Design of Air Clear Distance between Two-Sections Arrester and Valve Tower of ±1100kV UHVDC Converter Valve

The length of arrester is limited by the height of transport and the difficulty of assembly, so the arrester of ±1100kV UHVDC converter valve is designed as a two-sections arrester. The metal in the middle of the arrester cannot be equipotential with the valve tower. It is necessary to study the potential distribution characteristics of arrester metal, then to obtain the voltage difference between the arrester and the valve tower, which provides the basis for the design of air clear distance. According to the single valve withstand voltage requirements and non-uniform voltage coefficient. The air clear distance requirement between the valve tower and the metal at both ends of the arrester is calculated. The potential distribution characteristic of the intermediate metal and the voltage difference characteristic between the intermediate metal and the valve tower under different types of voltages are simulated. The maximum voltage difference and air clear distance requirement between the intermediate metal and the valve tower are calculated. Based on electric field simulation and single valve test, the safety of the design of air clear distance between the arrestor and the valve tower is verified.