Abstract: Abstract:The flow and the pressure of the closed water pump are usually adjusted by valve, but this causes large amount of energy waste. The permanent magnetic speed control and the variable frequency speed control are oftenused water pump speed control technologies, and the energy conservation effects of the two methods are roughly equal. Considering from the angle of longtime operation, the economic benefit of the permanent magnetic speed controller reformation is lager than the frequency converter, and the system reliability can be improved. So, in energysaving speedcontrol reformation of the closed water pump in Huadian International Laizhou Power Plant, the permanent magnetic speed controller was selected to control of the flow and the pressure of the pump and to reduce the energy consumption. After the reformation, the closed water pump operated more stably, the power consumption was reduced obviously, and the expected effect was achieved. 

Key words: Keywords:closed water pump, permanent magnet speed controller, frequency converter, type selection, economic benefit comparison, energy conservation reformation