Improvement of the De-excitation Methods for Large-Capacity Synchronous Generator

With the increase of single-machine capacity of synchronous generator, the excitation current for electromagnetic induction increases greatly. How to ensure fast, secure, flexible and effective de-excitation in the event of no-load mistaken over excitation, system faults and other extreme conditions has become a problem in urgent need of researches and solutions. In this paper, the mainstream excitation schemes for static self-parallel excitation-enabled hydroelectric generator units and brushless excitation for nuclear power generator units are analyzed. The main reasons of de-excitation accident of large capacity generator are studied, the key parameters of electromagnetic boundary conditions and de-excitation characteristics are analyzed, the topology of the de-excitation circuit is optimized, and the choice of de-excitation resistor is studied in depth. This paper will combine the Three Gorges hydropower 700MW self-excitation unit to carry out research work to improve the de-excitation characteristics of large-capacity synchronous generator.