electrical

1. POWER SYSTEM CONTROL

3. Generation system control

4. AVR (Automatic Voltage Regulator)
Q
EF=f(If)
V=f(Q)

5. AVR (Automatic Voltage Regulator)
Functional block diagram of the synchronous generator excitation control system

6. 1- Normally the excitation varies between 2 to 3.5 KW/MVA of
generator rating
2. for larger generator, the excitation current is 2800 to 7000 A for
voltage of 260- 400 V
AVR (Automatic Voltage Regulator)

7. AVR (Automatic Voltage Regulator)
Types of excitation system
1. DC excitation system
2. AC excitation system
3. Static excitation system

8. AVR (Automatic Voltage Regulator)
Types of excitation system
1. DC excitation system
Rectifier

9. AVR (Automatic Voltage Regulator)
Types of excitation system
2. AC excitation system (stationary rectifier system)

10. AVR (Automatic Voltage Regulator)
Types of excitation system
3. AC excitation system (Rotating rectifier system)

11. AVR (Automatic Voltage Regulator)
Types of excitation system
4. Static excitation

12. Excitation ceiling voltage

13. Excitation system stabilization circuit
Excitation System Stabilizing Circuits:
 excitation systems with significant time delays
have poor inherent dynamic performance
 unless very low steady-state regulator gain is
used, the control action is unstable when
generator is on open-circuit
 series or feedback compensation is used to
improve the dynamic response
 most commonly used form of compensation is
a derivative feedback
stablizer

14. Power System Stabilizer (PSS):
• uses auxiliary stabilizing signals (such as shaft speed, frequency, power) to modulate the generator field voltage
so as to damp system oscillations
• PSS are generator control equipment's which are used in feedback to enhance the damping of the rotor
oscillation caused due to small signal disturbance. This disturbance may be caused by the even small change in
the reference voltage of the automatic voltage regulator/exciter which result in ever increasing rotor oscillations
• This can be achieved by modulation the generator excitation so as to develop components of electric torque in
phase with rotor speed deviation. Therefore, it contribute to enhance the small signal stability of the power
system

15. Dynamic Performance
Block diagram for the excitation system

16. Dynamic Performance
DC Generator exciter model
KE=1 for separately excited DC G
KE=-0.1 for self excitation generator
TE= (0.5 to 1) sec

17. Dynamic Performance
Block diagram for the excitation system
DC Generator exciter model
KE=1 for separately excited DC G
KE=-0.1 for self excitation generator
TE= (0.5 to 1) sec

18. DC Generator exciter model
Sensor

19. Generator transfer function

26. thanks