Co-chord multi-arc phase comparison loss of synchronism protection method

Abstract

The invention relates to a co-chord multi-arc phase comparison loss of synchronism protection method. According to the method, an impedance plane is divided into five areas according to change of power angle Delta: 00-Delta 1, Delta 1-Delta 2, Delta 2-Delta 3, Delta 3-Delta 4, and Delta 4-3600, arc boundaries and reactance line boundaries of the five areas are divided, the area, in which measured impedance value ZC corresponding to current power angle Delta is, is detected according to the arc boundaries, historical logic of the ZC passing through the areas and dwell time thereof in the areas are judged, and whether a unit is in a step out state is confirmed; and the judgment result is generator step out or motor step out, pole slipping is recorded for once, and protection actuating signal is sent out through setting number of times of pole slipping. The Delta 1 and Delta 2 boundaries of the arc are corresponding to static stability boundary Delta J and moving stability boundary Delta M of the power angle of the unit, thereby being used as a boundary for unit step out logical judgment, being capable of preprocessing or warning early before step out, and simplifying loss of synchronization protection criteria; only sin Delta X value and cos Delta X value are needed, two multiplication computation are added in run, and then logic judgment is realized. The setting calculation process is simplified, and protection operation efficiency is improved.

Description

technical field [0001] The invention relates to the field of electric power systems, in particular to a phase-comparison out-of-synchronization protection method of multiple circular arcs on the same string. Background technique [0002] As the capacity of the power system continues to increase, the system impedance connected to the generator set is relatively small. Once the system is unstable and oscillated, its oscillation center can easily enter the generator set, which seriously threatens the safe operation of the generator set and the system. , my country's large generator sets are equipped with unit out-of-step protection, and there are many different types of criteria. see figure 1 and figure 2 , The common out-of-step protection criterion methods for large units include: 1. The out-of-step protection criterion of three impedance elements; 2. The out-of-step protection criterion of double shutters. [0003] Criteria for out-of-step protection of three-impedance el...

AI Technical Summary

Problems solved by technology

The out-of-step protection of the double shutter simply uses the resistance line R1 (R2, R3, R4) as the boundary. Under different operating modes of the unit, the same out-of-step oscillation period, the power angle δ corresponding to the resistance line boundary is different, so passing through The time of the zone is also different, so that in the same zone, the sliding time cannot be determined

The straight-line boundaries of R1 and R4 make it more difficult to scientifically determine the sliding time of areas IV and 0

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