Propagation Characteristics of Partial Discharge Pulse Current on 10kV Covered Conductor

Abstract

With the application of covered conductor in distribution overhead lines, the grounding and short circuit faults caused by foreign objects have been eliminated. But new partial discharge problem has appeared on the surface of the covered conductors around tower head. It may cause the single-phase grounding fault and affect the power supply reliability. To increase the reliability, status monitoring must be used to prevent the faults from beginning. Currently, the partial discharge on overhead lines is usually measured by coils. It utilizes pulse currents to check whether there is a partial discharge. However, it cannot be used in status monitoring as the propagation characteristics is not clear. This paper carried out a simulation study on the propagation characteristics. By constructing a simulation model of overhead lines with covered conductor by the distribution parameters, the initial pulse current amplitude and front time transformation rule in different transmission distance is obtained. Considering different conditions such as pulse current frequency domain (10~50MHz), covered conductor height (4.5~8.0m), covered conductors’ phase spacing (0.6~1.0m), and conductor cross-sectional area (50~185mm2), simulation results show that the amplitude attenuation rate is between 1.5% and 6.3% per 100m, and the front time growth rate is between 1.5% and 5.7% per 100m. The height of covered conductor has the greatest influence on the pulse current waveform transformation, and the main frequency of the pulse current takes the second place, while the difference between the phase spacing and the cross-sectional area has less than 1% influence on transformation.