Robust Voltage Resonance Feedforward Control Strategy for LCL-type Grid-connected Inverters under Weak Grid Condition

The quasi-proportional resonance feedforward (QPRF) control strategy was proposed to enhanced the robust ability of LCL-type grid connected in weak grid condition. The equivalent circuit model was developed and impedance analysis method(IAM) was adopted to analyze the stability of the control system. The gain at low frequency and the phase margin at cutoff frequency were detailed analyzed compared with the traditional proportional feedforward (PF) strategy in this paper. It was obtained that the robust ability of QPRF was enhanced than PF. And the gain of low frequency was ensured. Finally, results of simulation were given to verify the validity and feasibility of the proposed strategy.