Generator industrial-frequency variation equantity rate difference protection method

Abstract

A protection method of the industrial frequency variation ratio differential motion in the generator. A industrial frequency variation ratio differential motion element with high sensitivity is formed by the power variation of the machine-end current and neutral-point current in the generator microcomputer protection equipment and can be used to detect the low current fault which can not be or rarely be reflected in the routine steady ratio differential motion. The invention only reflects the fault component, and is unaffected by the load current in the normal running of the generator and transformer and is very little affected by the transition resistance. It adopts the high brake coefficient anti-TA (the current mutual inductor) saturation, and uses the floating threshold technology. The protection has a high sensitivity and a good reliability.

Description

1. Technical field [0001] The invention relates to a relay protection method, in particular to a generator power frequency variation ratio differential protection method. 2. Background technology [0002] The relay protection device is an important part of the safe operation of large-scale installations such as generators and transformers in the power grid. The generator power frequency variation ratio differential protection fully reflects the variation of differential current and braking current, and is not affected by the load current during normal operation. It can sensitively detect minor internal faults of transformers and generators. At the same time, the braking coefficient of the power frequency variation ratio differential is relatively high, and its ability to withstand TA (current transformer) saturation is relatively strong. [0003] At present, the existing generator differential protection has the following problems in protecting the internal minor faults of ...

AI Technical Summary

Problems solved by technology

[0004] 1) For slight faults between phases inside the unit, the protection is easily affected by the load current, and the sensitivity is low, especially in the case of heavy loads, it may not be able to operate

[0005] 2) The internal phase-to-phase fault may be affected by the transition resistance due to the low potential of the fault point.

[0006] 3) If the existing scheme wants to improve the sensitivity, it must be premised on the loss of reliability

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