Middle and low voltage power grid fault positioning system and method based on grid topology

Abstract

The invention discloses a middle and low voltage power grid fault positioning system and method based on grid topology, and relates to the technical field of power grid fault positioning, and the method comprises the steps: obtaining historical electrical parameter records of equipment nodes in grid topology modeling, evaluating the node abnormality degree of the equipment nodes, and obtaining abnormal equipment nodes; obtaining coordinates of the abnormal equipment nodes in the grid topology modeling, traversing the equipment nodes in the grid topology modeling, generating candidate abnormal regions, and evaluating region anomalies of the candidate abnormal regions to obtain a target abnormal region; acquiring traveling wave signal data in the target abnormal area, and positioning a fault in the target abnormal area based on the traveling wave signal data to obtain fault position data of the target abnormal area; and acquiring fault position data in the power grid in the current period, planning a fault maintenance path in the power grid, and dispatching maintenance personnel to sequentially maintain the faults in the power grid according to the fault maintenance path.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid fault location, and specifically to a medium and low voltage power grid fault location system and method based on grid topology. Background Art

[0002] The medium and low voltage power grid is an essential part of power supply, mainly responsible for gradually distributing high-voltage electrical energy to the user side. Its application scenarios are very extensive, covering all aspects of social life from cities to rural areas, from factories to families. Therefore, fault location in the medium and low voltage power grid is particularly important. Precise and efficient fault location can effectively ensure the normal operation of the power grid. Currently, common fault location methods all have the following disadvantages: 1. The manual inspection method requires manual inspection of power grid lines section by section, which consumes a long time and requires a large amount of manpower and material resources; 2. The fault indicator method installs fault indicators at key positions in the power grid. However, since fault indicators are usually only used on some equipment, it is difficult to accurately locate the specific location of the fault. Therefore, traditional location methods face problems such as insufficient accuracy and inability to adapt to the dynamic changes of the power grid in the medium and low voltage power grid, and it is difficult to meet the actual needs of quickly and accurately locating faults in the medium and low voltage power grid. Summary of the Invention

[0003] The purpose of the present invention is to provide a medium and low voltage power grid fault location system and method based on grid topology to solve the problems raised in the prior art.

[0004] To achieve the above purpose, the present invention provides the following technical solution: A medium and low voltage power grid fault location method based on grid topology, the method comprising: Step S100: Obtain the grid topology modeling of the power grid in the current cycle, obtain the historical electrical parameter records of the equipment nodes in the grid topology modeling, obtain the electrical parameter data of the equipment nodes in the current cycle, evaluate the node abnormality degree of the equipment nodes, and obtain abnormal equipment nodes; Step S200: Obtain the coordinates of the abnormal equipment nodes in the grid topology modeling, traverse the equipment nodes in the grid topology modeling, generate candidate abnormal regions, and evaluate the regional abnormality of the candidate abnormal regions to obtain target abnormal regions; Step S300: Obtain the traveling wave signal data in the target abnormal region, and based on the traveling wave signal data, locate the fault in the target abnormal region to obtain the fault location data of the target abnormal region; Step S400: Obtain the fault location data in the power grid in the current cycle, plan the fault repair path in the power grid, and dispatch maintenance personnel to repair the faults in the power grid in sequence according to the fault repair path.

[0005] Further, step S100 includes: Step S101: Obtain the historical electrical parameter records of the device node, and obtain the mean values of various electrical parameters of the device node from the historical electrical parameter records; The various electrical parameters in the above steps are mainly the voltage and current in the device node, because the voltage and current are the key parameters of the device node. By obtaining and analyzing the voltage and current of the device node, the device state of the device node can be quickly and accurately judged; Step S102: Obtain each historical electrical parameter record of the device node, obtain the average value and standard deviation of the mean values of various electrical parameters in each historical electrical parameter record of the device node, and obtain each candidate parameter range of the electrical parameters in the device node. Among them, the a-th candidate parameter range B of the electrical parameters in the device node a = [μ - a×σ, μ + a×σ], where μ is the average value of the mean values of the electrical parameters in each historical electrical parameter record, and σ is the standard deviation of the mean values of the electrical parameters in each historical electrical parameter record; Calculate the coverage ratio Q of the a-th candidate parameter range a = D （a,sum） / D sum where D （a,sum） is the total number of historical electrical parameter records of the electrical parameter within the a-th candidate parameter range B a , and D sum is the total number of each historical electrical parameter record; Obtain the coverage ratio threshold Q'. When the coverage ratio Q a ≥ Q', and the coverage ratio Q of the (a - 1)-th candidate parameter range B of the electrical parameter a-1 < Q', determine that the a-th candidate parameter range is the steady state range of the electrical parameter, and obtain the steady state range of various electrical parameters of the device node; a-1 < Q', determine that the a-th candidate parameter range is the steady state range of the electrical parameter, and obtain the steady state range of various electrical parameters of the device node; Step S103: Obtain the electrical parameter data of the device node in the current cycle. Among them, the electrical parameter data includes the data corresponding to various electrical parameters in the device node in the current cycle; Evaluate the node abnormality degree of the device node. The specific process is as follows: When the maximum or minimum value of a certain electrical parameter in the device node is not within the steady state range of a certain electrical parameter, it is determined that the device state of the device node is abnormal in the current cycle, and the device node is recorded as an abnormal device node.

[0006] Furthermore, step S200 includes: Step S201: Obtain the abnormal device nodes in the grid topology modeling within the current period, and obtain several abnormal device nodes that are directly or indirectly connected to the abnormal device nodes. When the time point at which the abnormal device node is determined to have an abnormal device state within the current period is earlier than the time points at which several abnormal device nodes are determined to have an abnormal device state, mark the abnormal device node as a marked abnormal device node, and gather the several abnormal device nodes to obtain an abnormal device node set corresponding to the marked abnormal device node; Step S202: Traverse the device nodes in the grid topology modeling. The specific process of generating candidate abnormal regions is as follows: Obtain the coordinates of the marked abnormal device nodes. Starting from the abnormal device node, according to the different upstream lines to which the abnormal device nodes in the abnormal device node set belong, generate several upstream candidate abnormal paths, and construct several candidate abnormal regions based on the lines and abnormal device nodes covered by each path; Starting from the marked abnormal device node, according to the different downstream lines to which the abnormal device nodes in the abnormal device node set belong, generate several downstream candidate abnormal paths, and construct several candidate abnormal regions based on the lines and abnormal device nodes covered by each path; Step S203: Obtain each candidate abnormal region of the marked abnormal device node, and evaluate the regional abnormality of each candidate abnormal region to obtain the target abnormal region. The specific process is as follows: Calculate the upstream abnormality value P´ of a certain upstream candidate abnormal path among several upstream candidate abnormal paths: P´ = 1 / (Z´ sum + ε), where Z´ sum is the total impedance of the candidate abnormal path corresponding to a certain upstream candidate abnormal path, and ε is a preset smoothing factor; Calculate the downstream abnormality value P of a certain downstream candidate abnormal path among several downstream candidate abnormal paths: P = max{0, (I - I th ) / (F - I th )}, where I and F are the current and line capacity of a certain downstream candidate abnormal path within the current period, and I th = α×F, and α is a preset load rate threshold; Step S204: Perform normalization processing on the downstream abnormality value P and the upstream abnormality value P´ respectively. Calculate the regional abnormality value S´ of the candidate abnormal region corresponding to a certain upstream candidate abnormal path: S´ = β×P´, and calculate the regional abnormality value S of the candidate abnormal region corresponding to a certain downstream candidate abnormal path: S = (1 - β)×P, where β is a preset upstream weight, and β ∈ [0, 1]; Obtain the regional anomaly values of each candidate abnormal area respectively, and select the candidate abnormal area corresponding to the maximum value of the regional anomaly value, which is denoted as the target abnormal area; For the candidate abnormal areas corresponding to the upstream candidate abnormal path and the downstream candidate abnormal path in the above steps, two different methods are used to analyze the degree of regional anomaly. This is because when tracing back from the fault point to the power source in the upstream candidate abnormal path to analyze the influence of system impedance on the fault response, the protection section can be accurately divided, which is suitable for complex network analysis. While in the downstream candidate abnormal path, the direct influence of the fault current is emphasized to meet the requirements of fast protection and simplify the calculation process. This division makes full use of the physical characteristics of current and impedance, taking into account both real-time performance and accuracy.

[0007] Further, step S300 includes: Step S301: Obtain the most upstream abnormal device node in the target abnormal area in the network topology modeling, which is denoted as the starting abnormal device node. Based on the starting abnormal device node, locate the fault in the target abnormal area. The specific location process is as follows: Obtain the most downstream abnormal device node in the target abnormal area in the network topology modeling, and denote it as the ending abnormal device node. Obtain the time point when the marked abnormal device node in the target abnormal area is determined to be in an abnormal device state, and denote it as the characteristic fault time point; Step S302: Obtain the traveling wave signal data in the target abnormal area. The traveling wave signal data includes the traveling wave signals X(t) and X´(t) collected by the traveling wave sensors installed at the starting abnormal device node and the ending abnormal device node at the characteristic fault time point. And use the wavelet transform modulus maximum detection method to process the traveling wave signals X(t) and X´(t), and respectively obtain the arrival times t and t´ of the first wave heads corresponding to the traveling wave signals X(t) and X´(t); Step S303: Calculate the fault distance L between the fault point and the starting abnormal device node in the target abnormal area x =L sum / 2 + v×(t - t´) / 2, where v is the speed of the traveling wave signal in the line corresponding to the target abnormal area, and L sum is the total length of the line corresponding to the target abnormal area; Obtain the geographical coordinates of the fault distance L between the starting abnormal device node in the line corresponding to the target abnormal area x and denote it as the fault point coordinate Y x , obtain the fault point coordinate Y x and gather them to obtain the fault location data of the target abnormal area.

[0008] Further, step S400 includes: Step S401: Obtain the data of each fault location in the power grid during the current period. Respectively obtain different fault point coordinates from the data of each fault location, and plan the fault repair path in the power grid. The specific planning process is as follows: Obtain the maintenance stations of the power grid. Starting from the maintenance stations, use the optimal path algorithm to generate the fault repair path. Among them, the fault repair path includes the order of repairing the faults corresponding to each fault location data; Step S402: Obtain the preset influence distance R. According to the fault repair path, dispatch maintenance personnel to go to the fault point coordinates in turn. Taking the fault point coordinates as the center and the influence distance R as the radius, divide the repair range and check and repair the faults within the repair range.

[0009] In order to better implement the above method, a medium and low voltage power grid fault location system based on grid topology is also proposed. The system includes a node anomaly degree evaluation module, a regional anomaly evaluation module, a fault location module, and a fault repair module; The node anomaly degree evaluation module is used to evaluate the node anomaly degree of the equipment nodes to obtain the abnormal equipment nodes; The regional anomaly evaluation module is used to obtain the coordinates of the abnormal equipment nodes in the grid topology modeling, generate candidate abnormal regions, and evaluate the regional anomaly of the candidate abnormal regions to obtain the target abnormal regions; The fault location module is used to locate the faults in the target abnormal region to obtain the fault location data of the target abnormal region; The fault repair module is used to obtain the fault location data of the power grid during the current period, plan the fault repair path in the power grid, and dispatch maintenance personnel to repair the faults in the power grid in turn according to the fault repair path.

[0010] Furthermore, the node anomaly degree evaluation module includes a steady-state range acquisition unit and a node anomaly degree evaluation unit; The steady-state range acquisition unit is used to obtain each candidate parameter range of the electrical parameters in the equipment nodes, calculate the coverage ratio of each candidate parameter range, and obtain the steady-state range of the electrical parameters in the equipment nodes according to the coverage ratio; The node anomaly degree evaluation unit is used to evaluate the node anomaly degree of the equipment nodes in the current period according to the steady-state range to obtain the abnormal equipment nodes.

[0011] Furthermore, the regional anomaly evaluation module includes a candidate abnormal region acquisition unit and a regional anomaly evaluation unit; The candidate abnormal region acquisition unit is used to obtain the coordinates of the abnormal equipment nodes in the grid topology modeling, traverse the equipment nodes in the grid topology modeling, and generate candidate abnormal regions; The regional abnormality evaluation unit is used to evaluate the regional abnormality of a number of generated candidate abnormal regions to obtain the target abnormal region.

[0012] Further, the fault location module includes a fault distance calculation unit and a fault location unit; The fault distance calculation unit is used to calculate the fault distance between the fault point in the target abnormal region and the starting abnormal device node in the target abnormal region; The fault location unit is used to locate the fault in the target abnormal region according to the fault distance to obtain the fault location data of the target abnormal region.

[0013] Further, the fault repair module includes a fault repair unit; The fault repair unit is used to obtain the fault location data of each grid in the current cycle, plan the fault repair path in the grid, dispatch the repair personnel in the grid, and repair the fault in the grid according to the fault repair path.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention realizes the intelligent location of faults in medium and low voltage power grids. By structuring and modeling the single-line diagram of the power grid, the grid topology model of the power grid is obtained. By obtaining the steady-state range of the electrical parameters in the device nodes, the device nodes in the grid topology model are evaluated for abnormalities, so as to obtain the abnormal device nodes. According to the distribution of the abnormal device nodes in the grid topology model, the target abnormal region where the abnormality occurs is obtained. Then, the traveling wave signal in the target abnormal region is used for fault location, so as to quickly find the location where the power grid fails. According to the different locations, the best fault repair path is planned, which not only quickly locates the faults in the power grid, but also speeds up the fault repair, effectively supporting the rapid isolation and power restoration of power grid faults. Description of the Drawings

[0015] Figure 1 is the method flow chart of the medium and low voltage power grid fault location method based on grid topology of the present invention; Figure 2 is the module schematic diagram of the medium and low voltage power grid fault location system based on grid topology of the present invention. Detailed Embodiments

[0016] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0017] Embodiment: As Figure 1 - Figure 2 shown, the present invention provides a technical solution, a method for fault location of medium and low voltage power grids based on grid topology, the method comprising: Step S100: Obtain the grid topology modeling of the power grid in the current period, obtain the historical electrical parameter records of the equipment nodes in the grid topology modeling, obtain the electrical parameter data of the equipment nodes in the current period, evaluate the node abnormality degree of the equipment nodes, and obtain abnormal equipment nodes; For example, the grid topology modeling is specifically: Based on the single-line diagram of the power grid, the equipment in the power grid is abstracted into equipment nodes, such as the equipment corresponding to the equipment nodes includes substations, circuit breakers, transformers, etc.; Define the connection routes of the equipment nodes as the edges of the graph; Among them, step S100 includes: Step S101: Obtain the historical electrical parameter records of the equipment nodes, and obtain the mean value of each electrical parameter of the equipment nodes from the historical electrical parameter records; For example, each electrical parameter includes the current, voltage, etc. of the equipment node; Step S102: Obtain each historical electrical parameter record of the equipment node, obtain the average value and standard deviation of the mean values of each electrical parameter in each historical electrical parameter record of the equipment node, obtain each candidate parameter range of the electrical parameters in the equipment node, where the a-th candidate parameter range B a = [μ - a×σ, μ + a×σ], where μ is the average value of the mean values of the electrical parameters in each historical electrical parameter record, and σ is the standard deviation of the mean values of the electrical parameters in each historical electrical parameter record; Calculate the coverage ratio Q a = D （a,sum） / D sum , where D （a,sum） is the total number of historical electrical parameter records of the electrical parameters within the a-th candidate parameter range B a , and D sum is the total number of each historical electrical parameter record; Obtain the coverage ratio threshold Q´. When the coverage ratio Q a ≥ Q´, and the coverage ratio Q a-1 of the (a - 1)-th candidate parameter range B a-1 of the electrical parameters < Q´, determine that the a-th candidate parameter range is the steady state range of the electrical parameters, and obtain the steady state range of each electrical parameter of the equipment node; Step S103: Obtain the electrical parameter data of the device node in the current cycle, where the electrical parameter data includes the data corresponding to each electrical parameter in the device node in the current cycle; Evaluate the degree of abnormality of the device node. The specific process is as follows: When the maximum or minimum value of a certain electrical parameter in the device node is not within the steady-state range of a certain electrical parameter, it is determined that the device state of the device node is abnormal in the current cycle, and the device node is recorded as an abnormal device node; Step S200: Obtain the coordinates of the abnormal device node in the network topology model, traverse the device nodes in the network topology model, generate candidate abnormal regions, and evaluate the regional abnormality of the candidate abnormal regions to obtain the target abnormal region; For example, the positions in the horizontal coordinate system and the vertical coordinate system in the space coordinate system where the abnormal device node is located in the network topology model; Among them, step S200 includes: Step S201: Obtain the abnormal device nodes in the network topology model in the current cycle, obtain several abnormal device nodes that are directly or indirectly connected to the abnormal device node. When the time point when the abnormal device node is determined to be in an abnormal device state in the current cycle is earlier than the time points when several abnormal device nodes are determined to be in an abnormal device state, the abnormal device node is recorded as a marked abnormal device node, and several abnormal device nodes are aggregated to obtain the set of abnormal device nodes corresponding to the marked abnormal device node; Step S202: The specific process of traversing the device nodes in the network topology model to generate candidate abnormal regions is as follows: Obtain the coordinates of the marked abnormal device node. Starting from the abnormal device node, according to the different upstream lines to which the abnormal device nodes in the abnormal device node set belong, generate several upstream candidate abnormal paths, and construct several candidate abnormal regions according to the lines and abnormal device nodes covered by each path; Starting from the marked abnormal device node, according to the different downstream lines to which the abnormal device nodes in the abnormal device node set belong, generate several downstream candidate abnormal paths, and construct several candidate abnormal regions according to the lines and abnormal device nodes covered by each path; For example, the upstream line traverses from the marked abnormal device node to the power supply side, where the power supply side is the device node that outputs electric energy in the network topology model; For example, the downstream line traverses from the marked abnormal device node to the load side, where the load side is the device node that consumes electric energy in the network topology model; Step S203: Obtain each candidate abnormal area of the marked abnormal device node, and evaluate the regional abnormality of each candidate abnormal area to obtain the target abnormal area. The specific process is as follows: Calculate the upstream abnormal value P' = 1 / (Z' sum + ε) of a certain upstream candidate abnormal path among several upstream candidate abnormal paths, where Z' sum is the total impedance of the candidate abnormal path corresponding to a certain upstream candidate abnormal path, and ε is a preset smoothing factor; For example, if the total impedance Z' sum of the candidate abnormal path corresponding to a certain upstream candidate abnormal path is 2Ω, and the preset smoothing factor ε is 0.001, calculate the upstream abnormal value P' = 1 / (2 + 0.001) ≈ 0.5; Calculate the downstream abnormal value P = max{0, (I - I th ) / (F - I th )} of a certain downstream candidate abnormal path among several downstream candidate abnormal paths, where I and F are the current and line capacity of a certain downstream candidate abnormal path in the current period respectively, and I th = α×F, and α is a preset load rate threshold; For example, if the current I of a certain downstream candidate abnormal path is 92A, the current F of a certain downstream candidate abnormal path is 100A, and the preset load rate threshold α is 0.9, then I th = 0.9×100A = 90A, calculate the downstream abnormal value P = max{0, (92A - 90A) / (100A - 90A)} = 0.2; Step S204: Normalize the downstream abnormal value P and the upstream abnormal value P' respectively. Calculate the regional abnormal value S' = β×P' of the candidate abnormal area corresponding to a certain upstream candidate abnormal path, and calculate the regional abnormal value S = (1 - β)×P of the candidate abnormal area corresponding to a certain downstream candidate abnormal path, where β is a preset upstream weight and β ∈ [0, 1]; For example, the upstream weight is generally an empirical value obtained according to the distribution of fault points in the historical target abnormal area from historical data; Obtain the regional abnormal values of each candidate abnormal area respectively, and select the candidate abnormal area corresponding to the maximum value of the regional abnormal value, which is denoted as the target abnormal area; Step S300: Obtain the traveling wave signal data in the target abnormal area, and based on the traveling wave signal data, locate the fault in the target abnormal area to obtain the fault location data of the target abnormal area; Among them, Step S300 includes: Step S301: Obtain the most upstream abnormal device node in the target abnormal area that is in the grid topology modeling, denoted as the starting abnormal device node. Based on the starting abnormal device node, locate the fault in the target abnormal area. The specific location process is as follows: Obtain the most downstream abnormal device node in the target abnormal area that is in the grid topology modeling, and denote it as the ending abnormal device node. Obtain the time point when the marked abnormal device node in the target abnormal area is determined to have an abnormal device state, and denote it as the characteristic fault time point; Step S302: Obtain the traveling wave signal data in the target abnormal area. The traveling wave signal data includes the traveling wave signals X(t) and X'(t) collected by the traveling wave sensors installed at the starting abnormal device node and the ending abnormal device node at the characteristic fault time point. And use the wavelet transform modulus maximum detection method to process the traveling wave signals X(t) and X'(t), and respectively obtain the arrival times t and t' of the first wave heads corresponding to the traveling wave signals X(t) and X'(t); For example, the processing methods of the traveling wave signals X(t) and X'(t) are the same. Therefore, taking the processing of the traveling wave signal X(t) by the wavelet transform modulus maximum detection method to obtain the arrival time t of the first wave head as an example for specific description: Perform multi-scale wavelet transform on the traveling wave signal X(t) to generate a wavelet coefficient matrix W(a,b): , where a is the scale factor for controlling the frequency resolution; b is the translation factor for controlling the time window position; Ψ*(t) is the complex conjugate of the wavelet basis function Ψ(t); Ψ(t) is commonly Daubechies 4 (db4); At the minimum a, find the modulus maximum points of the wavelet coefficients, that is: , , where W' is a preset traveling wave threshold; Obtain the arrival time t of the traveling wave head corresponding to the first modulus maximum point; Step S303: Calculate the fault distance L between the fault point in the target abnormal area and the starting abnormal device node x =L sum / 2 + v×(t - t') / 2, where v is the speed of the traveling wave signal in the line corresponding to the target abnormal area, and L sum is the total length of the line corresponding to the target abnormal area; Obtain the geographical coordinates of the fault distance L between the starting abnormal device node in the line corresponding to the target abnormal area x and denote it as the fault point coordinate Yx , obtain the fault point coordinate Y x Conduct aggregation to obtain the fault location data of the target abnormal area; Step S400: Obtain the fault location data in the power grid during the current period, plan the fault repair path in the power grid, and dispatch maintenance personnel to repair the faults in the power grid in sequence according to the fault repair path; Among them, step S400 includes: Step S401: Obtain the fault location data of each part of the power grid during the current period, respectively obtain different fault point coordinates from each fault location data, and plan the fault repair path in the power grid. The specific planning process is as follows: Obtain the maintenance stations of the power grid, start from the maintenance stations, and use the optimal path algorithm to generate the fault repair path. Among them, the fault repair path includes the order of repairing the faults corresponding to each fault location data; For example, the optimal path algorithms include the Dijkstra algorithm, A * algorithm, and the Bellman-Ford algorithm; For example, the Dijkstra algorithm is a greedy strategy. Each time, select the unvisited node closest to the starting point currently, update the shortest path of its neighbors, and conduct aggregation to obtain the fault repair path of the power grid during the current period; Step S402: Obtain the preset influence distance R. According to the fault repair path, dispatch maintenance personnel to go to the fault point coordinates in sequence. Taking the fault point coordinates as the center and the influence distance R as the radius, divide the maintenance range and check and repair the faults within the maintenance range; In order to better implement the above method, a medium and low voltage power grid fault location system based on grid topology is also proposed. The system includes a node abnormality degree evaluation module, a regional abnormality evaluation module, a fault location module, and a fault repair module; The node abnormality degree evaluation module is used to evaluate the node abnormality degree of the equipment nodes to obtain abnormal equipment nodes; The regional abnormality evaluation module is used to obtain the coordinates of the abnormal equipment nodes in the grid topology modeling, generate candidate abnormal areas, and evaluate the regional abnormality of the candidate abnormal areas to obtain the target abnormal areas; The fault location module is used to locate the faults in the target abnormal area to obtain the fault location data of the target abnormal area; The fault repair module is used to obtain the fault location data of the power grid during the current period, plan the fault repair path in the power grid, and dispatch maintenance personnel to repair the faults in the power grid in sequence according to the fault repair path; Among them, the node abnormality degree evaluation module includes a steady-state range acquisition unit and a node abnormality degree evaluation unit; A steady-state range acquisition unit is configured to acquire each candidate parameter range of the electrical parameters in the device node, calculate the coverage ratio of each candidate parameter range, and obtain the steady-state range of the electrical parameters in the device node according to the coverage ratio. A node abnormality degree evaluation unit is configured to evaluate the node abnormality degree of the device node in the current cycle according to the steady-state range, and obtain the abnormal device node. Among them, the regional abnormality evaluation module includes a candidate abnormal area acquisition unit and a regional abnormality evaluation unit. The candidate abnormal area acquisition unit is configured to acquire the coordinates of the abnormal device node in the grid topology modeling, and traverse the device nodes in the grid topology modeling to generate candidate abnormal areas. The regional abnormality evaluation unit is configured to evaluate the regional abnormality of the generated several candidate abnormal areas to obtain the target abnormal area. Among them, the fault location module includes a fault distance calculation unit and a fault location unit. The fault distance calculation unit is configured to calculate the fault distance between the fault point in the target abnormal area and the starting abnormal device node in the target abnormal area. The fault location unit is configured to locate the fault in the target abnormal area according to the fault distance to obtain the fault location data of the target abnormal area. Among them, the fault repair module includes a fault repair unit. The fault repair unit is configured to acquire the fault location data of each grid in the current cycle, plan the fault repair path in the grid, dispatch the repair personnel in the grid, and repair the fault in the grid according to the fault repair path.

[0018] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed claims.

Claims

1. A method for fault location of medium and low voltage power grids based on grid topology, characterized in that The method includes: Step S100: Obtain the grid topology modeling in the current cycle, obtain the historical electrical parameter records of the equipment nodes in the grid topology modeling, obtain the electrical parameter data of the equipment nodes in the current cycle, evaluate the node abnormality degree of the equipment nodes, and obtain abnormal equipment nodes; Step S200: Obtain the coordinates of the abnormal equipment nodes in the grid topology modeling, traverse the equipment nodes in the grid topology modeling, generate candidate abnormal areas, and evaluate the area abnormality of the candidate abnormal areas to obtain target abnormal areas; Step S300: Obtain the traveling wave signal data in the target abnormal area, and based on the traveling wave signal data, locate the faults in the target abnormal area to obtain the fault location data of the target abnormal area; Step S400: Obtain the fault location data in the grid in the current cycle, plan the fault repair path in the grid, and dispatch maintenance personnel to repair the faults in the grid in sequence according to the fault repair path.

2. The method for fault location of medium and low voltage power grids based on grid topology according to claim 1, wherein, The step S100 includes: Step S101: Obtain the historical electrical parameter records of the equipment nodes, and obtain the mean value of each electrical parameter of the equipment nodes from the historical electrical parameter records; Step S102: Obtain each historical electrical parameter record of the device node, obtain the average value and standard deviation of the electrical parameters in each historical electrical parameter record of the device node, and obtain each candidate parameter range of the electrical parameters in the device node, where the a-th candidate parameter range B of the electrical parameters of the device node a =[μ - a×σ, μ + a×σ], where μ is the average value of the mean values of the electrical parameters in each historical electrical parameter record, and σ is the standard deviation of the mean values of the electrical parameters in each historical electrical parameter record; Calculate the coverage ratio Q of the a-th parameter range to be selected a =D （a,sum） / D sum , where D （a,sum） is the total number of historical electrical parameter records of the electrical parameter within the a-th parameter range to be selected B a , and D sum is the total number of all historical electrical parameter records; Obtain the coverage ratio threshold Q´. When the coverage ratio Q a ≥Q´, and the coverage ratio Q of the (a - 1)-th candidate parameter range B a-1 of the electrical parameter a-1 <Q´, determine that the a-th candidate parameter range is the steady-state range of the electrical parameter, and obtain the steady-state ranges of the various electrical parameters of the device node; Step S103: Obtain the electrical parameter data of the equipment nodes in the current cycle, where the electrical parameter data includes the data corresponding to each electrical parameter in the equipment nodes in the current cycle; The process of evaluating the node abnormality degree of the equipment nodes is as follows: When the maximum or minimum value of a certain electrical parameter in the equipment node is not within the steady state range of the certain electrical parameter, it is determined that the equipment state of the equipment node is abnormal in the current cycle, and the equipment node is recorded as an abnormal equipment node.

3. The method for fault location of medium and low voltage power grids based on grid topology according to claim 2, wherein, The step S200 includes: Step S201: Obtain the abnormal equipment nodes in the grid topology modeling in the current cycle, obtain several abnormal equipment nodes directly or indirectly connected to the abnormal equipment nodes. When the time point when the abnormal equipment node is determined to be in an abnormal equipment state in the current cycle is earlier than the time point when the several abnormal equipment nodes are determined to be in an abnormal equipment state, the abnormal equipment node is recorded as a marked abnormal equipment node, and the several abnormal equipment nodes are aggregated to obtain the abnormal equipment node set corresponding to the marked abnormal equipment node; Step S202: The process of traversing the equipment nodes in the grid topology modeling to generate candidate abnormal areas is as follows: Obtain the coordinates of the marked abnormal equipment nodes, take the abnormal equipment node as the starting point, generate several upstream candidate abnormal paths according to the different upstream lines to which the abnormal equipment nodes in the abnormal equipment node set belong, and construct several candidate abnormal areas according to the lines and abnormal equipment nodes covered by each path; Starting from the marked abnormal device node, according to the different downstream lines to which the abnormal device nodes in the abnormal device node set belong, several downstream candidate abnormal paths are generated, and several candidate abnormal regions are constructed according to the lines and abnormal device nodes covered by each path; Step S203: Obtain each candidate abnormal region of the marked abnormal device node, and evaluate the regional abnormality of each candidate abnormal region to obtain the target abnormal region. The specific process is as follows: Calculate the upstream anomaly value P´ = 1 / (Z´ sum + ε) for a certain upstream candidate anomaly path among the several upstream candidate anomaly paths, where Z´ sum is the total impedance of the candidate anomaly path corresponding to the certain upstream candidate anomaly path, and ε is a preset smoothing factor; Calculate the downstream anomaly value P of a certain downstream candidate anomaly path among the several downstream candidate anomaly paths as P = max{0, (I - I th ) / (F - I th )}, where I and F are the current period's current and line capacity of the certain downstream candidate anomaly path respectively, and I th = α × F, with α being the preset load rate threshold; Normalize the downstream abnormal value P and the upstream abnormal value P' respectively. Calculate the regional abnormal value S' = β × P' of the candidate abnormal region corresponding to a certain upstream candidate abnormal path, and calculate the regional abnormal value S = (1 - β) × P of the candidate abnormal region corresponding to a certain downstream candidate abnormal path, where β is a preset upstream weight, and β ∈ [0, 1]; Obtain the regional abnormal values of each candidate abnormal region respectively, and select the candidate abnormal region corresponding to the maximum value of the regional abnormal value, which is denoted as the target abnormal region.

4. The method for fault location of medium and low voltage power grids based on grid topology according to claim 3, characterized in that, The step S300 includes: Step S301: Obtain the most upstream abnormal device node in the target abnormal region in the network topology modeling, which is denoted as the starting abnormal device node, and based on the starting abnormal device node, locate the fault in the target abnormal region. The specific location process is as follows: Obtain the most downstream abnormal device node in the target abnormal region in the network topology modeling, and denote it as the ending abnormal device node. Obtain the time point when the marked abnormal device node in the target abnormal region is determined to be in an abnormal device state, and denote it as the characteristic fault time point; Step S302: Obtain the traveling wave signal data in the target abnormal region. The traveling wave signal data includes the traveling wave signal X(t) and the traveling wave signal X'(t) collected by the traveling wave sensors installed at the starting abnormal device node and the ending abnormal device node at the characteristic fault time point, and use the wavelet transform modulus maximum detection method to process the traveling wave signal X(t) and the traveling wave signal X'(t), and respectively obtain the arrival times t and t' of the first wave heads corresponding to the traveling wave signal X(t) and the traveling wave signal X'(t); Step S303: Calculate the fault distance L between the fault point in the target abnormal area and the starting abnormal device node x =L sum / 2 + v×(t - t´) / 2, where v is the speed of the traveling wave signal in the line corresponding to the target abnormal area, and L sum is the total length of the line corresponding to the target abnormal area; Obtain the fault distance L between the starting abnormal device node in the line corresponding to the target abnormal area x of the geographical coordinates, and denote it as the fault point coordinate Y x , obtain the fault point coordinate Y x for aggregation to obtain the fault location data of the target abnormal area.

5. The method for fault location of medium and low voltage power grids based on grid topology according to claim 4, wherein The step S400 includes: Step S401: Obtain the fault location data of the power grid in the current cycle, respectively obtain different fault point coordinates from the fault location data, and plan the fault repair path in the power grid. The specific planning process is as follows: Obtain the repair stations of the power grid, take the repair stations as the starting point, and use the optimal path algorithm to generate the fault repair path, where the fault repair path includes the order of repairing the faults corresponding to each fault location data; Step S402: Obtain the preset influence distance R, and according to the fault repair path, dispatch repair personnel to go to the fault point coordinates in turn. Taking the fault point coordinates as the center and the influence distance R as the radius, divide the repair range and check and repair the faults within the repair range.

6. A medium- and low-voltage power grid fault location system based on grid topology, which is used to execute the medium- and low-voltage power grid fault location method based on grid topology described in any one of claims 1-5, characterized in that, The system includes a node anomaly degree evaluation module, a regional anomaly evaluation module, a fault location module, and a fault repair module; The node anomaly degree evaluation module is used to evaluate the node anomaly degree of the device nodes to obtain abnormal device nodes; The regional anomaly evaluation module is used to obtain the coordinates of the abnormal device nodes in the grid topology modeling, generate candidate abnormal regions, and evaluate the regional anomaly of the candidate abnormal regions to obtain target abnormal regions; The fault location module is used to locate the faults in the target abnormal regions to obtain the fault location data of the target abnormal regions; The fault repair module is used to obtain the fault location data of the power grid in the current cycle, plan the fault repair paths in the power grid, and dispatch maintenance personnel to repair the faults in the power grid in sequence according to the fault repair paths.

7. The fault location system for medium and low voltage power grids based on grid topology according to claim 6, characterized in that, The node anomaly degree evaluation module includes a steady-state range acquisition unit and a node anomaly degree evaluation unit; The steady-state range acquisition unit is used to obtain each candidate parameter range of the electrical parameters in the device nodes, calculate the coverage ratio of each candidate parameter range, and obtain the steady-state range of the electrical parameters in the device nodes according to the coverage ratio; The node anomaly degree evaluation unit is used to evaluate the node anomaly degree of the device nodes in the current cycle according to the steady-state range to obtain abnormal device nodes.

8. The fault location system for medium and low voltage power grids based on grid topology according to claim 6, wherein The regional anomaly evaluation module includes a candidate abnormal region acquisition unit and a regional anomaly evaluation unit; The candidate abnormal region acquisition unit is used to obtain the coordinates of the abnormal device nodes in the grid topology modeling, traverse the device nodes in the grid topology modeling, and generate candidate abnormal regions; The regional anomaly evaluation unit is used to evaluate the regional anomaly of several generated candidate abnormal regions to obtain target abnormal regions.

9. The fault location system for medium and low voltage power grids based on grid topology according to claim 6, wherein The fault location module includes a fault distance calculation unit and a fault location unit; The fault distance calculation unit is used to calculate the fault distance between the fault point in the target abnormal region and the starting abnormal device node in the target abnormal region; The fault location unit is used to locate the faults in the target abnormal region according to the fault distance to obtain the fault location data of the target abnormal region.

10. The medium and low voltage power grid fault location system based on grid topology according to claim 6, wherein The fault repair module includes a fault repair unit; The fault repair unit is used to obtain the fault location data of each part of the power grid in the current cycle, plan the fault repair paths in the power grid, and dispatch the maintenance personnel in the power grid to repair the faults in the power grid according to the fault repair paths.

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