A Fast and Adaptive PLL For Single Phase Grid-Connected PV Systems

Phase, frequency, and amplitude of grid voltage are important information in grid-connected photovoltaic systems. For proper and stable operation of a system, a fast and correct estimation of grid information under grid variations and disturbances is very crucial. In this paper, an adaptive phase-locked loop (PLL) structure is proposed which tracks the phase jumps of grid voltage fast and smoothly. If a jump occurs in grid voltage phase transient state at the frequency estimation of frequency lock loop (FLL) will be almost zero. The settling times of the estimated phase, frequency, and amplitude of the proposed PLL are also slightly low. The proposed PLL consists of the second-order generalized integrator (SOGI) and frequency locked loop (FLL). The whole system has been simulated in MATLAB/Simulink. The settling time of estimated frequency and amplitude for proposed PLL are 0.023 and 0.024 s, respectively.