Control Strategy of Active Damping Superposition for LCL Grid-Connected Inverter
LCL filter has superior high-frequency harmonic suppression capability,and therefore it has been widely used in grid-connected inverters.In order to suppress the resonance peak problem of LCL filters,active damping is usually used.Although the resonance peak is suppressed by this control strategy,the digital control delay can cause the inherent resonance point to shift.To solve these problems,a control strategy of active damping superposition based on the virtual impedance model is proposed,which not only suppresses the resonance peak but also avoids the shift of the inherent resonance point,and expands the effective damping zone to(0,fs/3).Finally,the simulation system of LCL single-phase grid-connected inverter and the hardware in-loop prototype are built to verify the correctness of the control strategy.The experimental results show that the control strategy has good anti-interference abil-ity,dynamic performance and steady performance.
LCL filtervirtual impedancedamping superpositioneffective damping zone
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