Control Design of Fast Response PLL for FACTS Applications

At most FACTS (Flexible AC Transmission System) applications, grid-connected photovoltaic systems, power conditioning and etc., for a proper operation and a synchronization with a power utility it is necessary to have an actual information about a phase angle or a fundamental frequency of three-phase grid voltages. For these purposes a special phase-locked loop (PLL) is used, which estimates the voltage quantities for a reference phase signal generation synchronized with the AC transmission line. A control design procedure of the PLL with a proportional-integral and a proportional-integral-derivative controller types under balanced and sinusoidal conditions of a grid, as well as a PLL-based algorithm control design under a grid fault operating condition with the voltage variations is briefly addressed by the report. Simulation results in the MATLAB/Simulink environment show that the proposed PLL control strategy can provide the fast dynamic response and be used under the harmonic distortions as well.