A Phase-Locked Loop algorithm for single-phase grid-connected systems with sub and interharmonics immunity

This paper proposes a new closed-loop synchronization algorithm, PLL (Phase-Locked Loop), for applications in power conditioner systems for single-phase networks. The structure presented is based on the correlation of the input signal with a complex signal generated from the use of an adaptive filter in a PLL algorithm in order to minimize the computational effort. Moreover, the adapted PLL, due to the use of the adaptive filter, presents a higher level of rejection for two particular disturbances: interharmonic and subharmonic, when compared to the original algorithm. Simulation and experimental results will be presented in order to prove the efficacy of the proposed adaptive algorithm. The algorithm will be exposed to several scenarios. The response of the algorithm also be compared to the synchronization system based on SOGIFLL.