A fuzzy-based hybrid PLL scheme for abnormal grid conditions

This paper presents a new family of fuzzy phase locked loop (FPLL)-fuzzy double decouple synchronous reference frame phase locked loop (FDDSRF-PLL)-that incorporated DDSRF-PLL into FPLL. FDDSRF-PLL enjoys both advantageous of DDSRF-PLL and fuzzy system to detect the fundamental-frequency positive-sequence component of the utility voltage under unbalanced and distorted conditions as well as fast and smooth tracking of phase jump. Furthermore, to achieve the best possible performance, a fuzzy adaptive particle swarm optimization (FAPSO) algorithm is considered to optimize parameters of the fuzzy system and DDSRF-PLL´s filters. The results show that, in comparison with DDSRF-PLL and FPLL, FDDSRF-PLL has better performance in tracking of the positive-sequence voltages of the three-phase system under unbalanced condition, phase and jump simultaneously.