An Enhanced Control Strategy for Multiparalleled Grid-Connected Single-Phase Converters with Load Harmonic Current Compensation Capability

To increase power rating, parallel-connected converters are widely used in power systems. However, it brings challenge to output harmonic current control. For active power filter, the harmonic current compensation performance worsens. A virtual resistor has significant effect on the amplitude and phase of the output current. Based on the analysis of current control loop with a virtual resistor, an enhanced current control method is proposed. The optimal value of a virtual resistor is used to stabilize the amplitude of the output harmonic current. The phase control of a filter capacitor harmonic voltage is used to regulate the phase of the output harmonic current. Finally, simulation and experimental results verify the correctness of theoretical analysis and effectiveness of the method. Load harmonic current compensation capability is guaranteed.