Study on Temperature Rise of Solid Insulated Energy Transfer Equipment under Harmonic Actions

Dry-type transformer adopts solid insulation structure, which is widely used in residential areas, basements and other densely populated areas. Compared with oilimmersed transformer, dry-type transformer has a higher security. With the adjustment of power grid structure, a large number of non-linear loads are connected to the power grid. Harmonic pollution has become an important factor affecting the normal operation of power equipment. In this paper, the temperature rise of solid insulated energy transfer equipment under harmonic actions is studied. Firstly, the load losses calculation model of dry-type transformer is established by analyzing the action mechanism of harmonic interference on each component. Secondly, the simulation model of temperature field distribution of dry-type transformer is established. Finally, combined with load loss calculation model and temperature field distribution simulation model, the actual operation of transformer is calculated and analyzed. The results show that the additional temperature rise caused by harmonic losses is mainly concentrated on windings and insulating resins. Moreover, if the dry-type transformer operates under the condition of serious current distortion for a long time, the aging of insulation material will accelerate and the insulation performance of transformer will be reduced.

I. Introduction

Dry-type transformer plays an important role in transmitting electric energy, and its usage is huge. The external insulation performance of the winding of dry-type transformer largely determines its service life and operation condition. At present, the harmonic content in power system is increasing. Harmonic current will increase the loss of dry-type transformer, and the increase of harmonic loss will bring additional temperature rise, which will accelerate the aging rate of transformer insulation resin and affect the insulation performance [1]. Therefore, it is of great significance to study the heating condition of dry-type transformer under harmonic current.