Control Strategies for Variable Speed Operation of Pumped Storage Plants with Full-size Converter Fed Synchronous Machines

The full-size converter fed synchronous machine (CFSM) for variable speed operation of a pumped storage power plant exhibits multiple advantages over the state-of-the-art Doubly Fed Induction Machine (DFIM) technology. The CFSM technology is emerging as the most preferred system for pumped storage plants for efficient operation in wide range of water flow which is not the case in existing power plants. This paper presents the steady state control strategies to execute the variable speed operation of the pumped storage power plants in both turbine and pump mode using full-size back-to-back converter. Also, how the power plant can be started in pump and turbine mode from standstill have been proposed. In addition, the seamless transition of operating modes from turbine to pump mode and vice versa are presented, which is not the case in today's pumped storage power plants. The proposed control strategies are experimentally verified with a 100 kVA machine and converter setup with emulated reversible pump turbine (RPT).