Measuring To Overvoltage On-line And Analysis For Insulation Condition Of Transformer

By means of measuring to transient overvoltage on-line in electric power system, the working condition of electric equipment can be known. It is important to be analyzed for these equipments in transformer substation. As the electric power system developing and demand for reliability of current supply, measuring to equipment on-line is more and more important. Moreover, measuring to transient overvoltage on-line becomes a thing of the first magnitude.The measuring equipments on-line can display waveform and last time of overvoltage. Comparing with outcome by traditional oscilloscope measuring, not only they are correct and can be quickly got, but also they include fast lightning surge. The equipment is composed of device of voltage be got, pre-circuit, collector and computer. At the present time, there are two mode in device of voltage be got: the one get low voltage from potential transformer;the other one has voltage from bleeder or photo-electricity feeler search. In this text the inner structure of TR2000 is narrated. Considering safety of power system, the mode of photo-electricity feeler search is the chief developing direction. It takes long time to develop CTV (capacitance transformer voltage), but it is necessary to be developed.In this paper, writer analyses those data which be got from fieldengineering from two aspects: single waveform analyzing and statistic analysis of overvoltage during period of time. In single waveform analyzing, those data are transferred decimal base from binary, and waveform is displayed. Then we can get the max and duration of overvoltage. We can judge the mode of this overvoltage and density of infection to electric equipments. In statistic analysis of overvoltage, those data can be calculated by using MATLAB and theory of statistics to get distributed function of those data. In this paper two assumptions are adopted: normal distribution be cut off and max distribution. In the end, the data submit normal distribution be cut off.The level of electric apparatuses' insulation is decided by distribution of overvoltage in power system. In the paper it take the theory of fuzzy mathematics to approach the level of transformer's insulation that is not restored if it is breakdown. When the proper failure rate is defined, we can determine the level of power voltage resistance. At the same time, overvoltage is the important factor for insulation life length of transformer. In the text, writer deduces some formula about the remainder longevity of transformer. It is necessary for transformer to operate normally. At last, there are summarization to this paper study and expectation for the next research.