2022 IEEE International Conference on High Voltage Engineering and Application (ICHVE 2022)

In high-voltage and high-power system, LCL bi-directional inverter adopts smaller filter inductance, can effectively reduce the system volume and loss, and has better harmonic suppression ability, so it has been widely used. However, LCL filter as a third order system,there are serious resonance problem, at the resonant frequency, the amplitude frequency curves will produce an almost infinite peak, will produce a phase frequency curve -180°phase mutation, so the resonance peak will seriously deteriorated grid current waveform quality, especially under the high pressure system will affect the inverter robustness,having an extremely serious consequences for the stability of the whole system. Aiming at this problem, this paper proposes a control method to improve the robustness of grid-connected inverter in hV power system. Firstly, the electrical topology of grid-connected inverter under high voltage system is designed, and the mathematical model of the topology is analyzed. Secondly, based on the weighted average current (WAC)method in the current inner ring of the deadbeat (DB) control: WAC can make the order reduction of third order system of inverter for a first order system, do not need to add damping ring and make the parameter design of current control loop is no longer limited to the LCL filter resonance peak, and therefore can obtain a bigger band width, and the control of low-frequency gain. DB controller has the characteristics of fast dynamic response and small steady-state error. Then, in order to effectively suppress the disturbance, a plug-in repetitive controller is added to the controller mentioned above to make the system have low total harmonic distortion (THD) and ensure the stable operation of the inverter. Finally, the simulation comparison with the traditional PI controller proves that the proposed control method can effectively suppress the resonance peak, ensure the accuracy and speed of the controller, and provide a good and stable current control scheme for the grid-connected inverter in the high voltage power system.
 

Grid-Connected Inverter,weighted average current,deadbeat controller,repetitive controller