Reverse action of on-load tap changer in association with voltage collapse

A discussion is presented of the reverse action that occurs when the secondary voltage of a transformer is pulled down and the tap position of an on-load tap changer is raised to increase the secondary voltage. A dynamic model of an induction motor is adopted as a load model simulating this kind of reverse action during voltage collapse. The transient mechanisms of the reverse action are analyzed using P -V curves. It is found that the reverse action caused by on-load tap changers may cause the operating condition to deteriorate in a heavily loaded power system where cascaded voltage collapse may occur