Analysis of acoustic sensor placement for PD location in power transformer

Abstract

Partial discharge (PD) is an abnormal activity that occurs in high-voltage components, such as power cables,switchgear, machines, and power transformers. Such activity needs to be diagnosed for the equipment to last longer asPD could harm the insulation and potentially lead to asset destruction from time to time. Moving one or more externallymounted acoustic sensors to different locations on the transformer tank is commonly used in order to detect and locatePD signal occurring in the power transformer. However, this procedure may lead to less accuracy in PD identification.Therefore, this research paper presents an analysis of acoustic sensor placement based on time of arrival (TOA) techniquefor PD location in a power transformer. The detection and location can be determined by permanently installing theacoustic sensor to provide valuable data in an early stage of occurrence for online condition PD monitoring. Severalmethods are available for the detection of PD signal, whereby one of the best choices is via acoustic emission (AE).PD creates an ultrasonic signal used for PD detection. This paper proposes the possible placement of AE sensors tobe mounted on the power transformer wall based on ideal and static PD signals. The sensors were placed in order tocapture the PD signal without any disturbance signal from inside or outside the tank. The time for the signal for the firstapproach for each sensor is recorded to estimate the PD location using the TOA technique. A comparison between theleast square method (LSM) and Gauss–Jordan elimination (GJE) for the TOA technique was analyzed to differentiatethe resulting performance. This research utilized three different PD sources to apply the performance analysis on PDlocations, while five cases were proposed to represent the five different placements of four sensors for the analysis. Thisresearch ultimately suggests that sensors be placed and randomly mounted on the four sides of the transformer tank,with one sensor allocated to one side. Among all five cases, Case 1 and Case 5 yielded a displacement error (DE) lessthan others, while between these two cases, Case 5 gave the lowest DE. The findings were recorded based on LSM andGJE methods used to differentiate the resulting performance.