An Approach to Voltage Quality Enhancement in Wind Energy Conversion Systems

Power generation is increasingly moving to renewable energy sources like wind and sun due to environmental concerns and the depletion of non-renewable energy sources. However, as the penetration of renewable generation sources increases, power system instabilities occur, especially in grid faults. Therefore, grid code requirements exist that wind farms must comply with to prevent the power system from collapsing. Transmission system operators introduced guidelines and grid code requirements to evaluate the power quality of wind for the integration of wind energy into the grid. One of the well-known and widely used guidelines to define the power quality of grid-integrated wind turbines is the IEC 6140021 standard. The primary focus of this paper is on voltage quality as one of the power quality issues that affect the connection of wind energy systems to the electrical grid. Furthermore, an approach to voltage quality enhancement is evaluated to mitigate the effects of voltage quality issues during any event disrupting the electrical grid. Static VAR compensator (SVC) and Static synchronous compensator (STATCOM) are Flexible AC transmission system (FACTS) controllers which are commonly used to improve power transfer capability in power systems. Wind energy conversion systems (WECS) have adopted FACTS controllers to enhance their transient stability and voltage quality and regulation. Simulation results in MATLAB/Simulink environment have illustrated that when SVC and STATCOM are connected to the electrical grid, their reactive power support to the electrical grid during transient-state significantly affects the voltage profile and improves the recovery time after any fault. SVC and STATCOM performed well, with STATCOM performing slightly faster during transient-state than the SVC and supplying more reactive power with severe faults where the bus voltage was lower.