Time-Frequency Modelling of Partial Discharge Radiation from Current Transformers

The non-contact detection of partial discharge (PD) from substation equipment is an important aspect of condition monitoring and asset management. This paper describes research using the finite difference time domain (FDTD) technique and the numerical electromagnetic code (NEC) in both time and frequency domains to simulate PD effects in a high-voltage current transformer (CT). The FDTD technique is widely applicable to electromagnetic computation, which is used to model the partial discharge pulse and the simplified CT. The frequency response of this system is obtained by first modelling the current transformer into a simplified antenna structure, and then simulating this structure using the NEC Win Professional v1.1 antenna simulation software. This paper firstly identifies the optimum directions for remote reception of the radiated field, and secondly estimates the dominant frequencies of radiation in order to optimize future measurement systems