ABSTRACT The damped alternating current (DAC) technique has been widely applied for partial discharge (PD) testing of high‐voltage (HV) cross‐linked polyethylene (XLPE) cables. However, for transmission applications, the unipolar DC charging stage required in conventional DAC systems leads to space charge accumulation, which deteriorates the cable insulation condition. CIGRE TB 841, therefore, recommends the use of a bipolar charging manner instead of the unipolar manner. To address this requirement, a compact bipolar HVDC generator based on a modified voltage multiplier is proposed. In the proposed design, bidirectional rectifier switches are employed in place of unidirectional diode stacks to enable flexible polarity switching of the output voltage. Simulation results demonstrate an 80% reduction in space charge accumulation under bipolar DAC voltage, validating the effectiveness of the mitigation strategy. A three‐stage prototype was constructed, which is capable of delivering up to 180 kV. Laboratory tests on a lumped capacitor and field tests on a 110 kV XLPE cable validated the feasibility and effectiveness of the proposed method. The system maintains the compactness and portability of conventional DAC systems while extending its capability to provide bipolar DAC voltage, thus providing a practical solution for on‐site PD detection of XLPE cables.
Chen et al. (2026) studied this question.