An Ultra-Fast DC Controllable Arrester With Hybrid Bypass Switch for Fast-Front Overvoltage Suppression

The controllable arrester is a new type of protection equipment that can effectively suppress overvoltage and improve the technical economy of the system, especially in DC transmission systems containing numerous voltage-sensitive semiconductor devices. Existing controllable arresters are unable to respond promptly to fast-front overvoltage, resulting in their inability to ensure voltage safety under all conditions. In this paper, an ultra-fast DC controllable arrester based on the hybrid bypass switch (HBS-CA) is proposed. By integrating breakable gaps and thyristors in the bypass switch, the proposed novel controllable arrester acquires the ability for ultra-fast active operation. Moreover, the modular design and the cooperation in the bypass switch effectively mitigate the uncertainties associated with the gap breakdown and the voltage unbalance risk for the thyristors. After the detailed analysis of the working principles and characteristics of the hybrid bypass switch, the control strategy and design method of HBS-CA are given. Furthermore, a 2kV prototype was built and the experimental results verified the response speed of the proposed scheme. The results show that fast-front surge can be decreased from 2.07p.u. to 1.57p.u. Finally, the simulation results of ±500kV/1100MW VSC-HVDC system verify its capability to suppress overvoltages. And the cost and performance comparisons are analyzed.