engleski

LOSS REDUCTION METHODS OF SALIENT POLE SYNCHRONOUS GENERATOR DAMPER WINDING BY MEANS OF SLOT SKEW

Slot skew is applied as a method to increase the quality of armature winding voltage waveform of synchronous hydro generators. Skew that matches the region of one slot pitch is most effective in dampening of stator slot harmonics, but can in some production cases be hard to achieve. This is especially true for machines that have greater axial length. That is why other methods are commonly used to increase the voltage waveform quality of large hydro generators. One such method is based on the damper winding slot pitch choice that ensures reduction of stator slot harmonics from the main magnetic field. Appropriate placement of damper bars over the pole shoe does not represent a significant technological problem, and is much easier to manufacture then the slot skew or the fractional armature winding. The downside of damper slot pitch adjustment method is the increase of damper bar currents in steady state conditions of the generator, and therefore the increase of damper winding losses and the rotor temperature. To decrease damper winding currents for long term operating conditions and enable the generator pole shoe design with damper bars of smaller cross section, a combination of damper slot pitch and partial slot skew can be utilized. This paper gives insight on consequences that can occur on voltage waveform if slot skew doesn't not fully match the slot stator pitch, and the advantages that the above mentioned combined method gives on the design optimization of salient pole synchronous generator.

Synchronous generator; electromagnetic calculations; dumper bar winding; slot skew; losses

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