A constant frequency hybrid exciter for an autonomous wind energy conversion system

This paper proposes a hybrid exciter for the standalone wind turbine driven induction generator. It consists of one set of fixed capacitor bank and a voltage source inverter connected in parallel at the stator terminals of the generator. The inverter provides the necessary variable component of lagging reactive power to the induction generator so that nominal output voltage is obtained even at lower speeds and higher loads. The dc bus voltage of inverter is maintained using the combination of a bidirectional dc-dc converter and a battery. The battery is used as a complementary energy source to minimise the impact of the fluctuations in the wind power on the connected load. The scheme has reduced control complexity because the inverter is operated with a fixed PWM and hence the control is restricted mainly to switching the bi-directional dc-dc converter. There is no need for a position or a speed sensor. The complete system is modeled and simulated in the MATLAB/Simulink environment. Simulation results validate the proposed power generation scheme as a viable alternative for remote areas.