Assessing Voltage Sags Caused by Transformer Energisation

H. Abdull Halim, M. Hatta and M. Amirruddin

Every electricity networks have some critical components and power transformers are one of it. Gathering the data on the severity of voltage sag occurred in a network is significant in a power quality monitoring program. During transformer energisation, there are three common problems occur which are number of inrush, sympathetic inrush current and voltage sag. With the increase of distributed generations with inherent high intermittency resulting in more switching events, the transformers are increasingly vulnerable to electrical transients. This project is to study and analyse the inrush current, sympathetic inrush current and voltage sags and its severity in transformer energisation. The magnitude and duration are two characteristics of voltage sags that need to study. To investigate this matter, the networks are designed using the PSCAD software. Same rated three phase 100 MVA, 230/33 kV transformers are used to analyse inrush current, sympathetic inrush current and voltage sag. Analysis for this project is carried out for assessing the voltage sags in several cases; (a) by different number connection of transformer, both when it is simultaneously energised or energised at different times, (b) different configuration of transformer (step-up and step-down) and (c) by varying the resistance source.

Volume 11 | 12-Special Issue

Pages: 871-878

DOI: 10.5373/JARDCS/V11SP12/20193287