Morphological PLL for potential applications on renewable energy

This paper proposes a new Phase Locked Loop (PLL) structure using a positive sequence component extraction based on Recursive Least Squares, altogether with a morphological filter and a fuzzy-tuned proportional-integral (PI) controller when the power quality conditions are degraded. A high detection accuracy in these conditions is achieved by means of the morphological filtering and the fuzzy-tuned PI controller. The performance of the novel PLL is appraised through a frequency variation, an asymmetrical voltage sag, and an odd harmonic distortion tests, with satisfactory simulated and experimental results which are compared with a Dual Second-Order Generalized Integrator – PLL (DSOGI-PLL).