Title :
Assessing and limiting impact of transformer inrush current on power quality
Author :
Nagpal, Mukesh ; Martinich, Terrence G. ; Moshref, Ali ; Morison, Kip ; Kundur, P.
Author_Institution :
BC Hydro, Burnaby, BC, Canada
fDate :
4/1/2006 12:00:00 AM
Abstract :
Transformers are essential elements, which facilitate the transmission of electric power at high voltages over long distances and transformer energization is a common occurrence. The energization can lead to excessive transient inrush current, especially when the transformer core has remnant flux that adds to the flux build-up after switching. Inrush current sags the system voltage, thereby affecting the power quality of the network in proximity of the transformer. The extent to which power quality is degraded depends on short circuit MVA at the source bus, and the magnitude and decay time constant of the transient current. Present day thyristor-controlled machinery used in mining, pulp and paper industries and semiconductor manufacturing require high quality power. Some of these industries even pay a premium price for high quality power. It is, therefore, necessary to first assess the impact of energizing a large transformer on power quality and then develop a technique to limit this impact. This paper presents results from field tests and simulations using Electromagnetic Transients Program a 138 kV 315 MVA transformer energization in the BC Hydro system. The transformer is situated close to a pulp and paper mill with voltage sensitive loads. Methods to assess and to limit the voltage sags during energization are discussed.
Keywords :
EMTP; power supply quality; power transformer testing; transients; 138 kV; 315 MVA; electric power transmission; electromagnetic transients program; hydrosystem; power quality; remnant flux; semiconductor manufacturing; thyristor-controlled machinery; transformer core; transformer energization; transformer inrush current; transient current; voltage sags; Circuits; Degradation; Machinery; Power quality; Power transmission; Pulp and paper industry; Pulp manufacturing; Surges; Transformer cores; Voltage fluctuations; Electromagnetic Transients Program (EMTP); inrush current; power quality; transformer modeling;
Journal_Title :
Power Delivery, IEEE Transactions on
DOI :
10.1109/TPWRD.2005.858782