Operation fault monitoring method, system and device applied to smart grid

Abstract

The present application relates to the technical field of power grid fault monitoring, and specifically to an operation fault monitoring method, system and equipment applied to a smart grid, the method comprising: obtaining the voltage of each node in the power grid at each moment, and each distributed power source connected to the node, wherein the node connected to the distributed power source is recorded as an access node, and the remaining nodes are recorded as unaccessed nodes; determining the voltage influence index of each distributed power source at each moment; determining the deviation credibility of each node at each moment; determining the degree of influence of each node at each moment; determining the correction factor of each node at each moment; determining the corrected correlation coefficient at each moment, determining the time when a single-phase grounding fault occurs; determining the corrected correlation coefficient between each node and any other node, and locating the single-phase grounding fault that occurs. The present application can avoid misjudgment of the location of a single-phase grounding fault, making the time when a single-phase grounding fault occurs and the fault location more accurate.

Description

Technical Field

[0001] The present application relates to the technical field of power grid fault monitoring, and in particular to an operation fault monitoring method, system and device applied to a smart grid. Background Art

[0002] Smart grid is a power system that uses modern communication technology, automation technology, information technology and computer technology to monitor, analyze and manage the production, transmission, distribution and consumption of electricity in real time. The distribution network is an important component of it, which is responsible for efficiently and reliably distributing electric energy from the transmission network to end users. Real-time monitoring of operating faults in the distribution network can quickly discover and locate faults, reduce power outage time, and improve the continuity and reliability of power supply.

[0003] Most of the power supply modes of my country's power system are three-phase AC, and most of the grounding modes are ungrounded neutral points. Therefore, the most common operating faults are single-phase grounding faults. The traditional fault location method is to locate the fault based on the correlation between the steady-state signals of different lines after a single-phase grounding fault occurs. However, with the development of smart grids, distributed generation (DG) is continuously connected to the grid, which will affect the electrical signals of the connected lines and change the correlation between different lines, resulting in inaccurate fault location. Summary of the invention

[0004] In order to solve the above technical problems, an operation fault monitoring method, system and device applied to a smart grid are provided to solve the existing problems.

[0005] The solution to the technical problem of the present application is to provide an operation fault monitoring method, system and device for smart grid, including the following steps:

[0006] In a first aspect, an embodiment of the present application provides an operation fault monitoring method applied to a smart grid, the method comprising the following steps:

[0007] Obtain the voltage of each node in the power grid at each time, and each distributed power source connected to the node, where the node connected to the distributed power source is recorded as the connected node, and the remaining nodes are recorded as the unconnected nodes;

[0008] Determine the voltage impact index of each distributed power source at each moment according to the voltage deviation of the access node and the non-access node connected to each distributed power source at each moment, and the difference in voltage deviation between the access node and the non-access node;

[0009] Determine the deviation credibility of each node at each moment according to the voltage fluctuation range of each node at each moment and in the previous moment, and the distribution difference of the fluctuation range of all nodes at each moment; analyze the distance relationship between each node and any distributed power source, and determine the degree of influence of each node at each moment by combining the deviation credibility and the voltage influence index;

[0010] Based on the degree of influence, a correction factor of each node at each moment is determined; based on the correction factor, the correlation degree of the voltages of all nodes at adjacent moments is corrected to determine the corrected correlation coefficient at each moment, and the time when the single-phase grounding fault occurs is determined based on the corrected correlation coefficient at each moment;

[0011] Based on the correction factor, the correlation degree of the voltage between each node and any other node at all times after the ground fault occurs is corrected, the corrected correlation coefficient between each node and any other node is determined, and the single-phase ground fault is located.

[0012] Preferably, the determining of the voltage impact index of each distributed power source at each moment includes:

[0013] Calculate the mean value of the voltages of all nodes at each moment, and record the difference between the voltage of the access node connected to each distributed power source at each moment and the mean value as a first difference;

[0014] The sum of the differences between the voltages of all non-connected nodes and the mean value at each moment is calculated, and a normalized result of the ratio of the first difference to the sum value is used as the voltage influence index of each distributed power source at each moment.

[0015] Preferably, determining the deviation credibility of each node at each moment includes:

[0016] The voltage of each node at each moment and at multiple moments before it is used to form a local voltage vector of each node at each moment;

[0017] Calculating the range of the local voltage vector; forming a two-dimensional array with the range at each moment and at each node;

[0018] Performing curve fitting on the two-dimensional array of all nodes at each moment to obtain a fitting curve at each moment;

[0019] The distance between the two-dimensional array of each node at each moment and the fitting curve at the corresponding moment is calculated, and the ratio between the voltage of each node at each moment and the distance is used as the deviation credibility of each node at each moment.

[0020] Preferably, determining the degree of influence of each node at each moment includes:

[0021] Counting the number of nodes between each node and any distributed power source, and recording the ratio between the voltage influence index of each distributed power source at each moment and the number as a first ratio;

[0022] The cumulative sum of the first ratios of each node to all distributed power sources at each moment is calculated, and a normalized result of the product of the cumulative sum and the deviation credibility is used as the degree of influence of each node at each moment.

[0023] Preferably, the correction factor of each node at each moment is determined by the following calculation formula: ,in, For the Moment The correction factor for each node is For the Moment The degree of impact on each node.

[0024] Preferably, the correlation coefficient after correction at each moment is determined by calculating: ,in, For the The correlation coefficient after correction at each moment is For the The correlation coefficient between the voltage of all nodes at a moment and the voltage of all nodes at the previous moment, For the Moment The correction factor for each node is is the number of all nodes, is the normalization function.

[0025] Preferably, the determining of the time when the single-phase grounding fault occurs includes:

[0026] The normalized result of the sum of the corrected correlation coefficients at each moment and the previous multiple moments is calculated. If the normalized result at each moment is less than a preset first threshold, a single-phase grounding fault occurs at the corresponding moment; otherwise, no single-phase grounding fault occurs.

[0027] Preferably, the determining of the corrected correlation coefficient between each node and any other node to locate the single-phase grounding fault comprises:

[0028] The voltage of each node at multiple times after the fault occurs is selected to form a fault response vector of each node;

[0029] Calculate the mean of the correction factor at the corresponding time in the fault response vector between each node and any other node, and normalize the sum of the mean values ​​at all times as the correction coefficient between each node and any other node;

[0030] Calculate the product of the correlation coefficient of the fault response vector between each node and any other node and the correction coefficient as the corrected correlation coefficient between each node and any other node;

[0031] The normalized result of the sum of the corrected correlation coefficients between each node and all other nodes is calculated. If the normalized result of each node is less than the preset second threshold, a single-phase grounding fault occurs at the corresponding node; otherwise, a single-phase grounding fault does not occur.

[0032] In a second aspect, an embodiment of the present application further provides an operation fault monitoring system applied to a smart grid, the system comprising:

[0033] The power grid data acquisition module obtains the voltage of each node in the power grid at each time, as well as each distributed power source connected to the node. The nodes connected to the distributed power source are recorded as connected nodes, and the remaining nodes are recorded as unconnected nodes.

[0034] The power supply impact correction module determines the voltage impact index of each distributed power supply at each moment according to the voltage deviation of the access node and the non-access node connected to each distributed power supply at each moment, and the difference in voltage deviation between the access node and the non-access node; determines the deviation credibility of each node at each moment according to the voltage fluctuation range of each node at each moment and the previous moment, and the distribution difference of the fluctuation range of all nodes at each moment; analyzes the distance relationship between each node and any distributed power supply, and determines the degree of influence of each node at each moment in combination with the deviation credibility and the voltage impact index; and determines the correction factor of each node at each moment based on the degree of influence;

[0035] The grounding fault locating module corrects the correlation degree of the voltages of all nodes at adjacent moments based on the correction factor, determines the corrected correlation coefficient at each moment, and determines the time when the single-phase grounding fault occurs based on the corrected correlation coefficient at each moment; based on the correction factor, corrects the correlation degree of the voltages of each node and any other node at all moments after the grounding fault occurs, determines the corrected correlation coefficient between each node and any other node, and locates the single-phase grounding fault that occurs.

[0036] In a third aspect, an embodiment of the present application further provides an operation fault monitoring device applied to a smart grid, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the computer program, the steps of any one of the above-mentioned operation fault monitoring methods applied to a smart grid are implemented.

[0037] This application has at least the following beneficial effects:

[0038] The present application determines the voltage impact index of each distributed power source at each moment according to the voltage deviation of the access node and the non-access node connected to each distributed power source at each moment, and the difference in voltage deviation between the access node and the non-access node. The beneficial effect is that the difference in voltage between each access node connected to the distributed power source and the non-access node not connected to the distributed power source is taken into account, thereby reflecting the impact of the access of the distributed power source on the distribution network; the deviation credibility of each node at each moment is determined according to the voltage fluctuation range of each node at each moment and the previous moment, and the distribution difference of the fluctuation range of all nodes at each moment; the distance relationship between each node and any distributed power source is analyzed, and the degree of influence of each node at each moment is determined in combination with the deviation credibility and the voltage impact index; based on the degree of influence, the correction factor of each node at each moment is determined, and the beneficial effect is that the deviation of the fluctuation range of the voltage change of each node over a period of time is taken into account , and analyze the distance between each node and the distributed power source to reflect the degree of influence of each node on the access of the distributed power source, and then determine the correction factor of each node; based on the correction factor, correct the correlation degree of the voltage of all nodes at adjacent moments, determine the corrected correlation coefficient at each moment, and determine the time when the single-phase grounding fault occurs based on the corrected correlation coefficient at each moment; based on the correction factor, correct the correlation degree of the voltage between each node and any other node at all moments after the grounding fault occurs, determine the corrected correlation coefficient between each node and any other node, and locate the single-phase grounding fault that occurs. The beneficial effect is that the influence of each node is taken into account, so as to correct the correlation coefficient, reduce the voltage fluctuations of different nodes caused by the access of distributed power sources, reduce the calculation error of the correlation coefficient, avoid the misjudgment of the single-phase grounding fault location, and make the time when the single-phase grounding fault occurs and the fault location more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The operation fault monitoring method applied to the smart grid of the present application is further described in detail below with reference to the accompanying drawings.

[0040] Figure 1 A flowchart of the steps of the operation fault monitoring method applied to the smart grid provided in the embodiment of the present application;

[0041] Figure 2 A schematic diagram of a power grid node distribution network topology provided in an embodiment of the present application;

[0042] Figure 3 A flowchart of the steps of a method for obtaining the voltage influence index of each distributed power source at each moment provided in an embodiment of the present application;

[0043] Figure 4A schematic diagram of the fitting curve at each moment provided in the embodiment of the present application;

[0044] Figure 5 A flowchart of the steps of a method for obtaining the degree of influence of each node at each moment provided in an embodiment of the present application;

[0045] Figure 6 A schematic diagram of the time when a ground fault occurs provided in an embodiment of the present application;

[0046] Figure 7 A schematic diagram of a ground fault occurrence node provided in an embodiment of the present application;

[0047] Figure 8 A block diagram of an operation fault monitoring system for a smart grid provided in an embodiment of the present application. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solution and advantages of this application more clear, the following is a further detailed description of the operation fault monitoring method, system and device for smart grid proposed in this application in combination with the accompanying drawings and implementation examples. It should be understood that the specific embodiments described here are only used to explain this application and are not used to limit this application.

[0049] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0050] See also Figure 1 , which shows a flowchart of a method for monitoring operation faults applied to a smart grid provided by an embodiment of the present application, the method comprising the following steps:

[0051] Step 1: Obtain the voltage of each node in the power grid at each time, and each distributed power source connected to the node, wherein the node connected to the distributed power source is recorded as the connected node, and the remaining nodes are recorded as the unconnected nodes.

[0052] The distribution network is at the end of the power supply system, with a complex structure. Single-phase grounding faults often occur. If a single-phase grounding fault occurs in the distribution network, if the fault is not isolated in time, the continuous line overvoltage may cause insulation breakdown, and then cause a phase-to-phase short circuit fault, expanding the fault range. Therefore, it is necessary to select and locate the location where the grounding fault occurs.

[0053] Figure 2A schematic diagram of the power grid node distribution network topology provided for this embodiment, wherein the node numbers of all nodes from 1 to 15 are represented by busbars, i.e., buses for electric energy transmission, which can connect generators, transformers, and power lines. The lines between adjacent nodes represent power lines, i.e., branches connecting end users. DG is a distributed power source, such as solar photovoltaic, wind power, and fuel cells.

[0054] Since the transmission line usually uses three-phase alternating current, that is, each node contains the voltage of a three-phase circuit, a synchronous phasor measurement unit (PMU) is installed on each node to collect the three-phase voltage of each node. The PUM collection frequency is set to f to obtain the three-phase voltage of each node at each moment.

[0055] Preferably, in this embodiment, the PUM acquisition frequency is set to 10 kHz. As other implementation modes, the implementer can set it by himself. Among them, the synchronized phasor measurement unit is a well-known technology and will not be described in detail here.

[0056] Secondly, when analyzing the voltage later, there is a complex electromagnetic coupling relationship between the three-phase alternating current. In order to avoid the complexity of calculation, the three-phase voltage of each node is transformed, specifically:

[0057] The synchronous phasor measurement unit is used to obtain the phase angle of each node, that is, the angle between the three-phase circuits. The Clarke transformation is used to transform the three-phase voltage of each node at each moment to obtain , Two orthogonal components and 0 component; The quadrature components are taken as the voltage at each node for subsequent analysis.

[0058] It should be noted that Clarke transformation is a well-known technology and will not be described in detail here. Assume that the three-phase circuits are ABC. Next, The quadrature components contain voltage information for all three phases, so The values ​​of the quadrature components are taken as the voltage at each node.

[0059] The collected data is normalized to obtain the voltage of each node at each moment, where the nodes connected to the distributed power source are recorded as connected nodes, and the remaining nodes are recorded as unconnected nodes.

[0060] Preferably, in this embodiment, the maximum and minimum normalization method is used for normalization processing, wherein the maximum and minimum normalization method is a well-known technology and will not be described in detail here. As other implementation methods, the implementer can adopt other methods of the prior art, such as the Z-score normalization method, etc. This embodiment does not impose any special restrictions on this.

[0061] It should be noted that in Figure 2 In the example, nodes 7, 11 and 14 are access nodes, and the other nodes are non-access nodes.

[0062] At this point, the voltage at each node in the distribution network at each moment is obtained.

[0063] Step 2: Determine the voltage impact index of each distributed power source at each moment according to the voltage deviation of the access node and the non-access node connected to each distributed power source at each moment, and the difference in voltage deviation between the access node and the non-access node.

[0064] Distributed generation (DG) is a small-scale power generation method close to the power consumption location, including various types such as solar photovoltaic, wind power generation and fuel cells. Connecting DG to the bus node can reduce the loss on the line, thereby improving the voltage level of the access node and its nearby nodes. Since the DG power supply may be unstable, it will cause voltage fluctuations at the access node and its nearby nodes.

[0065] The traditional single-phase grounding fault location method is mainly based on the correlation of voltage signals between different lines. Since the sampling frequency of PUM is very high, the voltage signals of nodes between adjacent sampling moments are highly correlated. If the correlation of voltage signals decreases, it is determined that a single-phase grounding fault has occurred at the corresponding node. The moment with the lowest correlation is the moment when the fault occurs.

[0066] However, the nodes connected to the DG will be affected by the DG access, resulting in a significantly greater voltage change at the access node than at the nearby nodes. At this time, the traditional correlation-based method is used to locate the single-phase grounding fault, which is very easy to misjudge the access node as a single-phase grounding fault when the DG power supply fluctuates. Therefore, it is necessary to analyze the degree of influence of DG on each access node, determine the correction factor, and correct the influence of DG on each node.

[0067] First, since the power generation and stability of each distributed generation (DG) are different, the degree of influence of each DG on the distribution network nodes is also different. By analyzing the relationship between the voltage fluctuation intensity between each connected node and the unconnected node, the voltage impact index of each distributed generation at each moment is determined, which is:

[0068] Calculate the mean value of the voltages of all nodes at each moment, and record the difference between the voltage of the access node connected to each distributed power source at each moment and the mean value as a first difference;

[0069] Preferably, in this embodiment, the absolute value of the difference between the voltage of the access node to which each distributed power source is connected at each moment and the mean value is recorded as the first difference.

[0070] Calculating the sum of the differences between the voltages of all non-connected nodes and the mean value at each moment; taking the normalized result of the ratio of the first difference to the sum as the voltage influence index of each distributed power source at each moment;

[0071] Preferably, in this embodiment, ,in, For the Moment The voltage impact index of a distributed generation (DG), For the Moment The voltage of the access node to which the DG is connected, For the The mean voltage of all nodes at a given moment is For the Moment The voltage of the unconnected node, is the number of all unconnected nodes, is a normalization function. In this embodiment, a sigmoid activation function is used for normalization. The sigmoid activation function is a well-known technology and will not be described in detail here. As other implementation methods, the implementer may use other methods of the prior art, such as the tanh function, etc. This embodiment does not impose any special restrictions on this. Secondly, The first difference.

[0072] It should be noted that the voltage fluctuation intensity is reflected by the voltage difference between the access node and the non-access node and all nodes. Since the non-access node is less affected by DG, the ratio of the voltage difference between the access node and the non-access node is calculated to reflect the degree of influence of the access node by DG. The larger the voltage influence index, the greater the voltage fluctuation intensity of the access node at each moment, that is, the greater the influence of the DG connected to the corresponding access node on the distribution network, and the greater the possibility of misjudgment when using voltage correlation to identify faults.

[0073] Further, the step flow chart of the method for obtaining the voltage influence index of each distributed power source at each moment provided in the embodiment of the present application is as follows: Figure 3 shown.

[0074] At this point, the voltage impact index of each distributed power source at each moment is obtained.

[0075] Step 3: Determine the deviation credibility of each node at each moment according to the voltage fluctuation range of each node at each moment and at the previous moment, and the distribution difference of the fluctuation range of all nodes at each moment; analyze the distance relationship between each node and any distributed power source, and determine the degree of influence of each node at each moment by combining the deviation credibility and the voltage influence index.

[0076] Furthermore, the above analysis reflects the degree of influence of different DGs on the distribution network at each moment, and it is impossible to measure the influence of DG access on each node. Therefore, the distribution distance of each node relative to the DG is analyzed to determine the influence coefficient of each node.

[0077] First, the voltage range of all nodes at the same time is used to determine the deviation of the voltage range. Further, the deviation credibility of each node affected by DG is reflected, which is:

[0078] The voltage of each node at each moment and at multiple moments before it is used to form a local voltage vector of each node at each moment;

[0079] Preferably, in this embodiment, the voltage at each moment and the voltage at the 35 moments before it are selected as other implementation modes, and the implementer can set them according to the actual situation.

[0080] Calculating the range of the local voltage vector; forming a two-dimensional array with the range at each moment and at each node;

[0081] Performing curve fitting on the two-dimensional array of all nodes at each moment to obtain a fitting curve at each moment;

[0082] Preferably, in this embodiment, the least square method is used for curve fitting, wherein the least square method is a well-known technology and will not be described in detail here.

[0083] Further, the schematic diagram of the fitting curve at each moment provided in the embodiment of the present application is as follows: Figure 4 As shown, the horizontal axis is the node number and the vertical axis is the range.

[0084] Calculating the distance between the two-dimensional array of each node at each moment and the fitting curve at the corresponding moment, and taking the ratio between the voltage of each node at each moment and the distance as the deviation credibility of each node at each moment;

[0085] Preferably, in this embodiment, the Euclidean distance between the two-dimensional array of each node at each moment and the fitting curve at the corresponding moment is calculated; it should be noted that when calculating the ratio, in order to avoid the denominator being 0, a preset value greater than 0 is added to the denominator, and the value is 0.01.

[0086] It should be noted that the distance reflects the degree of voltage deviation. The larger the distance, the larger the voltage deviation of the corresponding node, that is, the smaller the deviation credibility of the corresponding node; the larger the deviation credibility, the more reliable the analysis of the degree of DG influence on the corresponding node. It should be noted that the deviation credibility includes the magnitude of the influence, that is, the larger the deviation credibility, the greater the influence, because the greater the voltage range between two equally reliable nodes, the greater the influence.

[0087] Furthermore, the degree of influence of each node is also related to the distance from the DG. The farther the node is from the DG, the less it is affected by the DG. At the same time, a node may be affected by different DGs. Therefore, the distance between each node and different DGs is analyzed to determine the degree of influence of each node, specifically:

[0088] Counting the number of nodes between each node and any distributed power source, and recording the ratio between the voltage influence index of each distributed power source at each moment and the number as a first ratio;

[0089] Calculate the cumulative sum of the first ratios of each node to all distributed power sources at each moment, and use the normalized result of the product of the cumulative sum and the deviation credibility as the degree of influence of each node at each moment;

[0090] Preferably, in this embodiment, the calculation formula for the degree of influence of each node at each moment is: ,in, For the Moment The degree of impact of the nodes, For the Moment The deviation credibility of each node, For the The node and The number of nodes between distributed power sources, For the Moment The voltage impact index of a distributed power source, is the number of all distributed generation sources, is the normalization function; secondly, is the first ratio.

[0091] It should be noted that The larger the The distance between nodes The farther away a distributed power source is, the more likely it is to be affected by the The smaller the impact of a distributed generation, the greater the degree of influence, which means that the corresponding node is more affected by all DGs connected to the distribution network, that is, the correlation coefficient between the corresponding node and the adjacent nodes may differ more.

[0092] Furthermore, the step flow chart of the method for obtaining the degree of influence of each node at each moment provided in the embodiment of the present application is as follows: Figure 5 shown.

[0093] At this point, the degree of influence of each node at each moment is obtained.

[0094] Step 4, based on the degree of influence, determine the correction factor of each node at each moment; based on the correction factor, correct the correlation degree of the voltage of all nodes at adjacent moments, determine the corrected correlation coefficient at each moment, and determine the time when the single-phase grounding fault occurs based on the corrected correlation coefficient at each moment; based on the correction factor, correct the correlation degree of the voltage between each node and any other node at all moments after the grounding fault occurs, determine the corrected correlation coefficient between each node and any other node, and locate the single-phase grounding fault that occurs.

[0095] Further, based on the degree of influence, the correction factor of each node at each moment is determined, specifically:

[0096] The correction factor of each node at each moment is calculated as follows: ,in, For the Moment The correction factor for each node is For the Moment The degree of impact on each node.

[0097] It should be noted that the greater the degree of influence of each node at each moment, the greater the voltage change of the corresponding node, that is, the lower the voltage correlation with other nodes, and the greater the degree of correction of the corresponding node.

[0098] Furthermore, based on the correction factor, the correlation coefficient of each node at adjacent moments is corrected, specifically:

[0099] Calculate the correlation coefficient between the voltage of all nodes at each moment and the voltage of all nodes at the previous moment;

[0100] Preferably, in this embodiment, the Pearson correlation coefficient between the voltage of all nodes at each moment and the voltage of all nodes at the previous moment is calculated, wherein the Pearson correlation coefficient is a well-known technology and will not be described in detail here. As other implementation methods, the implementer can adopt other methods of the prior art, such as the Spearman correlation coefficient, etc., and this embodiment does not impose any special restrictions on this.

[0101] The calculation method of the corrected correlation coefficient at each moment is: ,in, For the The correlation coefficient after correction at each moment is For the The correlation coefficient at each moment, For the The node in The correction factor at that moment, is the number of all nodes, is the normalization function.

[0102] It should be noted that the larger the correction factor, the greater the impact of DG access on all nodes in the distribution network. Therefore, the correlation between the voltages of all nodes at adjacent moments may be lower, and the correlation coefficient is smaller. Therefore, no single-phase grounding fault occurs at the corresponding node. In order to avoid misjudgment of the location of the single-phase grounding fault, the moments and nodes that are more affected by DG access are corrected so that the corrected correlation coefficient is larger.

[0103] Further, based on the corrected correlation coefficient, the time when the single-phase grounding fault occurs is determined, specifically:

[0104] Calculate the normalized result of the sum of the corrected correlation coefficients at each moment and at multiple moments before it. If the normalized result at each moment is less than a preset first threshold, a single-phase grounding fault occurs at the corresponding moment; otherwise, no single-phase grounding fault occurs.

[0105] Preferably, in this embodiment, the corrected correlation coefficient of each moment and the 35 moments before it is selected, and the implementer can set it according to the actual situation. The preset first threshold value is 0.46. As other implementation methods, the implementer can set it according to the actual situation.

[0106] Further, the schematic diagram of the time when the ground fault occurs provided by the embodiment of the present application is as follows: Figure 6 As shown, the horizontal axis is time and the vertical axis is the normalized result, which is expressed as the normalized result of the sum of the corrected correlation coefficients at each moment and multiple moments before it. The dotted line in the figure represents the preset first threshold. It can be seen from the figure that the normalized result at the 5th second is less than the preset first threshold, indicating that a single-phase grounding fault has occurred at this time.

[0107] After a single-phase grounding fault occurs, since the power will not be cut off immediately, the voltage changes of each node and other nodes within a period of time after the fault occurs are analyzed, and the node where the fault occurs is further located, specifically:

[0108] After a single-phase grounding fault occurs, the voltage of each node at multiple times after the fault occurs is selected to form a fault response vector of each node;

[0109] Calculate the mean of the correction factor at the corresponding time in the fault response vector between each node and any other node, and normalize the sum of the mean values ​​at all times as the correction coefficient between each node and any other node;

[0110] Calculating the correlation coefficient of the fault response vector between each node and any other node, and taking the product of the correlation coefficient and the correction coefficient as the corrected correlation coefficient between each node and any other node;

[0111] Preferably, in this embodiment, the calculation formula of the corrected correlation coefficient between each node and any other node is: ,in, For the The node and The corrected correlation coefficient between nodes is For the The node and The correlation coefficient of the fault response vector between nodes, For the Moment The correction factor for each node is For the Moment The correction factor for each node is is the time when the single-phase grounding fault occurs, T is the number of all times in the fault response vector, is the normalization function, and secondly, is the correction factor.

[0112] Calculate the normalized result of the sum of the corrected correlation coefficients between each node and all other nodes. If the normalized result of each node is less than the preset second threshold, a single-phase grounding fault occurs at the corresponding node. If the normalized result of each node is greater than or equal to the preset second threshold, no single-phase grounding fault occurs.

[0113] Preferably, in this embodiment, the preset value of the second threshold is 0.55. As other implementation modes, the implementer can set it according to the actual situation.

[0114] Further, the schematic diagram of the ground fault occurrence node provided in the embodiment of the present application is as follows: Figure 7 As shown, the horizontal axis is the node number, the vertical axis is the normalized result, which is represented by the normalized result of the sum of the corrected correlation coefficients between each node and all other nodes. The dotted line in the figure represents the preset second threshold, which is Figure 7 It can be seen that the normalized result of the node corresponding to node number 10 is less than the preset second threshold, indicating that a single-phase grounding fault has occurred at the location of node 10; Figure 6 and Figure 7 , and finally determined that a single-phase grounding fault occurred at node 10 at the 5th second.

[0115] Therefore, the single-phase grounding fault is located by the time when the single-phase grounding fault occurs in the distribution network and the node position where the fault occurs.

[0116] The embodiment of the present application also provides an operation fault monitoring system applied to a smart grid, including:

[0117] The power grid data acquisition module obtains the voltage of each node in the power grid at each time, as well as each distributed power source connected to the node. The nodes connected to the distributed power source are recorded as connected nodes, and the remaining nodes are recorded as unconnected nodes.

[0118] The power supply impact correction module determines the voltage impact index of each distributed power supply at each moment according to the voltage deviation of the access node and the non-access node connected to each distributed power supply at each moment, and the difference in voltage deviation between the access node and the non-access node; determines the deviation credibility of each node at each moment according to the voltage fluctuation range of each node at each moment and the previous moment, and the distribution difference of the fluctuation range of all nodes at each moment; analyzes the distance relationship between each node and any distributed power supply, and determines the degree of influence of each node at each moment in combination with the deviation credibility and the voltage impact index; and determines the correction factor of each node at each moment based on the degree of influence;

[0119] The grounding fault locating module corrects the correlation degree of the voltages of all nodes at adjacent moments based on the correction factor, determines the corrected correlation coefficient at each moment, and determines the time when the single-phase grounding fault occurs based on the corrected correlation coefficient at each moment; based on the correction factor, corrects the correlation degree of the voltages of each node and any other node at all moments after the grounding fault occurs, determines the corrected correlation coefficient between each node and any other node, and locates the single-phase grounding fault that occurs.

[0120] Furthermore, the block diagram of the operation fault monitoring system for smart grid provided in the embodiment of the present application is as follows: Figure 8 shown.

[0121] Based on the same inventive concept as the above method, an embodiment of the present application also provides an operation fault monitoring device applied to a smart grid, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the computer program, the steps of any one of the above-mentioned operation fault monitoring methods applied to a smart grid are implemented.

[0122] It should be understood that although Figure 1 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 1 At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0123] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0124] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the present application. It should be pointed out that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application without departing from the content of the technical solution of the present application, shall fall within the protection scope of the technical solution of the present application.

Claims

1. An operation fault monitoring method applied to a smart grid, characterized in that: The method comprises the following steps: Obtain the voltage of each node in the power grid at each time, and each distributed power source connected to the node, where the node connected to the distributed power source is recorded as the connected node, and the remaining nodes are recorded as the unconnected nodes; Determine the voltage impact index of each distributed power source at each moment according to the voltage deviation of the access node and the non-access node connected to each distributed power source at each moment, and the difference in voltage deviation between the access node and the non-access node; Determine the deviation credibility of each node at each moment according to the voltage fluctuation range of each node at each moment and in the previous moment, and the distribution difference of the fluctuation range of all nodes at each moment; analyze the distance relationship between each node and any distributed power source, and determine the degree of influence of each node at each moment by combining the deviation credibility and the voltage influence index; Based on the degree of influence, a correction factor of each node at each moment is determined; based on the correction factor, the correlation degree of the voltages of all nodes at adjacent moments is corrected to determine the corrected correlation coefficient at each moment, and the time when the single-phase grounding fault occurs is determined based on the corrected correlation coefficient at each moment; Based on the correction factor, the correlation degree of the voltage between each node and any other node at all times after the ground fault occurs is corrected, the corrected correlation coefficient between each node and any other node is determined, and the single-phase ground fault that occurs is located; The step of determining the voltage impact index of each distributed power source at each moment includes: Calculate the mean value of the voltages of all nodes at each moment, and record the difference between the voltage of the access node connected to each distributed power source at each moment and the mean value as a first difference; Calculating the sum of the differences between the voltages of all non-connected nodes and the mean at each moment, and taking the normalized result of the ratio of the first difference to the sum as the voltage influence index of each distributed power source at each moment; The locating of the single-phase grounding fault comprises: The normalized result of the sum of the corrected correlation coefficients between each node and all other nodes is calculated. If the normalized result of each node is less than the preset second threshold, a single-phase grounding fault occurs at the corresponding node; otherwise, a single-phase grounding fault does not occur.

2. The operation fault monitoring method applied to the smart grid according to claim 1, characterized in that: Determining the deviation credibility of each node at each moment includes: The voltage of each node at each moment and at multiple moments before it is used to form a local voltage vector of each node at each moment; Calculating the range of the local voltage vector; forming a two-dimensional array with the range at each moment and at each node; Performing curve fitting on the two-dimensional array of all nodes at each moment to obtain a fitting curve at each moment; The distance between the two-dimensional array of each node at each moment and the fitting curve at the corresponding moment is calculated, and the ratio between the voltage of each node at each moment and the distance is used as the deviation credibility of each node at each moment.

3. The operation fault monitoring method applied to the smart grid according to claim 1, characterized in that: Determining the impact degree of each node at each moment includes: Counting the number of nodes between each node and any distributed power source, and recording the ratio between the voltage influence index of each distributed power source at each moment and the number as a first ratio; The cumulative sum of the first ratios of each node to all distributed power sources at each moment is calculated, and a normalized result of the product of the cumulative sum and the deviation credibility is used as the degree of influence of each node at each moment.

4. The operation fault monitoring method applied to a smart grid according to claim 1, characterized in that: The correction factor of each node at each moment is determined by the following calculation formula: ,in, For the Moment The correction factor for each node is For the Moment The degree of impact on each node.

5. The operation fault monitoring method applied to a smart grid according to claim 1, characterized in that: The correction correlation coefficient at each moment is determined by calculating: ,in, For the The correlation coefficient after correction at each moment is For the The correlation coefficient between the voltage of all nodes at a moment and the voltage of all nodes at the previous moment, For the Moment The correction factor for each node is is the number of all nodes, is the normalization function.

6. The operation fault monitoring method applied to a smart grid according to claim 1, characterized in that: Determining the time when the single-phase grounding fault occurs includes: The normalized result of the sum of the corrected correlation coefficients at each moment and the previous multiple moments is calculated. If the normalized result at each moment is less than a preset first threshold, a single-phase grounding fault occurs at the corresponding moment; otherwise, no single-phase grounding fault occurs.

7. The operation fault monitoring method applied to a smart grid according to claim 1, characterized in that: Determining the corrected correlation coefficient between each node and any other node includes: The voltage of each node at multiple times after the fault occurs is selected to form a fault response vector of each node; Calculate the mean of the correction factor at the corresponding time in the fault response vector between each node and any other node, and normalize the sum of the mean values ​​at all times as the correction coefficient between each node and any other node; The product of the correlation coefficient of the fault response vector between each node and any other node and the correction coefficient is calculated as the corrected correlation coefficient between each node and any other node.

8. An operation fault monitoring system applied to a smart grid, implementing the method as claimed in claim 1, characterized in that: The system comprises: The power grid data acquisition module obtains the voltage of each node in the power grid at each time, as well as each distributed power source connected to the node. The nodes connected to the distributed power source are recorded as connected nodes, and the remaining nodes are recorded as unconnected nodes. The power supply impact correction module determines the voltage impact index of each distributed power supply at each moment according to the voltage deviation of the access node and the non-access node connected to each distributed power supply at each moment, and the difference in voltage deviation between the access node and the non-access node; determines the deviation credibility of each node at each moment according to the voltage fluctuation range of each node at each moment and the previous moment, and the distribution difference of the fluctuation range of all nodes at each moment; analyzes the distance relationship between each node and any distributed power supply, and determines the degree of influence of each node at each moment in combination with the deviation credibility and the voltage impact index; and determines the correction factor of each node at each moment based on the degree of influence; The grounding fault locating module corrects the correlation degree of the voltages of all nodes at adjacent moments based on the correction factor, determines the corrected correlation coefficient at each moment, and determines the time when the single-phase grounding fault occurs based on the corrected correlation coefficient at each moment; based on the correction factor, corrects the correlation degree of the voltages of each node and any other node at all moments after the grounding fault occurs, determines the corrected correlation coefficient between each node and any other node, and locates the single-phase grounding fault that occurs.

9. An operation fault monitoring device for a smart grid, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of the operation fault monitoring method applied to the smart grid as described in any one of claims 1-7 are implemented.

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