Reserch On Several Problems Of Construction Of Relay Of Power Plants

This paper is prepared for main purpose of studying and discussing relative protection problems occurred in physical operation of power plant including mainly the problems happened during operation of high frequency protection passages, those in respect of interturn protections of generator and those regarding backup protections of self-shunt excitation generator. Through analysis and discussion of some problems happened during the operation of high frequency protections currently applied, this paper comprehensively performs study on high frequency protection operation indexes, passage commissioning and trouble-shooting methods, presents some suggestions for improvement of the availability of high frequency protections. On basis of discussion of interturn protection principles, protection ratings and protection anti-accident measures as well as in conjunction with one real error action happened on site, suggestion is given in this paper that locking in negative sequence power direction could be added for interturn protections. Since it is not optimistic for the configuration of backup protection of self-shunt excitation generator of small-sized unit and for the on-situ operations, this paper discusses the reasons for the rejection of the backup protection in an accident happened in a power plant, analyzes the current characteristics of the short circuit at the outlet of generator and provides for backup protections with cooperative schemes together with some opinions and suggestions.