Training manual generator introduction and electrical design

Generator Introduction and
Electrical Design

2013
Turbine Generator BG
DAE IL SONG,


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1. Generator Overview

2


Generator in Power Plant
“Generator”
BOP

The generator is a Energy Converter for Electric Power from Mechanical Energy.

Boiler

Turbine / Generator

3


Generator Electrical Design Concept

Electromagnetic Machine
Torque

Mechanical
Speed

Mechanical
Input

Loss

ElectroMagnetic
Field

Electrical
Loss

Voltage

Current

Electric
Output

4


Generator Electrical Design Concept
< Basic Electromagnetic >
• Ampere’s Law : Currents Create Magnetic Fields

• Faraday’s Law : Changing Magnetic Flux Induces Voltage

5


Generator Overview
Cooling Material : H2, Water

Stator Core

Inner Shield
Outer Shield
Bearing,
Hydrogen Seal,
Oil Deflectors

EXCITER
Armature
Winding

TURBINE
Rotor
Rotor Fan
Retaining Ring
Cooler Dome
Field Coil

Stator Foot
Stator Frame

High Voltage
Bushing
6


Generator Type
Air-Cooled

Hydrogen-Cooled

Water-Cooled

• 100 ~ 150 MW

• 150MW ~ 400 MW

• Above 400 MW

• O/V(Open Ventilated)

•

Vertical Cooler Design

• TEWAC (Totally Enclosed
Water to Air-cooled)

•

Gas Control System

• Twin Dome Cooler
Design

•

Shaft Seal Oil System

• Gas Control System
• Shaft Seal Oil System
• Stator Winding Liquid
Cooling System
7


Generator Product Lineup

4 Pole Steam Turbine
Generator

Water-Cooled

2 Pole Steam Turbine
Generator

HydrogenCooled

Gas/Steam Turbine
Generator

Air Cooled
: Below 150 MW
H2 Cooled
: 150 MW~400
MW
• H2/Water Cooled : Above 400 MW
•
•

Air-Cooled
Gas/Steam Turbine
Generator

0

50

100

150

200

350

400

600

800

1000

1500

Generator Rating (MW)
8


Air-Cooled Generator
Cirebon Projects

 60Hz, 150MW Air-Cooled Generator
 OCISE Co. Ltd. in KOREA

Rated MVA

168.7 MVA

Rated Voltage

17 kV

Power Factor

0.90

Cold Air Temp

42˚C

RPM

3600

▲ Air-cooled generator in the
progress of manufacturing
9


Hydrogen-Cooled Generator
 60Hz H2-Cooled STG 300MW 60Hz H2-Cooled GTG 200MW
 Korean Southern Power Co. Ltd. (KOSPO in Korea)
▼ Hydrogen-cooled generator installed in site

GTG

Rated MVA

STG

240 MVA

Rated Voltage

18 kV

Power Factor

0.90

H2 Pressure

Rated MVA

45 PSIG(3.16kg/cm )
2

RPM

3600

Cold Gas Temp

40˚C

340 MVA

Rated Voltage

18 kV

Power Factor

0.90

H2 Pressure

60 PSIG(4.22kg/cm2 )

RPM

3600

Cold Gas Temp

40˚C
10


Water-Cooled Generator
Shin Kori 3 & 4

 50Hz, 700MW Water-Cooled Generator
 AES-VCM MONG DUONG POWER COMPANY
in Vietnam

Rated MVA

752.512 MVA

Rated Voltage

23 kV

Power Factor

0.85

H2 Pressure

RPM
Cold Gas
Cooling Water

75 PSIG(5.27kg/cm2 )
3000
46.5˚C
38˚C

▲ MD2 generator in the progress
of manufacturing

11


2. Introduction to Electrical Design

12


Generator Function

GENERATOR

LOAD

Real Power (W)

~

Power System
(Looks Inductive)
Reactive Power (VAR)

Synchronous generator acts
like a capacitor or an
inductance

• Primary function of a synchronous generator is to provide real power to
the system
– This is what the Power Company sells to its customers!

• Secondary function is to become a source or sink of reactive power
(VAR)
– Needed for control of voltage on the grid
13


Select Power Factor
• Power Factor
I

V
V

I

Θ = Power Factor Angle
θ

cos Θ = Power Factor
θ

Capacitive Load

Inductive Load

Current Leads Voltage

Voltage Leads Current

- Lower power factors require greater
excitation, better cooling or else higher
temperatures, more losses, and lower
efficiency

338140kVA
178120kVAR

θ
287420kW

Θ = 31.8
PF = cos(θ) = 0.85

14


Select Rating
• Turbine MW Output

• Closed Cooling Water Temperature
• Codes & Standards
– ANSI C50.13
– IEC 60034

Number of
Poles

kVA Rating

Rated Speed

Armature
Voltage

22 Poles
Poles -- 752510
752510 kVA
kVA -- 3000
3000 RPM
RPM -- 23000
23000 Volts
Volts
639694
639694 kW
kW -- 0.85
0.85 PF
PF -- 0.500
0.500 SCR
SCR -- 75

75 PSIG
PSIG H
H22 Pressure
Pressure
Rated
Kilowatts

Rated
Power Factor

Guaranteed
Short Circuit
Ratio

Rated
Gas
Pressure
15


Generator Electrical Design Concept

kVA const  Mar N P  f
< Magnetic Flux() Vs Armature Reaction(Mar) >
A. Trade off in the machine
B. Material Cost vs. Cooling Cost
< Design Process>
- Check required kVA
- Evaluate flux and armature reaction
- Decide the magnetic volume, size of the machine, cooling cost

- Iterate to optimize the design

16


Armature Voltage & Flux

Ε 4.44f Ν Φ
f : Frequency
N : Number of turn
Φ : Flux density

17


Armature Current
Ground Insulation System : Micapal HT (Air/H2-Cooled),
Micapal II (Water-Cooled)

Air,H2-Cooled

Water-Cooled

Water-Cooled

Mixed Ratio 2:1

All Hollow

18

Speed & Poles
Frequency
(Hz)

Speed
(RPM)

Number
of Pole

60

3600

2

Fossil Fuel

50

3000

2

Fossil Fuel

60

1800

4

Nuclear Fuel

50

1500

4

Nuclear Fuel

120 f
RPM 
Np
- Np : Number of poles
- f : Frequency
-RPM: Rotational speed

Non Salient Pole (2 pole, 4 pole)

Salient Pole
(Hydrogenerator)
19


Short Circuit Ratio

- SCR is as measure of stability,
which means how much the field
current is affected by load variation
- SCR = AFNL/AFSI
( No Load Field Current /
Short Circuit Field Current )

20


Saturation and synchronous impedance curve
To increase SCR
- increase the air-gap
- increase the saturation

B’

- apply bigger machine

Modern Static Excitation Sys.
leads to lower SCR

21


Reactive Capability Curve

- Generator Capability is a related
to gas pressure.

A

- Curve AB is limited by field
winding heating

B

- Curve BC is limited by armature
heating
- Curve CD is limited by end iron
heating
C
D

22


V Curve

- Curve AB is limited by field
winding heating
C

- Curve BC is limited by
armature
heating
- Curve CD is limited by end iron
heating

B

A

D

23


Loss Curve

- Fan & Windage Loss
- Bearing & Friction Loss
- Core Loss
- Stray Load Loss
- Armature I2R Loss
- Field I2R Loss
- Excitation Sys. Loss

24


2.3 Generator Specification
Rotor Surface Loss
Rotor Coil Pump
Effect Loss
Fan
Brush Cooling
Wind
Fan Loss
Loss

..

• Distribution of Loss
- Fan & Windage Loss

.

Lead Resistance
Loss
Stator Coil
Resistance
Loss

Wind Loss

Bearing Loss

Stator Coil
Loss

- Bearing & Friction Loss

- Armature I2R Loss

Mechanical
Loss

Brush Abrasion
Loss

- Field I2R Loss

Fixed
Loss

Total Loss

Resistance
Loss

Iron Loss

- Excitation Sys. Loss

Load Loss

- Miscellaneous Loss

Rotor Coil

Stray Load
Loss

Resistance
Loss

.

Rotor Coil Loss

Stator End

.

Other
Stray Load
Loss

Eddy Current
Loss at
Eddy Current Loss

Eddy Current Loss
on Rotor Surface

of Stator Coil

.

- Stray Load Loss

Friction
Loss

Sealing Loss

.

- Core Loss

.

Brush Electrical Loss

25