Simulation of Partial Discharge Propagation and Location in Abetti Winding based on Structural Data Mohammad S. Naderi 1 *, M. Vakilian 1 , T.R. Blackburn 2 , B.T. Phung 2 , Hio Nam O 2 , Mehdi S. Naderi 3 , R. Ghaemmaghami 4 1 School of Electrical Engineering, Sharif University of Technology, Tehran 11365-9363, Iran 2 School of Electrical Engineering, University of New South Wales, Sydney, NSW 2052, Australia 3 School of Electrical Engineering, Amirkabir University of Technology, Tehran 15914, Iran 4 Faculty of Science and Information Technology, The University of Newcastle, NSW 2308, Australia * Visiting Fellow at the UNSW, E-mail: salaynaderi@hotmail.com Abstract--Power transformer monitoring as a reliable tool for maintaining purposes of this valuable asset of power systems has always comprised partial discharge offline measurements and online monitoring. The reason lies in non-destructive feature of PD monitoring. Partial discharge monitoring helps to detect incipient insulation faults and prevent insulation failure of power transformers. This paper introduces a software package developed based on structural data of power transformer and discusses the results of the simulation on Abetti winding, which might be considered as a basic layer winding. A hybrid model is used to model the transformer winding, which has been developed by first author. Firstly, winding is modeled by ladder network method to determine model parameters and then multi- conductor transmission line model is utilized to work out voltage and current vectors and study partial discharge propagation as well as its localization. Utilized method of modeling makes it possible to simulate a transformer winding over a frequency range from a few hundred kHz to a few tens of MHz. The results take advantage of accurate modeling method and provide a reasonable interpretation as to PD propagation and location studies. Index Terms--Partial Discharges, Power Transformer, Simulation Software, Transient Propagation I. INTRODUCTION Power transformers are indispensable for the interconnection between different voltage levels at the junctions of the energy supply systems. On the other hand, an important aspect of cost savings concept for the power systems lies in a delay in the procurement of transformers and a reduction in maintenance effort. Monitoring systems for power transformers can be of help to achieve these aims [1]. Experimental experiences prove that partial discharges are a major source of insulation failure in power transformers. On the other hand, PD measurements have emerged as a non- destructive, sensitive and powerful diagnostic tool. Partial discharge location and propagation studies have been a major issue for investigators in the past decade. While it is carrying out within power transformers, because of complicated structure of the active part and inner insulation system, accurate modeling of the windings and taking into account all the structural data is a challenging task for insulation designers. In characteristics point of view, partial discharges have very unsteady and random patterns. This is also a major problem in obtaining accurate measurement results due to inconsistency of partial discharge behavior. PD measurement analysis in conventional monitors depends in a high level on the operator experience. However, at the stage of data evaluation, quantitative interpretation can differ between operators. Although a catalogue of the PD patterns generated in a range of common situations is available in the literature, the interpretation of the simple visual PD pattern can be uncertain. In fact, it is a more qualitative judgment than quantitative. In order to overcome the aforementioned problems according to the data evaluation stage, this study conducted to investigate the propagation and location of partial discharge along the transformer winding. Considering Abetti winding, which is considered as a basic layer winding would provide reasonable results to clarify efficiency and accuracy of the method. II. HYBRID MODEL A. Model Description In frequency ranges associated with a PD, the transformer winding behaves as a complex ladder network consisting of inductance, capacitance, resistance and conductance elements [2]. Fig.1 demonstrated the ladder network model for a single, uniform transformer winding. Fig. 1. Ladder network model for a single, uniform transformer winding