Interpreting the frequency responses of PD signals for PD location in transformer windings - Gram schmidt orthonormalized method

The winding insulation plays a vital role in the design of transformer. The main function of winding insulation has to withstand the electric stress without any major damage during the expected life time in service. Most of the winding insulation failures are primly due to partial discharges (PDs). In this paper, Gram Schmidt orthogonalization method with Butterworth band pass filter is used in correlation method for location of PD pulse in transformer windings. Simulations and experiments studies are performed on lumped layer winding and interleaved windings to validate the feasibility of the method. The proposed method is further improved by using standard error and hypothesis t-test. After the location of PD, the magnitude of the PD is obtained using the reference winding responses.