Study On Key Technology Of On-Line Chromatographic Monitoring System For Dissolved Gases Of Transformer Oil

Techniques for on-line monitoring of oil-immersed power transformer play an important role in keeping the reliability and stability of electricity supply.Dissolved gas analysis in oil-immersed power transformer is an effective way for monitoring and diagnosing the early malfunction and preventing catastrophic accident. It has formed national criterion and is widely applied for practical production. In the dissertation, we study chromatography on-line monitoring and realization of the transformer based on analyzing actuality and development trend of domestic and overseas transformer's DGA techniques. And we put forward implementary project of the system that can detect the key gases of H₂, CO, CH₄, C₂H₆, C₂H₄, and C₂H₂ dissolved in oil timely and accurately. The key techniques in the system are separate membrane, chromatogram, chromatogram column, sensor. And we carry out in-depth theory analysis and experiment research. The primary studies as follows: (1) To decrease the detecting cycle, permeability of polyamide membrane, PFA membrane, polytetrafluoroethylene membrane and Microporous polytetrafluoroethylene membrane are compared in experiments. The microporous polytetrafluoroethylene membrane is better than other membranes; it only needs 24 hours to separate all the key gases dissolved in oil. (2) To make the system simple, a new chromatography column is developed, and it can separate 6 key gases with single column at atmospheric temperature. Based on theory analysis and experiments, the stationary phase and operating conditions, including column internal diameter, column length, column pressure, sample quantity and separating time are determined. (3) Hot wire semiconductor gas sensor is compared with side heat semiconductor gas sensor in experiments, and the former is better than the latter in performance. Besides, since the hot wire semiconductor sensor has a little volume, it can be fixed with the column properly and achieve a better output peak than other sensors. (4) We have designed the control unit of the system with high automa- tization and stability Through theory analysis and basic experiment, we validate that the theory of transformer chromatogram on-line DGA monitoring system is validity and the designing project is rationality. A new technique means provides for transformer state detecting.