Influence Analysis Method of Power Failure on Main Circulation Pump Operation for Converter Valve Cooling System

The reliable operation of the main circulation pump, which is the core equipment in valve cooling system, directly affects the safety and stability of the converter station. Aiming at the problems, e.g., deficient theoretical basis for determining the safe voltage range, irrational protection setting and abnormal switching of the main circulating pump, this paper investigates the influence of four common power supply faults on the operation of the pump. The considered faults include the overvoltage, the undervoltage, three-phase unbalance and phase loss. The results indicate that insulation degradation may occur if the power source operates at overvoltage for a long duration of time. The undervoltage or three-phase unbalance in the power supply will directly increase the current, and more seriously, the motor will cease working or sustain damage. The phase loss, as the most severe fault, can result in a multiplicity of current and abnormal noise, for which the motor will eventually burn out. Additionally, we also provide a reference for the design of the protection circuit of the main pump power supply and the value setting of the power protection in the voltage monitoring relay.