Best location of SVC to improve first swing stability limit of a power system

While the primary purpose of a static var compensator (SVC) is to regulate bus voltage, it can also improve stability and damping of a power system if located appropriately. This paper proposes a method of determining the location index of a SVC in a multi-machine system to improve the first swing stability limit of the system. Based on the concept of transient energy function method, the location index of a SVC is considered to be the additional critical energy supported by the SVC and is computed through controlling unstable equilibrium point and potential energy boundary surface methods. In computing the critical energy, the SVC is represented by its susceptance at the verge of stability and which can be justified by carefully observing a recent control strategy of SVC used to improve the first swing stability limit of a power system. The effectiveness of the proposed location index of SVC is then tested on the 10-machine New England system and the 20-machine IEEE test system. Results obtained by the proposed method are then verified by comparing the critical clearing time obtained through time domain simulations of system dynamic equations.