A hybrid topology for a variable speed wind-diesel generation system using wound rotor induction machines

In this paper a energy system topology consisting of a diesel and wind turbine generation units is presented. Wound rotor induction machines are considered to provide energy to an isolated load at constant voltage and frequency. Both generator rotor currents are vector controlled and operate at variable speed. The scheme uses a common DC bus for the voltage source PWM rotor side inverter of each machine. Another vector controlled voltage source PWM inverter is connected between the DC bus and the stator to allow sub and super synchronous speed operation of both generators. The diesel generator unit balances the system power and changes the speed according to power demand in order to minimise the fuel consumption. The variable speed operation of the wind energy conversion system maximises the energy capture by controlling the generator electric torque. An experimental prototype has been set with the diesel engine and the wind turbine emulated with a AC and DC drive respectively. The system has been tested to load impacts and step changes in wind velocity and experimental results for optimum speed tracking are shown.