Directional Sensitivity of a MEMS-Based Fiber-Optic Extrinsic Fabry–Perot Ultrasonic Sensor for Partial Discharge Detection

Abstract

Extrinsic Fabry–Perot (FP) interferometric sensors are being intensively applied for partial discharge (PD) detection and localization. Previous research work has mainly focused on novel structures and materials to improve the sensitivity and linear response of these sensors. However, the directional response behavior of an FP ultrasonic sensor is also of particular importance in localizing the PD source, which is rarely considered. Here, the directional sensitivity of a microelectromechanical system (MEMS)-based FP ultrasonic sensor with a 5-μm-thick micromechanical vibrating diaphragm is experimentally investigated. Ultrasonic signals from a discharge source with varying incident angles and linear distances are measured and analyzed. The results show that the sensor has a 5.90 dB amplitude fluctuation over a ±60° incident range and an exciting capability to detect weak PD signals from 3 m away due to its high signal–noise ratio. The findings are expected to optimize the configuration of a sensor array and accurately localize the PD source.

Gold-Diaphragm Based Fabry-Perot Ultrasonic Sensor for Partial Discharge Detection and Localization

“…The coordinates of four sensors are set to be (0, 0, 0), (1, 0, 0), (0, 1, 0) and (0, 0, 1) in meters, to form a pyramid. When the coordinate of the discharge source set to be (2,4,5) in meters, the time difference of the detected signals of sensor2, sensor3, sensor4 compared to sensor1 are shown in Fig. 13.…”

“…A MEMS-based fiber-optic extrinsic Fabry-Perot ultrasonic sensor demonstrates the performance of its PD detection at different distances and different incident angles. There exists a 5.9 dB amplitude fluctuation when incident angle within the ±60°limitation The sensor also exhibits an exciting ability to detect weak PD signals as far as 3 m away due to its high SNR [20]. In the above-mentioned works, PD signals are acquired by fiber-optic sensors as a novel way, but some of them are cost unfriendly and implementation complex or can just detect outside the power system which faces the problem of signal attenuation.…”

Research on Optical Fiber Sensor Localization Based on the Partial Discharge Ultrasonic Characteristics in Long-Distance XLPE Cables

“…A fiber Fabry-Perot (FP) interferometer integrated with the adaptive fiber ring laser was configured as a switchable multiwavelength fiber laser, which can be used to detect the ultrasonic signal of the discharge source with a variable incidence angle and linear distance [18]. Partial discharge detection and localization of the cable was realized by calculating the possible deviation in the measurement of the acoustic emission sensor to compensate for the measurement noise caused by the aging of the sensor or the environment [19][20]. A 10 kV oscillating wave system was built based on the wavelet transform modulus maximum method and related methods in the laboratory by the State Grid Corporation and North China Electric Power University [21][22].…”

Low-Cost, High-Performance Fiber Optic Fabry–Perot Sensor for Ultrasonic Wave Detection

“…To ensure that it has an efficient frequency response to ultrasonic waves, the diaphragm is generally designed to have a high natural frequency, which results in a low sensitivity. For this reason, the trade-off between the natural frequency and the sensitivity must be considered, and the material and dimension of a diaphragm need to be optimized in order to obtain a desired sensitivity as well as the required natural frequency [6]. Wonuk Jo et al fabricated an EFPI acoustic sensor using a photonic-crystal silicon diaphragm with a thickness of 450 nm.…”

“…At present, there are numerous methods to construct a Fabry–Perot (FP) cavity on the end surface of an optical fiber [6,7,8,9,10]. The traditional method consists in adjusting the distance between the fiber and the diaphragm by using a precise positioning platform under the continuous monitoring of a spectrometer and in performing bonding packaging when the cavity length is at the working point [8].…”