Dual-Loop Power Control for Single-Phase Grid-Connected Converters with LCL Filter

Grid-connected converters have widely adopted LCL filters to acquire high harmonic suppression. However, the LCL filter increases the system order so that the design of the system stability would be complicated. Recently, sole-loop control strategies have been used for grid-connected converters with L or LC filters. But if the sole-loop control is directly transplanted to gridconnected converters with LCL filters, the systems may be unstable. This paper presents a novel dual-loop power control strategy composed of a power outer loop and a current inner loop. The outer loop regulates the grid-connected power. The inner loop improves the system stability margin and suppresses the resonant peak caused by the LCL filter. To obtain the control variables, a single-phase current detection is proposed based on PQ theory. The system transfer function is derived in detail and the influence of control gains on the system stability is analyzed with the root locus. Simulation and experimental results demonstrate the feasibility of the proposed control.

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Cite this article

[IEEE Style]

S. Peng, A. Luo, Y. Chen, Z. Lv, "Dual-Loop Power Control for Single-Phase Grid-Connected Converters with LCL Filter," Journal of Power Electronics, vol. 11, no. 4, pp. 456-463, 2011. DOI: 10.6113/JPE.2011.11.4.456.

[ACM Style]

Shuangjian Peng, An Luo, Yandong Chen, and Zhipeng Lv. 2011. Dual-Loop Power Control for Single-Phase Grid-Connected Converters with LCL Filter. Journal of Power Electronics, 11, 4, (2011), 456-463. DOI: 10.6113/JPE.2011.11.4.456.