Abstract
To provide power to electrical power distribution systems cost effectively, it is necessary to understand the efficiency of large turbine generators. Stator cores, which account for 10%–15% of total generator losses, are supported by a either a dovetail key bar or a square key bar. The dovetail key bar, mainly used in large turbine generators, has a shallow depth of penetration into the stator core; consequently, the need for research related to core loss has been limited in the case of dovetail key bars. By contrast, the square key bar, which is attracting attention owing to its ease of assembly, deeply penetrates the stator core, and thus has a greater effect on core loss than the dovetail key bar. However, core losses due to the key bar design have not been examined quantitatively in the literature. This paper analyzes the core-loss changes due to the key bar. Using electromagnetic finite-element analysis, we calculate the differences in core loss between the two aforenoted key bar types, which are commonly used in large turbine generators. In addition, we propose points for consideration when designing key bars for large-capacity generators.
Highlights
Stable power generation is required to maintain electrical power-transmission systems that supply the baseload power needed for homes, hospitals, and factories.Solar power and wind power have recently been spotlighted as representative sources of renewable energy
The difference between the analysis results and factory-test data is caused by eddy-current loss in the key bars, generator-end-region loss owing to magnetic flux leakage [33], and the performance degradation of the stator cores owing to the manufacturing process [29]–[32]
In this paper, we describe the impact of the key bars used in large turbine generators on core loss
Summary
Stable power generation is required to maintain electrical power-transmission systems that supply the baseload power needed for homes, hospitals, and factories. Song et al.: Open-Circuit Core Loss of Large Turbine Generators Considering Influence of Key Bar Design TABLE 1. Dovetail key bars, which are mainly used in large turbine generators, entail shallow penetration into the stator core. Their effect on core loss is small enough to be neglected; the need for research regarding core loss when considering a dovetail key bar is minimal. Song et al.: Open-Circuit Core Loss of Large Turbine Generators Considering Influence of Key Bar Design. When designing an electrical generator, the core loss is calculated assuming that the magnetic flux density is distributed on the outer area of the stator core.
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