The Research And Application Of Large-scale Generator-Transformer Unit Protection

Large-scale Generator-Transformer Unit Protection is one of the most important part of the modern electrical power system. It' s costly and complex-structured. Once it fails, a long-term examination and repair is needed. It will bing huge economic losses directly and indirectly. The incorrect or rejected tripping of Large-scale Generator-Transformer Unit Protection will cause serious consequences. Therefore, it put forward higher requirements to the reliability, sensitivity, selectivity and speed of Large-scale Generator-Transformer Unit Protection. There are some inevitable faults and abnormal run mode with Large-scale Generator-Transformer, therefore, rapid removal or segregation point of failure is the main task of relay protection.This passage mainly introduces the purposes, principles of the modern Large-scale Generator-Transformer Unit Protection and systemly introduces the following main protections and back-up protections: the generator differential protection, the transformer differential protection, the protection of inter-turn, the stator ground fault protection, the generator symmetry overload protection, the negative sequence overload protection, the generator excitation-loss protection, the rotor earth-fault protection, the generator (or transformer) over excitation protection, the generator reverse power protection, etc. Meanwhile, the author put forward her point of view on some controversial issues. The development trend of microcomputer protection is also discussed.