Multistage hydraulic machines and methods of controlling operations thereof

摘要

A multistage hydraulic machine such as a pump/turbine having at least three pressure stages in which the highest and lowest pressure stages are provided with movable guide vanes the degree of opening of which are variable, and the other intermediate pressure stages are provided with stationary guide vanes the degree of opening of which are not variable. The movable and stationary guide vanes are simultaneously or independently controlled in accordance with a change of an operational condition at the time of steady operation in a manner such that the degree of opening of the movable guide vanes of the lowest pressure stage becomes relatively larger or smaller than that of the stationary guide vanes in a high flow-rate range or in a low flow-rate range, respectively, while maintaining the degree of opening of the movable guide vanes of the lowest pressure stage to be equal to or smaller than that of the highest pressure stage.