Static synchronous compensator sizing for enhancement of fault ride-through capability and voltage stabilisation of fixed speed wind farms

High penetration level of wind energy affects the generation profile of the power systems, which impose more stringent connection requirements of wind farms. The ability of wind power plant to remain connected during grid faults is very important to avoid cascaded outages because of power deficit. FACT devices are considered to be a key technology to accomplish these requirements. The implementation of three-level inverter based on a static synchronous compensator (STATCOM) for the improvement of the ride-through and stability of fixed speed wind farms is analysed here. This brings the challenges for system planner to determine the appropriate STATCOM rating. This study provides a simple approach to evaluate the STATCOM rating for voltage-level regulation at the point of common coupling around its pre-specified value. Vector current control is used as robust control to inject the required reactive power from STATCOM. This study emphasizes also on the analysis of torque speed curve to evaluate the induction generator speed limit and for defining the critical clearing time of the fault according to the selected STATCOM rating. Simulation results under fault conditions are performed to validate the enhancement of wind farm low-voltage ride-through capability and increasing the critical clearing time by installing STATCOM.