## 1 Introduction
[PERSON] [17] described a new material and fabrication technique for metal oxide varistors based on a novel oxide mixture, obtaining a new zinc oxide varistor with higher nonlinear electrical characteristics. These two researchers optimized the performance of the arrester by improving the material of the zinc oxide varistor. This material-level study applies to the voltage equalization aspect. However, this approach contributes less to current equalization in a multi-column parallel arrester. [PERSON] proposed a method to control the V-I characteristics of each column through the arrangement method and the inversion method to make the V-I characteristic curve of each column ZnO varistor as consistent as possible [18; 19]. However, this only applies to fixed impulse current waveforms and amplitude conditions. [PERSON] proposed a matching method based on equalizing the absorbed energy of each ZnO varistor in the arrester group and improved the current uniformity between columns through the iterative calculation of ZnO varistor position replacement [20]. This method equalizes the energy absorption of the ZnO varistors but does not consider the impact of temperature on the ZnO varistors. [PERSON] used ballast ZnO varistors to minimize the arrester mismatch effect and increase the energy absorption rating [21]. [PERSON] proposed that \(\beta\) is related to the V-I characteristics of the ZnO varistors and the temperature of the ZnO varistors [22]. These studies are directed towards the equalization of currents in multi-column parallel arresters. However, these methods of current equalization for surge arresters before assembly have limitations. It is more difficult to implement under various conditions. Once an arrester has been in operation for a longer period and is damaged, the arrester can only be replaced. [PERSON] proposed that when a specific column of the arrester is damaged, it can be replaced with a new ZnO varistor column [23]. However, this scheme of replacing the arrester column is cumbersome and inconvenient. Matching the new varistor column and the other varistor columns is difficult, and long-term use is more likely to result in damage. Replacing arresters is also more difficult for offshore wind farm converter platforms. Thus, the current methods cannot solve the problem of dynamic current equalization of a multi-column parallel arrester. All of them are dedicated to the assembly of the varistors before the arrester is assembled. In different scenarios, the nonlinear characteristics of the varistors is not the same, which gives these methods certain limitations. This paper therefore proposes a method for improving dynamic current uniformity using the self-generated inductance of a surge arrester core spiral structure. Unlike current methods in terms of material and matching aspects, the research in this paper is dedicated to the structural optimization of the traditional linear structure into a spiral structure. This approach results in a more compact surge arrester as well as the realization of dynamic current equalization. The spiral structure core of the arrester designed in this paper presents a novel way to achieve the current uniformity scheme of parallel arresters. The self-generated inductor of a unidirectional spiral structure can carry out dynamic current uniformity when the arrester is working. It further reduces the unevenness of the current distribution between columns based on arrester matching. In Section 2, the core structure of the \(\pm\)550 kV DC gas-insulated switchgear arrester (GISA) is optimized. Optimizing the core structure to a spiral structure makes the arrester more compact. Then, a multi-physics field simulation analysis is performed. Section 3 establishes a miniature prototype of the \(\pm\)66 kV DC GISA for the simulation analysis and experimental verification.