executed on a mobile terminal, computer terminal, or similar computing device. Taking running on a mobile terminal as an example, Figure 1 This is a hardware structure block diagram of a mobile terminal for a fault location method in a power distribution network according to an embodiment of the present invention. Figure 1 As shown, a mobile terminal may include one or more ( Figure 1 Only one is shown in the diagram. A processor 102 (which may include, but is not limited to, a microprocessor MCU or a programmable logic device FPGA, etc.) and a memory 104 for storing data are also shown. The mobile terminal may further include a transmission device 106 for communication functions and an input / output device 108. Those skilled in the art will understand that... Figure 1 The structure shown is for illustrative purposes only and does not limit the structure of the mobile terminal described above. For example, the mobile terminal may also include components that are more... Figure 1 The more or fewer components shown, or having the same Figure 1 The different configurations shown.

[0031] The memory 104 can be used to store computer programs, such as application software programs and modules, like the computer program corresponding to the fault location method for the power distribution network in this embodiment of the invention. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, thereby implementing the above-described method. The memory 104 may include high-speed random access memory 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 instances, the memory 104 may further include memory remotely located relative to the processor 102, and these remote memories can be connected to the mobile terminal via a network. Examples of the above-described networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof. The transmission device 106 is used to receive or send data via a network. Specific examples of the above-described networks may include wireless networks provided by the mobile terminal's communication 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 communicate 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] This embodiment provides a fault location method for a power distribution network that runs on a mobile terminal, computer terminal, or similar computing device. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Also, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0033] Figure 2 This is a flowchart of a fault location method for a power distribution network according to an embodiment of this application. Figure 2 As shown, the method includes the following steps:

[0034] Step S201: Obtain the zero-sequence voltage of the distribution network bus and determine the time of fault occurrence based on the aforementioned zero-sequence voltage of the bus.

[0035] Specifically, by extracting the zero-sequence voltage of the bus, the timing of the fault can be efficiently determined based on the fault judgment conditions, thereby improving the speed of fault recovery and reducing power outage time.

[0036] Determining the fault occurrence time based on the aforementioned 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 bus at time t, K1 is the proportional coefficient, and U P The phase voltage of the aforementioned distribution network;

[0038] Step S2012, if the above-mentioned bus zero-sequence voltage does not meet the above-mentioned fault judgment condition U0(t)>K1U P In the case of a fault, the current time is determined to be a non-fault occurrence time;

[0039] Step S2013, if the zero-sequence voltage of the above-mentioned bus meets the above-mentioned fault judgment condition U0(t)>K1U P In this case, the current time is determined to be the time when the above-mentioned fault occurred.

[0040] Specifically, based on the fault judgment conditions, the time and location of faults in the distribution network can be quickly identified, which helps improve fault handling efficiency and ensures the safety and reliability of the system. When the bus voltage meets the above fault judgment conditions, the time of fault occurrence is recorded as t0.

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

[0042] Specifically, in the fault judgment condition, the proportional coefficient K1 is a weight coefficient for quantifying and adjusting a specific variable or index, which adjusts, amplifies or reduces the influence of a specific factor to achieve more accurate and reasonable judgment of the fault condition. For different grounding modes of the distribution network, such as neutral point ungrounded system, resonance grounding system and small resistance grounding system, the proportional coefficient K1 has different values.

[0043] In step S202, the zero sequence currents of each measurement node on the feeder of the distribution network are obtained, and the base frequency zero sequence currents corresponding to each measurement node are determined according to the fault occurrence time and the zero sequence currents of each measurement node.

[0044] Specifically, by filtering to obtain the base frequency component and cutting it to one cycle after the fault, the base frequency zero sequence currents of each measurement node are obtained, which can timely discover the fault, evaluate the load imbalance, and provide effective data support for the stable operation of the distribution network.

[0045] Wherein, according to the fault occurrence time and the zero sequence currents of each measurement node, the base frequency zero sequence currents corresponding to each measurement node are determined, including the following steps:

[0046] In step S2021, the zero sequence currents of each measurement node are filtered by using fast Fourier transform to obtain the base frequency signals of each measurement node.

[0047] In step S2022, according to the fault occurrence time, the base frequency signals are cut to obtain the base frequency zero sequence currents of one cycle after the fault occurrence time.

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

[0049] In step S203, the similarity matrix is calculated according to the base frequency zero sequence currents of the measurement node at the head of each feeder.

[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 realized, which is suitable for complex distribution networks with multiple branches and photovoltaic power supply, and helps to realize the automatic operation of the distribution network.

[0051] Wherein, the distribution network has n feeders, and the similarity matrix is calculated according to the base frequency zero sequence currents of the measurement node at the head of each feeder, including the following steps:

[0052] Step S2031, the fundamental frequency zero sequence current of the measurement node at the head of each feeder is determined as the head fundamental frequency zero sequence current of each feeder.

[0053] Step S2032, the cosine similarity of the head fundamental frequency zero sequence currents of any two feeders is determined to obtain a plurality of cosine similarities.

[0054] Step S2033, the similarity matrix is determined according to all the cosine similarities. wherein ρ m,n is the cosine similarity of the mth feeder and the nth feeder, and ρ n,m is the cosine similarity of the nth feeder and the mth feeder.

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

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

[0057] Step S204, 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. If the fault type of the distribution network is the feeder fault, the fault location is determined according to the fundamental frequency zero sequence currents of the measurement nodes on the fault feeder.

[0058] Specifically, if the bus fault is determined, the fault interval positioning is not needed; if the feeder fault is determined, the fundamental frequency zero sequence current similarity of adjacent nodes on the feeder is compared to determine the fault interval. In this way, the distribution network with different grounding modes can be adapted, and high positioning accuracy can be ensured, while the requirement of the sampling device is low, and the economy is considered.

[0059] In one embodiment, asFigure 3 As shown, the specific fault location process includes: first detecting the fault occurrence time by using the bus zero sequence voltage, taking 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; the waveform similarity between the first measurement node of each feeder is used to complete fault line selection, and it is judged whether the fault line is a bus, and if so, the fault location result is output; if it is not a bus fault, it is judged whether the fault line contains a branch branch, if it contains, then the fault branch selection is completed by "fault line selection", and then fault section positioning is performed, if it does not contain, then the similarity of adjacent measurement nodes on the feeder is used to complete general fault section positioning, and finally the result is output.

[0060] The fault type of the power distribution network is determined according to the similarity matrix, including the following steps:

[0061] In step S301, the sum of each row element in the similarity matrix is calculated, and the size of all sums is compared to obtain the maximum value P k and the second 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;

[0062] In step S302, the bus fault judgment formula is obtained Where 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, and K2 is the sensitivity coefficient.

[0063] In step S303, when the bus fault judgment formula is established, the fault type of the power distribution network is determined to be the bus fault.

[0064] In step S304, when the bus fault judgment formula is not established, the fault type of the power distribution network is determined to be the feeder fault, and the fault feeder is determined to be the kth feeder.

[0065] Specifically, the bus fault judgment formula can be used to determine whether the fault is located on the bus or the feeder, and the fault type is more accurately positioned, thereby improving the fault recovery speed and reducing the power outage time. 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 power distribution network according to the similarity matrix, the method further includes the following steps:

[0067] In step S401, the waveform similarity of the zero sequence currents of any two adjacent measurement nodes on the fault feeder is calculated by cosine similarity.

[0068] Step S402, compare all the above waveform similarity, get the minimum similarity;

[0069] Step S403, in the above minimum similarity satisfies p min <K3 cases, determine the above fault location between the two adjacent above measurement nodes corresponding to the minimum similarity, wherein, p min is the minimum similarity, K3 is the positioning sensitivity coefficient;

[0070] Step S404, in the above minimum similarity satisfies p min ≥K3 cases, determine the above fault location at the end of the fault feeder.

[0071] Specifically, when the fault is located on the feeder, the above steps can be used to locate the fault section, improve the fault location method under complex conditions, and have good anti-interference performance for noise interference, transition resistance time-varying, small fault initial phase angle, unbalanced load, and access to distributed power supply.

[0072] When the fault is located on the feeder, first calculate the waveform similarity between the zero sequence currents of adjacent measurement nodes on the feeder by cosine similarity, and obtain the minimum value by traversing all the similarities and comparing it with the positioning sensitivity coefficient K3. Among them, for the neutral point ungrounded system, K3 takes-0.8; for the small resistance grounding system, K3 takes 0.2; for the resonance grounding system, K3 takes 0.7.

[0073] In one embodiment, a simulation model of a 10kV distribution network is established, as shown in Figure 4 6 typical fault cases are set for testing the fault location effect, and Table 1 gives the related parameters of the 6 typical fault cases.

[0074] Table 1. Typical fault case parameter table

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

[0076] In the neutral point ungrounded system, the small resistance grounding system and the resonance grounding system, the A-phase grounding fault with transition resistance of 10Ω or 1000Ω occurs. The corresponding characteristic correlation coefficients are shown in Table 2.

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

[0078]

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

[0080] In another embodiment, based on the above embodiment, a time-varying transition resistor is set, 5% Gaussian white noise is added to the current of each measurement node, the initial phase angle of the fault is changed from 85° to 5°, and the three-phase symmetrical load is changed to an asymmetrical load with 30% unbalance. Faults 1 to 6 are set sequentially, and the fault range location results under complex operating conditions are obtained, as shown in Table 3. The results show that this method has good noise immunity and advantages such as being able to identify fault sections under conditions of high-resistance time-varying transition resistors, small fault angles, and unbalanced loads.

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

[0082]

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

[0084] Table 4. Location results when connecting photovoltaic systems at different locations

[0085] Case Access upstream Access downstream Access sound 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 12 end / 12 end

[0086] The above fault positioning method of the power distribution network of the present application first acquires the bus zero sequence voltage of the power distribution network, and determines the fault occurrence time according to the bus zero sequence voltage; then acquires the zero sequence currents of each measurement node on the feeder of the power distribution network, and determines the base frequency zero sequence currents corresponding to each measurement node according to the fault occurrence time and the zero sequence currents of each measurement node; then calculates the similarity matrix according to the base frequency zero sequence currents of the measurement node at the head of each feeder; and finally determines the fault type of the power distribution network according to the similarity matrix, wherein the fault type is a bus fault or a feeder fault, and wherein, in the case of a feeder fault of the power distribution network, the fault position is determined according to the base frequency zero sequence currents of each measurement node on the fault feeder. The method can adapt to power distribution networks with different grounding modes, especially in a small current grounding system, can withstand a relatively high transition resistance, and can still guarantee a high positioning accuracy under a high resistance fault; can still complete fault positioning under complex working conditions, and has good anti-interference performance for noise interference, transition resistance time-varying, small fault initial phase angle, unbalanced load and access to distributed power supply; has a relatively low requirement for the sampling rate and can operate at a low sampling rate of 1200Hz, compared with technologies such as the traveling wave method which depends on a high sampling rate, greatly reduces the requirement of the system on the sampling equipment, makes the equipment design simpler and more economical, and solves the problems of low precision, high cost, low operation efficiency and poor stability of the existing power distribution network fault positioning technology.

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

[0088] The present embodiment relates to a specific fault positioning method of a power distribution network, as shown in Figure 5 The method comprises the following steps:

[0089] Step S1: Acquire the bus zero sequence voltage and determine the fault occurrence time.

[0090] Step S2: Extract the post-fault one-cycle base frequency zero sequence current waveform of each measurement node, and calculate the similarity matrix.

[0091] Step S3: Compare the similarity of the zero sequence currents at the head of each feeder, and determine the fault feeder.

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

[0093] 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 the logical order is shown in the flowchart, in some cases, the steps shown or described herein can be executed in an order different from that shown herein.

[0094] This application also provides a fault location device for a distribution network. It should be noted that the fault location device for a distribution network in this application can be used to execute the fault location method for a distribution network provided in this application. This device is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0095] The following describes the fault location device for power distribution networks provided in the embodiments of this application.

[0096] Figure 6 This is a schematic diagram of a fault location device for a power distribution network according to an embodiment of this 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 acquire the zero-sequence voltage of the bus of the distribution network and determine the fault occurrence time based on the bus zero-sequence voltage. The second acquisition unit 20 is used to acquire the zero-sequence current of each measuring node on the feeder of the distribution network and determine the fundamental frequency zero-sequence current corresponding to each measuring node based on the fault occurrence time and the zero-sequence current of each measuring node. The calculation unit 30 is used to calculate a similarity matrix based on the fundamental frequency zero-sequence current of the measuring node at the beginning of each feeder. The determination unit 40 is used to determine the fault type of the distribution network based on the similarity matrix. The fault type is either a bus fault or a feeder fault. In the case where 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 measuring node on the faulty feeder.

[0097] The above fault location device of the power distribution network of the present application comprises: a first acquisition unit, a second acquisition unit, a calculation unit and a determination unit, the first acquisition unit is configured to acquire the bus zero sequence voltage of the power distribution network, and determine the fault occurrence time according to the bus zero sequence voltage; the second acquisition unit is configured to acquire the zero sequence current of each measurement node on the feeder of the power distribution network, and determine the base frequency zero sequence current corresponding to each measurement node according to the fault occurrence time and the zero sequence current of each measurement node; the calculation unit is configured to calculate the similarity matrix according to the base frequency zero sequence current of the measurement node at the head of each feeder; and the determination unit is configured to determine the fault type of the power distribution network according to the similarity matrix, wherein the fault type is a bus fault or a feeder fault, and in the case that the fault type of the power distribution network is a feeder fault, the fault location is determined according to the base frequency zero sequence current of each measurement node on the fault feeder. The device is suitable for power distribution networks with different grounding modes, especially in a small current grounding system, can withstand a relatively high transition resistance, and can still ensure a high positioning accuracy under a high resistance fault; can complete fault location under complex working conditions, and has good noise interference, transition resistance time-varying, small fault initial phase angle, unbalanced load and distributed power source access anti-interference; has a lower requirement for sampling rate, can operate at a low sampling rate of 1200Hz, greatly reduces the requirement of the system on the sampling equipment compared with technologies such as the traveling wave method which depends on high sampling rate, makes the equipment design simpler and more economical, and solves the problems of low precision, high cost, low operation efficiency and poor stability of the existing power distribution network fault location technology.

[0098] In some examples, the first acquisition unit comprises a first acquisition module, a second acquisition module and a third acquisition module, the first acquisition module is configured to acquire the fault judgment condition U0(t) > K1U P , wherein U0(t) is the above bus zero sequence voltage at time t, K1 is a proportional coefficient, U P is the phase voltage of the above power distribution network; the second acquisition module is configured to determine that the current time is a non-fault occurrence time in the case that the above bus zero sequence voltage does not satisfy the above fault judgment condition U0(t) > K1U P ; and the third acquisition module is configured to determine that the current time is the above fault occurrence time in the case that the above bus zero sequence voltage satisfies the above fault judgment condition U0(t) > K1U P . This helps to improve the fault handling efficiency, and at the same time, ensures the safety and reliability of the system.

[0099] In some examples, the first acquisition module is configured to set K1 as 0.01 when the power distribution network is a small resistance grounding system, and set K1 as 0.05 when the power distribution network is a neutral point ungrounded and resonance grounding system. The proportional coefficient K1 is a weight coefficient for quantifying and adjusting a specific variable or index, which adjusts, amplifies or reduces the influence of a specific factor to achieve a more accurate and reasonable judgment of the fault condition.

[0100] In some examples, 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 of each measurement node by using fast Fourier transform to obtain a fundamental frequency signal of each measurement node. The fifth acquisition module is configured to cut the fundamental frequency signal according to the fault occurrence time to obtain the fundamental frequency zero sequence current of the next cycle after the fault occurrence time. The fast Fourier transform method can accurately distinguish the fundamental frequency and harmonic components, effectively filter out high-frequency noise, and provide more accurate and reliable measurement results, thereby improving the operation efficiency and stability of the power system and ensuring the reliability of power supply.

[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 configured to determine the fundamental frequency zero sequence current of the measurement node at the head of each feeder as the head fundamental frequency zero sequence current of each feeder. The second calculation module is configured to determine the cosine similarity of the head fundamental frequency zero sequence currents of any two feeders to obtain a plurality of cosine similarities. The third calculation module is configured to determine the similarity matrix according to all the cosine similarities. wherein ρ m,n is the cosine similarity between the mth feeder and the nth feeder, and ρ n,m is the cosine similarity between the nth feeder and the mth feeder. The cosine similarity can be used to measure the similarity between vectors in the direction and is not affected by the size of the vector, and has good anti-interference performance to noise

[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 configured to calculate the sum of elements in each row of the similarity matrix, compare the sizes of all the sums, and obtain a maximum value P k and a second maximum value Py. Wherein Pk is the sum of the elements in the kth row, and Py is the sum of the elements in the yth row. The second determination module is configured to obtain a bus fault judgment formula wherein ρ k,i is the value of the i th element in the k th row, and ρ m,iThe value of the mth row and ith element is K2, and K2 is a sensitivity coefficient; the third determination module is configured to determine that the fault type of the power distribution network is the bus fault when the bus fault judgment formula is established; and the fourth determination module is configured to determine that the fault type of the power distribution network is the feeder fault and determine that the fault feeder is the kth feeder when the bus fault judgment formula is not established. In this way, the fault type can be more accurately located, so that the fault recovery speed is improved and the power outage time is reduced.

[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 configured to calculate waveform similarity of zero sequence currents of any two adjacent measurement nodes on the fault feeder by using a cosine similarity. The sixth determination module is configured to compare all the waveform similarities to obtain a minimum similarity. The seventh determination module is configured to determine that the fault location is between the two adjacent measurement nodes corresponding to the minimum similarity when the minimum similarity satisfies ρ min ≤ K3, where ρ min is the minimum similarity, and K3 is a positioning sensitivity coefficient. The eighth determination module is configured to determine that the fault location is at the end of the fault feeder when the minimum similarity satisfies ρ min ≥ K3. In this way, the fault section can be specifically located, and the fault location method under complex conditions is improved

[0104] The fault location device of the power distribution network includes a processor and a memory. The first acquisition unit and the like are stored in the memory as program units, and the corresponding functions are realized by the processor executing the program units stored in the memory. The modules are located in the same processor, or the modules are located in different processors in any combination.

[0105] The processor includes a core, and the core retrieves the corresponding program unit from the memory. One or more cores can be provided, and the problem of low precision, high cost, low operation efficiency, and poor stability of the existing power distribution network fault location technology can be solved by adjusting the core parameters.

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

[0107] The embodiment of the present application provides a computer readable storage medium, and the computer readable storage medium includes a stored program. When the program runs, the computer readable storage medium controls the device where the computer readable storage medium is located to execute the fault location method of the power distribution network.

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

[0109] In step S201, the bus zero sequence voltage of the power distribution network is acquired, and the fault occurrence time is determined according to the bus zero sequence voltage.

[0110] Specifically, the bus zero sequence voltage is extracted, and the fault occurrence time can be efficiently determined according to the fault judgment condition, thereby improving the fault recovery speed and reducing the power outage time.

[0111] In step S202, the zero sequence current of each measurement node on the feeder of the power distribution network is acquired, and the fundamental frequency zero sequence current corresponding to each measurement node is determined according to the fault occurrence time and the zero sequence current of each measurement node.

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

[0113] In step S203, the similarity matrix is calculated according to the fundamental frequency zero sequence current of the measurement node at the head of each feeder.

[0114] Specifically, by extracting the zero sequence current waveform and calculating the similarity, high-precision and low-cost positioning of the fault feeder and the fault interval can be realized, which is suitable for complex power distribution networks with multiple branches and photovoltaic power sources, and is helpful for realizing the automatic operation of the power distribution network.

[0115] In step S204, the fault type of the power distribution network is determined according to the similarity matrix, and the fault type is a bus fault or a feeder fault, wherein in the case that the fault type of the power distribution network is the feeder fault, the fault position is determined according to the fundamental frequency zero sequence current of each measurement node on the fault feeder.

[0116] Specifically, if it is judged as a bus fault, fault interval positioning is not needed; if it is judged as a feeder fault, the similarity of the fundamental frequency zero sequence current of adjacent nodes on the feeder is compared to judge the fault interval. In this way, the power distribution network with different grounding modes can be adapted, and high positioning accuracy can be ensured, and the requirement of the system to the sampling device is low, and the economy is taken into account.

[0117] Optionally, the fault occurrence time is determined according to the bus zero sequence voltage, comprising: acquiring a fault judgment condition U0(t) > K1U P wherein U0(t) is the bus zero sequence voltage at time t, K1 is a proportional coefficient, U PThe phase voltage of the power distribution network; in the case that the bus zero sequence voltage does not satisfy the fault judgment condition U0(t)>K1U P , it is determined that the current time is the non-fault occurrence time; in the case that the bus zero sequence voltage satisfies the fault judgment condition U0(t)>K1U P , it is determined that the current time is the fault occurrence time.

[0118] Optionally, in the case that the power distribution network is a small-resistance grounding system, K1 is 0.01; in the case that the power distribution network is a neutral point ungrounded and resonance grounding system, K1 is 0.05.

[0119] Optionally, according to the fault occurrence time and the zero sequence currents of each measurement node, the fundamental frequency zero sequence currents corresponding to each measurement node are determined, including: filtering the zero sequence currents of each measurement node by using fast Fourier transform to obtain the fundamental frequency signals of each measurement node; and cutting the fundamental frequency signals according to the fault occurrence time to obtain the fundamental frequency zero sequence currents of the next cycle after the fault occurrence time.

[0120] Optionally, the power distribution network has n feeders, and a similarity matrix is calculated according to the fundamental frequency zero sequence currents of the measurement nodes at the head ends of each feeder, including: determining the fundamental frequency zero sequence currents of the measurement nodes at the head ends of each feeder as the head end fundamental frequency zero sequence currents of each feeder; determining the cosine similarity of the head end fundamental frequency zero sequence currents of any two feeders to obtain a plurality of cosine similarities; and determining the similarity matrix according to all the cosine similarities wherein, ρ m,n is the cosine similarity of the mth feeder and the nth feeder, ρ n,m is the cosine similarity of the nth feeder and the mth feeder.

[0121] Optionally, according to the similarity matrix, the fault type of the power distribution network is determined, including: calculating the sum of each row element in the similarity matrix, and comparing the sizes of all the sums to obtain a maximum value P k and a second maximum value Py, wherein Pk is the sum of the kth row element, and Py is the sum of the yth row element; and obtaining a bus fault judgment formula wherein, ρ k,i is the value of the kth row i th element, ρ m,i is the value of the mth row i th element, and K2 is a sensitivity coefficient; in the case that the bus fault judgment formula is established, it is determined that the fault type of the power distribution network is the bus fault; and in the case that the bus fault judgment formula is not established, it is determined that the fault type of the power distribution network is the feeder fault, and the fault feeder is the kth feeder.

[0122] Optionally, the fault type is the feeder fault, after determining the fault type of the power distribution network according to the similarity matrix, the method further comprises: calculating the waveform similarity of the zero sequence currents of any two adjacent measurement nodes on the fault feeder by cosine similarity; comparing all the waveform similarities to obtain the minimum similarity; in the case that the minimum similarity satisfies p min min ρ min ≥ K3, it is determined that the fault location is located at the last end of the fault feeder.

[0123] The embodiment of the application provides a processor, which is used for running a program, wherein the processor is used for executing the fault location method of the power distribution network when the program is running.

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

[0125] In step S201, the bus zero sequence voltage of the power distribution network is acquired, and the fault occurrence time is determined according to the bus zero sequence voltage;

[0126] Specifically, the bus zero sequence voltage is extracted, and the fault occurrence time can be efficiently determined according to the fault judgment condition, so that the fault recovery speed is improved and the power outage time is reduced.

[0127] In step S202, the zero sequence currents of each measurement node on the feeder of the power distribution network are acquired, and the base frequency zero sequence currents corresponding to each measurement node are determined according to the fault occurrence time and the zero sequence currents of each measurement node.

[0128] Specifically, the base frequency component is obtained through filtering and is cut to one cycle after the fault, so that the base frequency zero sequence currents of each measurement node are obtained, the fault can be found in time, the load imbalance condition is evaluated, and effective data support is provided for the stable operation of the power distribution network.

[0129] In step S203, the similarity matrix is calculated according to the base frequency zero sequence currents of the measurement node at the first end of each feeder.

[0130] Specifically, the zero sequence current waveform is extracted and the similarity is calculated, so that the high-precision and low-cost positioning of the fault feeder and the fault interval can be realized, which is suitable for complex power distribution networks with multiple branches and photovoltaic power sources, and is helpful for realizing the automatic operation of the power distribution network.

[0131] ​Step S204, according to the similarity matrix, determine the fault type of the power distribution network, the fault type is bus fault or feeder fault, wherein, in the case of the fault type of the power distribution network is the feeder fault, according to the fundamental frequency zero sequence current of each measurement node on the fault feeder, determine the fault location.

[0132] Specifically, if the bus fault is judged, the fault interval positioning is not needed; if the feeder fault is judged, the similarity of the fundamental frequency zero sequence current of adjacent nodes on the feeder is compared to judge the fault interval. In this way, the power distribution network with different grounding modes can be adapted, and high positioning accuracy is ensured, while the requirement of the system to the sampling device is low, and the economy is taken into account.

[0133] The embodiment of the application provides a device, the device comprises a processor, a memory and a program stored on the memory and executable on the processor, and at least the following steps are implemented when the processor executes the program:

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

[0135] Specifically, the bus zero sequence voltage is extracted, and the fault occurrence time can be efficiently determined according to the fault judgment condition, so as to improve the fault recovery speed and reduce the power outage time.

[0136] Step S202, obtaining the zero sequence current of each measurement node on the feeder 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;

[0137] Specifically, the fundamental frequency component is obtained by filtering and is cut to one cycle after the fault, so as to obtain the fundamental frequency zero sequence current of each measurement node, which can timely find the fault and evaluate the load imbalance, and provide effective data support for the stable operation of the power distribution network.

[0138] Step S203, calculating the similarity matrix according to the fundamental frequency zero sequence current of the measurement node at the head of each feeder;

[0139] Specifically, the zero sequence current waveform is extracted and the similarity is calculated, so as to realize the high-precision and low-cost positioning of the fault feeder and the fault interval, which is suitable for the complex power distribution network with multiple branches and photovoltaic power supply, and is helpful to realize the automatic operation of the power distribution network.

[0140] Step S204, according to the similarity matrix, determine the fault type of the power distribution network, the fault type is bus fault or feeder fault, wherein, in the case of the fault type of the power distribution network is the feeder fault, according to the fundamental frequency zero sequence current of each measurement node on the fault feeder, determine the fault location.

[0141] Specifically, if the bus fault is determined, the fault interval positioning is not needed; if the feeder fault is determined, the similarity of the fundamental frequency zero sequence currents of the adjacent nodes on the feeder is compared to determine the fault interval. In this way, the power distribution network with different grounding modes can be adapted, and high positioning accuracy is ensured, while the requirements of the sampling device of the system are low, and the economy is considered.

[0142] The device herein can be a server, a PC, a PAD, a mobile phone, etc.

[0143] The application also provides a computer program product adapted to execute the program of at least the following method steps when executed on a data processing device:

[0144] In step S201, the bus zero sequence voltage of the power distribution network is acquired, and the fault occurrence time is determined according to the bus zero sequence voltage.

[0145] Specifically, the bus zero sequence voltage is extracted, and the fault occurrence time can be efficiently determined according to the fault judgment condition, so as to improve the fault recovery speed and reduce the power outage time.

[0146] In step S202, the zero sequence currents of each measurement node on the feeder of the power distribution network are acquired, and the fundamental frequency zero sequence currents corresponding to each measurement node are determined according to the fault occurrence time and the zero sequence currents of each measurement node.

[0147] Specifically, the fundamental frequency component is obtained by filtering and is cut to one cycle after the fault, so as to obtain the fundamental frequency zero sequence current of each measurement node, which can timely discover the fault and evaluate the load imbalance, and provide effective data support for the stable operation of the power distribution network.

[0148] In step S203, the similarity matrix is calculated according to the fundamental frequency zero sequence currents of the measurement node at the head of each feeder.

[0149] Specifically, by extracting the zero sequence current waveform and calculating the similarity, high-precision and low-cost positioning of the fault feeder and the fault interval can be realized, which is suitable for complex power distribution networks with multiple branches and photovoltaic power sources, and is helpful for realizing the automatic operation of the power distribution network.

[0150] In step S204, the fault type of the power distribution network is determined according to the similarity matrix, and the fault type is a bus fault or a feeder fault. In the case where the fault type of the power distribution network is the feeder fault, the fault position is determined according to the fundamental frequency zero sequence currents of each measurement node on the fault feeder.

[0151] Specifically, if the bus fault is determined, the fault interval positioning is not needed; if the feeder fault is determined, the similarity of the fundamental frequency zero sequence currents of adjacent nodes on the feeder is compared to determine the fault interval. In this way, the distribution network with different grounding modes can be adapted, and high positioning accuracy is ensured, while the requirement of the sampling device is low, and economy is considered.

[0152] It is apparent that those skilled in the art will recognize that the modules or steps of the present application described above can be implemented with general computing devices, which can be centralized on a single computing device or distributed on a network composed of multiple computing devices, and can be implemented with program codes executable by the computing devices, so that they can be stored in storage devices and executed by the computing devices, and in some cases, the steps shown or described can be executed in different orders, or some of them can be made into individual integrated circuit modules or a single integrated circuit module. Therefore, the present application is not limited to any specific combination of hardware and software.

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

[0154] The present application is described with reference to flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, as well as combinations of flows and / or blocks in the flowcharts and / or block diagrams, 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 apparatus to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing apparatus produce a means for implementing the functions specified in the flowcharts and / or block diagrams. Figure 1 The functions specified in a flow or multiple flows and / or blocks Figure 1 The means for implementing the functions specified in a flow or multiple flows and / or blocks.

[0155] These computer program instructions can also be stored in a computer-readable memory that can direct the computer or other programmable data processing apparatus to work in a specific manner, so that the instructions stored in the computer-readable memory produce a product including instruction means, which implement the functions specified in the flowcharts and / or block diagrams. Figure 1 The functions specified in a flow or multiple flows and / or blocks Figure 1the function(s) specified in the block or blocks.

[0156] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the operations specified in the flowchart block or blocks. Figure 1 one or more flowcharts and / or blocks Figure 1 the function(s) specified in the block or blocks.

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

[0158] The memory can include non-persistent memory and / or volatile memory, such as random access memory (RAM) about which the processor can execute instructions. The memory can also include non-volatile memory, such as read only memory (ROM), electrically programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), flash memory, or other memory technologies, CD-ROM, digital versatile disc (DVD), or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to store information for access by a computing device. In no case does the disclosure rely on any

[0159] Computer readable media includes permanent and non-permanent, removable and non-removable media implemented in any method or technology for storage of information such as 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 programmable read only memory (EEPROM), flash memory or other memory technologies, compact disc read only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to store information accessible by a computing device. According to the definition 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 "comprising," "including," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements in the list, but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises a" does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article, or apparatus that includes the element.

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

[0162] 1) The above power distribution network fault locating method of the present application first acquires the bus zero sequence voltage of the power distribution network, and determines the fault occurrence time according to the bus zero sequence voltage; then acquires the zero sequence current of each measurement node on the feeder of the power distribution network, and determines the base frequency zero sequence current corresponding to each measurement node according to the fault occurrence time and the zero sequence current of each measurement node; then calculates the similarity matrix according to the base frequency zero sequence current of the measurement node at the head of each feeder; finally, determines the fault type of the power distribution network according to the similarity matrix, and the fault type is either a bus fault or a feeder fault, wherein, in the case of a feeder fault of the power distribution network, the fault location is determined according to the base frequency zero sequence current of each measurement node on the fault feeder. This method can adapt to power distribution networks with different grounding modes, especially in a small current grounding system, it can withstand a relatively high transition resistance, and still ensure a high positioning accuracy under a high resistance fault; it can still complete fault location under complex working conditions, and has good anti-interference performance for noise interference, transition resistance time-varying, small fault initial phase angle, unbalanced load, and access to distributed power supply; it has a relatively low requirement 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, greatly reducing the requirement of the system on sampling equipment, making the equipment design simpler and more economical, and solving the problems of low precision, high cost, low operation efficiency and poor stability of the existing power distribution network fault locating technology.

[0163] 2) The fault location device of the power distribution network of the present application comprises a first acquisition unit, a second acquisition unit, a calculation unit and a determination unit, the first acquisition unit is used for acquiring the bus zero sequence voltage of the power distribution network, and determining the fault occurrence time according to the bus zero sequence voltage; the second acquisition unit is used for acquiring the zero sequence current of each measurement node on the feeder of the power distribution network, and determining the base frequency zero sequence current corresponding to each measurement node according to the fault occurrence time and the zero sequence current of each measurement node; the calculation unit is used for calculating the similarity matrix according to the base frequency zero sequence current of the measurement node at the head of each feeder; the determination unit is used for determining the fault type of the power distribution network according to the similarity matrix, and the fault type is a bus fault or a feeder fault, wherein, in the case of the fault type of the power distribution network being a feeder fault, the fault position is determined according to the base frequency zero sequence current of each measurement node on the fault feeder. The device is suitable for power distribution networks with different grounding modes, especially in a small current grounding system, it can withstand a high transition resistance, and can still ensure high positioning accuracy under high resistance faults; it can still complete fault location under complex working conditions, and has good anti-interference performance for noise interference, transition resistance time-varying, small fault initial phase angle, unbalanced load and distributed power access; the requirement for sampling rate is low, and it can operate at a low sampling rate of 1200Hz, compared with technologies such as traveling wave method which depend on high sampling rate, the system greatly reduces the requirement for sampling equipment, makes the equipment design simpler and more economical, and solves the problems of low precision, high cost, low operation efficiency and poor stability of the existing power distribution network fault location technology.

[0164] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for fault location of a power distribution network, characterized in that, The method comprises the following steps: acquiring a bus zero sequence voltage of a power distribution network, and determining a fault occurrence time according to the bus zero sequence voltage; acquiring zero sequence currents of each measurement node on a feeder of the power distribution network, and determining a base frequency zero sequence current corresponding to each measurement node according to the fault occurrence time and the zero sequence currents of each measurement node; calculating a similarity matrix according to the base frequency zero sequence currents of the measurement nodes at the head ends of each feeder; determining a fault type of the power distribution network according to the similarity matrix, wherein the fault type is a bus fault or a feeder fault, and wherein, in a case where the fault type of the power distribution network is the feeder fault, a fault position is determined according to the base frequency zero sequence currents of each measurement node on the fault feeder; in a case where the fault type is the feeder fault, after the fault type of the power distribution network is determined according to the similarity matrix, the method further comprises the following steps: calculating waveform similarities of the zero sequence currents of any two adjacent measurement nodes on the fault feeder by using cosine similarity; comparing all the waveform similarities to obtain a minimum similarity; In the case that the minimum similarity degree satisfies , it is determined that the fault location is between two adjacent measurement nodes corresponding to the minimum similarity degree, wherein, is the minimum similarity degree, is a positioning sensitivity coefficient. In the case that the minimum similarity meets the fault location is determined to be at the end of the fault feeder.

2. The method of claim 1, wherein, determining the fault occurrence time according to the bus zero sequence voltage comprises the following steps: Acquiring a fault judgment condition Wherein, U0(t) is the bus zero sequence voltage at t moment, K1 is a proportional coefficient, U P is the phase voltage of the power distribution network; In the case that the bus zero sequence voltage does not satisfy the fault judgment condition , it is determined that the current time is determined as a non-fault occurrence time. In the case that the bus zero sequence voltage satisfies the fault judgment condition , the current time is determined as the fault occurrence time.

3. The method of claim 2, wherein, in a case where the power distribution network is a small-resistance grounding system, K1 is 0.01, and in a case where the power distribution network is a neutral point ungrounded and resonance grounding system, K1 is 0.

05.

4. The method of claim 1, wherein, determining the base frequency zero sequence current corresponding to each measurement node according to the fault occurrence time and the zero sequence currents of each measurement node comprises the following steps: filtering the zero sequence currents of each measurement node by using fast Fourier transform to obtain base frequency signals of each measurement node; cutting the base frequency signals according to the fault occurrence time to obtain the base frequency zero sequence current of a next cycle after the fault occurrence time.

5. The method of claim 1, wherein, in a case where the power distribution network has n feeders, the similarity matrix is calculated according to the base frequency zero sequence currents of the measurement nodes at the head ends of each feeder, and the calculation comprises the following steps: determining the base frequency zero sequence currents of the measurement nodes at the head ends of each feeder as head end base frequency zero sequence currents of each feeder; determining cosine similarities of the head end base frequency zero sequence currents of any two feeders to obtain a plurality of cosine similarities; determining the similarity matrix from all the cosine similarities wherein, is the cosine similarity of the mth feeder with the nth feeder, is the cosine similarity of the nth feeder with the mth feeder.

6. The method of claim 1, wherein, determining the fault type of the power distribution network according to the similarity matrix comprises the following steps: calculating the sum of elements of each row in the similarity matrix, and comparing the sizes of all the sums to obtain a maximum value P k and a second maximum value Py, wherein Pk is the sum of the elements of the kth row, and Py is the sum of the elements of the yth row; Acquisition bus fault determination formula wherein, is the value of the element in the kth row and ith column, is the value of the element in the mth row and ith column, and K2 is a sensitivity coefficient. in a case where a bus fault judgment formula is established, determining that the fault type of the power distribution network is the bus fault; in a case where the bus fault judgment formula is not established, determining that the fault type of the power distribution network is the feeder fault, and determining the fault feeder as the kth feeder.

7. A fault location device for an electrical distribution network, characterised in that, The method comprises the following steps: a first acquisition unit is configured to acquire a bus zero sequence voltage of a power distribution network, and determine a fault occurrence time according to the bus zero sequence voltage; a second acquisition unit is configured to acquire zero sequence currents of each measurement node on a feeder of the power distribution network, and determine a base frequency zero sequence current corresponding to each measurement node according to the fault occurrence time and the zero sequence currents of each measurement node; a calculation unit is configured to calculate a similarity matrix according to the base frequency zero sequence currents of the measurement nodes at the head ends of each feeder; A determining unit is configured to determine a fault type of the power distribution network according to the similarity matrix, the fault type being a bus fault or a feeder fault, wherein, in a case where the fault type of the power distribution network is the feeder fault, a fault location is determined according to the fundamental frequency zero sequence current of each measurement node on the fault feeder. The determining unit further comprises a fifth determining module, a sixth determining module, a seventh determining module and an eighth determining module. The fifth determining module is configured to calculate waveform similarity of zero sequence currents of any two adjacent measuring nodes on the fault feeder by cosine similarity. The sixth determining module is configured to compare all the waveform similarities to obtain a minimum similarity. The seventh determining module is configured to determine that the fault location is between two adjacent measuring nodes corresponding to the minimum similarity when the minimum similarity satisfies . is the minimum similarity, is a positioning sensitivity coefficient. The eighth determining module is configured to determine that the fault location is at the end of the fault feeder when the minimum similarity satisfies .

8. A computer-readable storage medium, characterized in that, The computer readable storage medium comprises a stored program, wherein the computer readable storage medium controls a device where the computer readable storage medium is located to execute the fault locating method of the power distribution network according to any one of claims 1 to 6 when the program is executed.

9. An electronic device, comprising: The computer readable storage medium comprises a stored program, wherein the computer readable storage medium controls a device where the computer readable storage medium is located to execute the fault locating method of the power distribution network according to any one of claims 1 to 6 when the program is executed. The computer readable storage medium comprises a stored program, wherein the computer readable storage medium controls a device where the computer readable storage medium is located to execute the fault locating method of the power distribution network according to any one of claims 1 to 6 when the program is executed. The computer readable storage medium comprises a stored program, wherein the computer readable storage medium controls a device where the computer readable storage medium is located to execute the fault locating method of the power distribution network according to any one of claims 1 to 6 when the program is executed.

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