A distribution network fault location method and device based on power frequency wide area information

Abstract

The present invention relates to the technical field of distribution network fault location, specifically providing a distribution network fault location method and apparatus based on power frequency wide area information. The method comprises: dividing the branch lines in the distribution network topology network into main branch lines and auxiliary branch lines; selecting a reference node based on the absolute difference between the calculated terminal voltage value corresponding to a node on the main branch line and the measured terminal voltage value corresponding to the node, and calculating the difference variation factor of the reference node; determining the fault section based on the difference variation factor of the reference node; calculating the difference variation factor of each preset point in the fault section, and selecting the preset point with the smallest difference variation factor as the fault point. This solution can accurately detect the fault section and achieve precise fault location with limited voltage measurement.

Description

Technical Field

[0001] The present invention relates to the field of distribution network fault location, and in particular to a distribution network fault location method and device based on power frequency wide area information. Background Art

[0002] In recent years, with the continuous increase in electricity demand, the scale of distribution networks has continued to grow, and urban distribution networks have become increasingly complex in terms of grid structure and topology. Using only a single electrical information quantity at the head end of the substation for fault location is prone to the problem of multiple fault point estimation, which makes it difficult to meet the requirements of complex radial distribution networks for accurate fault location. Summary of the Invention

[0003] In order to overcome the above-mentioned defects, the present invention proposes a distribution network fault location method and device based on power frequency wide area information.

[0004] In a first aspect, a method for locating a distribution network fault based on power frequency wide area information is provided, the method comprising:

[0005] Dividing the branch lines in the topological network of the distribution network into main branch lines and auxiliary branch lines;

[0006] Selecting a reference node based on the absolute difference between the calculated terminal voltage value corresponding to the node on the main branch line and the measured terminal voltage value corresponding to the node, and calculating the difference change factor of the reference node;

[0007] determining a fault section based on a difference variation factor of the reference node;

[0008] Calculate the difference variation factor of each preset point in the fault section, and select the preset point with the smallest difference variation factor as the fault point.

[0009] Preferably, the dividing of the branch lines in the topological network of the distribution network into main branch lines and auxiliary branch lines includes:

[0010] The branch line with the largest number of nodes in the distribution network topology is regarded as the main branch line, and the branch line other than the main branch line and containing one or more section lines is regarded as the secondary branch line.

[0011] Preferably, the calculation formula for the terminal voltage calculation value corresponding to the node on the main branch line is as follows:

[0012]

[0013] In the above formula, is the calculated value of the terminal voltage corresponding to the nth node, is the calculated voltage value of the nth node, z iis the impedance from the i-1th node to the i-th node, is the current between the i-1th node and the i-th node, and N is the total number of nodes on the main branch line.

[0014] Furthermore, the voltage calculation value of the nth node is calculated as follows:

[0015]

[0016] In the above formula, is the initial voltage.

[0017] Furthermore, the current between the i-1th node and the i-th node is calculated as follows:

[0018]

[0019] In the above formula, is the initial current, y1 is the admittance of the starting node, y x-1 is the admittance from the i-2th node to the i-1th node, y x is the admittance from the x-1th node to the xth node, Y sub is the admittance matrix of the main branch line, Calculate the voltage of the x-th node.

[0020] Preferably, the step of selecting a reference node based on an absolute difference between a calculated terminal voltage value corresponding to a node on the main branch line and a measured terminal voltage value corresponding to the node includes:

[0021] The node with the smallest absolute difference between the corresponding terminal voltage calculation value and the corresponding terminal voltage measurement value is selected as the reference node.

[0022] Preferably, the calculation formula of the difference change factor of the reference node is as follows:

[0023]

[0024] In the above formula, ξ(T min +Δl) is the voltage distribution curve of the through-line min +Δl position point corresponding to the amplitude, ξ(T min ) is the voltage distribution curve of the through-line min The amplitude corresponding to the position point, ξ(T min -Δl) is the voltage distribution curve of the through-line min -Δl position point corresponding to the amplitude, k R is the right difference change factor of the reference node, k L is the left difference change factor of the reference node, Δl is the step size, Tmin It is the position point corresponding to the reference node on the line voltage distribution curve of the through line, the horizontal coordinate of the line voltage distribution curve of the through line is the distance corresponding to each node on the main branch line, and the vertical coordinate is the absolute difference between the terminal voltage calculation value corresponding to each node on the main branch line and the terminal voltage measurement value corresponding to each node.

[0025] Furthermore, the determining of the fault section based on the difference change factor of the reference node includes:

[0026] Step 1: When the reference node is a T-type node, if k R >0 and k L <0, the fault section is located on the secondary branch line connected to the reference node; otherwise, the fault section is located on the main branch line where the reference node is located. When the reference node is not a T-node, the fault section is located on the main branch line where the reference node is located;

[0027] Step 2 When k R <0 or k L <0, the fault section is the section between the reference node on the branch line where it is located and the next node in the positive direction of the current. R >0 or k L When >0, the fault section is the section between the reference node on the branch line where it is located and the previous node of the reference node in the positive direction of the current.

[0028] Preferably, the preset points in the fault section are equally spaced, and the difference change factor of each preset point in the fault section is the absolute difference between the terminal voltage calculation value corresponding to each preset point in the fault section and the terminal voltage measurement value corresponding to each preset node.

[0029] In a second aspect, a distribution network fault location device based on power frequency wide area information is provided, wherein the distribution network fault location device based on power frequency wide area information comprises:

[0030] A division module, used for dividing branch lines in the topological network of the distribution network into main branch lines and auxiliary branch lines;

[0031] A first calculation module is configured to select a reference node based on an absolute difference between a calculated terminal voltage value corresponding to a node on the main branch line and a measured terminal voltage value corresponding to the node, and calculate a difference change factor of the reference node;

[0032] a determination module, configured to determine a fault section based on a difference change factor of the reference node;

[0033] The second calculation module is used to calculate the difference change factor of each preset point in the fault section, and select the preset point with the smallest difference change factor as the fault point.

[0034] In a third aspect, a storage device is provided, which stores a plurality of program codes, wherein the program codes are suitable for being loaded and run by a processor to execute the distribution network fault location method based on power frequency wide area information as described in any of the above technical solutions.

[0035] In a fourth aspect, a control device is provided, which includes a processor and a storage device, wherein the storage device is suitable for storing multiple program codes, and the program codes are suitable for being loaded and run by the processor to execute the distribution network fault location method based on industrial frequency wide area information described in any of the above technical solutions.

[0036] The above one or more technical solutions of the present invention have at least one or more of the following beneficial effects:

[0037] The present invention provides a distribution network fault location method and device based on power frequency wide area information, including: dividing the branch lines in the topological network of the distribution network into main branch lines and auxiliary branch lines; selecting a reference node based on the absolute difference between the terminal voltage calculated value corresponding to the node on the main branch line and the terminal voltage measured value corresponding to the node, and calculating the difference change factor of the reference node; determining the fault section based on the difference change factor of the reference node; calculating the difference change factor of each preset point in the fault section, and selecting the preset point with the smallest difference change factor as the fault point. This solution can accurately detect the fault section and achieve precise fault location under limited voltage measurement;

[0038] Furthermore, the location, number, and type of loads have no significant impact on the fault location method of the present invention. This is because the wiring of the low-voltage transformer makes the loads equivalent to open circuits in the zero-sequence network, meaning that the load parameters are not factored into the fault location calculation. Experimental results show that the technical solution provided by the present invention can accurately identify the fault section under various fault resistance conditions, with a fault ranging error of no more than 50m, demonstrating excellent fault location performance for various fault resistances.

[0039] Furthermore, the present invention has a certain ability to resist interference and measurement errors. Since the voltage amplitude at the end of the line needs to be measured, measurement errors are inevitably introduced. Simulations show that as noise and measurement errors increase, the effectiveness of fault location is affected to a certain extent. For simple distribution lines, when the noise reaches 20dB, fault distance identification will fail. For a 34-node distribution network, when the measurement deviation reaches 5%, the fault range of some fault points will be misjudged, but the ranging error will still be within 200m. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a flow chart of the main steps of the method for locating a distribution network fault based on power frequency wide area information according to an embodiment of the present invention;

[0041] Figure 2 IEEE-34 node radial distribution network topology diagram in an embodiment of the present invention;

[0042] Figure 3 is a simplified circuit diagram of the main branch circuit in an embodiment of the present invention;

[0043] Figure 4 1 is a line distribution voltage curve diagram in an embodiment of the present invention;

[0044] Figure 5 is a zero-sequence network diagram equivalent to a fault in an embodiment of the present invention;

[0045] Figure 6 is a simplified circuit diagram of a secondary branch circuit in an embodiment of the present invention;

[0046] Figure 7 1 is a waveform diagram of voltage and current at the main substation and terminal node voltage in an embodiment of the present invention;

[0047] Figure 8 is a graph showing the difference change factors of main branches at different nodes in an embodiment of the present invention;

[0048] Figure 9 is a graph showing a trend of changes in the neighborhood of node 20 in an embodiment of the present invention;

[0049] Figure 10 20, 21, 22} is a curve diagram showing a voltage difference variation of the branch circuits {20, 21, 22} according to an embodiment of the present invention;

[0050] Figure 11 1 is a schematic diagram of the structure of a distribution network test system of 1 IEEE-134 node in an embodiment of the present invention;

[0051] Figure 12 This is a main structural block diagram of a distribution network fault location device based on power frequency wide area information according to an embodiment of the present invention. DETAILED DESCRIPTION

[0052] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0054] See attached Figure 1 , Figure 1 FIG. 1 is a flow chart showing the main steps of the method for locating a distribution network fault based on power frequency wide area information according to an embodiment of the present invention. Figure 1 As shown, the distribution network fault location method based on power frequency wide area information in the embodiment of the present invention mainly includes the following steps:

[0055] Step S101: dividing branch lines in the topological network of the distribution network into main branch lines and auxiliary branch lines;

[0056] Step S102: selecting a reference node according to the absolute difference between the calculated terminal voltage value corresponding to the node on the main branch line and the measured terminal voltage value corresponding to the node, and calculating the difference change factor of the reference node;

[0057] Step S103: determining the fault section based on the difference change factor of the reference node;

[0058] Step S104: Calculate the difference variation factor of each preset point in the fault section, and select the preset point with the smallest difference variation factor as the fault point.

[0059] In this embodiment, the branch lines in the topological network of the distribution network are divided into main branch lines and auxiliary branch lines, including:

[0060] The branch line with the largest number of nodes in the distribution network topology is regarded as the main branch line, and the branch line other than the main branch line and containing one or more section lines is regarded as the secondary branch line.

[0061] In one embodiment, a fault location method based on a distributed voltage characteristic curve requires voltage measurements at the line's end nodes as a reference. When setting measurement nodes, the present invention considers installing measurement points at branch lines with at least two or more sections. Therefore, for radial distribution networks with complex branches, network segmentation is necessary.

[0062] like Figure 2As shown in the figure, there are 9 branches, including {1-2-3-4-5}; {1-2-3-4-6-7-8-9-10-11-12}; {1-2-3-4-6-7-8-9-13-14}; {1-2-3-4-6-7-8-9-13-15-16-17-18}; {1-2-3-4-6-7-8-9-13-15-16-17-19-20-21-22}; {1-2-3-4-6-7-8-9-13-15- 16-17-19-20-23-24};{1-2-3-4-6-7-8-9-13-15-16-17-19-20-23-25-26-27-28};{1-2-3-4-6-7-8-9-13-15-16-17-19-20-23-25-26-27-29-30};{1-2-3-4-6-7-8-9-13-15-16-17-19-20-23-25-31-32-33-34}. The configuration principles of distributed voltage measurement are as follows: (1) Select the main branch line. The present invention sets the branch with the largest number of nodes as the main branch line. Figure 2 In the branches {1-2-3-4-6-7-8-9-13-15-16-17-19-20-23-25-26-27-29-30} and {1-2-3-4-6-7-8-9-13-15-16-17-19-20-23-25-31-32-33-34}, there are 20 nodes respectively. In this case, any one of the branches can be selected as the main branch. The present invention selects the branch {1-2-3-4-6-7-8-9-13-15-16-17-19-20-23-25-31-32-33-34} as the main branch line in the analysis process. Therefore, a voltage measuring device is installed at the 34th node. (2) Select the secondary branch line. Except for the main branch line, the end nodes of other branch lines containing more than one interval need to be installed with a voltage measuring device. The secondary branch lines that meet this condition are: {9-10-11-12}, {20-21-22}, {25-26-27-29-30}. Therefore, voltage measuring devices should be installed at nodes 12, 22, and 30.

[0063] In summary, Figure 2 In the distribution network topology shown, the distributed voltage measurement points that need to be installed are nodes 12 , 22 , 30 and 34 .

[0064] Furthermore, before locating the fault section, the following parameters need to be calculated: The calculation formula for the terminal voltage calculation value corresponding to the node on the main branch line is as follows:

[0065]

[0066] In the above formula, is the calculated value of the terminal voltage corresponding to the nth node, is the calculated voltage value of the nth node, z i is the impedance from the i-1th node to the i-th node, is the current between the i-1th node and the i-th node, and N is the total number of nodes on the main branch line.

[0067] The voltage calculation value of the n-th node is calculated as follows:

[0068]

[0069] In the above formula, is the initial voltage.

[0070] The current between the i-1th node and the i-th node is calculated as follows:

[0071]

[0072] In the above formula, is the initial current, y1 is the admittance of the starting node, y x-1 is the admittance from the i-2th node to the i-1th node, y x is the admittance from the x-1th node to the xth node, Y sub is the admittance matrix of the main branch line, Calculate the voltage of the x-th node.

[0073] Preferably, the step of selecting a reference node based on an absolute difference between a calculated terminal voltage value corresponding to a node on the main branch line and a measured terminal voltage value corresponding to the node includes:

[0074] The node with the smallest absolute difference between the corresponding terminal voltage calculation value and the corresponding terminal voltage measurement value is selected as the reference node.

[0075] Preferably, the calculation formula of the difference change factor of the reference node is as follows:

[0076]

[0077] In the above formula, ξ(T min +Δl) is the voltage distribution curve of the through-line min +Δl position point corresponding to the amplitude, ξ(T min ) is the voltage distribution curve of the through-line min The amplitude corresponding to the position point, ξ(T min -Δl) is the voltage distribution curve of the through-line min-Δl position point corresponding to the amplitude, k R is the right difference change factor of the reference node, k L is the left difference change factor of the reference node, Δl is the step size, T min It is the position point corresponding to the reference node on the line voltage distribution curve of the through line, the horizontal coordinate of the line voltage distribution curve of the through line is the distance corresponding to each node on the main branch line, and the vertical coordinate is the absolute difference between the terminal voltage calculation value corresponding to each node on the main branch line and the terminal voltage measurement value corresponding to each node.

[0078] Due to the complex radial distribution network, there are a large number of branch lines, such as Figure 2 As shown. Therefore, the fault location algorithm is easily affected by the multi-estimation problem. Therefore, for this type of complex distribution network, the first step is to determine the fault branch. The main branch line after network division can provide the corresponding fault information. The simplified main branch line is as follows Figure 3 shown.

[0079] Figure 4 The following is a plot of the voltage distribution curve for the through-line. It shows that the voltage difference decreases monotonically with increasing distance before the fault point, while it increases monotonically with increasing distance after the fault point. Therefore, the voltage variation of the line is a monotonic function of distance, both before and after the fault point. Here, the relative position of the transformer point to the fault point is determined by the slope of the characteristic curve near the minimum. In other words, if the transformer point is located in the region with a positive slope, it is to the left of the fault point. Conversely, if the transformer point is located in the region with a negative slope, it is to the right.

[0080] Specifically, determining the fault section based on the difference change factor of the reference node includes:

[0081] Step 1: When the reference node is a T-type node, if k R >0 and k L <0, the fault section is located on the secondary branch line connected to the reference node; otherwise, the fault section is located on the main branch line where the reference node is located. When the reference node is not a T-node, the fault section is located on the main branch line where the reference node is located;

[0082] Step 2 When k R <0 or k L <0, the fault section is the section between the reference node on the branch line where it is located and the next node in the positive direction of the current. R >0 or k LWhen >0, the fault section is the section between the reference node on the branch line where it is located and the previous node of the reference node in the positive direction of the current.

[0083] After the fault section is identified, the fault point needs to be identified. In this embodiment, the preset points in the fault section are equally spaced, and the difference change factor of each preset point in the fault section is the absolute difference between the terminal voltage calculation value corresponding to each preset point in the fault section and the terminal voltage measurement value corresponding to each preset node. In one embodiment, Figure 4 As shown in Figure 2, further search work needs to be done on the red curve part within the fault interval. Assume that the fault occurs at node T n-2 With node T n-1 The equivalent of the calculation model is as follows Figure 5 The specific calculation steps are as follows:

[0084] (1) Select a certain step size Δl, from node T n-2 To node T n-1 Calculate the end-of-line voltage.

[0085] Different distances are used to calculate the end node T n Here, in order to improve the search accuracy as much as possible, the search step length Δl of this embodiment is 1m.

[0086] (2) Compare the calculated and measured values ​​between the preset points and finally locate the fault point.

[0087] In one embodiment, the present invention provides different types of test results based on the above method:

[0088] a. Tests for different fault types

[0089] The present invention tests single-phase ground faults, including Ag, Bg, Cg, and two-phase ground faults, including ABg, ACg, BCg, as shown in Table 1. When there is a metallic ground fault between nodes 20 and 21, the fault distance is 720m. The voltage and current waveforms at the main substation and the terminal node voltage waveform are as follows: Figure 6 As the data window moves, the main branch voltage difference sequence ξ in different windows main The result is Figure 7 It can be observed that the main branch voltage difference sequence ξ in the first cycle after the fault mainThe values ​​are: 3.836,3.7808,3.7435,3.0482,2.2394,1.7413,1.6976,1.5940,1.3751,1.2864,0.8475,0.8103,0.0904,0.0785,0.0927,0.2089,0.3563,0.5984,0.7085,1.0075; in the second period, the values ​​are 3.8485,3.7934,3.7563,3.0633,2.2573,1.7609,1.7174,1.6142,1.3960,1.307 6,0.8703,0.8332,0.0471,0.0179,0.0579,0.1824,0.3292,0.5705,0.6803,0.9782; in the third period, the values ​​are: 3.8484,3.7933,3.7562,3.0637,2.2583,1.7623,1.7188,1.6156,1.3976,1.3093,0.8723,0.8352,0.0496,0.0081,0.0552,0.1797,0.3264,0.5675,0.6772,0.9749. From the results, we can see that no matter which cycle is selected, node 20 is always at the minimum voltage difference. Considering that node 20 is a branch node, the changes in the left and right neighborhoods of this node need to be judged. The results are as follows: Figure 8 As shown in the figure, in the three cycles, the voltage differences between the left and right neighborhoods are: 0.07701(↑) / 0.0778(↑); 0.01821(↑) / 0.01904(↑); 0.008652(↑) / 0.01046(↑), that is, k L =-0.002<0and k R =0.0099>0;k L =-0.0025<0and k R =0.0108>0;k L =-0.0053<0and k R =0.0234>0. It can be determined that the fault is on branch {20,21,22}. According to the fault location process, further judgment is required on the branch line. Figure 10 As shown, the first cycle of ξ sub =[0.0709,0.0183,0.1802]; ξ of the second period sub =[0.0735,0.0086,0.1775]; ξ of the third period sub =[0.0735,0.0086,0.1775].

[0090] Therefore, it can be seen that node 21 is the lowest node of the voltage characteristic curve. Since this node is not a branch node, only the right neighbor can be used to determine it. Figure 9 , the voltage difference variation factor k of node 21 within three cycles R The values ​​are 0.042, 0.139, and 0.209, respectively, all greater than 0. This means that the slope of the voltage difference curve at the lowest point, node 21, is positive, thus confirming that the fault lies between nodes 20 and 21. Finally, by iterating with a step size of 1 meter, starting the search at node 20 and ending at node 21, the fault locations for the three cycles are 563.5 meters, 639.4 meters, and 677.9 meters, respectively. This means that the fault location errors are 156.5 meters, 80.6 meters, and 42.1 meters, respectively. This shows that fault segment determination and fault location are possible for all post-fault cycles. However, it can be observed that the voltage difference distribution obtained in the second and third cycles is more concentrated, and the values ​​are closer to 0. This is because the fault transients gradually disappear in the second and third cycles compared to the first cycle, resulting in more stable phasor extraction.

[0091] Table 1

[0092]

[0093]

[0094] As shown in Table 1, when a two-phase AB metallic ground fault occurs between node 23 and node 24 and the fault distance is 300m, the main branch voltage difference sequence ξ can be obtained. main =[2.5958 2.5592 2.5345 2.0733 1.5371 1.20691.1779 1.1092 0.9641 0.9053 0.6143 0.5896 0.0666 0.0317 0.0121 0.0860 0.18370.3443 0.4173 0.6155]. Node 23 has the smallest voltage difference. Since node 23 is a branch T-node, the voltage difference change factor of its left and right neighbors is k R =0.0065>0,k L = -7.529e-4 < 0. Therefore, the fault is located on branch {23, 24}. Considering that there is no voltage measurement device installed at the end of network node 24, the conventional single-ended ranging method can be used to obtain a preliminary fault location within the fault section, or additional voltage measurement points can be added to obtain a more accurate fault location. The results in Table 1 demonstrate that the algorithm proposed in this invention can accurately detect the fault section and achieve precise fault location with limited voltage measurement.

[0095] b. Different fault resistance tests

[0096] Assume that a phase A ground fault occurs between nodes 9 and 10, with a fault distance of 220 m. The measured fault resistance ranges from 0.01 Ω to 2000 Ω. The test results are shown in Table 2.

[0097] Table 2

[0098]

[0099] In Table 2, all tests show that node 9 is identified as the node with the smallest difference value in the main branch line. The difference values ​​of node 9 under different resistances are: 0.0182, 3.64e-4, 1.43e-4, 6.57e-5, 3.25e-5, 1.70e-5, 9.12e-6, 4.73e-6, 2.39e-6 and 1.68e-6. Since node 9 is a T-node with a secondary branch line, it is necessary to calculate the change trend of the left and right neighbors of node 9. As shown in the table, the slope k of the right neighbor is R are 0.0252, 0.0310, 0.0114, 0.0069, 0.0050, 0.0039, 0.0032, 0.0027, 0.0023 and 0.0017; the slope k of the left neighborhood L The results show that it meets the criterion k. R >0 and k L <0, so the fault is on the secondary branch line {9,10,11,12}. The voltage value of the M3 measuring point at the end of the secondary branch line is introduced to further determine the fault range and fault location. When the fault resistance is 500Ω, in the branch voltage difference sequence θ sub In the example, node 9 is still identified as the minimum point, and the slope factor of its right neighbor is -0.0069<0, so the fault is between node 9 and node 10. Through iteration, it can be seen that the error of fault location is 39.90m. When the fault resistance is 2000Ω, in the branch voltage difference sequence θ sub In the example, node 10 is identified as the minimum point, and the slope factor of its right neighbor is 0.0018 > 0. Therefore, the fault is located between nodes 9 and 10. Finally, after iteration, the fault location error is 47.10 m. As shown above, this method can correctly identify the fault section under different fault resistance conditions, with a fault location error of no more than 50 m. This method has good fault location performance for different fault resistances.

[0100] c. Tests of different load positions and load types

[0101] This embodiment evaluates different load point locations, load quantities, and load types. Taking the fault occurring at node 15 to node 16 as an example, the fault resistance is 10Ω and the fault distance is 2000m. The fault condition of test number 1 is shown in Table 3. In test number 2, the loads at nodes 13, 14, 15, and 16 are removed. In test number 3, the corresponding loads are added at nodes 15 and 16. In test number 4, a distributed power supply with an inverter-type PQ control capacity of 2MW is connected at node 18. In test number 5, a 0.4MW13.8kV motor load is connected at node 18. In the five groups of tests shown in Table 3, in the main branch line difference sequence, node 15 is identified as the smallest difference value. Since node 15 does not belong to a T-type node, only the slope of the right neighbor of the node is used to determine the fault interval. It can be seen that in the five groups of tests, k is satisfied. R <0, so the fault interval can be determined to be between nodes 15 and 16. The fault distance errors were 8.50m, 17.30m, 18.80m, 17.70m, and 17.90m, respectively. The test results show that the location, quantity, and type of loads have no significant impact on the fault location method. This is because the wiring method of the low-voltage side transformer makes the loads equivalent to open circuits in the zero-sequence network, meaning that the load parameters are not included in the fault location calculation.

[0102] Table 3

[0103]

[0104]

[0105] d. Test on the impact of measurement error

[0106] Measurement errors affect the estimation of voltage and current phasors at the node main substation and the extraction of terminal voltage amplitudes, thus directly affecting the accuracy of voltage difference sequence calculations. This paper tested the sensitivity analysis of the fault location method to measurement errors. Generally speaking, errors are composed of measurement background errors and measurement device errors. Regarding measurement device errors, since smart meters undergo rigorous testing before market launch, the errors are generally relatively small. This paper applies normally distributed noise with standard deviations of 0.1%, 0.5%, and 1% for each measurement device. Table 4 shows the statistical results of fault location. When the measurement data error is 0.1% standard deviation, all fault intervals can be accurately identified, and the errors of the 28 measurable fault distances are within 0-100m. When the measurement data error reaches 0.5% and 1% standard deviation, the statistical results show that 3-5 fault intervals are misidentified as adjacent intervals. Although fault location accuracy decreases with increasing measurement error, the fault distance error remains within the range of 0-200m.

[0107] Table 4

[0108]

[0109] e.134 node network test

[0110] This embodiment tests the algorithm for a 134-node power distribution system with more complex feeders. Based on the configuration principle of the measurement device, such as Figure 11 The 134 test system in the system needs to be configured with at least 20 measurement points. The simulation results of fault location are shown in Table 5. In most of the test results, the fault location method can correctly identify the fault interval, and the fault distance error is within 100m. However, when the fault occurs between node 97 and node 98, node 130 to node 132, and node 108 to node 109, the fault branch cannot be accurately determined using the measurement information at the end of the main branch line. The reason is that when the fault occurs near the end of the system, the zero-sequence current on the main branch line is very weak, which reduces the accuracy of the fault location algorithm. In this case, the measurement point at the end of the secondary branch line can be used for calculation. For example, when the fault occurs between node 97 and node 98, node 95 in the main branch line is located as the node closest to the fault. However, using this information will misjudge the fault branch. At this time, if the voltage amplitude information of node 101 is used, node 98 is identified as the point with the smallest difference value. Since node 98 is a T-node, the slopes of the left and right neighbors need to be calculated, which are k R =0.0086 and k L =0.0114. Therefore, the fault interval is between nodes 97 and 98, and the estimated fault distance error is 19.2m. Similarly, when the fault occurs between nodes 130 and 132, the voltage amplitude at node 134 is used to calculate the correct fault interval, and the fault distance estimation error is 41.4m. In addition, when the fault occurs between nodes 108 and 109, the measurement point at node 111 shows that node 109 is the node closest to the fault point. The slope k of the right neighbor of this node is R =0.0611>0, so the fault is between nodes 108 and 109, and the fault distance error is 13.9m. Therefore, when the fault is near the end of the main branch line, using the node voltage at the end of the main branch can easily lead to misidentification of the faulted branch. In this case, using the node voltage at the end of the secondary branch line where the fault is located can serve as a supplementary fault location judgment to accurately determine the fault location.

[0111] Table 5

[0112]

[0113] Based on the same inventive concept, the present invention also provides a distribution network fault location device based on power frequency wide area information, such as Figure 12 As shown, the distribution network fault location device based on power frequency wide area information includes:

[0114] A division module, used for dividing branch lines in the topological network of the distribution network into main branch lines and auxiliary branch lines;

[0115] A first calculation module is configured to select a reference node based on an absolute difference between a calculated terminal voltage value corresponding to a node on the main branch line and a measured terminal voltage value corresponding to the node, and calculate a difference change factor of the reference node;

[0116] a determination module, configured to determine a fault section based on a difference change factor of the reference node;

[0117] The second calculation module is used to calculate the difference change factor of each preset point in the fault section, and select the preset point with the smallest difference change factor as the fault point.

[0118] Preferably, the dividing of the branch lines in the topological network of the distribution network into main branch lines and auxiliary branch lines includes:

[0119] The branch line with the largest number of nodes in the distribution network topology is regarded as the main branch line, and the branch line other than the main branch line and containing one or more section lines is regarded as the secondary branch line.

[0120] Preferably, the calculation formula for the terminal voltage calculation value corresponding to the node on the main branch line is as follows:

[0121]

[0122] In the above formula, is the calculated value of the terminal voltage corresponding to the nth node, is the calculated voltage value of the nth node, z i is the impedance from the i-1th node to the i-th node, is the current between the i-1th node and the i-th node, and N is the total number of nodes on the main branch line.

[0123] Furthermore, the voltage calculation value of the n-th node is calculated as follows:

[0124]

[0125] In the above formula, is the initial voltage.

[0126] Furthermore, the current between the i-1th node and the i-th node is calculated as follows:

[0127]

[0128] In the above formula, is the initial current, y1 is the admittance of the starting node, y x-1 is the admittance from the i-2th node to the i-1th node, y x is the admittance from the x-1th node to the xth node, Y sub is the admittance matrix of the main branch line, Calculate the voltage of the x-th node.

[0129] Preferably, the step of selecting a reference node based on an absolute difference between a calculated terminal voltage value corresponding to a node on the main branch line and a measured terminal voltage value corresponding to the node includes:

[0130] The node with the smallest absolute difference between the corresponding terminal voltage calculation value and the corresponding terminal voltage measurement value is selected as the reference node.

[0131] Preferably, the calculation formula of the difference change factor of the reference node is as follows:

[0132]

[0133] In the above formula, ξ(T min +Δl) is the voltage distribution curve of the through-line min +Δl position point corresponding to the amplitude, ξ(T min ) is the voltage distribution curve of the through-line min The amplitude corresponding to the position point, ξ(T min -Δl) is the voltage distribution curve of the through-line min -Δl position point corresponding to the amplitude, k R is the right difference change factor of the reference node, k L is the left difference change factor of the reference node, Δl is the step size, T min It is the position point corresponding to the reference node on the line voltage distribution curve of the through line, the horizontal coordinate of the line voltage distribution curve of the through line is the distance corresponding to each node on the main branch line, and the vertical coordinate is the absolute difference between the terminal voltage calculation value corresponding to each node on the main branch line and the terminal voltage measurement value corresponding to each node.

[0134] Furthermore, the determining of the fault section based on the difference change factor of the reference node includes:

[0135] Step 1: When the reference node is a T-type node, if k R >0 and k L<0, the fault section is located on the secondary branch line connected to the reference node; otherwise, the fault section is located on the main branch line where the reference node is located. When the reference node is not a T-node, the fault section is located on the main branch line where the reference node is located;

[0136] Step 2 When k R <0 or k L <0, the fault section is the section between the reference node on the branch line where it is located and the next node in the positive direction of the current. R >0 or k L When >0, the fault section is the section between the reference node on the branch line where it is located and the previous node of the reference node in the positive direction of the current.

[0137] Preferably, the preset points in the fault section are equally spaced, and the difference change factor of each preset point in the fault section is the absolute difference between the terminal voltage calculation value corresponding to each preset point in the fault section and the terminal voltage measurement value corresponding to each preset node.

[0138] Furthermore, the present invention provides a storage device storing a plurality of program codes, wherein the program codes are suitable for being loaded and run by a processor to execute the distribution network fault location method based on power frequency wide area information as described in any of the above technical solutions.

[0139] Furthermore, the present invention provides a control device, which includes a processor and a storage device, wherein the storage device is suitable for storing multiple program codes, and the program codes are suitable for being loaded and run by the processor to execute the distribution network fault location method based on industrial frequency wide area information described in any of the above technical solutions.

[0140] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0141] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0142] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0143] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0144] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A distribution network fault location method based on power frequency wide area information, characterized in that: The method comprises: Dividing the branch lines in the topological network of the distribution network into main branch lines and auxiliary branch lines; Selecting a reference node based on the absolute difference between the calculated terminal voltage value corresponding to the node on the main branch line and the measured terminal voltage value corresponding to the node, and calculating the difference change factor of the reference node; determining a fault section based on a difference variation factor of the reference node; Calculate the difference change factor of each preset point in the fault section, and select the preset point with the smallest difference change factor as the fault point; The calculation formula of the difference change factor of the reference node is as follows: In the above formula, ξ(T min +Δl) is the voltage distribution curve of the through-line min +Δl position point corresponding to the amplitude, ξ(T min ) is the voltage distribution curve of the through-line min The amplitude corresponding to the position point, ξ(T min -Δl) is the voltage distribution curve of the through-line min -Δl position point corresponding to the amplitude, k R is the right difference change factor of the reference node, k L is the left difference change factor of the reference node, Δl is the step size, T min It is the position point corresponding to the reference node on the line voltage distribution curve of the through line, the horizontal coordinate of the line voltage distribution curve of the through line is the distance corresponding to each node on the main branch line, and the vertical coordinate is the absolute difference between the terminal voltage calculation value corresponding to each node on the main branch line and the terminal voltage measurement value corresponding to each node.

2. The method according to claim 1, wherein The method of dividing the branch lines in the topological network of the distribution network into main branch lines and auxiliary branch lines includes: The branch line with the largest number of nodes in the distribution network topology is regarded as the main branch line, and the branch line other than the main branch line and containing one or more section lines is regarded as the secondary branch line.

3. The method according to claim 1, wherein The calculation formula of the terminal voltage calculation value corresponding to the node on the main branch line is as follows: In the above formula, is the calculated value of the terminal voltage corresponding to the nth node, is the calculated voltage value of the nth node, z i is the impedance from the i-1th node to the i-th node, is the current between the i-1th node and the i-th node, and N is the total number of nodes on the main branch line.

4. The method according to claim 3, wherein The voltage calculation value of the nth node is calculated as follows: In the above formula, is the initial voltage.

5. The method according to claim 4, wherein The calculation formula of the current between the i-1th node and the i-th node is as follows: In the above formula, is the initial current, y1 is the admittance of the starting node, y x-1 is the admittance from the i-2th node to the i-1th node, y x is the admittance from the x-1th node to the xth node, Y sub is the admittance matrix of the main branch line, Calculate the voltage of the x-th node.

6. The method according to claim 1, wherein The step of selecting a reference node according to an absolute difference between a calculated terminal voltage value corresponding to a node on the main branch line and a measured terminal voltage value corresponding to the node includes: The node with the smallest absolute difference between the corresponding terminal voltage calculation value and the corresponding terminal voltage measurement value is selected as the reference node.

7. The method according to claim 1, wherein The determining of the fault section based on the difference change factor of the reference node includes: Step 1: When the reference node is a T-type node, if k R >0 and k L <0, the fault section is located on the secondary branch line connected to the reference node; otherwise, the fault section is located on the main branch line where the reference node is located. When the reference node is not a T-node, the fault section is located on the main branch line where the reference node is located; Step 2 When k R <0 or k L <0, the fault section is the section between the reference node on the branch line where it is located and the next node in the positive direction of the current. R >0 or k L When >0, the fault section is the section between the reference node on the branch line where it is located and the previous node of the reference node in the positive direction of the current.

8. The method according to claim 1, wherein The preset points in the fault section are equally spaced, and the difference change factor of the preset points in the fault section is the absolute difference between the terminal voltage calculation value corresponding to each preset point in the fault section and the terminal voltage measurement value corresponding to each preset node.

9. A device for locating a distribution network fault based on power frequency wide area information according to any one of claims 1 to 8, characterized in that: The device comprises: A division module, used for dividing branch lines in the topological network of the distribution network into main branch lines and auxiliary branch lines; A first calculation module is configured to select a reference node based on an absolute difference between a calculated terminal voltage value corresponding to a node on a main branch line and a measured terminal voltage value corresponding to the node, and calculate a difference change factor of the reference node; a determination module, configured to determine a fault section based on a difference change factor of the reference node; The second calculation module is used to calculate the difference change factor of each preset point in the fault section, and select the preset point with the smallest difference change factor as the fault point.

10. A storage device storing a plurality of program codes, characterized in that: The program code is suitable for being loaded and run by a processor to execute the power frequency wide area information-based distribution network fault location method according to any one of claims 1 to 8.

11. A control device comprising a processor and a storage device, wherein the storage device is adapted to store a plurality of program codes, wherein: The program code is suitable for being loaded and run by the processor to execute the power frequency wide area information-based distribution network fault location method according to any one of claims 1 to 8.

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