Simplified magnetic field modeling and calculation of large air-core reactor coils

A simplified magnetic field model for large air-core reactor coils is proposed. It uses three flexible magnetic dipoles with their numbers of turns and positions flexible. The magnetic flux density was calculated along 5 typical traverses for three different types of coils. At designated field points, close to the coil, the calculation error of the proposed model is less than 5%. The three flexible dipole model proposed is not only simple and easy to be implemented but also gives satisfactory accuracy in the regions of practical interest. It can be applied easily to the calculation of the three dimensional power frequency magnetic field distribution of substations