A Transmission Line Fault Detection Method Based on Positive Sequence Current Fault Component

A technology of positive sequence current and fault components, applied in fault location, measurement of electrical variables, emergency protection circuit devices, etc., can solve the problems of reducing the fault sensitivity of differential protection in the area, protection refusal to act, etc.

Active Publication Date: 2020-03-17
SOUTHWEST JIAOTONG UNIV
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Problems solved by technology

[0007] The purpose of the present invention is to provide a transmission line fault detection method based on positive sequence current fault components, which can effectively solve the problem of reducing the sensitivity of differential protection faults in the area due to load current, transition resistance, and power flow transfer, which may cause Protect the problem of refusal to move, and can accurately detect the fault line under various fault conditions

Method used

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  • A Transmission Line Fault Detection Method Based on Positive Sequence Current Fault Component
  • A Transmission Line Fault Detection Method Based on Positive Sequence Current Fault Component
  • A Transmission Line Fault Detection Method Based on Positive Sequence Current Fault Component

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Embodiment

[0116] Using the electromagnetic transient software PSCAD / EMTDC to build an IEEE 10-machine 39-node system, the system structure diagram is as follows Figure 4 as shown, Figure 4 G in the circle represents the generator, and the number represents the number of each bus. The system voltage level is 345kV, the frequency is 60Hz, and the sampling frequency is 1.2kHz. MATLAB is used to realize the identification algorithm and fault location of the faulty line. AG stands for A-phase ground fault, ABG stands for AB phase-ground fault, AB stands for AB phase short-circuit fault, and ABC stands for ABC three-phase.

[0117] Example 1

[0118] In order to verify the effectiveness of the algorithm when a fault occurs at different locations and different transition resistances, the line L 4_7 , L 1_2 In the test, at 0.25s, faults occurred in different positions and through different transition resistances. See Table 1 for the calculation results of d and a after two cycles at the ...

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Abstract

The disclosure of the invention provides a transmission line fault detection method based on positive sequence current fault components. The invention subtracts the positive sequence current six cycles before the positive sequence current at any time to obtain the positive sequence current fault component of the line. Construct the ratio of the modulus of the vector sum of the positive sequence current fault components on both sides of a line to the modulus of the vector difference, as the fault judgment quantity of the line, and give its calculation formula. From this formula, it can be deduced that the fault judgment quantity of the fault line is greater than 1, and its value has nothing to do with the transition resistance. If the fault judgment amount of the line is greater than 1, it is judged that the line is faulty. When the power grid oscillates, establish the equation to solve the fault point position, and solve the fault point position a. When a is between 0 and 1, it can assist in judging the line fault. The invention can accurately judge various types of faults of the line without being affected by the fault location, fault type and transition resistance, and can also detect faulty lines during non-full-phase operation and load flow transfer.

Description

technical field [0001] The invention relates to the technical field of power grid wide-area backup protection. Background technique [0002] As the main protection of the line, the longitudinal differential protection has the advantages of simple principle and is not affected by the operation mode of the system, so it is widely used. However, the traditional differential protection relies on the empirical values ​​of the maximum unbalanced current and maximum load current when avoiding the external short circuit for setting. Refuse to move. Scholars have studied some differential protection algorithms that develop from the initial phase-separated current differential to zero-sequence current components and fault components as input quantities. [0003] Li Jie, Miao Shihong, Liu Pei, Lin Xiangning. High-resistance grounding protection criterion of line based on phase-separated active power differential principle[J]. Power Grid Technology, 2011,35(08):197-201. Through the an...

Claims

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Application Information

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Patent Type & AuthorityPatents(China)
IPC IPC(8): G01R31/08H02H7/26
CPCG01R31/085G01R31/088H02H7/26
Inventor童晓阳余森林
OwnerSOUTHWEST JIAOTONG UNIV