Development of a Novel Extendable Damped AC Testing System

This paper proposes a novel extendable damped AC (DAC) generator based on voltage multipliers, which could be employed for partial discharge (PD) testing of power cables. The traditional DAC generator is extremely difficult to extend to a higher voltage level due to the traditional HVDC source, while the circuit topology proposed in this paper simply needs to increase the number of the stage of the VM so as to increase the output voltage level. All the diodes in the traditional VM are replaced with HV switches consisting of series-connected IGBTs with anti-parallel diodes. This paper formulates the detailed implementation of the proposed DAC generator circuit applied to a 10 kV cable. The high-frequency inverter power supply is used as the power source to increase the charging speed during the charging process. Each stage of voltage multipliers is composed of two circuit boards to enhance its extensibility. The practicality of this novel generator has been proved through experiments on a 1400-m cable. Finally, in order to prove its expansibility, two more stages are added to the designed two-stage voltage double circuit to increase the output voltage from 30kV to 60kV.