CAPACITOR CURRENT FEEDBACK ACTIVE DAMPING STRATEGY FOR LCL GRID CONNECTED INVERTER BASED ON SECOND-ORDER PHASE COMPENSATOR
Under the influence of the control delay link,the grid-connected inverter system has the problem of too narrow effective damping region.In view of this,it is proposed to add a novel second-order phase overrun compensation link in the capacitive current feedback branch,and the effective damping boundary frequency of the capacitive current feedback active damping(CCFAD)is improved from fs/6 to 0.34 fs after the compensation.The parameter design method of the capacitive current feedback coefficients is optimised,and the closed-loop pole trajectories of the proposed control strategy are analysed in the discrete domain.Comparison and analysis with simulation and experimental results of existing strategies show that the proposed strategy has higher robustness under the operating conditions of increased grid impedance and wide range of filter parameter fluctuations.
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