Simulation on THD performance of photovoltaic flyback
grid-connected micro-inverter
AI Qing-lin1，LOU Yong-liang1，XV Jian-feng2，DU Xue-wen1，HU Ke-yong3
（1. Key Laboratory of E&M Ministry of Education & Zhejiang Province，Zhejiang University of Technology，
Hangzhou 310014，China；2. Fair Friend Institute of Electromechanics，Hangzhou Vocational&Technical College，Hangzhou 310018，China；3. Qianjiang College，Hangzhou Normal University，Hangzhou 310036，China）
Abstract：Aiming at the problem of photovoltaic flyback grid-connected micro-inverter output power changing continuously with thesolar cell output power in a relatively low output power level，the total harmonic distortion（THD）performance of grid-connected currentcan not meet requirement of the utility grid，the PI quasi resonant controller for flyback grid-connected inverter was investigated. Themathematical model of photovoltaic flyback grid-connected micro-inverter was set up by using the state space averaging method. Thesimulation model based on the mathematical model was established and the performance of traditional PI controller and PI quasi resonantcontroller were analyzed. The results indicate that the THD of grid-connected inverter output current is the larger by using PI controllerwhich can not meet the requirement of the utility grid and the THD is less then 5% by using PI quasi resonant controller which can meetthe demand of utility grid at the different input voltages and load conditions. So this method can verify the effectiveness of the newcontrol method.
Key words：photovoltaic flyback grid inverter；PI resonance control；total harmonic distortion（THD）