Motor Generators

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Motor - Generators


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Motor-Generators

Table of Contents

General

Cooling

Bearing

Rotor dynamic

Shaft current

Reference list


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Two operating modes: Generator mode / Motor (pump) mode

Various starting methods:

Back to back

Starting by pony motor

Starting by turbine

Starting by frequency converter

High number of starts and stops:

Higher material stress

Smaller utilization factor: e.g. rotor rim 50%

Lifespan calculation

Robust design

FE-calculation of ro tor

Motor-Generators

General


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Motor-Generators

Cooling

Radial fans with straight blades mounted directly on the rotor

More losses than conventional radial fans

Rim duct cooling

No fans necessary (except possible small auxiliary fans)

Uniform temperature distribution on pole winding and stator

More losses than conventional fans

Motor driven fans

Possibiliy of speed controlled fans

Higher partial load efficiency

Constant temperature condition during operation

If two directions of rotation => different types of possible cooling methods:


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Thrust bearing

Thrust bearings program (Genmat):Temperature/pressure distribution on a thrust pad

high-pressure oil

supply

white metal

3 mm thick

steel body

oil feed in edge on both sides

pad arc-length

to radial width

ratio: 0,7 max. 1

W

L

Motor-Generators

Bearing

Higher stressed appropriate dimensioned Oil feed in edge on both sides required

Pivoted on center

Criteria for thrust bearing segments in case of two directions of rotation:



Motor-Generators

Rotor Dynamic

High speed units

Typical speed range: 250 to 1000 rpm (28 to 6 poles)

The required safety margin between runaway and 1st cr itical bending speed is

determined by the client

Hence the sti ffness of the shaft and the total bearing support structure has to

be appropriate higher



Wehr rotor

Mass distribution along the axis of the rotation parts

Bending stiffness of the shaft

Distance between guide bearings below and upper the rotor

Rotor design

Dimension of shaft

Total bearing support structure st iffness

Dynamic foundation stiffness

Bracket and stator housing stiffness

Bearing component stiffness

Bearing collar stiffness of the shaft

Oil film stiffness

The crit ical speed depends on:

Motor-Generators

Rotor Dynamic


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Radial stiffness calculation of upper

bracket and stator hous ing

Radial sti ffness calculation

of lower bracket

Radial stiffness calculation of

bearing collar

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Rotor Dynamic


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Radial stiffness calculation

of bearing component

FE calculation of the rotor

design

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Rotor Dynamic


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Kopswerk II

Motor-Generators

Shaft Current

If pump-turbine below the generator (conventional):

To prevent shaft current the bearings above the generator have tobe insulated

If pump below and turbine above the generator:

To prevent shaft current special insulation methods have to be

applied, e.g. insulated couplings

Like Kopswerk II

In addition, sandwich insulation can be supplied if

required


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Motor-Generators

Selected References

Project Country Year z MVA rpm

Vianden II Luxembourg 2010 1 230.0 333.3 Baixo S.-E. de Jusante Portugal 2009 2 20.0 150.0

Baixo S.-E. de Montante Portugal 2009 2 85.0 214.3

Limberg II Austria 2006 2 270.0 428.6

Hintermuhr Austria 2005 1 78.0 1000.0

Nestil Switzerland 2005 1 175.0 600.0

Kopswerk II Austria 2004 3 180.0 500.0 Lower Olt Rumania 2004 20 14.5 130.4

Lang Ya Shan China 2002 4 180.0 230.8

Cruachan U.K. 2001 2 144.4 500.0

Tong Bai China 2001 4 377.0 300.0

Limberg II


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References 1970 1999

Project Country Year z MVA rpm

Goldisthal (synchron) Germany 1998 2 331.0 333.3 Goldisthal (asynchron) Germany 1998 2 340.5 300-346.6

Tian Tang China 1998 2 40.0 157.9

Tian Huang Pin China 1994 6 333.3 500.0

Shi san Ling China 1992 4 222.0 500.0

Yang Zhou Yong China 1992 4 25.0 750.0

Husling Austria 1981 2 200.0 600.0 Nassfeld Austria 1980 1 36.0 1000.0

Oschenik 3 Austria 1979 1 42.0 750.0

Khtai Austria 1977 2 160.0 600.0

Malta HS 2/4 Austria 1973 2 220.0 500.0

Rodund II Austria 1973 1 310.0 375.0 Limberg II


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Year of contract 2004

Number of units 3

Rated output generator 200 MVA

Rated output motor 180 MW

Max. output 210 MVA

Number of poles 12

Rated power factor generator 0.8

Rated voltage 13 kV +13/-10 %

Rated speed 500 rpm

Runaway speed 925 rpm

First critical speed 1156 rpm (25%)

Rated efficiency generator 98.87 %

Type of construction IM8427

Directions of rotation 1

Motor-Generators

References Kopswerk II/Austria

Motor-Generator main data:


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Motor-Generators


Stator

Frame diameter 6.200 mm Stator bore 3.930 mm

Core length 2.900 mm

Stator weight 204 t

Rotor

Pole design Double dovetails

Rotor design Rotor body

Rotor weight 270 t

Moment of inertia 480 tm

Special

Ternary unit configuration

Joint venture with ALSTOM


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Motor-Generators


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Motor Generators