Theoretical Research Of Transformer Operating Performance Based On Electrical Measurement Information

With the reform of maintenance system in our country and the popularity of SCADA system in the grid, how to make full use of the more and more abundant electrical monitoring information of transformer provided by SCADA system to make a scientific and rational judgment, has become a research focus in the power system. It has important significance to reduce unnecessary preventive test and maintenance, it can prolong the service life of the transformer and ensure the safety and reliability of power grid.First of all, the concept of health status assessment of Transformer is given in this article, and this article simply introduces the nature of the health assessment, when transformer has latent fault, electric parameters are often the first changes. Based on electrical monitoring information of transformer, the article discusses the dialectical relationship between monitoring information and their health status. Health state evaluation is different from the traditional concept of condition assessment, the evaluation of health status aims at rapidly response to the bad state of transformer, to avoid frequent and unnecessary preventive test and maintenance, and provide the basis for timely arrange the plan of maintenance. When the failure has not been formed, via uninterrupted monitoring the operating state of transformer given by SCADA system, to establish the historical data record, and implementation of dynamic tracking, according to the change of its characteristic, find the abnormal state of transformer in time.Secondly, on the basis of the relationship between the transformer electrical monitoring information and health status, through the analysis of the aging process and the structure foundation of transformer, transformer equivalent physical model is established. Considering the analysis of transformer’s structure and operation performance, and combining the two dialectical relationship, the longitudinal admittance modulus, the transverse impedance modulus and transmission efficiency is derived in this paper in theory, based on the performance of the electric parameters measurement information selection of indicators, then the article analyzes the dialectical relationship between each performance indicators. And then the reliability of transformer health assessment directly depends on the accuracy of the monitoring data provided by the SCADA system, so we must detect the bad data from electrical monitoring dates, based on the above research results, according to continuous measurement of electric parameters information provided by SCADA system, make fully use of the smoothness of information measurement and bad data respectively, give the estimation of data acquisition time, give the method of positioning and replace the bad data. Then determine the scope of the data of normal fluctuations, by comparing the difference between estimated value and real value and the range of size, give the location and correction of bad data.Finally the article introduces the basic theory of random process, gives the definition of the mean sequence and variance of the sequence; based on transformer relatively stable structure, the performance indicators should change gradually for basic basis, overall consideration performance indicators change trend and the dialectical relationship between each other, based on the stochastic process theory, implicit numerical characteristics regularity of mining operation performance indicators, the article gives the criterion and the flow chart of performance evaluation.In conclusion, we can find the relationship between the transformer health and its operation performance by deeply digging the electrical information based on SCADA, and also proved the feasibility and effectiveness of the evaluation algorithm. This exploratory research is a good supplement for condition based maintenance.