DSP Implementation of Three-Phase PLL using Modified Synchronous Reference Frame

This paper proposes a new algorithm for three-phase digital PLL based on modified synchronous reference frame (MSRF). This MSRF-PLL is suitable DSP implementation applied to grid connected utility equipments. The algorithm guaranty fast transient response, robust operation under grid disturbance and noise tolerance. The strategy does not use PI controller, what improves the transient response and accuracy of synchronizing output signal. The algorithm is described in details and the practical results, under all types of severe disturbances, are presented and discussed.