Influence of PD source and AE sensor distance towards arrival time of propagation wave in power transformer

Abstract

Partial discharge (PD) often begins with cracks or gas-filled voids in solid insulation or with gaseous bubbles in liquid insulation. These presences can degrade the quality of insulator. PD detection can identify these cracks at high voltage equipment such as power cables and power transformer at the early stage. One of PD detection methods is acoustic emission (AE) detection. PD produces an ultrasonic signal that can be captured by an AE sensor. The signal captured is then analysed by capturing the time of the receiving signal onto the sensor. The information related to time can be used for allocating the PD for maintenance purpose. This paper shows the influence of the distance between PD source and the AE sensor towards the arrival time of propagation wave in power transformer. In this study, the four placements of sensors were analysed by having three possible PD sources to represent the variety of distances between the PD source and the sensor. The simulated signal is generated by MATLAB and the arrival time is captured using time of arrival (TOA) method. The time captured and the distance between the PD source and arrival time showed that the relationship is proportional to one another.

Effect of sensor position on the measurement of acoustic wave produced by partial discharges

“…This exponential growth shows that the determination of the position of the PD source can only be made for certain positions of the sensor on the tank. Several previous works [ 7 , [25] , [26] , [27] ] highlighted the errors in the location of the source of PD, something that completes its explanation by this study.…”

“…It can be considered as an ultrasonic pulse of Gaussian shape in a frequency range between 20 kHz and 1 MHz [ 8 , 25 , 30 ] or even in sinusoidal form modulated by a Gaussian. The various previous works have made it possible to define a mathematical model of the acoustic signals generated by the PDs in the power transformers as defined by equation (2) [ 13 , 27 , [31] , [32] , [33] ]. where τ is the time constant, f is the frequency of the acoustic wave which is 100 kHz, A defines the energy flow and is taken as a constant equal to 1.…”

“…To arrive at this conclusion, they consider 7 different configurations and calculate the position of the PD source and the error. Khalid et al [ 27 ] have shown by numerical work that the relation between the time of arrival of the acoustic wave and the distance between the sensor and the source of PD is linear, but this linearity also depends on the position of the source of PD. Rathod et al [ 2 ] in their numerical work on a planar air-filled transformer model evaluated the arrival time of the acoustic wave for a Gaussian partial discharge at different positions.…”

“…The localization of the source of DP is done by the method of triangulation [ 24 , 28 ], this method is based on the determination of the time of flight of an acoustic wave from the discharge source to the sensor placed on the tank following a direct path, the simultaneous use of several sensors thus makes it possible to determine the position of the source [ 27 ]. The phenomena of reflection and refraction give rise to several possible paths taken by the acoustic wave to arrive at the sensor.…”

Study on the Influence of Measuring AE Sensor Type on the Effectiveness of OLTC Defect Classification

“…The AE signal may be distorted and reverberated along with its propagation; therefore, the number and type of AE sensor, its installation, and placement must be carefully investigated [26,27]. In [28], authors investigate the influence of the distance between AE transmitter and receiver on the gathered analysis results. In this work, five types of acoustic-electric transducers are used to measure AE signals generated by OLTC: The broadband transducer type WD AH 17 (WD) was attached to the outer wall of the ladle with a permanent magnet.…”