Study On Dynamic Measurement Of DC Resistance In Power Transformer

DC Resistance Measurement of Power Transformer is one of the main items in factory test and preventive test of transformer.However,the inherent time constant of power transformer is large,and it is of great significance to study how to shorten the measurement time of DC resistance of power transformer.Dynamic measurement method as a rapid measurement of transformer DC resistance,no longer rely on the measurement loop to achieve stability but in the transient direct measurement,the fundamental increase in measurement speed.Therefore,the dynamic measurement of DC resistance as the future research direction of DC resistance measurement,is a hot research topic today.As a dynamic measurement method of DC resistance of transformer,"same dynamic measurement method" has the characteristics of fast measurement and high measurement accuracy.It is a good method to measure the direct resistance of transformer.However,there are still some problems with this method in practice.In this paper,the problems existing in the measurement of Y-junction and side-side DC resistance of Y/(35)junction transformer are analyzed in detail in "the same dynamic measurement method".Based on simulink simulation software,the measurement of DC resistance of Y/(35)junction transformer winding by "same dynamic measurement method" Situation simulation.First of all,in the simulation experiment of measuring the DC resistance of Y-winding of transformer by using the "same dynamic measurement method",the effect of side-loop flow on Y-side DC resistance measurement is eliminated by changing the voltage access method,which greatly improves the accuracy of the measurement.Then,the influence of DC resistance parameter,mutual inductance parameter and unbalance ratio parameter on the measurement accuracy of Y-side DC resistance is discussed through simulation experiments.Finally,in the simulation experiment of DC resistance measurement of transformer side winding by using the "same dynamic measurement method",the simulation measurement is carried out respectively for the normal situation of the transformer and the case of the direct resistance failure of the transformer,the measurement results are analyzed and the measurement results In the regularity of the summary,the final conclusion.