Study On On-Line Moitoring Of Winding Deformation Of Power Transformer

Power transformer is one of the important and costly equipments in electric power system, whose windings are one of more fault components. The safe running of transformer is of great importance for ensuring the security of electric power system running. Statistics indicates that transformer windings deformation is hidden trouble for the safe running of electric power system. It is important how to realize on-line monitoring the deformation windings.The low voltage impulse method, frequency response analysis method and short-circuit reactance method, which can be used to measure and diagnose the deformation of power transformer winding, are introduced in the paper. These methods are all off-line monitoring. The post research and statistics indicate that measuring the short-circuit reactance of power transformer is an effective method to estimate transformer winding deformation.Two kinds of new on-line monitoring methods, which are based on measuring primary, secondary currents and voltages to calculate the short-circuit reactances of windings for detecting the deformation windings of power transformer, are proposed in the paper. The methods used for on-line measuring the short-circuit reactances of traction transformer in electric railways, are designed. The effects of the error of CT and VT, hysteresis and load variation to short-circuit reactances are discussed also. By using error analysis and simulation analysis, this paper discussed the feasibility in engineering. Based on the same AC voltage and current inputs in the back-up protection of transformer, the software module of on-line monitoring the short-circuit reactance can be added in the back-up protection device and the software flow chart are given in the paper.