부산대학교 도서관

The low damping of a multi-terminal low-voltage direct current (MT-LVDC) system with the influence of negative impedance characteristic in DC network, can reduce the system stability. This study aims to find an additional control method to extend the system stable operating region on the premise of not changing the local control system of each converter and not affecting the accurate tracking of each converter’s power command under their normal dispatching, thereby significantly extending the stable operating region of a MT-LVDC system by small damping powers, and ensuring the stable DC voltage when operating point changes. First, an additional control method based on feedback linearization is proposed. Then an analytical expression of damping powers required to realize additional control is built, and a method to obtain the overall stable operating region is established. Furthermore, a multi-objective optimization model for additional control is proposed, and the optimized additional controller is obtained using Pareto front solution. The proposed method is experimentally verified to be able to provide an effective method to improve the system stability with simple control structure and low complexity, which can be conveniently implemented in the MT-LVDC system.