基于PI控制器有源阻尼的并网逆变器自适应改进策略

ADAPTIVE IMPROVEMENT STRATEGY FOR GRID-CONNECTED INVERTER BASED ON ACTIVE DAMPING OF PI CONTROLLERS

弱电网条件下,随着电网阻抗的增大,网压比例前馈与锁相环会导致系统鲁棒性大幅降低。为此,建立包含锁相环以及网压比例前馈的LCL型并网逆变器阻抗模型,并使用阻抗分析法进行稳定性分析。提出采用PI控制器有源阻尼的改进策略对逆变器等效输出阻抗相位进行补偿,从而扩大系统对弱电网的适应范围。然而,改进策略具有一定的局限性,因此在改进策略的基础上加入自适应环节,通过粒子群优化算法结合电网阻抗测量技术对所加控制器参数进行自适应优化,从而进一步提升系统在电网阻抗宽范围变化时的鲁棒性。最终通过仿真与实验验证自适应改进策略的正确性和有效性。

Under weak grid conditions,as the impedance of the grid increases,the grid voltage proportional feed-forward and phase-locked loops will lead to a significant reduction in system robustness.To this end,the impedance model of the LCL type grid-connected inverter containing the phase-locked loop and the grid-voltage proportional feed-forward is first established,and the stability analysis is performed using the impedance analysis method.An improvement strategy of active damping using PI controller is proposed to compensate the equivalent output impedance phase of the inverter,thereby expanding the system’s adaptation range to weak grids.However,the improvement strategy still has certain limitations,so on the basis of the improvement strategy,an adaptive link is added,and the added controller parameters are adaptively optimized by the particle swarm optimization algorithm combined with the grid impedance measurement technology,so as to further improve the system Robustness over a wide range of grid impedance variations.Finally,simulation experiments verify the correctness and effectiveness of the adaptive improvement strategy.