A method for locating line induced lightning

Abstract

The application relates to a line induced lightning positioning method and belongs to the technical field of power system relay protection. When lightning strikes near a power transmission line, first, power transmission line electric field data are extracted through the measuring points arranged on each tower to form a power transmission line electric field change data set, and the data are screened by using extension fusion. The effective data are screened out, and a new type of induced lightning positioning method is used for lightning positioning calculation. The new type of induced lightning positioning method can exclude induced lightning overvoltage interference data and improve the accuracy of the calculation result.

Description

Technical Field

[0001] This invention relates to a method for locating induced lightning on power lines, belonging to the field of power system relay protection technology. Background Technology

[0002] Lightning discharge is a long-gap discharge phenomenon. Below the cloud layer, corona discharge first occurs, which then transforms into a streamer. When the streamer reaches a certain temperature, a leader forms. The leader originates in the cloud and gradually develops towards the ground, eventually forming a lightning discharge channel. The process of lightning striking a ground object is generally considered to involve the convergence of an upward and downward leader to form a lightning channel, followed by the first return stroke. After the first return stroke, there are usually 2 to 4 subsequent return strokes, with an average time difference of approximately 60 milliseconds between each stroke.

[0003] Currently, in the analysis methods of transmission lines, such as electrical geometric models, it is often assumed that the lightning channel is a single discharge channel perpendicular to the ground. However, this assumption is overly simplistic. In reality, lightning in nature usually involves multiple impact points, i.e., it exhibits a branching phenomenon. Multi-point lightning strikes have a serious impact on transmission lines. When a lightning strike occurs near a transmission line, induced lightning overvoltages are generated. Induced lightning overvoltages refer to the instantaneous overvoltage phenomenon in the power system caused by changes in the electromagnetic field near the lightning channel during the lightning discharge process. This overvoltage is usually caused by the instantaneous current generated during the lightning discharge, which induces a high voltage on the transmission line. In multi-point lightning, different return strikes in a single lightning event may hit different ground objects sequentially or simultaneously.

[0004] In the event of multiple lightning strikes, induced lightning overvoltages can have various adverse effects on the power system, including equipment damage, line interruptions, operational risks, data loss, and economic losses. High-voltage pulses can damage equipment such as insulators and transformers, causing equipment failures and outages, thereby affecting the continuity and stability of power supply. Furthermore, overvoltage events may cause line tripping or interruptions in the power system, leading to power outages and disruptions to production and daily life for users. Operational risks and data loss may also occur, creating difficulties in the operation and management of the power system, resulting in economic losses. Therefore, effective prevention and control of induced lightning overvoltages are crucial, including the implementation of appropriate protective devices, insulation measures, grounding systems, and regular inspection and maintenance of the health status of power system equipment. Summary of the Invention

[0005] This invention relates to a method for locating induced lightning strikes on power lines, belonging to the field of power system relay protection technology. When a lightning strike point is within a certain distance from a transmission line, lines closer to the strike point will experience induced overvoltages. The most obvious characteristic is a significant voltage increase and a change in the electric field on the transmission line. Therefore, when a lightning strike occurs near a transmission line, the electric field data of the transmission line is first extracted through measuring points set on each tower, forming a data set of electric field changes in the transmission line. Extension fusion is then used to filter the data. Valid data is selected, and a novel induced lightning strike location method is applied to calculate the lightning strike location.

[0006] The specific steps are as follows:

[0007] Step 1: When a lightning strike occurs near the transmission line, the electric field data of the transmission line is extracted through the measuring points set on each tower to form a set of electric field change data of the transmission line;

[0008] Step 2: Perform extension fusion on the electric field data of transmission lines and filter out effective electric field data; including: establishing a matter-element model, calculating the extension correlation function, determining the feature weight coefficients, calculating the data correlation confidence, and filtering effective data.

[0009] Step 3: Use the valid data to perform positioning calculations to finally obtain the location of the lightning strike point; this includes: calculating the direction angle between the lightning strike point and the measurement point based on the valid data, using geometric methods to calculate the straight-line distance between the measurement point and the lightning strike point, and finally calculating the latitude and longitude of the lightning strike point.

[0010] The specific steps of Step 1 are as follows:

[0011] Electric field meters are installed on transmission line towers to monitor changes in the electric field data of the transmission line, centered on the tower. Assume that lightning strikes the transmission line near the (i-1)th and ith measuring points. At the moment of the lightning strike, each measuring point collects a set of electric field strength data, i.e., the electric field strength value E = [E1, E2, E3, ..., E...]. n ].

[0012] The specific steps of Step 2 are as follows:

[0013] Step 2.1: Use the extension fusion algorithm to determine the three elements of the matter element. That is, the set of lines whose electric field may be affected by nearby lightning strike points, I = {I1, I2, ..., I...} n}, where I1, I2, ..., I n Let transmission lines 1 to n be represented. The set of characteristics for each element is C = {C1 C2}, where characteristic C1 is the component E of the induced electric field change of each line. dcFeature C2 is the correlation coefficient Q between the positional distances of each measuring point. The determination of the measurement range of each feature should satisfy the condition that the feature value of the faulty line is within the determined measurement range, while the feature value of the healthy line is outside the determined measurement range.

[0014] Step 2.2: Let E dc,i E dc,j E dc,k Let be the induced electric field variation components of any three adjacent transmission lines. Based on the characteristics of the lightning-induced electric field variation components, when the lightning strike point is not at the line intersection, the domain of this characteristic regarding the lightning-induced electric field variation components should be divided into two parts:

[0015] (1) If E dc,i >E dc,j +E dc,k If this condition is not met, then the lightning strike point is not within the measurement area. In this case, the domain of the characteristic component of the change in the lightning-induced electric field is V. i11 for

[0016] V i11 = < E dc,i +0.5E dc,k E dc,i +0.5E dc,j >

[0017] (2) If E dc,i >E dc,j +E dc,k If this condition is met, then a lightning strike occurs near line i. In this case, the domain V representing the characteristic of the change component of the lightning-induced electric field is... i12 for

[0018] V i12 = < E dc,i -0.5E dc,j E dc,i +0.5E dc,k >

[0019] Step 2.3: Let Q max Q,Q set These represent the position coefficients of the measuring point where the maximum electric field change component is measured, the position coefficients of the measuring point where any electric field change component is measured, and the difference in the position coefficients of the measuring points. Based on the characteristic analysis of transmission lines when the lightning strike point is located at the junction of two line segments, it can be seen that when the lightning strike point is located at the junction of two line segments, the domain for determining the actual range of the lightning strike point should also be divided into two parts, namely…

[0020] (1) If Q max -Q<Q set =1 is not true, indicating a multi-point mine. Therefore, the range V of the correlation coefficient between the distances of the measuring points is... i21 for

[0021] V i21 = <Q set ,1.2>

[0022] (2) If Q max -Q<Q set If = 1 holds true, then the line corresponding to Q is an invalid line. In this case, the range of the correlation coefficient between the measurement point location and distance is V. i22 for

[0023] V i22 = < 0, Q set >

[0024] Step 2.4: Assuming a lightning strike causes a change in the induced electric field of the i-th transmission line, establish the corresponding matter-element model.

[0025]

[0026] In the formula, R i For the matter-element model of the i-th line, V ij = < n ij ,m ij > For line i faults, regarding feature C j The allowed range of values ​​(i = 1, 2, ..., n; j = 1, 2).

[0027] Step 2.5: Divide the domain of each feature into two parts according to the value of the feature, namely the domain V of feature C1. i11 and V i12 The range of characteristic C2 is V. i21 and V i22 Based on the quantity range and fault characteristics of each faulty line, the section range V′ is determined. ij = < c ij ,d ij >for

[0028] V′ i11 = < E dc,i +E dc,k E dc,i +E dc,j >

[0029] V′ i12 = < E dc,i -E dc,k E dc,i +E dc,j >

[0030] V′ i21 = <Q set ,1>

[0031] V′ i22 = < 0, Q set>

[0032] Step 2.6: Calculate the correlation function value

[0033]

[0034] In the formula, For point v tj With interval V ij The distance represents the positional relationship between the actual fault characteristic value and the determined measurement range. tj For any point V in the real field (-∞, +∞), ij = < n ij ,m ij > represents any interval in the real domain, μ ij (v tj ) for v tj Regarding interval V ij , V′ ij The correlation function.

[0035] When μ ij (v tj When )≤-1, it means v tj Not belonging to V ij When -1 < μ ij (v tj When v < 0, it is called an extensional field, representing v. tj There is still a chance for V. ij And the larger the value, the better v tj The easier it is to convert to V ij middle.

[0036] Step 2.7: Determine the weighting coefficients. In the case of a single-point lightning strike, the method of selecting the line using the change component of the induced electric field is preferred. In the case of multiple-point lightning strikes, the method of selecting the line using the distance between the measuring points is preferred. The two methods have the same weight, according to τ=E. t -E d Weights are assigned to the components of the lightning-induced electric field variation data.

[0037] Where E t E represents the electric field value of the transmission line at the moment of lightning strike. d Let τ be the electric field value of the transmission line during normal operation, and τ be the difference in electric field between the two times.

[0038] Step 2.8: Calculate the correlation confidence level of the circuit to be affected by the lightning strike and thus overvoltage.

[0039]

[0040] When line i's v tj In the interval < n ij ,m ij >Internal time μij (v tj )≥0, that is, ξ(I) i If )≥0, it indicates that line i has characteristic C j Under the given conditions, if the correlation confidence level is within the range, it is determined that there was a lightning strike near the line; otherwise, μ ij (v tj ) < 0, that is, ξ(I) i If ) < 0, it indicates that the line is in characteristic C j If the correlation confidence level is not within the range, it is determined that there was no lightning strike near the line.

[0041] The specific steps of Step 3 are as follows:

[0042] Step 3.1: Calculate the azimuth of the lightning strike point relative to the measuring point based on the effective electric field change components obtained from the extension fusion.

[0043]

[0044] Where α is the azimuth angle of the lightning strike point relative to the measuring point, with the measuring point as the center, and E min E is the minimum value of the effective electric field variation component. max This represents the maximum value of the effective electric field variation component.

[0045] Step 3.2: Assuming a lightning strike occurs near location A, the latitude and longitude of the lightning strike location can be calculated based on the distance and angle between point A and the lightning strike point. The mathematical expression for this calculation is as follows:

[0046]

[0047] Latitude in the formula i+1 Longitude represents the latitude of the (i+1)th point. i+1 lat represents the longitude of the (i+1)th point. i Let represent the latitude of the i-th point, d represent the straight-line distance from point A to the lightning strike point, R represent the radius of the Earth (taken as 6371 km), and θ represent the angle between point A and the lightning strike point, with due north as the positive direction and clockwise angle as the positive angle, calculated using radians.

[0048] The beneficial effects of this invention are:

[0049] 1) This invention proposes a novel method for locating lightning strikes by filtering and calculating the electric field data of transmission lines during a lightning strike to determine the location of the lightning strike point.

[0050] 2) This invention can eliminate interference data from induced lightning overvoltage, thereby improving the accuracy of calculation results. Attached Figure Description

[0051] Figure 1This is a flowchart of the line-induced lightning location method of the present invention. Detailed Implementation

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

[0053] Example: Using COMSOL to model transmission lines and lightning strikes, a method for locating line-induced lightning is presented. Table 1 shows the simulation model parameters.

[0054] Table 1 Simulation Model Parameters

[0055]

[0056] An omnidirectional electric field meter is placed on each tower to measure the electric field distribution on the transmission line. The electric field meter is located at the junction of two transmission lines, and the electric field value of the transmission line is measured within a 5m radius of the tower.

[0057] This embodiment will use the electric field data collected from four towers, #1 to #4, as an example. Figure 1 As shown, the specific steps are as follows:

[0058] Step 1: Assume the transmission line is struck by lightning near the 2nd and 4th measuring points. At the time of the lightning strike, each measuring point collects a set of electric field strength data, i.e., the electric field strength value E = [E1, E2, E3, ..., E...]. n As shown in Table 2.

[0059] Table 2. Electric field data of the transmission line collected at various measuring points when lightning strikes occurred near the transmission line.

[0060]

[0061] Step 2: Perform extension fusion on the data and filter out the effective data for calculation.

[0062] Step 2.1: Use the extension fusion algorithm to determine the three elements of the matter element. This involves the set of lines that may be affected by changes in the electric field caused by nearby lightning strikes, I = {I1, I2, I3, I4}, where I1, I2, I3, and I4 represent transmission lines 1 to 4. The feature set of each element is C = {C1 C2}, where feature C1 is the induced electric field change component E of each line. dc Feature C2 is the correlation coefficient Q between the positional distances of each measuring point. The determination of the measurement range of each feature should satisfy the condition that the feature value of the faulty line is within the determined measurement range, while the feature value of the healthy line is outside the determined measurement range.

[0063] Step 2.2: Let E dc,i E dc,j E dc,kFor any three adjacent transmission lines, the domain for determining the characteristic of the induced electric field variation components of lightning strikes should be divided into two parts:

[0064] (1) If E dc,i >E dc,j +E dc,k If this condition is not met, then the lightning strike point is not within the measurement area. In this case, the domain of the characteristic component of the change in the lightning-induced electric field is V. i11 for

[0065] V i11 = < E dc,i +0.5E dc,k E dc,i +0.5E dc,j >

[0066] (2) If E dc,i >E dc,j +E dc,k If this condition is met, then a lightning strike occurs near line i. In this case, the domain V representing the characteristic of the change component of the lightning-induced electric field is... i12 for

[0067] V i12 = < E dc,i -0.5E dc,j E dc,i +0.5E dc,k >

[0068] Step 2.3: Let Q max Q,Q set These are the position coefficients of the measuring point where the maximum electric field change component is measured, the position coefficients of the measuring point where any electric field change component is measured, and the difference in the position coefficients of the measuring points. The domain for determining the characteristic of the actual range of the lightning strike point is divided into two parts:

[0069] (1) If Q max -Q<Q set =1 is not true, indicating a multi-point mine, and the range of the correlation coefficient between the measurement point location and distance is V. i21 for

[0070] V i21 = <Q set ,1.2>

[0071] (2) If Q max -Q<Q set If = 1 holds true, then the line corresponding to Q is an invalid line. In this case, the range of the correlation coefficient between the measurement point location and distance is V. i22 for

[0072] V i22 = < 0, Q set>

[0073] Step 2.4: Establish the corresponding matter-element model

[0074]

[0075] In the formula, R i For the matter-element model of the i-th line, V ij = < n ij ,m ij > For line i faults, regarding feature C j The allowed range of values ​​(i = 1, 2, 3, 4; j = 1, 2).

[0076] Step 2.5: Divide the domain of each feature into two parts according to the value of the feature, namely the domain V of feature C1. i11 and V i12 The range of characteristic C2 is V. i21 and V i22 Based on the quantity range and fault characteristics of each faulty line, the section range V′ is determined. ij = < c ij ,d ij >for

[0077] V′ i11 = < E dc,i +E dc,k E dc,i +E dc,j >

[0078] V′ i12 = < E dc,i -E dc,k E dc,i +E dc,j >

[0079] V′ i21 = <Q set ,1>

[0080] V′ i22 = < 0, Q set >

[0081] Step 2.6: Calculate the correlation function value

[0082]

[0083] In the formula, For point v tj With interval V ij The distance represents the positional relationship between the actual fault characteristic value and the determined measurement range. tj For any point V in the real field (-∞, +∞), ij = < n ij,m ij > represents any interval in the real domain, μ ij (v tj ) for v tj Regarding interval V ij , V′ ij The correlation function.

[0084] When μ ij (v tj When )≤-1, it means v tj Not belonging to V ij When -1 < μ ij (v tj When v < 0, it is called an extensional field, representing v. tj There is still a chance for V. ij And the larger the value, the better v tj The easier it is to convert to V ij middle.

[0085] Step 2.7: Determine the weighting coefficients. In the case of a single-point lightning strike, the method of selecting the line using the change component of the induced electric field is preferred. In the case of multiple-point lightning strikes, the method of selecting the line using the distance between the measuring points is preferred. The two methods have the same weight, according to τ=E. t -E d Weights are assigned to the components of the lightning electric field variation data.

[0086] Where E t E represents the electric field value of the transmission line at the moment of lightning strike. d Let τ be the electric field value of the transmission line during normal operation, and τ be the difference in electric field between the two times.

[0087] Step 2.8: Calculate the correlation confidence of the line to be affected by lightning and generated overvoltage. The results are shown in Table 3.

[0088]

[0089] When line i's v tj In the interval < n ij ,m ij >Internal time μ ij (v tj )≥0, that is, ξ(I) i If )≥0, it indicates that line i has characteristic C j Under the given conditions, if the correlation confidence level is within the range, it is determined that there was a lightning strike near the line; otherwise, μ ij (v tj ) < 0, that is, ξ(I) i If ) < 0, it indicates that the line is in characteristic C j If the correlation confidence level is not within the range, it is determined that there was no lightning strike near the line.

[0090] Table 3 Confidence level of electric field data for transmission lines

[0091]

[0092] The confidence level of the data obtained by extension fusion is shown in Table 4: one lightning strike occurred near the transmission line between tower #1 and tower #2, and the other lightning strike occurred between tower #3 and tower #4. The change in electric field on the transmission line between tower #2 and tower #3 was caused by the lightning strike between tower #1 and tower #2, which is interference data.

[0093] Table 4 shows the effective electric field data after extension fusion filtering.

[0094]

[0095] Step 3.1: Based on the effective electric field change components obtained from the extension fusion, calculate the azimuth angle between the lightning strike point and the measuring point. The location of the lightning strike point can be determined using the azimuth angles of the two measuring points through a geometric method.

[0096]

[0097] Where α is the azimuth angle of the lightning strike point relative to the measuring point, with the measuring point as the center, and E min E is the minimum value of the effective electric field variation component. max This represents the maximum value of the effective electric field variation component.

[0098] Substituting the data from towers #1 and #2 into the formula, we obtain the azimuth angle of the first lightning strike point relative to towers #1 and #2 as follows:

[0099]

[0100] Substituting the data from towers #3 and #4 into the formula, we obtain the azimuth angles of the second lightning strike point relative to towers #3 and #4 as follows:

[0101]

[0102] After obtaining the azimuth data, the distance from the lightning strike point to point A was measured to be 102m using a geometric method, and the azimuth angle was 11.309 degrees.

[0103] Step 3.2: Assuming a lightning strike occurs near location A, the latitude and longitude of the lightning strike location can be calculated based on the distance and angle between point A and the lightning strike point. The mathematical expression for this calculation is as follows:

[0104]

[0105] Latitude in the formula i+1 Longitude represents the latitude of the (i+1)th point. i+1lat represents the longitude of the (i+1)th point. i Let represent the latitude of the i-th point, d represent the straight-line distance from point A to the lightning strike point, R represent the radius of the Earth (taken as 6371 km), and θ represent the angle between point A and the lightning strike point, with due north as the positive direction and clockwise angle as the positive angle, calculated using radians.

[0106] Assuming the coordinates of point A are 22.5426°N 113.9461°E and the coordinates of point B are 22.5439°N 113.9461°E, converting the coordinates of point A to radians gives 0.3934 and 1.9887.

[0107]

[0108] We obtain Latitude2 = 0.393458 = 22.5435°

[0109]

[0110] We obtain Longitude² = 1.9887383 = 113.9463°

[0111] Therefore, the latitude and longitude of the lightning strike point are 22.5435°N 113.9463°E. Similarly, the latitude and longitude of the other lightning strike point are calculated to be 22.5458°N 113.9468°E.

Claims

1. A method for locating line-induced lightning, characterized in that, Includes the following steps: Step 1: When a lightning strike occurs near the transmission line, the electric field data of the transmission line is extracted through the measuring points set on each tower to form a set of electric field change data of the transmission line; Step 2: Perform extension fusion on the electric field data of transmission lines and filter out effective electric field data; including: establishing a matter-element model, calculating the extension correlation function, determining the feature weight coefficients, calculating the data correlation confidence, and filtering effective data. Step 3: Use the valid data to perform positioning calculations to finally obtain the location of the lightning strike point; including: calculating the direction angle between the lightning strike point and the measurement point based on the valid data, using geometric methods to calculate the straight-line distance between the measurement point and the lightning strike point, and finally calculating the latitude and longitude of the lightning strike point. The specific steps of Step 2 are as follows: Step 2.1: Use the extension fusion algorithm to determine the three elements of the matter element, namely the set of lines whose electric field may be affected by changes caused by nearby lightning strike points. ,in Indicates transmission line The set of characteristics of all things ,feature The components of the induced electric field change in each line ,feature The correlation coefficient between the location distances of each measuring point ; Step 2.2: Set For any three adjacent transmission lines, the induced electric field variation components are defined. When the lightning strike point is not at the line intersection, the domain of this characteristic component of the induced electric field variation is divided into two parts: (1) If If this condition is not met, then the lightning strike point is not within the measurement area. In this case, the domain of the characteristic component of the change in the lightning-induced electric field is... for: ； (2) If If established, then the line A lightning strike occurs nearby. What is the domain of the characteristic component of the change in the lightning-induced electric field at this time? for: ； Step 2.3: Set These are, respectively, the position coefficient of the measuring point for the maximum electric field change component, the position coefficient of the measuring point for any electric field change component, and the difference in the position coefficients of the measuring points; when the lightning strike point is located at the junction of two line segments, the domain of measurement for the actual range of the lightning strike point is divided into two parts, namely... (1) If This is not valid; it is a multi-point mine. Therefore, the domain of the correlation coefficient between the distances of the measuring points is... for: ； (2) If If it is established, then The corresponding line is an invalid line, and at this time, the range of the characteristic related to the distance correlation coefficient of the measuring point location is... for: ； Step 2.4: Assume the transmission line is... A lightning strike caused a change in the induced electric field on the line, and a corresponding matter-element model was established: ； In the formula, For the reason about the The matter-element model of the line, For the line Fault characteristics Allowable range ( ; ); Step 2.5: Divide the domain of each feature into two parts according to the value of the feature, namely, the domain of the feature. The range and Regarding features The range is and Based on the quantity range and fault characteristics of each faulty line, determine the section range. for: ； ； ； ； Step 2.6: Calculate the correlation function value ； In the formula, For point and interval The distance is the positional relationship between the actual fault characteristic value and the determined measurement range; For real domain any point on, For any interval in the real field, for Regarding the interval , The correlation function; when When, it means Not belonging to ;when When the time is right, it is called an extensional region, which represents There is still a chance to belong And the larger the value, The easier it is to convert to middle; Step 2.7: Determine the weighting coefficients. For single-point lightning strikes, use the lightning-induced electric field change component selection method; for multi-point lightning strikes, use the measurement point distance method. Weights are assigned to the components of the lightning-induced electric field variation data; whereby The electric field value of the transmission line at the moment of lightning strike. This represents the electric field value of the transmission line during normal operation. The difference in electric field of the transmission line at two different times; Step 2.8: Calculate the correlation confidence level of the circuit to be affected by the lightning strike and thus subjected to overvoltage. ； When the line of In the interval At that time, ,Right now This indicates the line In features Under the given conditions, if the correlation confidence level is within the range, it is determined that there was a lightning strike near the line; otherwise... ,Right now This indicates that the line has characteristics If the correlation confidence level is not within the range, it is determined that there was no lightning strike near the line.

2. The method for locating line-induced lightning according to claim 1, characterized in that, The specific steps of Step 1 are as follows: Electric field meters are installed on transmission line towers to monitor changes in the electric field data of the transmission line, centered on the towers. Assume the transmission line... The and the first A lightning strike occurred near each measuring point, and a set of electric field strength data, i.e., electric field strength values, was collected at each measuring point at the time of the strike. .

3. The method for locating line-induced lightning according to claim 1, characterized in that, The specific steps of Step 3 are as follows: Step 3.1: Calculate the azimuth of the lightning strike point relative to the measuring point based on the effective electric field change components obtained from the extension fusion. ； in The azimuth angle of the lightning strike point relative to the measuring point is the measuring point. For the minimum effective electric field variation component, This represents the maximum value of the effective electric field variation component; Step 3.2: Assuming a lightning strike occurs near location A, the latitude and longitude of the lightning strike location can be calculated based on the distance and angle between point A and the lightning strike point. The mathematical expression for this calculation is as follows: ； ； In the formula Indicates the first The latitude of each point Indicates the first The longitude of each point Indicates the first The latitude of each point This represents the straight-line distance from point A to the point of lightning strike. Represents the radius of the Earth. Let A be the angle between point A and the point of lightning strike, with due north as the positive direction and clockwise angle as the positive angle, calculated using radians.

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