Research On The Fault Detecting System For Power Transformer Based On Photo-acoustic Technique

Power transformer, as the core equipment, was widely used in the power system. The reliability and security of its service determines the stability and security of the whole power system. It is of great importance to detect the underlying faults in the power transformer at an early stage.Methods concerning Dissolved gases in oil (DGA) such as Gas Chromatography (GS) and Fourier Transform Infrared Spectrometry (FTIR) were the most popular and comprehensive way for power transformer fault detecting. However, weaknesses corresponding with carrier gases and chromatography column for GS method and the problems of lower detecting precision and worse linearity of FTIR are calling for a new method for the detection.The paper studied the basic theory and the application of the photo-acoustic effect at the beginning. Four sets of power transformer fault detecting system designs were proposed after in-depth study of the theory and one of them was selected for research after comparison. Meanwhile, a set of gas-oil separating system was designed for the on-line monitoring. In addition, two kinds of photo-acoustic cells were made and carefully studied in respect of the structure, materials, working modes and performance as well. And then, Lock-in Amplifier for the photo-acoustic detecting system was designed and manufactured. At last, the performance of the whole photo-acoustic fault detecting system was tested in the lab and the algorithm for cancling the cross-interuption was approved.