Design of High-Power Energy Storage Bidirectional Power Conversion System

Aiming at problems of the energy storage PCS (power conversion system) with more applications and complicated working conditions, it is difficult to cover all applications with a single control scheme. This paper analyzes and designs the energy storage PCS in the state of grid-tied and islanding operation modes. Control schemes are designed for PCS working in different applications. The output current control in synchronous rotating coordinate system is adopted during grid-tied operation. The droop control is used during stand-alone parallel operation. In order to verify the design and control, a 500 kW PCS prototype was built and tested. The experiments show that the prototype has good performance and high working stability, including output current or voltage THD, efficiency, steady state, transition between grid-tied and stand-alone mode etc. The output current control and droop control adopted by the system can meet the requirements under different working conditions.