Novel power distribution short‐circuit testing technique based on supercapacitor and modular multi‐ports AC/DC conversion

Abstract

With the growing capacity of the distribution network, the probability of short circuit accidents gradually increases. Accidents such as deformation of distribution transformer windings, shift of laminations, fracture and even explosion of mechanical and insulation components caused by insufficient short‐circuit withstand ability seriously affect the safe and stable operation of the distribution network. The short‐circuit test proved to be an effective way to detect the performance of equipment under fault impact. A power source with supercapacitor is proposed here for short‐circuit test of 10 kV distribution transformers, which can realize the short‐circuit test application economically and flexibly with expandable capacity. First, the advantages and disadvantages of test power source by short‐circuit test generators, special power line, and the proposed method are compared. Second, the structure, working principle, design scheme, and control strategy of the novel short‐circuit testing device are introduced. Furthermore, a 14 MVA/5 MJ energy storage short‐circuit test power source is designed for the testing requirements of 10 kV/630 kVA distribution transformers. Finally, the simulations and experiments are used to verify its feasibility.