Problems in Leading of Startup (Standby) Power Supplied by Power Grid for Large Power Plant and its Solution

With wide application of transformer with high transformation ratio in recent years,the option for startup(standby)power source leading in large power plant is changed to be supplied by high voltage bus bar in power plant.For main wiring,considering economic running,a scheme of a breaker with two disconnecting switches which connects to two bus bars,is adopted.The main wiring forms brings a series of new problems to configuration operation of relay protection.This paper emphatically analyzes the new main wiring forms for power plant and proposes a perfect scheme for the configuration of the relay protection.