Transition resistance-resistant semi-decoupling multi-terminal differential line fault positioning and distance measuring method

Abstract

The invention discloses an anti-transition resistance semi-decoupling multi-terminal differential line fault positioning and distance measuring method, belongs to the field of power system relay protection, and solves the problems of complex calculation, weak anti-transition resistance and difficult equipment upgrading caused by multi-terminal data coupling in the existing method. The method comprises the following steps: S1, calculating a distance ratio based on local side voltage and current, and preliminarily positioning a fault branch; s2, constructing an equation containing transition resistance R and fault impedance ZL-1, and generating a transition resistance matrix r and a fault impedance matrix z (dimensionality is adaptive to CPU computing power); s3, denoising through a Hankel matrix and singular value decomposition to obtain an accurate sequence; and S4, verifying the sequence consistency within 20-40ms after the fault, and outputting a result or repositioning. The method is free of iteration and high in transition resistance resistance, the complexity is linearly improved along with the number of T-connection terminals, hardware computing power and old equipment upgrading are adapted, and the method is suitable for a new energy T-connection multi-terminal network.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power system relay protection technology, in particular to a kind of anti-transition resistance's semi-decoupling multi-terminal differential line fault positioning and ranging method, especially for high-precision positioning demand in large transition resistance scene, it can realize the linear matching of calculation complexity and end number, adapt to old equipment upgrading and multi-terminal network expansion. BACKGROUND

[0002] Wind power, photovoltaic and other new energy generation projects are connected to the main grid in large scale through public tie lines in T-connection mode, forming a complex network structure of multi-terminal power supply. In this kind of network, multi-terminal differential line relay protection products have become the main supporting protection application scheme for multi-terminal transmission lines due to their natural good selectivity, speed and sensitivity, and the accuracy of fault positioning and ranging directly determines the fault troubleshooting efficiency and power grid recovery speed.

[0003] Currently, the ranging algorithm of multi-terminal differential line protection mainly includes two directions based on traveling wave principle and fault steady-state component: 1. Traveling wave ranging method: high-frequency transient traveling wave signals generated at the moment of fault and propagating to each end of the line are used to record the time difference of traveling wave front arriving at each end through high-precision synchronous clock (such as Beidou satellite navigation system), and the fault location is calculated based on the constant wave speed principle. This method is based on high-frequency transient signals, which is theoretically independent of power characteristics, can effectively overcome the problem of weak inverter feeding, and has high ranging accuracy. However, it has significant defects: high requirements for sampling rate and time synchronization accuracy, large amount of calculation; in the case of large transition resistance fault, the traveling wave signal is weak and difficult to capture, resulting in ranging failure; and it needs to configure a separate traveling wave ranging special product, which has high equipment cost and is difficult to integrate with existing multi-terminal differential protection devices.

[0004] 2. Fault steady-state component ranging method: the fault voltage and current after fault are used to calculate the fault location based on the line distribution parameter model, which can be integrated with multi-terminal differential protection devices without additional hardware cost. However, the traditional fault steady-state component ranging method has the following principle limitations: (1) Single-end and double-end ranging method: as the fault point may be located at any branch of the multi-terminal line, it is difficult to determine the fault branch reliably, resulting in large error in ranging result and difficulty in meeting the needs of multi-terminal network; (2) Algorithm based on node impedance matrix: based on the node impedance matrix in circuit theory, the system node impedance model containing fault line is established to realize ranging, but the calculation process needs to traverse all possible fault branches, resulting in high calculation complexity, and the adaptability decreases sharply with the increase of the number of multi-terminal lines; (3) High-precision iterative method: based on the distributed parameter model of the line, the theoretical ranging accuracy is the highest, but the calculation process is complex, time-consuming, and depends on high-precision line parameters (such as resistance, reactance, and admittance) and full branch measurement data, the data coupling is strong, and the calculation amount increases exponentially with the increase of the number of terminals, which cannot meet the demand of rapid fault location.

[0005] In summary, the existing multi-terminal differential line fault location technology has the following core problems: multi-terminal data coupling leads to complex calculation, and with the increase of the number of multi-terminal differential terminals, the calculation complexity increases exponentially, and it is greatly affected by the transition resistance, and the ranging accuracy is significantly reduced in the case of large transition resistance; the secondary problem: the high calculation complexity leads to difficulty in upgrading the existing equipment, and when new multi-terminal lines are added, the protection and ranging equipment related to them need to be replaced, increasing the cost and period of power grid transformation.

[0006] To solve the above problems, the present application provides a semi-decoupled multi-terminal differential line fault location and ranging method with anti-transition resistance, which reduces the calculation complexity while ensuring the ranging accuracy through the semi-decoupled data processing logic and linear calculation method, and improves the adaptability of multi-terminal network and the convenience of equipment upgrade. SUMMARY

[0007] The purpose of the present application is to overcome the defects of the existing multi-terminal differential line fault location method, such as "multi-terminal data coupling leading to complex calculation, weak anti-transition resistance ability, and difficulty in equipment upgrade", and to provide a semi-decoupled multi-terminal differential line fault location and ranging method with anti-transition resistance.

[0008] To solve the above technical problems, the technical scheme of the present application is as follows: A semi-decoupled multi-terminal differential line fault location and ranging method with anti-transition resistance, comprising the following steps: S1: preliminary fault location, each side device in the multi-terminal differential line performs single-end fault assumption steady-state fault ranging based on the local voltage and current, calculates the ranging ratio, and the ranging ratio is defined as the ratio of the preliminary ranging length l n to the full length L n of the local line branch; select the line branch corresponding to the minimum ranging ratio, if the minimum ranging ratio is less than 1, preliminarily determine that the fault occurs in the line branch, and it is a metallic fault or a small transition resistance fault; if there is no need to improve the ranging accuracy or the hardware CPU computing power is limited, directly output the ranging result of the preliminary location, otherwise go to step S2; S2: anti-transition resistance correction using multi-terminal data, based on the power system analysis theory, construct a solving equation containing transition resistance R and impedance Z L-1 from the fault point to the local side, generate multiple groups of (R, Z L-1) the calculated values are respectively arranged into a transition resistance matrix r and a fault impedance matrix z with a dimension of 1x3k, where k is the number of sampling points, and the matrix dimension can be flexibly adjusted according to the hardware CPU processing capability; S3: singular spectrum analysis is introduced for denoising and accurate estimation, based on the transition resistance matrix r and the fault impedance matrix z obtained in step S2, an m*n order Hankel matrix H is constructed, satisfying N=3k=m+n-1 and m<=n; singular value decomposition is performed on the Hankel matrix H, and the original signal is decomposed into a linear superposition of multiple sub-signals, where the singular values are σ1 to σ m are sorted in descending order; a large interference lower bound p and a small interference upper bound q are selected according to the 90% confidence interval of the transition resistance mean value, the singular values greater than p are scaled to remove power system transient large noise, and the singular values less than q are set to zero to remove sampling small noise; inverse transformation is performed on the denoised matrix to obtain accurate transition resistance sequences and fault distance impedance sequences, the fault distance impedance sequences including resistance components and reactance components of the fault impedance; S4: verification of the reliability of the distance measurement result, accurate transition resistance sequences and fault distance impedance sequences within 20ms-40ms after the fault occurs are selected as the data to be verified, if the fault current duration is short, the accurate sequences before the current is disconnected are selected; a variance statistical method is used to verify the consistency of the data to be verified, if the consistency meets a preset threshold, the transition resistance and the fault distance corresponding to the sequence are output as the final result; if the consistency does not meet the preset threshold, it is determined that the minimum distance measurement ratio selected in step S1 corresponds to a non-fault branch of the branch, the branch corresponding to the second minimum distance measurement ratio is selected, and steps S2-S4 are repeated until a sequence with consistent consistency meeting the preset threshold is obtained; When the fault occurs on the common tie line of the multi-terminal differential line, steps S2-S4 are repeated, only the line parameters for solving the equation in step S2 are replaced by the impedance parameters of the common tie line, and the positioning and distance measurement of the tie line fault are completed; when the number of T-connected out-line branch terminals of the multi-terminal differential line increases, the basic form of the equation for solving in step S2 is kept unchanged, only the equation corresponding to the new out-line branch power current is added, and the operation logic of subsequent steps S3-S4 remains the same.

[0009] Preferably, in step S2, the different equation combinations are constructed based on the measurement parameters of the local side and the opposite side of the multi-terminal differential line, and specifically include at least one of the three types of combinations of "local side current-local side voltage", "local side current-opposite side current", and "local side voltage-opposite side voltage", each combination independently generates a group of (R, Z L-1 ) calculated values, and the number of equation combinations can be flexibly adjusted to 2 groups, 3 groups or more groups according to the hardware CPU computing power.

[0010] Preferably, in step S4, the statistical method of consistency verification further includes any one of the mean deviation method and the standard deviation method, and when the replacement variance statistical method is used, the corresponding consistency preset threshold needs to be adjusted synchronously.

[0011] Preferably, in step S3, when the Hankel matrix H is constructed, the value ratio of m to n is 1:2-1:3, and the value range of m is 5-15.

[0012] Preferably, in step S1, the single-end fault hypothesis steady-state fault measurement distance adopts a fault measurement distance algorithm based on a line lumped parameter model, and the calculation error of the algorithm is controlled within 5%.

[0013] Preferably, in step S2, the value range of the number of sampling points k is 3-10, and the time interval of each sampling point is 2ms-5ms.

[0014] Preferably, when the number of T-connected line branch ends of the multi-terminal differential line is expanded from 4 to N (N≥5), the number of equations for solving the equation in step S2 is increased to N-1, the dimensions of the matrix r and the matrix z are expanded to 1×(N-1)k, and the calculation complexity is linearly improved with the increase of the number of ends.

[0015] Preferably, in step S3, when the singular values are scaled, a linear scaling coefficient is used, and the value of the scaling coefficient is 0.8-1.2.

[0016] Preferably, in step S4, the consistency preset threshold is that the variance of the transition resistance sequence is less than 0.05Ω 2 , the variance of the fault distance impedance sequence is less than 0.1Ω 2 When other consistency verification methods are used, the preset threshold is adapted and adjusted according to the industry standard of the corresponding statistical quantity.

[0017] Preferably, the multi-terminal differential line includes T-connected line branches and a common connection line, the number of the line branches is 2-10, and the number of the common connection lines is 1-3, and the method is suitable for multi-terminal differential lines of different topological scales.

[0018] Compared with the prior art, the beneficial technical effects of the present application at least include any one of the following: 1. Decoupling and cost reduction: breaking through the multi-terminal data coupling bottleneck, using linear calculation without iteration, the complexity is linearly improved with the increase of the number of T-connected line ends, and the algorithm does not need to be reconstructed to adapt to the expansion of the multi-terminal network; the matrix dimension can be flexibly adjusted according to the CPU computing power of the existing equipment, without the need to replace the hardware, facilitating the upgrade of old equipment, and reducing the cost of transformation and expansion.

[0019] 2. Anti-resistance refinement, stable and reliable: through multi-end data combination to generate calculation sequence, combined with singular spectrum analysis denoising, effectively filtering transient and sampling noise, even through large transition resistance fault, still can accurately obtain transition resistance and fault distance data, greatly improve the ranging accuracy; through 20ms-40ms data consistency verification, when inconsistent, automatically switch branch recalculation, strong fault tolerance, reliable result.

[0020] 3. Integrated and convenient, cost-effective: based on fault steady-state quantity calculation, can be integrated with existing multi-end differential protection device, no need to separately configure special equipment, reduce hardware cost and system compatibility risk. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is an embodiment of the application four-terminal power transmission system structure diagram; Figure 2 It is an algorithm flowchart of the application anti-transition resistance semi-decoupling multi-end differential line fault positioning and ranging method. DETAILED DESCRIPTION

[0022] The specific embodiments of the application will be further described below in conjunction with the drawings. It should be noted that the description of these embodiments is used to help understand the application, but does not constitute a limitation on the application. In addition, the technical features involved in the various embodiments of the application described below can be combined with each other as long as they do not conflict with each other.

[0023] In order to better describe the application, first of all, the system topology and parameters are defined as shown in Figure 1 Take four-terminal T-connected line as an example.

[0024] In the figure, the outgoing branch of devices 1~4 to the corresponding node is line 1~4, the common tie line between the two nodes is line 0, and the corresponding line length is L1~L4 and L T , the line impedance is Z1~Z4 and Z T . K1 and K2 are fault points (for convenience, take grounding as an example), R is the assumed fault transition resistance (0 when metallic grounding). The total impedance Z1 of line 1 is divided into two segments by fault point K1, corresponding to Z L-1 and Z L-2 . The total impedance Z T of tie line 0 is divided into two segments by fault point K2, corresponding to Z T-1 and Z T-2 . According to the symmetry theory, fault ranging can be divided into two categories, one is fault K1 on the outgoing branch, and the other is tie line fault K2.

[0025] Referring to Figure 2 , the algorithm process is as follows: 1. Preliminary fault location. After the fault occurs, each side device first calculates the single-end distance of the steady-state fault quantity based on the single-end fault assumption according to the voltage and current on the side (the fault distance algorithm based on the line lumped parameter model is adopted, and the calculation error is controlled within 5%). The distance ratio is calculated in turn , and the distance ratio is defined as , that is, the ratio of the preliminary calculated distance length l n on the side to the full length L n of the outgoing line branch on the side. Considering the minimum distance ratio corresponding to the outgoing line branch (according to the symmetry principle, it is assumed that the line 1), if is less than 1, it can be preliminarily judged that the fault occurs on the corresponding outgoing line branch, and it can be preliminarily determined as a metallic fault or a fault through a small transition resistance. At this time, if higher accuracy is not pursued or the CPU chip computing power of the original platform is limited and cannot be upgraded, the result can be output, otherwise, process 2 is entered.

[0026] 2. Anti-transition resistance correction using multi-terminal data. According to the power system analysis theory, the following formula can be obtained when K1 fault occurs.

[0027] (1) In formula (1), and are the current and voltage phase quantities collected at the installation of the four-terminal protection of T connection. For a multi-terminal differential system, the quantities to be solved in formula (1) are the transition resistance R and the impedance Z L-1 from the fault point to the side, obviously, a plurality of groups (R, Z L-1 ) can be solved by combining different equations in formula (1). This patent solves three pairs of distance values by using "local current-local voltage", "local current-remote current" and "local voltage-remote voltage" three combinations respectively, and arranges them into a 1x3 matrix [R1, R2, R3] and [Z L-1 1, Z L-1 2, Z L-1 3] (in actual application, different combinations can be used according to the CPU chip computing power, and three pairs of distance values are not necessarily used, more or fewer can be used, and the number of equation combinations can be flexibly adjusted to 2 groups, 3 groups or more groups). It should be pointed out that formula (1) can be satisfied within tens of milliseconds after the fault occurs and before the fault is cleared, and each sampling point will output the corresponding matrix r(t) and z(t). Different output points (the value of the sampling point number k is 3-10, and the time interval of each sampling point is 2ms-5ms) can be selected according to the CPU processing capacity, and a 1x3k matrix is formed.

[0028] r = [R1(1), R2(1), R3(1), R1(2), R2(2), R3(2)…R1(k), R2(k), R3(k)] = [R(1), R(2), R(3), R(4)…R(3k-2), R(3k-1), R(3k)] (2) z = [Z L-1 1(1), Z L-1 2(1), Z L-1 3(1), Z L-1 1(2), Z L-1 2(2), Z L-1 3(2)…Z L-1 1(k), Z L-1 2(k), Z L-1 3(k)] = [Z L-1 (1), Z L-1 (2), Z L-1 (3), Z L-1 (4)…Z L-1 (3k-2), Z L-1 (3k-1), Z L-1 (3k)] (3) Since R1~R3 and Z L-1 1~3 are all estimates of the transition resistance and impedance of the same fault point, their physical meanings are consistent, but they are disturbed by the transient process of the power system, sampling noise, etc., and enter process 3.

[0029] 3, introduce singular spectrum analysis method based on Hankel matrix (Hankel Matric) and singular value decomposition (Singular Value Decomposition, SVD) to denoise and estimate the transition resistance sequence r and the fault impedance sequence z, and obtain the final transition resistance and fault distance impedance. Taking the analysis of the transition resistance sequence as an example (the fault distance impedance is divided into resistance and reactance two parts, and the same reason can be obtained), let N = 3k, construct an m x n order Hankel matrix H (N = m + n - 1 and m ≤ n) from formula (2), as shown in formula (4).

[0030] (4) Perform singular value decomposition on the constructed Hankel matrix H, decompose the original signal into linear superposition of sub-signals with different proportions, that is: (5) Where σ1 to σ mSort from large to small, by the larger singular value using linear scaling factor (scaling factor value is 0.8-1.2) scaling, remove the power system transient process and other large noise interference, to the smaller singular value is zero to remove the small noise interference in the sampling signal, finally complete signal denoising, as shown in equation (6).

[0031] (6) In the formula, p is the lower bound of large interference factors, q is the upper bound of small interference factors, and the upper and lower bounds can be selected according to the 90% confidence interval of the calculated transition resistance average. After denoising, the matrix inverse transformation is performed to obtain the accurate transition resistance sequence.

[0032] 4. The reliability of the ranging result is verified. Considering the duration of the transient process and the calculation of the steady-state electrical quantity, the accurate calculation sequence within 20-40 ms after the fault occurs is used as the final output in this patent (if the fault current duration is short, the accurate sequence before the current is disconnected is selected). The sequence should have good consistency, which can be judged by using statistical schemes such as variance (any one of mean deviation method and standard deviation method can also be used, and the corresponding consistency preset threshold value needs to be adjusted synchronously), which is not limited in this patent. The consistency preset threshold value is that the variance of the transition resistance sequence is less than 0.05Ω 2 , and the variance of the fault distance impedance sequence is less than 0.1Ω 2 . If the consistency is poor, it is judged that the outgoing line branch with the smallest ranging ratio selected in process 1 is not the fault occurring branch, and the process is repeated by selecting the second smallest ranging ratio. Until the ranging sequence obtained has good consistency. Note that for some fast action and tripping, the fault current duration is short, and the data before the current is disconnected is used, which does not affect the scheme described in this patent.

[0033] 5. When K2 point fault occurs, similar to the method in 2, the same data sequence can be formed, and the transition resistance and fault distance impedance can also be obtained through singular spectrum analysis, denoising and inverse transformation, which will not be repeated here.

[0034] 6. When the number of outgoing line branches of the T connection line is expanded (such as from 4 to N, N≥5), the basic type of equation (1) remains unchanged, only the current provided by the new power supply is added, and the corresponding equation (the number of equations increases to N-1) is additionally generated, and the subsequent solving method is exactly the same. The dimensions of matrix r and matrix z are expanded to 1×(N-1) k, and the complexity increases linearly with the increase of the number of branches.

[0035] 7. When the multi-terminal differential line contains 2-10 outgoing line branches and 1-3 common tie lines, this method can adapt to the fault location and distance measurement requirements of multi-terminal differential lines with different topologies by adjusting the line parameters in step S2 (such as replacing the tie line impedance parameters when the common tie line fails).

[0036] The embodiments of the present application in conjunction with the drawings are described in detail above, but the present application is not limited to the described embodiments. For those skilled in the art, various changes, modifications, replacements and variations of the embodiments are made without departing from the principles and spirits of the present application, and still fall within the protection scope of the present application.

Claims

1. A method for fault location and ranging in a semi-decoupled multi-terminal differential line with resistance to transition resistance, characterized in that, Includes the following steps: S1: Preliminary fault location. In a multi-terminal differential circuit, each side device performs steady-state fault measurement based on its own voltage and current, assuming a single-terminal fault, and calculates the ranging ratio. The ranging ratio is defined as the preliminary ranging length l of each side. n The total length L of the outgoing branch line on this side n The ratio; select the outgoing branch corresponding to the minimum ranging ratio. If the minimum ranging ratio is less than 1, it is initially determined that the fault occurs in the outgoing branch and is a metallic fault or a fault through a small transition resistor; if there is no need to improve the ranging accuracy or the hardware CPU computing power is limited, directly output the ranging result of the preliminary positioning; otherwise, proceed to step S2. S2: Utilize multi-terminal data for transition resistance correction, and construct a system based on power system analysis theory that includes the transition resistance R and the impedance Z from the fault point to the local side. L-1 Solving the equations involves generating multiple sets of (R, Z) equations through different combinations of equations. L-1 The calculated values ​​are then organized into a 1×3k dimension transition resistance matrix r and a fault impedance matrix z, where k is the number of sampling points, and the matrix dimensions can be flexibly adjusted according to the hardware CPU processing capability. S3: Introduce singular spectrum analysis for denoising and accurate estimation. Based on the transition resistance matrix r and fault impedance matrix z obtained in step S2, construct an m×n order Hankel matrix H, satisfying N=3k=m+n-1 and m≤n; perform singular value decomposition on the Hankel matrix H, decomposing the original signal into a linear superposition of multiple sub-signals, where the singular values ​​σ1 to σ2 are... m Sort by size from largest to smallest; select the lower bound p for large disturbances and the upper bound q for small disturbances based on the 90% confidence interval of the mean transition resistance; scale the singular values ​​greater than p to remove large transient noise in the power system; and set the singular values ​​less than q to zero to remove small sampling noise. The denoised matrix is ​​inversely transformed to obtain the accurate transition resistance sequence and fault distance impedance sequence, wherein the fault distance impedance sequence includes the resistive component and the reactance component of the fault impedance. S4: Verification of the reliability of the ranging results. The precise transition resistance sequence and the fault distance impedance sequence within 20ms-40ms after the fault occurs are selected as the data to be verified. If the fault current duration is short, the precise sequence before the current is disconnected is selected. The consistency of the data to be verified is verified by the variance statistics method. If the consistency meets the preset threshold, the transition resistance and fault distance corresponding to the sequence are output as the final result. If the consistency does not meet the preset threshold, the branch corresponding to the smallest ranging ratio selected in step S1 is determined to be a non-faulty branch. The branch corresponding to the second smallest ranging ratio is selected, and steps S2-S4 are repeated until a sequence with consistency that meets the preset threshold is obtained. When a fault occurs on the common tie line of a multi-terminal differential line, repeat steps S2-S4, only replacing the line parameters in the equations solved in step S2 with the impedance parameters of the common tie line to complete the location and ranging of the tie line fault. When the number of T-connected outgoing branches of the multi-terminal differential line increases, keep the basic form of the equations solved in step S2 unchanged, only adding an equation for the power supply current of the corresponding new outgoing branch, and keep the operation logic of subsequent steps S3-S4 consistent.

2. The method for fault location and ranging of a semi-decoupled multi-terminal differential line with anti-transition resistance according to claim 1, characterized in that, In step S2, the different equation combinations are constructed based on the measurement parameters of the local and opposite sides of the multi-terminal differential circuit. Specifically, they include at least one of three types of combinations: "local current - local voltage", "local current - opposite current", and "local voltage - opposite voltage". Each combination independently generates one set (R, Z). L-1 The number of calculated values ​​and equation combinations can be flexibly adjusted to 2, 3 or more groups depending on the computing power of the hardware CPU.

3. The method for fault location and ranging of a semi-decoupled multi-terminal differential line with anti-transition resistance according to claim 1, characterized in that, In step S4, the statistical method for consistency verification also includes any one of the mean deviation method and the standard deviation method. When replacing the variance statistical method, the corresponding consistency preset threshold needs to be adjusted simultaneously.

4. The method for fault location and ranging of a semi-decoupled multi-terminal differential line with anti-transition resistance according to claim 1, characterized in that, In step S3, when constructing the Hankel matrix H, the ratio of m to n is 1:2 to 1:3, and the value range of m is 5 to 15.

5. The method for fault location and ranging of a semi-decoupled multi-terminal differential line with anti-transition resistance according to claim 1, characterized in that, In step S1, the steady-state fault measurement of the single-ended fault assumption adopts a fault location algorithm based on the line lumped parameter model, and the calculation error of the algorithm is controlled within 5%.

6. The method for fault location and ranging of a semi-decoupled multi-terminal differential line with anti-transition resistance according to claim 1, characterized in that, In step S2, the number of sampling points k ranges from 3 to 10, and the time interval between each sampling point is 2ms to 5ms.

7. The method for fault location and ranging of a semi-decoupled multi-terminal differential line with anti-transition resistance according to claim 1, characterized in that, When the number of T-connection outgoing branches of a multi-terminal differential line expands from 4 to N (N≥5), the number of equations to be solved in step S2 increases to N-1, and the dimensions of matrices r and z expand to 1×(N-1)k. The computational complexity increases linearly with the number of branches.

8. The method for fault location and ranging of a semi-decoupled multi-terminal differential line with anti-transition resistance according to claim 1, characterized in that, In step S3, when scaling the singular values, a linear scaling factor is used, and the scaling factor ranges from 0.8 to 1.

2.

9. The method for fault location and ranging of a semi-decoupled multi-terminal differential line with anti-transition resistance according to claim 1, characterized in that, In step S4, the consistency preset threshold is that the variance of the transition resistance sequence is less than 0.05Ω. 2 The variance of the fault distance impedance sequence is less than 0.1Ω. 2 When other consistency verification methods are used, the preset threshold is adapted and adjusted according to the industry standard of the corresponding statistics.

10. The method for fault location and ranging of a semi-decoupled multi-terminal differential line with anti-transition resistance according to claim 1, characterized in that, The multi-terminal differential line includes outgoing branches with a T-connection structure and a common tie line. The number of outgoing branches is 2-10, and the number of common tie lines is 1-3. The method is adaptable to multi-terminal differential lines of different topologies.

Images