Research on control strategy of power conversion system based on discrete state-space model

Power conversion system (PCS) as a key equipment of the energy storage grid-connected system, have important influence on the battery energy storage system and power grid. At present, the control model is based on the continuous time, but due to the actual control system adopts computer control usually, so it is necessary to study the control strategy based on the discrete system. In this paper, the discrete state space model was built for the PCS and its characteristics was analyzed. Based on the proposed model, multi-variable full state feedback was introduced to guarantee the stability of inner loop by increasing the system damping, then suppressed the resonant of the LCL filter system. A novel method of the pole assignment based on virtual resistor was proposed to tuning the state feedback gain matrix. The stability and response of the system was analyzed in z plane by using the virtual resistor, based on the simulations and experimental results, the whole control system has good dynamic and static characteristics, and a good engineering application value.