Development of a compact very low frequency cosine‐rectangular and damped alternating current voltage generator for insulation testing of medium‐voltage power cables

Abstract

This study describes the research and design of a novel and compact very low frequency cosine-rectangular (VLF-CR) and damped alternating current (DAC) voltage generator that can be used to test the insulation condition of the mediumvoltage power cables. Further, a complete system based on a voltage multiplier (VM), which can be cascaded to increase the output voltage, is proposed to simultaneously realise VLF-CR and DAC voltages for the withstand voltage and offline partial discharge (PD) tests, enabling the test system to be lightweight and efficient. The system principle and operating characteristics associated with the generation of two different voltages are analysed in detail according to the new circuit topology of the proposed generator. Furthermore, oscillation suppression and multiple output units are considered to improve the voltage waveform and provide power supply to the VM module, respectively. A laboratory prototype is also developed and tested. Finally, the integrated generator is used for the PD testing on cables with artificial defects, verifying the practicability of the proposed system.

Novel dual‐resonance damped alternating current testing system for offline partial discharge measurement of power cables

“…To improve trigger synchronization, each IGBT subunit used a copy unit format in the software design, and various components used the same batch. Fibre‐optic triggering and a flyback supply were employed to achieve HV isolation of the IGBT chips [23]. An important concern is the generation of switching noise by the flyback circuit.…”

Partial Discharge Characteristics and Mechanism of Medium Voltage Power Cable Defects under Different Voltage Stresses

“…3. The generator was capable of producing both DAC and VLF-CR voltages; the detailed operation of the system is described in [18]. The 200 and 400 nF compensation capacitors were individually connected in parallel with the source.…”

“…Their results also showed some similarities. In principle, DAC voltage can be considered a special operating mode of the VLF-CR system [12,18]. Therefore, the discussion in this section focuses on the analysis of the space charge dynamic behavior at VLF-CR voltage and investigates its relationship with the PD characteristics.…”