Research On Frequency Response Analysis For Measurement Of Transformer Winding Deformation

The stable operation of power transformers ensures the security and reliability of power networks.Winding deformation of transformers caused by short current rush accounts for a large proportion of transformer faults.The frequency response analysis method(FRA)is comparatively widely used among many other methods of transformer winding deformation detection.But at the same time,this method is easily influenced by external factors to lead a misdiagnosis.In the paper,the FRA method is used to the field test of transformer winding deformation for many power transformers.Six main factors are found that affect the test results,which are wiring method,different tap position of transformer taps,ground state of the shield signal,test of bushing and end hold of transformer,ground state of transformer clamping piece ground state of test instruments respectively.The six factors are summarized and analyzed,then experience rules are concluded,further,solutions are given.Finally,a set of improved FRA is developed which can avoid the all six main interferences factors,and can get more reliable test results.The improved FRA is used to a large number of field test and part of the transformers were disassembly inspection,and test results proved the solution of the paper is reasonable and feasible.