ROBUST CONTROL STRATEGY OF LCL-TYPE GRID-CONNECTED INVERTER BASED ON DELAY COMPENSATION

Liang Junyang; Kong Fannie; Wang Zhenmin; Li Xiang; Ding Xin; Chen Yanming

doi:10.19912/j.0254-0096.tynxb.2022-1371

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Acta Energiae Solaris Sinica ›› 2023, Vol. 44 ›› Issue (12) : 444-452. DOI: 10.19912/j.0254-0096.tynxb.2022-1371

ROBUST CONTROL STRATEGY OF LCL-TYPE GRID-CONNECTED INVERTER BASED ON DELAY COMPENSATION

Liang Junyang¹, Kong Fannie¹, Wang Zhenmin², Li Xiang¹, Ding Xin³, Chen Yanming¹

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Abstract

In order to reduce the influence of control delay on active damped equivalent virtual impedance in LCL grid-connected inverter control, an improved control strategy based on active damped inner loop cascaded lead is proposed in this paper. Firstly, a mathematical model including the delay is established, which shows that the time delay will damage the positive frequency range of virtual impedance, threatening the stability of the inverter. Meanwhile, the mechanism of traditional inverter-side current feedback active damping lowering the low-frequency gain is analyzed. Then, an improved delay compensation scheme with a cascaded leading compensator is proposed to widen the stability region. The low-frequency gain reduction can be improved by designing a suitable gain function in the damping loop. Through the proposed delay compensation scheme, the equivalent positive damping frequency range extends to （0,0.48f_s）. An expected active damping performance and strong stability of the system is obtained. Simulation and experimental results verified the validity of the proposed strategy.

Key words

grid-connected inverter / weak grid / active dampening / delay compensation / robustness

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Liang Junyang, Kong Fannie, Wang Zhenmin, Li Xiang, Ding Xin, Chen Yanming. ROBUST CONTROL STRATEGY OF LCL-TYPE GRID-CONNECTED INVERTER BASED ON DELAY COMPENSATION[J]. Acta Energiae Solaris Sinica. 2023, 44(12): 444-452 https://doi.org/10.19912/j.0254-0096.tynxb.2022-1371

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