Basic Theories of Power System Relay Protection

This chapter first introduces the basic theories of power system relay protection, summarizes the functions and basic requirements of relay protection, and illustrates the basic principles of relay protection. The basic task of relay protection is to identify the fault and quickly clear it, and to ensure that the non‐faulty part can continue in normal operation. Relay protection with good performance should meet the requirements of reliability, selectivity, speed and sensitivity. In order to meet the requirements of a complex network, relay protection principles with better performance must be applied, among which is distance protection. Compared with distributed substation area protection, substation centralized protection could acquire more information, locate the fault from the whole station level, simplify the cooperation of protection operating time and also improve the selectivity and reliability of protection, which is beneficial for intelligent protection decision‐making.