Coordinated control of FACTS devices in power systems for security enhancement

FACTS devices provide the possibility to control voltages and power flows in a power system and therefore to improve the security of the system. In order to make use of this possibility, the set values of the FACTS controllers have to be chosen appropriately. A valuable option is the application of Optimal Power Flow control, where the set values are determined such that an objective function is minimized given the model of the system. But due to the large size of power systems, it is often difficult for different reasons to include the entire system into the optimization process. In this paper, sensitivity analysis is used to determine the area on which the FACTS device has considerable influence and then only this limited area is included in the Optimal Power Flow control. If there are several devices placed in the same system, the areas assigned to these devices might overlap indicating mutual influences. Therefore, a coordination of the control entities is needed in order to avoid conflicting behavior of the devices rising the issue of Multi-Area Control. Here, the method based on Approximate Newton Directions is extended for the case of overlapping areas which are determined by sensitivity analysis.