短路冲击状态下的变压器振动特性及匝间短路故障检测

Vibration Characteristics and Detection of Inter-turn Short-circuit Fault Under Transformer Suffering Short-circuit Impact

对现场变压器进行短路冲击来研究绕组状态的方法,虽能够正确反映实际变压器绕组变形的过程,但其投入较大且费时费力。为此,利用冲击电流发生器在实验室中建立了一套较为简便的变压器短路冲击实验平台,对短路冲击下的变压器箱体振动与冲击电流的耦合关系进行了探讨,提出了基于频响函数相关系数的变压器绕组状态评价方法,并通过在绕组中设置故障研究了在短路冲击条件下的匝间短路故障对频响函数的影响。试验结果表明：1）该短路冲击试验平台能够产生接近工频的短路电流,其有效值可达到变压器额定电流的十几倍,符合实际变压器的短路情况,能够用于模拟短路冲击试验;2）当变压器发生匝间短路故障时,其频响函数的相关系数最大为0.549 3,远小于其正常状况的阈值1.1,验证了相关系数判据的正确性。

The method in which the on-site short circuit impact is adopted to study transformer winding condition can correctly reflect transformer winding deformation process, however, it takes much time and comsumes a large quantity of money. Consequently, we developed a relatively simple experimental system for simulating the short circuit impact within the transformer based on the impulse current generator. After studying the coupling relationship between the vibration of the transformer tank and the impact current, we proposed a diagnosis method of the transformer condition on account of the correlation coefficient on the frequency response function, and researched the influences of inter-turn short-circuit faults on frequency response function by presetting faults within the testing transformer. The experiment results show that： 1） This short-circuit impact test platform can generate short-circuit current close to power frequency, with its Root Mean Square（RMS） ten times the rated current of the transformer, which agrees well with the actual short-circuit condition, and thus this platform is applicable in simulating short-circuit impact test. 2） When turn-to-turn short circuit faults occur, the maximal correlation coefficient of the frequency response function is 0.549 3, far less than the threshold of normal condition, 1.1, which verifies the correctness of the correlation coefficient criteria.