Technical Investigation on Robustness Enhancement of Single-phase Grid-connected Inverter Based on Synthesis-admittance-phasor Scheme in Weak Grid
For grid-connected inverter,phase-locked loop(PLL)is generally adopted to obtain the voltage phase information in order to make the grid current be synchronized with the grid voltage.In the meantime,the grid voltage feedforward scheme is usually employed to improve the grid current quality.However,both of these two factors may cause negative impacts on the stability in weak grid.This paper focuses on the single-phase LCL-type grid-connected inverter,aiming to explore the causes of instability and optimize its performance accordingly.In view of the existence of dual unstable factors,a synthesis-admittance-phasor scheme is proposed to analyze the influence mechanism.Considering the attenuation effect of the band-pass filter(BPF),the design goal of the band-pass link is determined according to the analysis results of the synthesis-admittance-phasor scheme,and the specific design process of the parameters is further given.The results show that the grid-connected inverter with the optimally designed band-pass link can still work stably even when it is against the wide grid-impedance variation.
grid-connected inverterphase-locked loopgrid voltage feedforwardweak grid
国家科技期刊平台
NSTL
万方数据
