Using Simplified Models to Assist Fault Detection and Diagnosis in Large Hydrogenerators

Table 4

Comparison of the natural frequencies of Itaipu LHG obtained by the manufacturer Transfer Matrix Method (TMM), using the software RotMEF and using the Rigid Body Model, with the generator unexcited and excited.

Generator operating condition	Mathematical model	Natural frequencies [Hz]
		1st mode	2nd mode	3rd mode	4th mode
Unexcited	Manufacturer (TMM)	4.46	4.95	5.80	6.91
	RotMEF (FEM)	4.40	5.47	6.94	7.31
	Rigid Body Model	5.24	5.74	7.28	7.93
Excited	Manufacturer (TMM)	3.79	4.05	5.56	6.90
	RotMEF (FEM)	4.05	4.89	6.63	7.22
	Rigid Body Model	4.71	5.12	7.18	7.91