Comparative study of single-phase PLLs based on PI controller design and a nonlinear fuzzy synchronism algorithm

The correct current or voltage phase angle of a power electronics equipment is an essential information, especially in those connected to grid as: thyristor rectifiers, active power filters and distributed generation systems. For this reason, up to this day there are several Phase-Locked Loop (PLL) algorithms presented. However, those algorithms usually suffer from unsatisfactory dynamic response when phase angle jumps or harmonic distortion are presented. In this paper, 3 single-phase PLL strategies are discussed and compared to a PLL based on Fuzzy Logic theory. From this, the dynamic behavior of each of the PLLs concerning relevant aspects such as response time, steady-state error and disturbance rejection are evaluated showing that the fuzzy based PLL presents better harmonic disturbance rejection capability and response time.