Abstract: The rationality of the technical water supply of the hydropower station buildings directly related to the safe operation of the unit and the economical benefit of the hydropower station. The main problems existing in the technical water supply system of the Fourth Cascade Hydropower Station of Huadian Yunnan Yilihe Hydropower Plant were analyzed. A reformation scheme was put forward, in which the water supply pump will be replaced by the variable frequency and constant pressure pump. The scheme can increase the operation reliability of the hydropower station remarkably and provide the good foundation for operation of the main equipments in the hydropower station.

Key words: unit, cooling, technical water supply, variable frequency and constant pressure water supply pump