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Affiliation of Author(s):自动化学院

Journal:Dianli Xitong Zidonghue

Abstract:In the grid-connected system with paralleled inverters, the safe operation of inverters is challenged by the resonant circulating current which is usually located beyond the control bandwidth. In order to analyze the characteristics of resonant circulating current, the digital control and the nonlinear link of pulse width modulation are taken into consideration. Based on the one-dimensional spectrum analysis method, this paper studies the harmonic component of the inverter output voltage when the modulated wave is disturbed. Then the multi-frequency impedance model for the single-phase paralleled grid-connected inverters is developed. Based on the generalized Nyquist stability criterion, the influence of the control carrier phase on the parallel system stability is analyzed, and the frequency of the resonant circulating current can be readily predicted. Finally, it is pointed out that the enlargement of the modulus of the output impedance contributes to suppressing the resonant circulating current. The experimental results verified the correctness and effectiveness of the proposed multi-frequency impedance model. © 2019 Automation of Electric Power Systems Press.

ISSN No.:1000-1026

Translation or Not:no

Date of Publication:2019-08-10

Co-author:Qian, Qiang,Wei, Qi,xsj,F70206578,Wang, Weijian

Correspondence Author:Qian, Qiang,wqy