A Cable Insulation Condition Detection Method Based on H-Bridge Cascading and Resonance

Partial discharge (PD) and dielectric dissipation factor (DDF) tests are important to ensure the safe and stable operation of high-voltage power cables. However, it is difficult for the existing test system to meet the requirements of both tests. Therefore, this article presents a short-time ac high-voltage generator and testing system for cable’s PD and DDF measurement. First, the schematics based on cascade H-bridge and series resonance are presented. Then some key technologies and design methods of key components are given, including the design of the inductor based on optimization principle and field-circuit coupling, the DDF measuring method which can ensure the safety of the test cable, and the optimization control algorithm based on state equation. The implementation then is given and an experiment is carried out to generate the target voltage. A variable DDF standard capacitor is used to verify the effectiveness in DDF measurement and a field test case is given where the effectiveness in measuring PD is verified. Compared to existing methods, the proposed approach provides greater load capacity, a more compact and lightweight design, and extended nominal voltage duration. Additionally, it enhances DDF precision, achieving a 1e−4 resolution for more accurate measurements.