Cutsem, “Prospects of an improved system protection scheme against voltage instability

Abstract- This paper reports on prospective tests of a system protection scheme against long-term voltage instability relying on a set of distributed controllers, each monitoring a transmission voltage, blocking tap changers and shedding loads in a zone. The emergency actions adjust in magnitude and loca-tion to the disturbance. Each controller acts in closed-loop, which guarantees robustness. The method is il-lustrated on a real-life model of the Western region of the RTE system. The choice of the controller settings is discussed in some detail and examples of performance are given, combining the above remedial action with capacitor switching and secondary voltage control. Keywords- voltage stability, emergency control, system protection schemes, tap changer blocking, load shedding