Improved Top-oil Temperature Model for Unsteady-State Conditions of Power Transformers

摘要

This paper presents a long-term period investigation of some dynamic top-oil temperature models to be used in an on-line monitoring and diagnostic system for power transformers. Some parameters in the models were estimated by the least square optimization technique. The calculation of top-oil temperature was performed at varying load current for a 150 MVA-ONAF and 333 MVA-OFAF Transformer units. The effect of varying conditions of the cooling unit and the unsteady-state behaviour of load current and ambient temperature on the transformer thermal behaviour has been investigated.