Transformer Insulation Faults On-line Monitoring Technique Based On Oil Chromatogram Analysis For Yongchang Power Plant

Power transformer, one of the most important devices, directly relates to the security and stability of power system. The gas solved in oil may inflect the inner insulation aging status and defects in transformer. On the base of deep research of gas solved in oil on-line monitoring and diagnosing technique, this paper states the relations between density of gas solved in oil and electrical defects of transformer. presents the principle and solution of on-line monitoring system with eigenvalue of gas solved in oil. Analyzed the errors and its effecting factors of conventional off-line measuring the gas solved in oil. Studied the mechanism of macromolecule permeation pellicle, namely different gas permeation rate for different permeation pellicle, selectivity of pellicle to gas. Researched the characteristics and its important effect on gas monitoring of Sn02-majored N type semiconductor gas sensitivity elements. Stated the circuit principle and controlling procedure of computer-controlled system. Generalized the features of program software. It has implemented the installation, test and operation of oil-gas separating unit, gas measurement unit, computer controlled unit and data processing unit in monitoring system using gas sensor and oil gas permeation pellicle. From installation and on-site test of on line monitoring system for No.6 and 7 transformers in Gansu Yongchang power plant, it also analyses the reliability of testing results Practical data has showed that on line monitoring system with eigenvalue of gas solved in oil is continuous and efficient, it can inflect insulation status, increase sampling density while faults occurring, decrease the effects of manual operation on measurement results, recognize types of defect with high stability, accuracy and little maintenance work.