Research on A Transition Circuit of Vacuum On-Load Tap-Changer

As an important component of transformers and converter transformers, vacuum on-load tap-changers directly affect the reliability of power grid operation. In order to improve the reliability of the tap-changer, it is necessary to study the transition circuit of the tap-changer and its operation method in order to improve it. This paper analyzes two kinds of transition circuits of vacuum on-load tap-changers and their operation methods, and analyzes the breaking tasks of each contact in the transition circuit. It is found that the two topologies have an imbalance in the breaking capacity of the two internal vacuum tubes. This paper proposes a type of vacuum on-load tap-changer topology, which adds a vacuum tube and a transition resistance. At the same time, an operation method is proposed, which changes the vacuum tube with heavy switching task into two vacuum tubes that operate alternately in the adjacent switching, and changes one transition resistance into two transition resistances that work alternately. It reduces the burden of a single auxiliary vacuum tube, balances the contact ablation of each vacuum tube under long-term operation, and reduces the temperature rise of the transition resistance, which improves reliability of the tap-changer.