Condition Comprehensive Assessment Of Power Transformers Based On Online Monitoring And Software Development

Large power transformer is one of the important equipment in powersystem, the stability and reliability of its running state will directly impactthe normal and safe operation of the whole power system. Correctassessment of transformer condition can control the transformer accidentseffectively, and guarantee the safe operation of power grid. In addition, itcan not only improve the transmission capacity of the transformer, but alsocontrol the overload risk by predicting the transformer overload capacityreasonably, so as to ensure safety operation of power grid. Aiming at theabove problems, this thesis mainly did the following research:For condition assessment of power transformer, this thesis proposesusing real-time data of transformer online monitoring system to acquire theweight of assessment factors， according to the information entropyprinciple. In this way, the influence of man-made factor in expert’s scoringprocess can be deduced, and the weight can be more scientific andobjective. In order to avoid equalization, the weight is modified by thecoefficient of variation. Finally, preliminary assessment evidence wasachieved through Fuzzy evaluation model, and then by combining all ofthe evidence using the D-S evidence theory to acquire the final assessmentconclusion. Example was taken to prove the validity of the method.For overload capacity assessment of power transformer, this thesisproposes that using factory test data and real-time data of onlinemonitoring system of power transformer to calculate the overload capacity, and adjust the transformer load distribution accordingly, in this way, thetransformer’s transmission capacity can be released as much as possible,and also ensure the safety of power grid.Finally, this thesis developed the software system of powertransformer condition comprehensive assessment based on onlinemonitoring. This system acquires the monitoring data from the IEDs, andassesses the condition state and overload capacity of power transformer. Itprovides methods and basis for power transformer’s status maintenanceand transmission capacity improvement.