Stable operation of multiple power routers

With the ability to improve grid reliability and reduce overall costs, the number of FACTS devices on the transmission grid is growing. With advances in power semiconductor technology, the rate of growth is expected to increase as well. Multiple FACTS controllers installed on the same network, with each trying to control system parameters to achieve their own objectives, can introduce high-frequency interactions. This paper proposes conditions for controller design that can ensure stable operation of multiple controllers. In contrast with a coordinated controller design, the proposed approach is independent of other controllers at the controller design stage. This paper uses power routers (UPFC, SSSC, BTB etc.) and a standard PI controller for analysis, but the results can be extended to any FACTS controller.