Achieving the exact equivalent circuit of a large-scale transformer winding using an improved detailed model for partial discharge study

•A generalized state-space algorithm for PD studies in transformer winding is developed.•High matching of measured and simulated responses at wide frequency range is achieved.•FEM for accurate calculation of equivalent circuit parameters is employed.•Modeling of layer and disk windings and PD signal propagation is presented.•The proposed method improved frequency validity range (100 kHz ≤ f ≤ 5 MHz).