Optical fiber‐triggered solid‐state switch applied in power cables damped AC voltages test system

Abstract

The damped AC voltage (DAC) cable partial discharge test system is an effective approach to diagnose offline cross‐linked polyethylene (XLPE) power cables. The high‐voltage solid‐state switch, as its core component, should meet the requirements of withstanding the high voltage, short conduction time, and low resistance. This paper reports the development of a solid‐state switch for 35 kV DAC test system using insulated gate bipolar transistors (IGBTs) connected in series. To improve the synchronization of the trigger signal, a trigger circuit based on optical fiber is designed. In order to solve the unbalanced voltage distribution of multilevel IGBTs in series, an RCD (resistor–capacitor–diode) snubber circuit is designed and utilized. Especially, lithium batteries were used to drive the trigger circuit, thereby avoiding the problem of isolation of power supplies. Besides, the problem of high‐voltage insulation was solved by designing a reasonable structure and layout. Test results show that the proposed solid‐state switch, with partial discharge inception voltage >62.5 kV, conduction time <320 ns, and conduction resistance <3.31 Ω, meets the special demands of the 35 kV DAC test system. It is demonstrated that the solid‐state switch based on optical‐fiber‐triggered IGBTs in series can be effectively applied in the DAC test system. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.