Studying the influence of electromagnetic forces on core blocks of the shunt reactors by using the analytical model and finite element approach

Abstract

The shunt reactor (SR) is widely used in power transmission systems of 110kV, 220kV and 500kV to absorb the reactive power and
avoid overvoltage at the end of the line when the system is operating with no-load or low load. In order to avoid the phenomenon of circuit
saturation, air gaps are often designed along the SR core to divide the large core into smaller segments (core blocks). However, the
presence of air gaps around the core blocks will cause fringing flux and leakage flux components, which vary from this core to another.
This makes the distribution of magnetic flux density uneven on the core blocks and will appear electromagnetic force acted directly on
the core blocks. The electromagnetic force tends to push/press these core blocs together, causing them to vibrate, oscillate and generate
noise, affecting the operation of the SR. In this study, the analytic model and finite element technique are developed to calculate the
distribution of the flux around the slots/air gaps between the core blocks and the electromagnetic forces acting on the core blocks of
the SR. The developed method will be applied to directly calculate a single-phase SR with a capacity of 40Mvar and a voltage of 500/√3.