The on-site DGA detecting and analysis system based on the Fourier transform infrared instrument

Abstract

Currently, the oil-immersed power transformer on-site detecting and analysis systems for dissolved gas analysis (DGA) were usually based on the gas chromatography, electrochemical sensor array or other sensors. But these methods had the defects such as needing standard carrier gas, regularly instrument calibration, low security, long analysis time and so on. For these reasons, an innovative method of using Fourier transform infrared (FTIR) instrument to detecting and analysis the transformer oil dissolved gas was proposed in this paper. This method has the features, such as maintenance free, no carrier gas in site, analysis time shortly (time constant below one second is possible). The detecting and analysis system was consisted by the oil sample continuous automatic collection device, oil dissolved gases separation equipment, gases analytical instruments (FTIR), data acquisition and processing module. The situation of the transformer in-site operation was simulated and a complete experimental system was set up in the laboratory. When we used the FTIR to analyze the gases on site for a long time and continuously, some key technologies (spectral baseline drift and distortion, dimension reduction and so on) needed to resolve. For the spectral baseline drift and distortion problem, the spectral baseline correction by piecewise dividing (SBCPD) baseline correction algorithm was used to preprocess the spectral data. For the problem of high-dimensional data characteristic variables selection in the spectral analysis, Tikhonov regularization algorithm was used to select spectral features variable. After the above step, the dimensions of the original spectrum was reduced from 10165 to 3~7, the computing workload was greatly reduced and the accuracy of the calculation results was improved. Finally, the sparse partial least squares algorithm was adopted to establish the quantitative analysis model of transformer dissolved gas analysis on-line monitoring system, and 7 kinds of mixed gases were analyzed. The results showed that the sparse partial least squares algorithm was superior to the traditional partial least squares algorithm. The feasibility of Fourier transform infrared spectroscopy for oil dissolved gas multi-component on-line detection and analysis system was preliminary verified by the simulation and experiment system in the laboratory. Keywords-Fourier Transform infrared spectroscopy; dissolved gas analysis; oil-immersed power transformer; sparse partial least squares

Multi-gas detection in power transformer oil based on tunable diode laser absorption spectrum

“…Chen et al [18] carried out optical detection of DGA based on laser Raman spectroscopy (LRS). Based on Fourier transform infrared spectroscopy (FTIR), Tang et al [19] utilized algorithms to enhance the measurement. Although the high sensitivity had been achieved, the complex and fragile components are not suitable to the field application.…”

Characteristics of Tin Oxide Chromatographic Detector for Dissolved Gases Analysis of Transformer Oil

“…Unlike FID + TCD, no hydrogen which is flammable gas is needed, hence the structure of the system is simplified and the security can be improved. It is worth mentioning that the degassing process of transformer oil is not considered in the calculation process, in the practical application of engineering, gas extraction methods, e.g., shaking technique [36], or vacuum degasification [37] are commonly used techniques, in which the degassing rate and oil temperature should be considered, and the gas-in-gas value should be corrected to obtain the final gas-in-oil results.…”

Failures statistics of on-line monitoring devices for gases dissolved in oil

“…According to the detection principle, the on-line monitoring device of dissolved gas in oil can be divided into gas chromatography, photoacoustic spectroscopy, infrared spectroscopy and sensor array method [4][5][6]. Gas chromatography is the earliest and the technology is relatively mature.…”