A Method for Constructing Short-Time AC Voltage Generator to Evaluate Cable Conditions

Power cables are widely used in transmission and distribution systems. Due to the high capacitance of the power cable, it is difficult for existing high-voltage excitation to meet the diagnostic test requirements at the same time. This article presents a method of generating a short-time ac (STAC) voltage for power cable condition evaluations simultaneously. First, the circuit structure based on the principle of resonance is given. Then, an algorithm based on optimization is given to control the resonance process. By using this method, a variety of high-voltage waveforms are excited by low voltage. This method makes the resonance process controllable and produces multiple waveforms suitable for cable condition evaluations. Several examples of diagnosing the state of a power cable, such as the detection and location of partial discharge (PD), precise tests of PD inception voltage and PD extinction voltage, and a dielectric dissipation factor test were carried out in the laboratory. In addition, an in-field test of a medium-voltage cable was performed. All the results show that the proposed STAC can be used to evaluate cable conditions effectively and simultaneously.