Simulation of FACTS for wind farm applications

The simulation of FACTS (flexible AC transmission systems) is essential in order to provide insight on the interaction of FACTS, wind farm(s) and the grid prior to any application of such systems. A typical wind farm-FACTS arrangement is considered. Two FACTS-devices are utilised. Firstly a dump load sheds the extra power produced, or is activated during a wind farm cut out to prevent the isolated wind farm voltage to shoot up. A unified power flow controller (UPFC) is also considered which combines reactive power compensation (instead of an SVC) and voltage control (instead of a TCSC). The wind farm considered is comprised of 5 horizontal axis turbines, each having a capacity of 300 kW. The 3 blade hub is coupled to a step up gear and through a coupling mechanism (usually fluid), to an induction generator. Wind farm temporal and spatial dynamics as well as tower structural dynamics have also been considered. It is shown how SABER, a special simulation package built around MAST, was used to simulate a system containing a resistive brake and a UPFC. Finally SABER simulation results were used to indicate that the resistive brake can be used as a dump load for isolated wind farms and that the UPFC can provide both voltage control and the reactive power of a grid connected wind farm