A Class of Active Fault-tolerant Loop Filters for Phase-Locked Loop

This paper investigates a class of fault-tolerant loop filters designed by improved active disturbance rejection algorithm for phase-locked loop (PLL), which can accurately estimate the the phase of three-phase power grid in consideration of phase voltage unbalance, voltage harmonics and direct current offset. Firstly, this letter proposes a class of fault-tolerant loop filters derived from part known fault information. Furthermore, simulations are finished to validate that the performance of the proposed loop filters is better than the conventional loop filters.