Research on Single-Phase LCL Dual-Loop Grid Current Control Based on the Modified PR Regulator

Abstract

Abstract:

With the advantages of good filter property and small size, LCL filter is widely applied in single-phase grid inverter. However, its capacitance branch is extremely vulnerable to resonances, which are harmful to the design of control circuit, so many strategies are proposed to solve the problem. Monocyclic grid current control strategy is a severe under damped system and the existence of resonant peaks can cause the distortion of current waveform. PI regulator is unable to stabilize the closed-loop system. In terms of PR regulator, by increasing the current loop gain of specific frequency, the error of harmonic can be restricted, but the frequency variations influences and controls the band width of the system. A kind of frequency variations influences is proposed and the double loop current control strategy is adopted in the paper. The experimental result indicates that this kind of strategy can effectively solve the problem of the inverter, in the case of the grid frequency fluctuation, giving rise to the grid current resonance and the power factor of the grid current.

Key words: Grid-connected inverter, PI controller, PR controller, frequency feedback, dual-loop current controller

CLC Number:

TM464

Qin Weikun,Hu Cungang. Research on Single-Phase LCL Dual-Loop Grid Current Control Based on the Modified PR Regulator[J]. Journal of Electrical Engineering, 2015, 10(8): 40-44.

Figures/Tables 12

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