Multiresolution signal decomposition: a new tool for fault detection in power transformers during impulse tests

Detection of major faults in power transformers during impulse tests has never been an issue, but is rather dimcult when only a minor fault, say a sparkover between adjacent coils or turns, lasting for a few microseconds occurs. However, detection of such type of fault is very important to avoid any catastrophic situation. In this paper, we have proposed a new and powerful method capable of detecting minor incipient faults. The approach is based on wavelet transform analysis, particularly the dyadicorthonormal wavelet transform. The key idea underlying the approach is to decompose a given faulty neutral current response into other signals which represent a smoothed and detailed version of the original. The decomposition is performed by multiresolution signal decomposition technique. Preliminary simulation work demonstrated here, shows that the proposed method is robust and far superior to other existing methods to resolve such type of faults.