Impact of Load Tap Changing Transformers on Power Transfer Capability


Power transfer margins are studied with under load tap changing (ULTC) transformers based on both static and dynamic analysis. Static analysis results show that the ULTC can effectively increase the power transfer capability from a generation area to a load center by matching the generation side impedance with the load impedance. In dynamic analysis, both the ULTC and the load are considered as dynamic devices. The dynamic mechanism of mid-term voltage instability is analyzed using a load gain factor. Discrepancies in results from the two methods are explained. The effects of two types of ULTC--the network transformer and the distribution transformer are investigated. Both theoretical analysis and simulation results show that the network transformer is more beneficial for increasing the power transfer capability.


Electrical and Computer Engineering

Keywords and Phrases

Power Transfer Capability; Stability Margin; Tap Changer; Voltage Stability

International Standard Serial Number (ISSN)

1532-5008; 1532-5016

Document Type

Article - Journal

Document Version


File Type





© 2004 Taylor & Francis, All rights reserved.

Publication Date

01 Jan 2004