A robust and efficient PLL algorithm for single-phase grid-connected renewable energy sources

An accurate and robust and efficient transport delay based phase-lock loop (TDPLL) is proposed for single phase grid-connected renewable energy sources. Although the conventional TDPLL has low complexity with smooth and fast transient response, its performance is significantly affected by any deviations in the grid normal frequency. The proposed TDPLL has the smooth and fast transient of the conventional TDPLL and is robust against any grid frequency variations. The proposed method uses two delays instead of one in order to cancel the grid frequency variation effect while it requires fewer calculations than the conventional TDPLL. A method to tune the TDPLL parameters is presented. The effectiveness of the proposed PLL is validated through simulations and experimental results.