Performance Evaluation of R-PLL for Robust Sensorless Operation of DFIG under Harmonics, DC Offset and Phase Jump in Grid Voltage

Abstract

The increasing demand for electric power have brought new paradigms in the global perspective, leading to a major drift in the penetration of renewable sources with the grid, resulting in severe grid instability issues. Thus, for precise power control of grid integrated DFIGs, accurate angular grid frequency, rotor speed signal and rotor position are necessary owing to the severe power and torque pulsations DFIG is encountering under grid voltage imperfections like harmonics, phase jump and DC offset. In this regard, the crux of this paper is to validate the performance of R-PLL in computing the angular stator flux frequency, rotor speed and position under grid voltage imperfections like harmonics, Phase Jump and DC Offset in addition to unbalanced grid voltage in facilitating reliable and robust operation of DFIG. The efficacy of R-PLL scheme in computing the rotor speed, position and angular gird frequency for a grid connected DFIG subjected to grid voltage imperfections like harmonics, DC Offset and phase jump is demonstrated using simulations in PSCAD/EMTDC for a 2.3kW DFIG.