Power Factor Control in a Wind Energy Conversion System via Synchronous Generator Excitation

This paper proposes a novel control technique to improve the power factor over a wide range of wind speeds in a wind energy conversion system (WECS) using a current source inverter (CSI) and an electrically excited synchronous generator. The system consists of diode rectifier on the generator side, while a pulsewidth modulated CSI is on the grid side. In the proposed control scheme, the generator excitation is controlled with the wind speed to improve the grid power factor, while the control freedoms of the CSI are used to regulate the power output of the WECS to meet maximum power point tracking of wind energy. Theoretical analysis is conducted to investigate the feasibility and limits of this approach. The simulation model for the proposed WECS is developed, and the simulation results confirm the validity of the theoretical analysis. With the proposed power factor control scheme, improvements of grid-side power factor are achieved over a wider range of wind speeds.