Model predictive control-based real-time power system protection schemes

The objective of power system controls is to keep the electrical flow as well as voltage magnitudes within acceptable limits in spite of the load and network topology changes. The control of voltage level is accomplished by controlling the production, absorption as well as flow of reactive power at various locations in the system. This paper presents an approach to determine a real-time system protection scheme to prevent voltage instability and maintain a desired amount of post-transient voltage stability margin (an index of system security) following the occurrence of a contingency by means of reactive power control. This approach is based on the model predictive control (MPC) theory. According to an economic criterion and control effectiveness, a control switching strategy consisting of a sequence of amounts of the shunt capacitors to switch is identified for voltage restoration. The effect of the capacitive control on voltage recovery is measured via trajectory sensitivity. The sensitivity of voltage stability margin with respect to the capacitive control is used to construct a security constraint for post-fault operation in the MPC formulation. The efficacy of the proposed approach is illustrated through applications to the WECC system for enhancing the voltage performance and to the 39-bus New England system for preventing voltage collapse.