Optimal control of three-level multi-functional inverter based on dynamic switching system model

A control strategy of three-level multi-functional grid-connected inverter for distributed grid is proposed. According to different conditions of distributed generation, the multi-functional inverter can realize the function of injecting power from the distributed generation and suppling power into the grid simultaneously or separately, and the function of shunt active power filters such as the harmonic current control, load reactive power compensation as well as three-phase unbalance load compensation at the point of common connection So it could improve the utilization and efficiency of inverters and significantly reduce the hardware cost of power quality device in the distribution network. A current control strategy of three-level multi-functional inverter based on switched system model with dynamic switching frequency is proposed, the stability of the system is ensured by large signal modeling under large disturbances. Meanwhile, according to the inverter operating mode, the switching frequency could be adjusted dynamically to reduce the switching losses under the condition of ensuring the premise of system power, the neutral point potential and other indicators. Finally, the control strategy of the multi-functional grid-connected inverter is validated by simulation and experiment. The simulation and experimental results verify the correctness and feasibility of the related design.