Partial Discharge Ultrasound Detection Using the Sagnac Interferometer System

Abstract

Partial discharge detection is crucial for electrical cable safety evaluation. The ultrasonic signals frequently generated in the partial discharge process contains important characteristic information. However, traditional ultrasonic transducers are easily subject to strong electromagnetic interference in environments with high voltages and strong magnetic fields. In order to overcome this problem, an optical fiber Sagnac interferometer system is proposed for partial discharge ultrasound detection. Optical fiber sensing and time-frequency analysis of the ultrasonic signals excited by the piezoelectric ultrasonic transducer is realized for the first time. The effective frequency band of the Sagnac interferometer system was up to 175 kHz with the help of a designed 10 kV partial discharge simulator device. Using the cumulative histogram method, the characteristic ultrasonic frequency band of the partial discharges was between 28.9 kHz and 57.6 kHz for this optical fiber partial discharge detection system. This new ultrasound sensor can be used as an ideal ultrasonic source for the intrinsically safe detection of partial discharges in an explosive environment.

Extraction of Partial Discharge Pulses from the Complex Noisy Signals of Power Cables Based on CEEMDAN and Wavelet Packet

“…The electrical insulation of high-voltage power cables is subject to stresses that can result in local dielectric breakdowns that are typically preceded by partial discharge (PD) pulse signals. As such, the online detection of the PD signals of power cables can provide information regarding the locations of weak points or line faults in power distribution systems according to the characteristics of the PD signals obtained at monitoring points, such as arrival times or received signal strengths, and thereby provides an effective means for ensuring the economic and reliable operation of power systems via timely repair [1][2][3][4]. In recent years, the PD pulse signals of line faults have been commonly detected by coupling power cable signals with a high-frequency current sensor (HFCT).…”

Review of Fiber Optic Diagnostic Techniques for Power Transformers

“…Concerning optical fibers for detection of partial discharge, there are two main types of technology [20,21] The ultra-high-frequency (UHF) PD detection method has become an attractive research topic due to its high sensitivity, high anti-interference capacity, good reliability, and capacity to recognize and locate discharge sources [18]. Unfortunately, such methods are affected by electromagnetic interference and may be a source of pollution for the power grid and equipment [19]. Therefore, nonelectrical measurement methods are gradually attracting more attention, because they are not prone to electromagnetic interference.…”

“…Therefore, nonelectrical measurement methods are gradually attracting more attention, because they are not prone to electromagnetic interference. Concerning optical fibers for detection of partial discharge, there are two main types of technology [20,21] Depending on their structure, these sensors have different sensing performances (as to sensitivity and frequency response), and are applied in different ways, like placed inside or outside transformers, or both [19]. Fiber optic interferometers have high sensitivity and a large flat response range but are difficult to multiplex.…”

“…Wang et al [19] presented an optical fiber sensing probe to detect the ultrasonic signals of PD based on linear Sagnac optical interferometry. As was experimentally shown, the PD signals had a time-domain amplitude range of 0.8-1.9 V, and a frequency response range up to 58 kHz, with a 10 kV voltage.…”

“…A detection limit of about 0.26 Pa was observed when the distance between the sensor's head and the ultrasonic source was 300 mm in the oil. Depending on their structure, these sensors have different sensing performances (as to sensitivity and frequency response), and are applied in different ways, like placed inside or outside transformers, or both [19]. Fiber optic interferometers have high sensitivity and a large flat response range but are difficult to multiplex.…”