The Research And Application Of Sweep Frequency Short Circuit Impedance Transformer Winding Deformation Tester

The transformer failure caused by winding deformation in running of transformer has become increasingly frequent to severely impair stable operation of power grid.The ability to rapidly and effectively judge the winding state after the transformer winding deforms to reduce the failure caused is of vital significance for stable operation of power grid.Currently the method to diagnose the deformation of transformer winding comprises frequency response analysis method and low voltage short-circuits impedance method,whose relevant standards have been promulgated.Besides,the two methods exert certain function in diagnosing winding deformation.However,as the excitation signal used in test using frequency response analysis method is small,it is prone to be subjected to site interference and is insensitive to changes of inductance;while the low voltage short-circuit impedance method is insensitve to slight winding deformation.So neither the two test methods can comprehensively diagnose the winding state,leading to mis-judgment and judgment omission in application.To comprehensively diagnose the winding state,the sweep frequency of short-circuit impedance method which integrates the advantages of the above two test methods becomes a focus for current research.To apply this method to actual diagnosis of deformation of transformer winding as soon as possible,the test principle of sweep frequency of short-circuit impedance method is based on to develop the tester based on this method,with prototype used to research the field performance test and application of sweep frequency of short-circuit impedance method.Main content:(1)Theoretical research.The principle and testing method of existing diagnosis methods for winding deformation is analyzed,with focus on test principle and testing method of sweep frequency of short-circuit impedance method.(2)Development of prototype.According to the measuring principle and method of sweep frequency of short-circuit impedance method,the function composition of prototype is raised,with the implementation method of each function researched and realized,including:design of hardware circuit for tester and development of testing software in upper computer,and verification of performance of prototype.(3)Application research of sweep frequency of short-circuit impedance method:mainly comprising research on wiring method of field performance test for sweep frequency of short-circuit impedance method;and experimental study on the factors influencing measurement result such as whether the secondary winding of transformer is earthed after short-circuited and whether transformer lead is dismantled,etc.The major result is:the test principle of sweep frequency of short-circuit impedance method is researched,and tester prototype based on this testing method is developed,whose performance is verified via on-site and testing laboratory tests.Lastly the prototype is used to research the wiring method of field performance test for frequency sweeping short-circuit impedance method and the factors possibly influencing the test result.