Modelling, simulation and testing of grid connected small scale wind systems

This paper will show the theory, simulation and application of maximum power point tracking for small scale wind turbines. The theoretical section of this paper will cover modelling of the wind turbine, the and the power electronic converters (the full-bridge DC/DC converter and the grid connected current controlled voltage source inverter (CCVSI)). It is shown that by controlling the duty ratio of the DC/DC converter, the wind turbine generator is operated at the maximum power point. This is achieved without measuring the wind speed using a look up table where the power output vs the shaft speed is recorded. In order to keep the output current waveform sinusoidal at varying wind speeds, the DC link voltage of the CCVSI is kept constant. This system meets the utility requirements such as galvanic isolation, anti-islanding protection and protection of the wind turbine at high wind speeds.