Quantification of the performance of iterative and non-iterative computational methods of locating partial discharges using RF measurement techniques

Abstract

Partial discharge (PD) is an electrical discharge phenomenon that occurs when the insulation material of high voltage equipment is subjected to high electric field stress. Its occurrence can be an indication of incipient failure within power equipment such as power transformers, underground transmission cable or switchgear. Radio frequency measurement methods can be used to detect and locate discharge sources by measuring the propagated electromagnetic wave arising as a result of ionic charge acceleration. An array of at least four receiving antennas may be employed to detect any radiated discharge signals, then the three dimensional position of the discharge source can be calculated using different algorithms. These algorithms fall into two categories; iterative or non-iterative.This paper evaluates, through simulation, the location performance of an iterative method (the standard least squares method) and a non-iterative method (the Bancroft algorithm). Simulations were carried out using (i) a “Y” shaped antenna array and (ii) a square shaped antenna array, each consisting of a four-antennas. The results show that PD location accuracy is influenced by the algorithm’s error bound, the number of iterations and the initial values for the iterative algorithms, as well as the antenna arrangement for both the non-iterative and iterative algorithms. Furthermore, this research proposes a novel approach for selecting adequate error bounds and number of iterations using results of the non-iterative method, thus solving some of the iterative method dependencies.