CN-121983924-A - Distribution line pilot protection method, system, equipment and medium

CN121983924ACN 121983924 ACN121983924 ACN 121983924ACN-121983924-A

Abstract

The invention belongs to the technical field of relay protection of power distribution networks, and discloses a distribution line pilot protection method, a system, equipment and a medium, wherein the distribution line pilot protection method comprises the steps of judging whether to start a protection algorithm based on phase current abrupt change; if a protection algorithm is started, three-phase current sampling data of the installation position of the protection device are obtained after a preset time period, a local current sampling sequence is sent to the opposite-end protection device, the current sampling sequence of the opposite-end protection device is obtained, weights of the local current sampling sequence and the opposite-end current sampling sequence are calculated, a weighted dynamic time regular distance between the local current sampling sequence and the opposite-end current sampling sequence is calculated, the weighted dynamic time regular distance is compared with an action threshold value, and a tripping command is judged to be sent or the protection device is reset. Compared with the traditional differential protection method, the method has higher sensitivity, reliability and robustness, and is not influenced by the loss of transmission data.

Inventors

ZHOU CHENGHAN
HUANG MIN
WU YING
HE BANGWEI
SU GUOQIANG
LIU HEJIN
YOU XINHONG
ZHANG PENGPING
HE JIAHUI
SUN JIYUAN
YUAN TONG
LI LISHENG
YIN ZIYANG
LIU YANG
ZHANG LINLI
XU DING
SUN YONG
WANG FENG
YU HAIDONG
LIU WENBIN

Assignees

国网山东省电力公司电力科学研究院
国家电网有限公司

Dates

Publication Date: 20260505
Application Date: 20251211

Claims (16)

1. The utility model provides a distribution line pilot protection method which characterized in that, this distribution line pilot protection method includes: judging whether to start a protection algorithm or not based on the phase current abrupt change; if a protection algorithm is started, acquiring three-phase current sampling data of the installation part of the protection device after a preset time period, and sending a local current sampling sequence to the opposite-end protection device; acquiring a current sampling sequence of an opposite-end protection device, and calculating weights of the current sampling sequence of the local end and the current sampling sequence of the opposite end; calculating a weighted dynamic time warping distance between the current sampling sequence of the local end and the current sampling sequence of the opposite end; And comparing the weighted dynamic time regulation distance with an action threshold, judging that the short-circuit fault in the area occurs and sending a tripping command if the weighted dynamic time regulation distance is larger than the action threshold, and judging that the short-circuit fault is in normal operation or out-of-area if the weighted dynamic time regulation distance is smaller than or equal to the action threshold, and resetting the protection device.
2. The method of claim 1, wherein the determining whether to start the protection algorithm based on the phase current abrupt change amount comprises: According to the three-phase current at the installation position of the protection device, the abrupt change of each phase of current in the three-phase current is calculated in real time, and when the abrupt change of any one phase of current exceeds the load current amplitude of the sensitivity coefficient times, a protection algorithm is started.
3. The method for pilot protection of a distribution line according to claim 2, wherein the expression for determining whether to start the protection algorithm is: ||i(n)-i(n-N)|-|i(n-N)-i(n-2N)||>K S I L ; Wherein I (N) is the value of the nth sampling point of a certain phase of current, N is the total number of sampling points in one cycle, K S is a sensitivity coefficient, and I L is the amplitude of load current in normal operation.
4. The method of claim 1, wherein calculating weights for the local current sampling sequence and the opposite current sampling sequence comprises: Calculating the first-order difference of each sampling point in the current sampling sequence of the local terminal, and calculating the sum of absolute values of all the first-order differences; dividing the absolute value of the first-order difference of each sampling point in the current sampling sequence of the local end by the sum of the absolute values of all the first-order differences to obtain the importance weight of the sampling point; calculating the first-order difference of each sampling point in the opposite-end current sampling sequence, and calculating the sum of absolute values of all the first-order differences; Dividing the absolute value of the first-order difference of each sampling point in the opposite-end current sampling sequence by the sum of the absolute values of all the first-order differences to obtain the importance weight of the sampling point.
5. The method for pilot protection of a distribution line of claim 4, wherein the expression for calculating the weight of the local current sampling sequence is: wherein a i is the importance weight of the i-th sampling point in the current sampling sequence of the local terminal, 1< i < m, m is the total number of sampling points of the current sampling sequence of the local terminal; And is the i-th element in the current sampling sequence of the local terminal, d represents the dimension of the sequence, and v x i is the first-order difference of the sampling points in the current sampling sequence of the local terminal.
6. The distribution line pilot protection method according to claim 5, wherein the sequence dimension value is 1 for describing a single-dimensional signal, and the sequence dimension value is greater than 1 for characterizing a multi-dimensional feature; And the first-order difference of sampling points in the local current sampling sequence is ∈ i ＝|x i -x i-1 |, and is used for describing the local change intensity of the signal.
7. The method for pilot protection of a distribution line of claim 5, wherein the expression for calculating the weight of the opposite current sampling sequence is: wherein b j is the importance weight of the j-th sampling point in the current sampling sequence of the local terminal, and 1< j < n, n is the total number of sampling points of the current sampling sequence of the opposite terminal; And is the j-th element in the opposite current sampling sequence, d represents the sequence dimension, y l is the first-order difference of the sampling points in the opposite current sampling sequence, and Y l ＝|y l -y l-1 l for characterizing the local change severity of the signal.
8. The method of claim 1, wherein calculating the weighted dynamic time warping distance between the local current sample sequence and the opposite current sample sequence comprises: Calculating Euclidean distance between each sampling point in the current sampling sequence of the local end and each sampling point in the current sampling sequence of the opposite end; Multiplying the importance weight of each sampling point in the current sampling sequence of the local end by the importance weight of each sampling point in the current sampling sequence of the opposite end to obtain a weight product; constructing an accumulated distance matrix between the local current sampling sequence and the opposite current sampling sequence based on the weighted point pair distance matrix; the smallest cumulative distance matrix is determined as the weighted dynamic time warping distance between the local current sampling sequence and the opposite current sampling sequence.
9. The method of claim 8, wherein the expression for calculating the weighted dynamic time warping distance between the local current sampling sequence and the opposite current sampling sequence is: D(i,j)=d Attn (x i ,y i )+min{D(i-1,j),D(i,j-1),D(i-1,j-1)}; wherein D (i, j) is an accumulated distance matrix, D Attn (x i ,y i ) is a weighted point pair distance matrix.
10. The method of claim 8, wherein the weighting point-to-distance matrix is expressed as: d Attn (x i ,y i )＝d(x i ,y i )·(1+a i ·b j ); Wherein d Attn (x i ,y i ) is a weighted point pair distance matrix, a i ·b j is a weighted product of an ith sampling point in the current sampling sequence of the local end and a jth sampling point in the current sampling sequence of the opposite end, and d (x i ,y i ) is Euclidean distance between the ith sampling point in the current sampling sequence of the local end and the ith sampling point in the current sampling sequence of the opposite end.
11. A distribution line pilot protection system, the distribution line pilot protection system comprising: the starting judging module is used for judging whether to start a protection algorithm or not based on the phase current abrupt change; The sampling and transmitting module is used for acquiring three-phase current sampling data of the installation part of the protection device after a preset time period if the protection algorithm is started, and transmitting a local current sampling sequence to the opposite-end protection device; The weight calculation module is used for acquiring a current sampling sequence of the opposite-end protection device and calculating weights of the current sampling sequence of the local end and the current sampling sequence of the opposite end; The distance calculation module is used for calculating the weighted dynamic time warping distance between the current sampling sequence of the local end and the current sampling sequence of the opposite end; The fault judging module is used for comparing the weighted dynamic time regular distance with the action threshold, judging that the short circuit fault occurs in the area and sending a tripping command if the weighted dynamic time regular distance is larger than the action threshold, and judging that the short circuit fault occurs in the normal operation or outside the area if the weighted dynamic time regular distance is smaller than or equal to the action threshold, and resetting the protection device.
12. The pilot protection system of claim 11, wherein the start-up determination module is configured to determine whether to start up the protection algorithm based on the phase current abrupt change, and the start-up determination module is configured to calculate, in real time, an abrupt change of each phase current in the three phase currents according to the three phase current at the installation location of the protection device, and start up the protection algorithm when the abrupt change of any one phase current exceeds a load current amplitude that is a multiple of the sensitivity coefficient.
13. The distribution line pilot protection system according to claim 11, wherein the weight calculation module is configured to calculate the weights of the local current sampling sequence and the opposite current sampling sequence, and the weight calculation module is configured to calculate a first order difference of each sampling point in the local current sampling sequence and calculate a sum of absolute values of all the first order differences, divide the absolute value of the first order difference of each sampling point in the local current sampling sequence by the sum of absolute values of all the first order differences to obtain an importance weight of the sampling point, calculate the first order difference of each sampling point in the opposite current sampling sequence and calculate a sum of absolute values of all the first order differences, and divide the absolute value of the first order difference of each sampling point in the opposite current sampling sequence by the sum of absolute values of all the first order differences to obtain the importance weight of the sampling point.
14. The distribution line pilot protection system according to claim 11, wherein the distance calculation module, when calculating the weighted dynamic time warping distance between the local current sampling sequence and the opposite current sampling sequence, includes calculating euclidean distances between each sampling point in the local current sampling sequence and each sampling point in the opposite current sampling sequence, multiplying importance weights of each sampling point in the local current sampling sequence and importance weights of each sampling point in the opposite current sampling sequence to obtain a weight product, creating a weighted point-to-distance matrix according to the euclidean distances and the weight product, constructing an accumulated distance matrix between the local current sampling sequence and the opposite current sampling sequence based on the weighted point-to-distance matrix, and determining a minimum accumulated distance matrix as the weighted dynamic time warping distance between the local current sampling sequence and the opposite current sampling sequence.
15. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor implements the steps of the method of any one of claims 1 to 10 when the computer program is executed.
16. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the steps of the method of any of claims 1 to 10.

Description

Distribution line pilot protection method, system, equipment and medium Technical Field The invention relates to the technical field of relay protection of distribution networks, in particular to a distribution line pilot protection method, a distribution line pilot protection system, distribution line pilot protection equipment and a distribution line pilot protection medium. Background For helping hand build with new forms of energy as the novel electric power system of core, new forms of energy such as wind energy, solar energy realize quick scale popularization, a large amount of renewable energy are incorporated into the distribution network with inverter type distributed power supply (Inverter Based Distributed Generation, IBDG) form, promote traditional single-ended power supply distribution network upgrade to the active distribution network (Active Distribution Network of multiport power supply, ADN), this conversion seriously weakens the running efficiency of syllogic overcurrent protection, leads to current overcurrent protection scheme to face refusing action, malfunction's potential safety hazard. Aiming at the technical bottleneck of relay protection of an active power distribution network, partial researchers try to apply current differential protection (Current Differential Protection, CDP) to the power distribution network scene. The current differential protection is used as a main protection scheme of the power transmission line, the protection performance of the current differential protection is fully verified in practice, and the current differential protection has application potential for solving the protection problem of the active power distribution network. At present, active power distribution network current differential protection schemes based on positive sequence fault components are proposed, action criteria are built through the amplitude ratio of currents at two ends of a protected line, a braking criterion is designed through a phase difference, the active power distribution network current differential protection scheme is suitable for power distribution network feeder lines accessed by various types of distributed power sources, active power distribution network positive sequence current differential protection based on 5G communication is also researched and designed, a 5G technology with low time delay and high reliability is selected as a communication carrier, and two-side protection devices only transmit current positive sequence components, so that communication data volume is reduced by two thirds. However, the traditional current differential protection is designed based on the fault characteristics that both ends of a power transmission line are synchronous power supplies, and the highest sensitivity is achieved only when the fault current amplitudes at two sides are equal and the phases are consistent. Under the control strategies of low voltage ride through, output current limiting and the like of an inversion type distributed power supply, the provided short circuit current has the characteristics of limited amplitude and controllable phase, and is difficult to meet the optimal action condition of the traditional current differential protection, so that the application effect of the protection scheme in an active power distribution network is limited, the sensitivity attenuation problem of the traditional current differential protection is caused, and meanwhile, when the packet loss problem occurs in the current data transmission process, the traditional method faces the risks of refusal operation and misoperation. In a comprehensive view, the current differential protection scheme of the existing active power distribution network is easily interfered by factors such as failure electric characteristics of a reverse distribution power supply, passing current, packet loss of data transmission and the like, and the protection performance is required to be improved. Therefore, how to provide a solution capable of overcoming the influence of the failure characteristics of the inverter type distributed power supply and improving the protection sensitivity and reliability of the active power distribution network becomes a current urgent problem to be solved. Disclosure of Invention The embodiment of the invention provides a distribution line pilot protection method, a system, equipment and a medium, which are used for solving the problems that the current differential protection of an active distribution network is easily influenced by the failure characteristic of an inversion type distributed power supply, the sensitivity is attenuated and the protection performance is reduced due to the packet loss of data transmission in the prior art. According to a first aspect of an embodiment of the present invention, a pilot protection method for a distribution line is provided. In one embodiment, the distribution line pilot protection method comprises the steps of judging