A Novel Control Scheme for Wind Driven DFIG Interfaced with Utility Grid

Abstract

This paper proposes a phase-locked loop (PLL) based novel control scheme for a wind driven doubly fed induction generator (DFIG) connected to the utility grid. The wind driven DFIG has two converters namely rotor side converter (RSC) and grid side converter (GSC) with a battery energy storage (BES) connected at DC link. The control of GSC, is modified to export/import constant power to/from the grid. The averaged wind power and state of charge of BES, help in deciding the reference export power to the grid apart from the manual selection. The RSC and GSC have taken care of unity power factor operation at stator terminals and to mitigate harmonics, grid currents balancing, respectively. The system performance is found robust as the PLL response is not affected even under grid voltages with DC offset. To validate the effectiveness of the proposed control scheme, a prototype of the system is developed. Test results demonstrate the satisfactory performance under various operating conditions such as varying wind speeds, change in the load, change in export and import of grid power and nonlinear load connected at point of common coupling (PCC). The grid currents and voltages are achieved according to the IEEE-519 standard.