Load frequency control by using demand response with ℋ∞ in isolated power systems

Currently, there are several published reports on the wind turbine generation (WTG) for output power control by pitch angle control. A battery energy storage system (BESS) proposed with the WTG is installed for small power systems to reduce the adverse effects of frequency deviation. This paper presents a coordinated control method for frequency control by a demand response (DR) and a BESS using H_∞ control theory. The output power command for the DR is based on the frequency deviation using a H_∞ controller. Another H_∞ controller is used in the output power command system of the BESS which is determined according to the frequency deviation and the state of charge. By using the proposed method, good frequency control performance, effective use of wind energy and reduction of the battery capacity can be achieved. Simulation results demonstrate the validity of the proposed method.