Replacing an existing Synchronous Generator Motor With a Variable Speed Double Fed Induction Machine In a Pump Storage Scheme

摘要

With the continued growth of renewable energy into the power grids, larger amounts of electricity storage are needed as well as faster plant regulation and an increased capacity for regulation. Currently pumped storage power plants (PSP) provide the most cost effective means of storing large amounts of energy while at the same time compensation for large wind power fluctuations into the grid. The variable speed technology can offer additional network flexibility to conventional PSP by allowing the power regulation in pumping mode. The paper will discuss the benefits of variable speed units in a pump storage scheme on a grid point of view. Indeed, upgrading existing PSP into variable speed PSP does require special consideration on the electrical machinery and electrical connection to grid when considering electrical transient, harmonics and grid code requirements. Also, will be discussed challenges to be faced in order to replace an existing 1975 synchronous generator motor rated 270MVA with an upgraded double fed induction machine rated 305MVA. The main issues dealing with a completely new rotor technology have to be addressed and include weight management, handling, electrical behavior of insulation under high frequency stress, rotor current and voltage management during grid transient. These aspects shall be dealt with and the paper shall give a first experience feedback of the Cheylas project (France) where such undertaking is ongoing.