SOFC Detector with OCA Approach to Quantify Trace Gases Dissolved in Transformer Oil

Dissolved gas analysis (DGA) is vital to status evaluation of power transformers. In this study, a solid oxide fuel cell (SOFC) gas sensor was fabricated and applied to DGA. Then, a gas chromatographic system was developed on basis of the SOFC detector. From Nernst function of SOFC, a mathematical model based on oxygen consumption accumulation (OCA) has been proposed to quantify trace gases dissolved in oil. Based on the OCA of SOFC, the gas concentration can be calculated though the chromatogram directly, no calibrating gas is needed, thereby greatly simplifying the quantification process. Following peak detection based on the improved filter matching method, tests were conducted to verify the validity of the OCA method. The experimental results demonstrated that the repeatability represented by relative standard deviation is less than 0.5%; high precision can be achieved, measurement error for five feature gases are less than 10% at given concentrations, providing a competitive performance against other gas sensors with curve fitting method.