This document discusses power system modeling and excitation systems for alternators, detailing their function, types, and characteristics. It explains the process of strengthening the magnetic field of alternators through direct current supplied by exciters and compares various excitation systems, including DC and AC types. The conclusion highlights that the choice of excitation system is influenced by factors such as power, size, speed, and maintenance costs.

1. POWER SYSTEM MODELING
UNIT 4 & 5
EXCITATION SYSTEM &
EXCITATION SYSTEM
MODELING
Represented By:
CHAITRA NITIN PANAT
EPS M-Tech 1 sem

2. Content:
1. Alternator
2.Excitation System
3.Function Of Excitation System
4.Types Of Excitation System
5.Description Of Each Type
6.Conclusion

3. ALTERNATOR

4. 1. It is an electrical machine which
converts mechanical power into
electrical power by the principle of
Electro-magnetic induction.
2. Alternators are the primary source of
all the electrical energy .

5. EXCITATION SYSTEM

6. 1. The process of creating and
strenthening the magnetic field of the
alternator by providing the necessary
direct current to the field winding of the
alternator.
2. The direct current is supplied to the
rotor by a separate DC source called
as Exciter.

8. Function Of Excitation System
1.Supply direct current to the field
winding for creating magnetic field.
2. Control Voltage.
3. Control Reactive Power.
4. Perform Protective Function.

9. TYPES OF EXCITATION
SYSTEM
1.DC Excitation System
2. AC Excitation System
1.Brushless Excitation System
2. Rotating Thyristor Excitation
System
3. Static Excitation System

10. DC EXCITATION SYSTEM

11. 1. The DC excitation system has two
exciters
a. Main Exciter
b. Pilot Exciter
2. The exciter output is adjusted by an
automatic voltage regulator for
controlling the output terminal voltage
of the alternator.
3. The voltage rating of the main exciter
is about 400V.

12. ADVANTAGES:
1. It is more reliable
2. It is compact in size
3. It can be brought anywhere due to its
low weight.

13. DISADVANTAGES:
1.High cost
2. Not much preferrable
3.low efficient as compared to other
excitation system

14. AC EXCITATION SYSTEM

15. 1. It consist of AC generator and
Thyristor rectifier bridge directly
connected to the alternator shaft or
driven by separate motor.
A. Brushless Excitation System
1. Main exciter is separately excited.
B. Rotating Thyristor Excitation System
1. Main excxiter is self excited.

16. Block Diagram:

17. BRUSHLESS EXCITATION
SYSTEM

18. 1. Elimination of brush and slip rings.
2. Less maintenance.
3. Fast response time.

19. Block Diagram

20. ROTATING THYRISTOR TYPE
EXCITATION SYSTEM
1. This system consists an AC exciter,
stationary field and a rotating armature.
2. The output of the exciter is rectified
by a full wave thyristor bridge rectifier
circuit and is supplied to the main
alternator field winding.

21. Block Diagram

22. STATIC EXCITATION SYSTEM
1. There is no rotating part in static
excitation system.
2. So no windage loss.
3. Small size.

23. CONCLUSION:
Selection of excitation system depends
on various factors:
1. Alternator Power
2. Alternator Size
3. Alternator Speed
4. Maintenance Cost

24. THANK YOU