An Advance Repetitive Control Scheme for Fuzzy Current Control Based Grid-Connected Inverter with Frequency-Adaptive Capability

In this paper, an advance repetitive control method (RCM) for fuzzy current control based grid connected inverter with a frequency adaptive capability is proposed. The main objective of the proposed scheme is to reduce total harmonic distortion (THD) such that by changing the FIR filter according to varied grid frequency and keeps the resonant frequencies fitting the grid fundamental and harmonic ones. The repetitive control scheme is adopted because it is very efficient in tracking periodic signals and low output total harmonic distortion (THD) where it is required that the ratio of sampling frequency be an integer. However, in real industrial application the ratio may be a non-integer then the resonant frequencies of RCM will diverts from the real grid fundamental and harmonic frequencies and this will take down the system performance. In order to establish the improvement of performance the proposed control scheme is compared with traditional repetitive control scheme based on PI controller. The control strategy is evaluated in grid -connected mode with experiments under different frequencies. The proposed controller effectively shows that it is better than the other control schemes in terms of the THD level and component harmonic of inverter systems .