Design Optimization of Gapped-Core Shunt Reactors

Shunt reactors are important components for the development of UHV power systems since they compensate large capacitive currents generated by HV transmission lines over great distances. Shunt reactors can also limit over voltages resulting from load shedding operations or from a line-to-ground fault. With regard to construction, shunt reactors are designed in distributed gapped-core which has one winding and a core divided into several laminated magnetic steel disks separated by air-gap wedges. The Volume of the gap is in relation with reactive power (Q) of the reactor and maximum magnetic flux density (B_m) as well. After calculating the gap volume, the way for separating of the gap area (Ag) and length (ΣIg) is an important matter. It plays main role in reactor dimensions, used materials and power losses. In this paper a method based on minimizing the cost is presented for selecting the gap area and length by finding an optimum value for Ag/ΣIg ratio with constant volume constraint.