Modeling and control of voltage source converters for grid integration of a wind turbine system

Wind energy is one of the most promising renewable energy sources for generating electricity due to its cost competitiveness when compared to the conventional energy sources (fossil fuels). Wind farms are usually located far from the loads for minimal disturbances and optimal power generation. High Voltage Direct Current (HVDC) transmission is the preferred bulk power transmission system over long distances due to the minimal transmission losses, low costs and reduced environmental impacts. In this research investigation, a 690V, 2MW wind turbine equipped with a PMSG is modelled to be integrated into a local 33kV AC grid via a 2-level VSC-based HVDC transmission system. Three control schemes are implemented on the proposed system: a blade-pitch-angle controller applied on the wind turbine model, a field-oriented rotor speed controller applied on the rectifier for maximum power extraction, and a vector-oriented direct-current-link voltage controller applied on the grid-side inverter to keep the DC-link voltage constant and to ensure unity power factor. The proposed subsystems are implemented in MATLAB/Simulink and simulations are carried out to analyze the overall system's performance.