A Novel Approach for the Modeling of Electromagnetic Forces in Air-Gap Shunt Reactors

Shunt reactors are usually used in electrical systems to imbibe reactive powers created by capacitive powers on the lines when the system is operating on low or no loads. Moreover, they are also used to balance reactive powers and maintain the stability of a specified voltage. In general, the air gaps of a magnetic circuit shunt reactor are arranged along the iron core to reduce the influence of fringing and leakage fluxes. Therefore, non-magnetic materials made of ceramics or marbles are often used in air gaps to separate the iron core packets. The direction of the fringing flux is perpendicular to the laminations, so the core packets of the shunt reactor are generally made from radially laminated silicon steels. Due to the alternating electromagnetic field through the core, a periodically altered electromagnetic force is produced between the core packets, tending to compress the ceramic spacers. This electromagnetic force causes vibration and noise in the core. In this research, a finite element approach based on the Maxwell stress tensor was developed to compute the magnetic flux density and the electromagnetic forces appearing in a shunt reactor.