Improvement of a voltage-stabilizing control system for integration of wind power generation into a small island power system

In order to demonstrate the large-scale integration of wind power generation into small isolated island power systems, a test facility composed of two wind turbine generator systems (WTs) and a flywheel energy storage system (FESS) was introduced in a remote island in Okinawa prefecture, Japan in 2009. Since large-scale integration of wind energy may cause fluctuations in the frequency and voltage of the power system, the FESS was equipped with both frequency- and voltage-stabilizing control systems. The new frequency-stabilizing control scheme developed for the FESS has been in operation since March 2010. This paper describes improvement of the voltage-stabilizing control system of the FESS. The proposed system was examined in the actual power system and proved to reduce voltage fluctuation successfully. In addition, numerical simulations revealed that the improvement of the voltage-stabilizing control system also helped to stabilize frequency.