Study on pump mode cavitation characteristic of variable speed pump turbine

The continuous variable speed technology is a key technology in the development of pumped storage units. When the operating range of the rotation speed is widened, the unit's stable and safe operation range will be constrained by conditions, such as cavitation, hump, and power limit. This paper uses a traditional fixed-speed pumped storage station as the research object. Based on the complete characteristic curves of the unit, the modification hypothesis after the application of variable speed technology is carried out, and the preferred operation curve of the pump working condition is obtained. The improvement of the cavitation characteristics of the fixed speed unit by the variable speed technology is studied in this paper, and the problems in the prediction of cavitation of prototypes based on model tests are also analyzed. In this paper, the cavitation characteristics of the model and prototype of a pump turbine are analyzed using computational fluid dynamics simulation, with the initial cavitation coefficient as the basis for judging the cavitation. This paper points out that there is a deviation in the direct prediction of the cavitation characteristics of the prototype through the model test and provides a more accurate method to predict the cavitation limit range of variable speed units, which provides a reference for practical engineering.