Security constrained coordinated dynamic voltage stabilization based on model predictive control

Voltage instability and voltage collapse are complicated phenomenon which can be influenced by the interactions of all power system components. This paper presents an approach for optimal coordination of static Var compensators (SVCs), transformer under load tap changers (ULTCs) and load shedding to improve voltage performance following disturbances and also to ensure a desired amount of post-transient voltage stability margin (an index of system security). The approach is based on model predictive control (MPC) with a decreasing control horizon. Since both continuous and discrete controls are considered, the MPC formulation leads to a mixed integer quadratic programming (MIQP) problem. Trajectory sensitivities are used to evaluate the effect of controls on voltage performance. The sensitivity of voltage stability margin with respect to the various control mechanisms is used to construct a constraint for guaranteeing certain post-fault stability margin in the MPC formulation. The MPC based coordination of these controls is applied to a modified 39-bus New England system to prevent voltage collapse.