Investigating partial discharge UHF electromagnetic waves propagation in transformers using FDTD technique and 3D simulation

On-line partial discharge (PD) measurement in power transformers has become increasingly popular in recent years. Measuring PD signals at ultra high frequency (UHF) range have many advantages. So, numerical methods have been implemented to model the propagation of electromagnetic (EM) wave in power transformers. Utilizing conventional softwares, such as CST to simulate EM wave propagation in power transformers need tremendous amount of time and memory. So such packages are difficult to be used in these fields of study. In this paper we will verify the program written in C++ environment to simulate UHF wave propagation using the results obtained from CST package in small scale. Using the proposed FDTD code, it is possible to simulate EM wave propagation inside large power transformer. This task cannot be accomplished by CST software in a simple PC. To ensure the validity of the proposed codes, results of simulating EM wave propagation in small volumes such as distribution transformer is compared with CST software package results. After validation, these codes are used to model larger transformers. Finally, the characteristics of PD source are investigated using simulated PD signals detected at different sensor locations.