Grid-Connection Control of Doubly Fed Variable Speed Pumped Storage Unit

Abstract

To avoid the harmonics voltage interfering in the control of the stator voltage amplitude and phase of doubly fed induction machine in the process of grid-connection, and improve the accuracy of voltage synchronization, this paper presents a grid-connection control method based on ButterWorth low-pass filter. The parameter design principles of ButterWorth filter are analyzed based on the filter's responding characteristic and the stator harmonics voltage component. Instead of using the phase of stator voltage, the filtered voltage amplitude is used for phase synchronization. The compensators of rotor current and rotor initial position are designed to control the amplitude and phase of the filtered stator voltage respectively. The simulation results show that compared with the traditional control strategy, the proposed control strategy has better dynamic response performance and higher control accuracy. A 30kW experimental platform is implemented to verify the effectiveness of the proposed control strategy.