A Nonlinear Control of PMSG based Variable Speed Wind Energy Generation System Connected to the Grid

Renewable energies, known as ‘clean’, do not give off or little polluting emissions. They contribute to the fight against the greenhouse effect and CO2 emissions into the atmosphere. This paper deals with nonlinear control technique for the variable speed grid connected wind energy generation system. A Maximum Power Point Tracking (MPPT) control technique is presented for extracting the maximum power from the wind turbine. The nonlinear control applied to the three-phase inverter can deal with highly unbalance load. The high passive filter to extract the current harmonics with low cut off frequency is able to compensate an unbalance load, but the dynamic response will be slow, for this reason, the Multi-Variable Filter (MVF) is able to compensate highly unbalance load without affecting the dynamic response of the system. The inverter allows full control of dc bus voltage regulation, and it acts as power transfer from the wind turbine to the grid and to the load. The MVF filter is used to estimate a fundamental voltage source which gives very good performance when the voltage source is distorted. Also, a positive sequence of the voltage source is proposed in case of unbalance voltage source. The later is controlled to achieve balanced sinusoidal grid currents at unity power factor under varying speed operation of PMSG. The simulation uses “Power system Blockset” simulator operating under Matlab/Simulink environment under various values of the wind speed of the wind turbine.