A monitoring system of the present disclosure reduces the sampling and processing requirements for on-line/in-flight monitoring of structural components and thus facilitates detection of high cycle/low amplitude fatigue damage. Moreover, the monitoring system can develop a physical failure model based on information received from monitoring sensors that can be used to determine the remaining useful life (RUL) of structural components. In an exemplary embodiment, the incorporation of low cost, light weight, bused sensors would facilitate in-flight load tracking and detection of high cycle/low amplitude fatigue damage. In this embodiment, a model based on the physical degradation process of the material under analysis (e.g., a physical failure model based on cumulative damage estimation, i.e., based on an AE events count) can be generated using measurable and quantifiable parameters from these sensors and accordingly the RUL of structural components can be determined.

Structural fatigue crack monitoring system and method

The invention discloses an online monitoring system of an all-fiber grating power transformer The online monitoring system comprises a main control unit, a high-speed Ethernet fiber network and a plurality of sets of monitoring unit; the monitoring units are interlinked with the main control unit through the high-speed Ethernet fiber network, wherein the monitoring units comprise module controllers and a plurality of measuring modules, and the measuring modules comprise at least one of temperature measuring modules, vibration measuring modules, micro-water measuring modules and partial discharge modules which are respectively connected with the input ends of the module controllers; and the measuring modules comprise fiber grating sensors and sensor demodulation modules According to the online monitoring system of the all-fiber grating power transformer, the simultaneous monitoring to a plurality of parameters can be realized, the precisions of measurement and fault positioning are greatly improved, the operation reliability of the power transformer is further improved, and the safe operation of the power system is guaranteed

Online monitoring system of all-fiber grating power transformer

The invention relates to a partial discharge detecting system for all-fiber power transformer and a detecting method thereof. The system comprises a controller, a transmission device and a detecting device. The detecting device comprises four groups of fiber bragg grating F-P ultrasonic sensors, optical fiber delayers are arranged between every two fiber bragg gratings, and the four groups of fiber bragg grating F-P ultrasonic sensors and a fluorescent probe are in serial connection on an optical fiber. The transmission device is connected with the detecting device through a through part. The controller is connected with the transmission device. In the calculation processing end, the partial discharge position can be calculated and determined through the time difference for the four groups of sensors to receive sound wave and by taking time division multiplexing time error into consideration. According to the strength of stimulated emission light signals of the fluorescent probe, the apparent discharge magnitude of the partial discharge is calculated. Through the comparison between the ultrasonic sensors and the signals of the fluorescent probe, whether the system is interfered by external environment to cause error judgment is judged. Furthermore, false alarm of the system is avoided. The partial discharge detecting system has the advantages of being simple in structure, facilitating networking, resisting to electromagnetic interference and the like.

Partial discharge detecting system for all-fiber power transformer and detecting method thereof

The invention relates to a wood damage monitoring device based on an acoustic emission technique. The wood damage monitoring device comprises a wood damage signal acquisition system based on acoustic emission and an analysis and monitoring system; the wood damage signal acquisition system comprises an acoustic emission sensor, a pre-amplifier, a filter circuit, a main amplifying circuit, an analog-to-digital conversion circuit, an FPGA (Field Programmable Gate Array) control module and a wireless transmission module, wherein the acoustic emission sensor selects an ultrasonic wave sensor with the frequency of 60 Hz-400 KHz and the central frequency of 150 KHz; the analysis and monitoring system comprises a wood damage source positioning analysis module and an accumulative energy prediction analysis module, wherein the wood damage source positioning analysis module can carry out wavelet denoising and reconstruction on an acquired acoustic emission signal, then position an acoustic emission source by adopting a linear positioning method and display on a wood damage acoustic emission source positioning monitoring interface; the accumulative energy prediction analysis module is used for extracting energy characteristic values of the acoustic emission signal by applying wavelet packet analysis to construct a neural network and to realize the valid prediction of accumulative energy of the wood stress acoustic emission signal through predicting accumulative energy values, so that effective data is provided for monitoring, corresponding prevention measures are conveniently taken, and the loss caused by wood damage is avoided.

Wood damage monitoring device based on acoustic emission technique

The invention provides a fiber mach-zehnder interferometer-based power transformer partial discharge detection system and a detection method. The fiber mach-zehnder interferometer-based power transformer partial discharge detection system comprises a narrow band light source, a first fiber coupler, a second fiber coupler, a phase modulator, a fiber loop, a first photoelectric detector, a second photoelectric detector, a differential trans-resistance amplifier, an integrator, a band pass filter, an amplifier, an acquisition card and a computer, wherein the narrow band light source is connected with an input end of the first fiber coupler; an output end of the first fiber coupler is connected with an input end of the phase modulator, and another output end of the first fiber coupler is connected with an input end of a fiber loop sensor; an input end of the second fiber coupler is connected with an output end of the phase modulator, and another input end of the second fiber coupler is connected with an output end of the fiber loop sensor. The equipment is simple and can be placed in a transformer to perform in-service real-time and continuous monitoring, and the system has the advantages of high partial discharge detection rate, high sensitivity, good stability, high anti-electromagnetic interference capacity, small temperature influence and good flexibility.

Fiber mach-zehnder interferometer-based power transformer partial discharge detection system and detection method

Power transformer partial discharge detection system and method based on fiber bragg grating

The invention provides an acoustic emission signal sensing system based on matching-type fiber Bragg grating (FBG), which aims to overcome limitation of the prior art and introduce an FBG sensor into the acoustic emission detection field. The acoustic emission signal sensing system comprises a broadband light source, a first fiber coupler, a second fiber coupler, the FBG, a tunable FBG filter, a first photoelectric detection circuit, a second photoelectric detection circuit, an analog-to-digital conversion circuit, an FBG array (FBGA) and a computer. The acoustic emission signal sensing system is mainly applied to structural safety monitoring of an aerospace plane and damage detection of important components, and has the advantages of high sensitivity, high response speed, long transmission distance and strong resistance to electronic interference; and compared with the power-type FBG acoustic emission sensing system, the acoustic emission signal sensing system based on the matching-type FBG provided by the invention has the beneficial effects that wavelength shift information is demodulated by a matching grating method so as to obtain information of an original acoustic emission wave, the detection object is optical wavelength rather than optical power, and optical wavelength information is not affected by optical power loss during the optical transmission process, thus the detection precision is higher, the resolution power is higher and the noise is smaller.

Acoustic emission signal sensing system based on matching-type fiber Bragg grating (FBG)

Acoustic emission based detection method for damage position of fastener

Method for identifying damage of aircraft structural parts based on acoustic emission detection

The invention provides an acoustic emission signal sensing system based on fiber Bragg grating (FBG). The system comprises a fiber grating sensing unit and a signal processing unit; the fiber grating sensing unit comprises an FBG sensor, a light source, an isolator and a Y-type fiber coupler; the signal processing unit comprises a photoelectric switching circuit, an amplification circuit, a filter circuit, an A/D circuit and an FPGA (field-programmable gate array); the FBG sensor is firmly fixed in a packaging material, and a couplant is added between the packaged FBG sensor and a member to be detected. The system provided in the invention has the following advantages: a wide detection frequency band, detection scope being in a range of 50 KHz to 300 KHz; high sensitivity, strain resolution being 2 (mu epsilon) microstrani; a fast response speed more than 10 MHz; a long transmission distance which enables long distance between a detection spot and a monitoring spot to be feasible thanks to low loss transmission of fibers; strong capability in resisting electromagnetic interference, vibration, dampness, corrosion, etc., which enables the system to be used normally for a long time in a severe environment. A sensor made of fibers in the invention has the advantages of light weight, small volume, good imbedibility, etc.

Liu Qi

Papers

Power transformer partial discharge detection system and method based on fiber bragg grating

Acoustic emission signal sensing system based on matching-type fiber Bragg grating (FBG)

Acoustic emission based detection method for damage position of fastener

Method for identifying damage of aircraft structural parts based on acoustic emission detection

Acoustic emission signal sensing system based on fiber Bragg grating