Power Loss Computation in High-current Generator Bus Ducts of Rectangular Cross-section

Abstract

Due to the medium voltage level of generator terminals and very high-current output, generator connection to the step-up transformer is often carried out with a so-called high-current air-insulated bus duct system. Due to these high currents, during normal generator operation, accompanying Joule power losses are often very high, which in turn, results in excessive (and even non-permissive) heating of the bus duct system. The solution to the mentioned power loss problem involves a determination of currents in phase conductors and in the shield of the metal-enclosed bus duct system. A bus duct transmission line consists of either a segregated or a non-segregated air-insulated three-phase system. Phase conductors and metal enclosures are both rectangular in cross-section. Here, the developed computation model is based on the conductor filament method with application of the geometric mean distance method. It takes into account both skin effect and proximity effects, as well as complete electromagnetic coupling between phase conductors and metal enclosure.