1. ECE 576 POWER SYSTEM DYNAMICS AND STABILITY
Lecture 9
Synchronous Machine Controls - Excitation
Professor Pete Sauer
Department of Electrical and Computer Engineering
© 2000 University of Illinois Board of Trustees, All Rights Reserved

2. Speed and voltage control

3. Exciter models
(to sync
mach)

4. constant 1

6. use

8. For the self-excited dc machine, the result is:

9. is the output of an amplifier
(error voltage amplified)
This determines

10. Steady state

11. Exciter saturation example
Given:
Find:

12. Voltage regulator model
Amplifier
In steady state
Big
There is often a droop in regulation

13. This control can exhibit instabilities.
The open-loop eigenvalue can be positive for small saturation.
Add a stabilizing transformer.

14. Large Lt2 so It2  0

17. Make voltage regulator control a different voltage.
Load compensation circuit
Make voltage regulator control a
different voltage.
b. Reactive power sharing.

18. Example

20. Balance 3-phase, ABC sequence

21. Example 1

22. If the Vref = 1.0, volt. reg. will tell the exciter to lower Vt

23. Example 2

24. VR1 will lower excitation. VR2 will increase excitation.
Reactive power sharing
Suppose Q = 0 and
VR1 will lower excitation.
VR2 will increase excitation.

26. IEEE Type I excitation system model
Vt may be uncompensated or compensated