Research On Leakage Magnetic Field And The Ability To Withstand Short-circuit Force Of The 10kV Oil-immersed Distribution Transformer

The 10 kV oil-immersed distribution transformer is one of the most critical equipment in the power grid and the power transmission.The short-circuit withstanding ability is directly related to the ability to operate safely and reliably.And the short-circuit faults will affect the power supply and even threaten the service life of the transformer.On the basis of summarizing the related documentations,the leakage field and the short-circuit force are calculated and analysed,against the leakage field and the short-circuit force between the obround windings and the circular windings we have compared the theoretical calculation and the simulated results,and referential rules are provided to improve the ability to withstand short-circuit faults.This paper first introduces the background and significance of the issue and also discusses the research status at home and abroad about the transformer leakage magnetic field and short-circuit force. Then the simplified 2D model of 200kVA/10 kV oil-immersed distribution transformer is built,the electromagnetic field and the short-circuit electromagnetic force under different short-circuit conditions are calculated based on Magnet,and the corresponding distribution regularities are shown.Finally we have compared the short-circuit electromagnetic force of the obround windings and the circular windings,and the models of obround windings are built based on keeping the perimeter of iron cores equal and keeping the radius of round edge side decreasing,the force on obround windings is close to that on circular windings and in the obround windings the force on circular edge side is bigger than that on straight side.Also the technological innovation measures about the number of the stays is suggested to improve the ability to withstand short-circuit force.