Hybrid optimisation method for optimal power flow using flexible AC transmission system devices

This study proposes a hybrid optimisation method for optimal power flow using a flexible AC transmission system (FACTS). The FACTS plays an important role in the dynamic stability and steady-state control of power systems. This study achieves steady-state control by determining the types and the optimal locations of the FACTS devices and their associated values in the transmission lines. To determine the optimal solutions to the FACTS allocation problem, a hybrid optimisation method that combines a harmony search algorithm and an ant system is proposed. The objective functions of power flow considered are the active power transmission loss, the performance index of the active power flow in the transmission lines and the performance index of the voltage difference between buses. The proposed method was verified on the IEEE 30-bus and Taiwan Power Company 345 kV simplified systems. The results demonstrate that the proposed method improves the total transfer capability and provides better steady-state control of power systems than existing methods do.