Application and Improvement of Ratio Method for Power Transformer DGA Data Diagnosis

摘要

Dissolved Gas Analysis (DGA) can be performed to monitor and diagnose the insulation condition of oil-immersed power equipment without request of power outage, with the advantages of easily performing, less interference and high sensitivity, et al. It has been considered as one of the best methods to diagnose the early fault and to prevent the catastrophic accident of power transformer. Based on the statistical disciplines between gas contents in oil and on-site fault results, many researchers proposed many effective ratio methods for DGA diagnosis. Seven kinds of DGA ratio methods are introduced, including the improved method from electrical cooperation association, IEC60599 method, Dornenburg ratios, four ratios in Germany, hydrogen-methane-ethine (HAE) triangle figure, simplified Duval method and thermal-discharge figure, et al, and based on more than 500 groups of on-site DGA data, their advantages and disadvantages are summarized. Some improvements and suggestions are proposed against their disadvantages.