CONTROLAND STABILITY ANALYSIS OF GRID-CONNECTED INVERTER UNDER LOW SWITCHING FREQUENCY

Huang Lulu; Gao Bo

doi:10.19912/j.0254-0096.tynxb.2021-1055

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Acta Energiae Solaris Sinica ›› 2023, Vol. 44 ›› Issue (4) : 332-340. DOI: 10.19912/j.0254-0096.tynxb.2021-1055

CONTROLAND STABILITY ANALYSIS OF GRID-CONNECTED INVERTER UNDER LOW SWITCHING FREQUENCY

Huang Lulu, Gao Bo

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Abstract

The stability of damping resonance of grid-side current feedback control and inverter-side current feedback control of LCL grid-connected inverter is analyzed. From the standpoint of the dominant poles, the positions of the two conjugate complex roots at low switching frequency determine the direction of the root locus, which in turn affects the stability of the system. The existing active damping methods are proposed independently, and there is a lack of systematic synthesis in order to propose novel active damping control methods. The essence of the damping resonance can be obtained by analyzing the stability control of grid-connected inverters. Digital time-delay is essentially a series correction, revealing that the delay changes the system phase characteristics. The phase lag of the digital delay is beneficial to system stability in some cases, but it depends on resonance frequency and the position of current sensor which is utilized for feedback variable. The paper designs the current controller parameters in the discrete domain, and gives a method to determine controller parameters quickly and exactly from the point of view of engineering practicality. The theoretical analysis is validated by simulation and experimental results.

Key words

LCL filter / current regulator / grid side current feedback / inverter side current feedback / digital time-delay / phase lag

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Huang Lulu, Gao Bo. CONTROLAND STABILITY ANALYSIS OF GRID-CONNECTED INVERTER UNDER LOW SWITCHING FREQUENCY[J]. Acta Energiae Solaris Sinica. 2023, 44(4): 332-340 https://doi.org/10.19912/j.0254-0096.tynxb.2021-1055

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