Design and operating experience with fast acting load shedding scheme in the Entergy System to prevent voltage collapse

The Western Region of the Entergy System is limited in both generation and transmission. Steady State and Dynamic Voltage stability analysis has indicated that the region can be subjected to severe voltage instability followed with possible voltage collapse under certain critical double contingencies. In order to prevent voltage collapse in the region, Entergy developed a fast acting load shedding scheme called VSHED. This scheme utilizes the existing Supervisory Control and Data Acquisition (SCADA) System to perform load shedding without manual intervention. This paper discusses the results of the voltage stability analysis performed to analyze the problem, the design and development of the VSHED scheme, computer implementation and a recent disturbance during which the VSHED scheme operated successfully and saved the Western Region of the Entergy System.