A method for judging abnormalities in small current tests of excitation systems

Abstract

The invention relates to a small current test abnormality judging method for an excitation system. The technical scheme is as follows: A, collecting three-phase input currents IA, IB`, IC of an AC side of a rectifier and load currents IR of a DC side of the rectifier; B, obtaining an AC average current IAV and a differential current ID through calculation; C, if |IF-IR|>0.6IR, judging that small current test abnormality of an excitation system exists; if |IF-1.2IAV|>0.6IR, judging that small current test abnormality of an excitation system exists; if ID>0.6IR, judging that small current test abnormality of an excitation system exists. According to the method, the technical status and deterioration laws of equipment can be known anytime by monitoring current signals of the rectifier of theexcitation system online and calculating the differential current and average current. Moreover, the temperature of bridge arms is monitored, the average temperature of the six bridge arms is calculated and is compared with the maximum temperature and the minimum temperature of the bridge arms, and the data serves as an auxiliary criterion, thereby avoiding sudden accidents, controlling gradual failure and improving the reliability of the system.

Description

technical field [0001] The invention relates to a method for judging abnormality of a small current test of an excitation system, which is used for rapidly diagnosing abnormal faults of the excitation system and preventing expansion of accidents, and belongs to the field of measurement technology. Background technique [0002] The excitation system is one of the important components of the generator excitation system, and its operation reliability is related to the stable operation of the excitation system and the power grid. When the thyristor rectifier bridge fails, it will not only cause the excitation voltage to drop, make the excitation transformer in an asymmetrical or phase-lack operating state, but also cause DC magnetization to overload the other phase thyristors, affecting the safety of the generator excitation system Reliable operation; when the fuse of the power cabinet is blown or the trigger pulse is lost, the output voltage will drop to varying degrees, but du...

AI Technical Summary

Problems solved by technology

The judgment method is based on indirect quantities, which cannot directly reflect the abnormal nature of the current in the actual operation process.

This includes that the temperature signal measurement is prone to errors, the criterion is not accurate, and the temperature change is a gradual process. Compared with the instantaneous characteristics of the current signal, the measurement period is too long, which can be used as an auxiliary judgment basis, but if it is used as the main criterion. It greatly affects the timeliness of judging the abnormality of the small current test; in addition, the travel switch of the fan is easy to jam, which is greatly interfered by its own physical characteristics, resulting in misjudgment of faults

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