Application of STATCOMs to wind farms

Effective reactive power control in distribution networks can have an important influence on the level of embedded generation that is acceptable and on the costs of its connection. A comprehensive study was undertaken to investigate how STATCOMs could be used with fixed-speed wind turbines, which use induction generators, to improve both the steady-state state and dynamic impact of a wind farm on the network. An optimal power flow model based on loss minimisation was developed and used to show that operation of a wind farm at unity power factor is unlikely to allow maximum penetration of wind energy into a weak distribution circuit. The results of the electromagnetic simulations showed that the use of a STATCOM improves the steady-state stability limits of the network. They also showed that the use of a STATCOM with an appropriately designed control strategy can prevent damaging overvoltages that may occur under islanding conditions. The results also demonstrated that a STATCOM can be used to mitigate voltage fluctuations at blade passing frequency, which may occur if the rotors of a number of wind turbines fall into synchronism