As the hub of the power system, the operation status of the transformer is directly related to the safety and stability of the power system. In the process of operation, when thermal fault, discharge fault or oil and paper aging occur inside the transformer, H2, CH4, C2H6, C2H4, C2H2, CO, CO2 and other fault characteristic gases will be generated, and the content of fault gas is an important indicator of the type and severity of the internal fault of the transformer.In order to realize the best monitoring of gases in oil, a variety of methods have been proposed, such as gas chromatography, gas sensors, infrared photoacoustic spectroscopy, etc. However, in long-term use, these methods have problems such as complex sampling, cross-sensitivity, poor long-term stability, and incomplete gas components. To this end, Wuhan Halma Optoelectronics Technology Co., Ltd. pioneered the combination of semiconductor laser technology and photoacoustic spectroscopy technology, and developed and produced the PASL-3000 laser photoacoustic spectroscopy transformer oil gas monitoring system, which has the advantages of high accuracy, good stability, no need to replace the carrier gas, and no gas cross-interference.
Technical features:
Photoacoustic spectroscopy is a spectroscopic technique based on the photoacoustic effect, in which gas molecules absorb modulated optical radiation energy of a specific wavelength, transition from the vibrational ground state to the excited state, and then return to the ground state through a rapid radiation transition or no radiation transition process. The gas molecules return to the ground state through the radiation-free transition process to produce heat energy, which leads to the change of gas temperature, which correspondingly causes the change of gas pressure, thereby generating a sound signal, the strength of the signal is proportional to the incident light intensity and the gas absorption size, and the gas concentration can be indirectly determined by detecting the sound signal. Gas is both the target gas and the detector that absorbs optical radiation, and a variety of gases can be detected by changing the wavelength of the light source using the same photoacoustic cell detection device.
Tunable diode lasers have become an ideal choice for photoacoustic spectroscopy systems in recent years due to their advantages of narrow bandwidth, continuously adjustable, small size, light weight, can work at room temperature, and can be combined with optical fibers. Through the combination of multi-band tunable semiconductor lasers, the test requirements of dissolved gas and micro-water in transformer oil can be met.
Technical Advantages:
1) Non-contact measurement, no consumption of any standard gas;
2) There is no need to separate gases, directly determine the composition and content of gases, the detection speed is fast, and continuous measurement can be realized;
3) Direct measurement of the amount of light energy absorbed by the gas, high detection sensitivity, small volume of the gas chamber;
4) Using semiconductor laser, direct electrical modulation, reliable system performance and good stability;
5) Semiconductor lasers with different wavelengths can be used for the measurement of multiple gases by simply driving different wavelengths.
Specifications:
High precision:Acetylene concentration measurement sensitivity 01ppm, methane, ethane, ethylene, carbon monoxide, carbon dioxide and other gases 05ppm, hydrogen 2ppm, micro water 05ppmï¼›
Rapid Detection:The headspace degassing process is shortened to 20 minutes, and it only takes 5-10 minutes for a single detection, and the system can reach a detection frequency of 1 hour;
Low maintenance costs:Except for the pumps necessary for oil and gas circuits, no other mechanical parts are required, which prolongs the service life of the system. There is no chemical reaction between the whole detection process and the detected gas, no new components are generated, and the detection results can maintain high stability for a long time, without frequent calibration of zero points, without consumables, reducing the intensity of maintenance work and saving maintenance costs.
At present, the PASL-3000 laser photoacoustic spectroscopy transformer gas-in-oil monitoring system has been tested by China Electric Power Research Institute and has been widely used and praised in 220kV substations in many provinces and cities. The system runs stably, has high reliability, and can find potential faults of transformers in time, providing a strong guarantee for the safe operation of the power system.