适用于电网不对称下的自同步电压源逆变器控制策略

It is one of the challenges faced in practical engineering applications of the self-synchronous voltage source inverter (SVI) to realize balance control of the three-phase current under asymmetric grid voltage conditions when connected to the grid, and take into account the stability of the terminal voltage control when it runs independently off the grid. First, under the asymmetric condition of the power grid, on the basis of a brief description of the working principle of the SVI, this paper analyzes in detail the limitations of applying in conventional positive and negative sequence separation control to SVI, and the instability mechanism when the system operates independently from the grid. Then, based on the single-mode control idea of the SVI, a suppression strategy of SVI negative sequence current based on a quasi-resonant controller is proposed, which achieves the balance of current output to the grid under the asymmetric grid condition. At the same time, the system stability of the SVI is guaranteed when it switches between on-grid and off-grid modes and operates off-grid (including multi-machine parallel) independently. Finally, simulation and experimental results verify the correctness and effectiveness of the proposed system control strategy.