Overvoltage Propagation from Transmission Line into Transformer Winding

Vaclav Kotlan,Zdenka Benesova

doi:10.15598/aeee.v13i5.1421

Abstract

The paper deals with very fast transient phenomena in a system consisting of two parts: a cable line and a transformer winding. In this case an adequate model should be considered as a circuit with distributed parameters. Its description is given by a system of partial differential equations of hyperbolic type. Our approach is based on a numerical solution in the time domain and the method FDTD has been used. It allows obtaining results in a form of time-space voltage and current wave distribution along the cable line and the transformer winding. This distribution is depending on many factors some of them were studied in this paper.

Highlights

It is a common practice to connect a transformer in a substation to the incoming line through a cable
The paper deals with very fast transient phenomena in a system consisting of two parts: a cable line and a transformer winding
Its description is given by a system of partial differential equations of hyperbolic type

Summary

Introduction

It is a common practice to connect a transformer in a substation to the incoming line through a cable. Due to different surge impedances of both, the cable and the transformer winding, reflections appear at the transformer winding input Because of these reflections the voltage or current peak value can reach higher values than it was considered in the design of the isolation and protection systems. According to practical experiences the distribution of voltage and current wave in a transformer winding depends on transformer parameters and on the shape of a travelling surge wave which is propagating from the transmission line connected to the transformer. In this case is necessary to study an influence of line parameters. This approach allows a for- The first order derivatives have been replaced by the mulation of a common algorithm for numerical compu- following differences: tation

Mathematical Model

Algorithm for Numerical Solution

Illustrative Examples

Overvoltage Induced by Step Voltage Surge Wave

Overvoltage Induced by Voltage Surge Wave

Conclusion