Comparison of two control approaches for stability enhancement using STATCOM with active power injection capability

The application of two control strategies for shunt-connected FACTS devices to enhance the transient stability of a power system will be discussed in this paper. The main focus will be on the use of active power in the FACTS device and therefore a STATCOM with active power injection capability will be considered. The first approach represents the classical cascade controller that consists of an inner vector-current controller and various outer-control loops. The alternative approach controls the converter in a similar fashion as a synchronous generator, where the mechanical behavior of the machine is emulated in the control structure using the active power injection capability of the device. Using various simulation and experimental tests, the two methods will be compared in terms of their advantages and disadvantages, and a recommendation will be made on the use of the methods for transient stability enhancement.