On-line detection method of power grid fault based on relative protection entropy and nominal transition resistance

Abstract

The invention discloses an online grid fault detection method based on relative protection entropy and nominal transition resistance. According to the method, when a regional online detection system operating in a main unit on the monitoring layer of a transformer substation finds out that a protection signal, corresponding to a protection device, of a certain circuit in the station is started, online grid fault detection is started, seven kinds of protective action values of the two ends of the circuit and adjacent circuits are collected through a local area network and a wide area communication network, the relative protection entropy values of the circuit and adjacent circuits are calculated and ranked from large to small, circuits the relative protection entropy values of which are ranked first and second are taken as suspected circuits, and the relative protection entropy values of the two circuits are compared with a relative protection entropy threshold value to judge the fault circuit with multiple criteria. According to the method, the relative protection entropy fault detection method and the limited PMU-based nominal transition resistance fault detection method are combined, faults of a single circuit, double faults of two non-adjacent circuits and complicated faults of two adjacent circuits can be detected effectively, and fault tolerance of grid fault detection is improved greatly.

Description

technical field [0001] The invention belongs to the field of relay protection of electric power systems, and in particular relates to an online fault detection method of a power grid based on relative protection entropy and nominal transition resistance. Background technique [0002] With the rapid development of my country's economy, the demand for electricity is increasing day by day, especially for high-quality electricity. Under the implementation of the strategy of "power transmission from west to east, mutual supply between north and south, and national networking", the scale of my country's power system is getting larger and larger, and the structure of the power grid is becoming more and more complex. It will cause a wider range of losses, thus bringing new challenges to the reliability of the relay protection system. As the "first line of defense" to ensure the safe operation of the power grid, the correct action of the protection device ensures the safe and reliabl...

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Problems solved by technology

The above literatures are mainly aimed at single faults or non-adjacent multiple line faults, but none of the existing literatures involves the simultaneous failure of two adjacent lines

In the calculation of the transition resistance, the existing literature considers that there are PMUs at both ends of the line, and does not consider the calculation of the transition resistance under the limited PMU.

[0006] In addition, the existing literature uses the switching values ​​of multi-point protection and circuit breakers in the area, and the electrical quantities of PMUs in the area, but does not compare the switching values ​​of multi-point protection and circuit breakers in the area with the electrical quantities of multi-point PMUs in the area. Although the literature [9] studies the wide-area backup protection algorithm using traditional protection elements and PMU data at the same time, the fault probability of wide-area protection action obtained in real time is determined by the positive sequence voltage amplitude and the positive sequence voltage on both sides of the line. The sequence current phase angle difference is used to calculate the fault probability corresponding to the electrical quantity, and then the two fault probabilities are weighted and synthesized

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