Hybrid Control Model of Under Load Tap Changers

This paper proposes a hybrid control model of under load tap changer transformers. The proposed model is based on the well-known discrete and continuous control models of such device, and is designed so that it preserves the discrete behavior of the tap ratio while allowing solving small-signal stability and eigenvalue analysis. The proposed model is tested through the IEEE 14-bus test system and a real-world 1488-bus model of a sub-transmission and distribution system.