Design of power supply for pollution flashover test under superimposed AC/DC voltage.

This article focuses on investigating the flashover behavior of insulators under combined Alternating Current–Direct Current (AC–DC) composite voltage conditions, a scenario increasingly relevant due to the rise of flexible DC transmission systems. It presents the design of a novel AC–DC superimposed power supply system based on a single AC source and voltage doubler rectifier circuits, capable of generating specific AC/DC voltage ratios (1:1 and 1:3) for artificial pollution flashover testing. The study includes theoretical analysis and simulation of the power supply's steady-state and transient behaviors under varying load conditions, revealing that the ratio of diode protection resistance to load resistance primarily governs steady-state voltage characteristics, while capacitance influences transition dynamics. Experimental results demonstrate that the presence of a DC component significantly lowers the AC voltage required to initiate pollution flashover on insulators, indicating increased flashover risk in power systems where DC components are superimposed on AC voltages. These findings provide a foundation for designing insulation systems and testing protocols in mixed AC–DC voltage environments, with implications for the reliability and safety of high-voltage transmission infrastructure.