Abstract- This paper deals with the circulating current distribution calculation and its resultant ohmic losses in a large synchronous generator. Circulating currents are produced by the induced voltage differences between parallel strands in a bar that cause high ohmic losses in high power synchronous generators. In this paper, three different cases are assumed for the armature end winding structure, and a 3-D finite element model is adopted to calculate the effectiveness and resultant losses of these cases. As mentioned later, by the use of an appropriate transposition in slot area, both main and leakage fluxes inside the machine are the same for all transposed strands bundle in active part and consequently the induced voltage difference in each strand in a bundle is negligible. However, the currents flowing in the end winding of the generator produce leakage flux in the slot region that causes circulating currents in strands, and consequently electrical power losses in the machine.
Index terms— Synchronous generator, slot region, end winding, circulating current, finite element method.
I. INTRODUCTION
Circulating currents are produced by the induced voltage differences between parallel strands in a bar due to different linkage magnetic flux. In large synchronous generator with high power density, the Roebel bars are used for the stator windings in which strands in a bundle are completely transposed in slot region by different arrangement.
By the use of this procedure, the overall physical position of each strand in a bundle is the same. Therefore, the both main and leakage fluxes are the same for each strand in each bundle, and consequently the induced voltage difference in each strand is negligible. Anyway, the curr...
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Offshore wind power has become a need of the hour in renewable energy production due to the rising prices of oil and continually increasing demand for a separate energy sector. Offshore wind has the prospective to deliver at least four times the current U.S. demand of energy, as per mentioned by the Global Wind Energy Council. However, there are many challenges and advantages that are significant for us to comprehend.
As the conductor rotates toward 90 degrees, the component of horizontal velocity becomes. greater, thus generating a higher voltage. The voltage starts from zero, increases in a. positive direction to a maximum value at 90 degrees, decreases to zero at 180 degrees. increases in the opposite or negative direction until it attains a maximum negative value at 270 degrees, and finally decreases to zero value again at 360 degrees. It follows, then, that the induced emf can be completely described by the relation.
In order to calculate such wind turbines, it depends on three main variables: the size of the turbine, the speed of the wind, and the efficiency of the turbine as well as the generator. The formula in order to calculate the wind power is: P=½ρAV³.
To capture the flow physics near the engine wall we need to increase the density of the cells near the wall. A grid was generated in the computational domain of the simulations using grid generator package ICEM cfd (Ansys 14.5). The first grid layer near the engine wall was nearly 20microns and hence the grid is finer at the walls of the engine and relatively coarser away from the walls of the engine.
Saravanamutto, H. I. H., Rogers, G. F. C., Cohen, H., & Straznicky, P. V. (2009). Gas turbine theory (6th ed.). London, UK: Prentice Hall.
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The wind is an incredibly valuable renewable energy source and is in the forefront of renewable energy developments. It is used to convert wind energy into energy that can be harnessed and used via a variety of methods, including; wind turbines, windmills, sails and windpumps. For a renewable energy source, however, it is wind turbines that are used to generate electricity (see figure 1). Wind power has been used for this since the end of the nineteenth century, after Professor James Blyth of the Royal College of Science and Technology first attempted it (Boyle, 2012). However, It wasn’t until the 1980s that using wind power technology was sufficient enough to experience a rapid growth of the technology.
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