Investigation of interactions among the multi-control channels of UPFC using normal forms of vector fields

One of the most important features of the unified power flow controller (UPFC) is its multiple control functions which are implemented by multiple controllers. However, recent simulation studies have demonstrated the existence of dynamic interactions among different controller channels of UPFC, i.e., the power flow controller, the AC voltage controller and the DC voltage controller. The paper is concerned with the application of normal forms to analyze the interactions among the multi-controller channels of UPFC in power systems. Moreover, a non-linear interaction index is developed to investigate the interactions among these UPFC controllers. The employed approach has been applied to the New England test power system (NETPS). The simulation results validate the proposed approach.