ECE 576 POWER SYSTEM DYNAMICS AND STABILITY Lecture 10 Synchronous Machine Controls – Turbine/Governor Professor Pete Sauer Department of Electrical and Computer Engineering © 2000 University of Illinois Board of Trustees, All Rights Reserved
Speed and voltage control
Possible prime movers gas engine diesel engine jet engine water wheel steam turbine
model shaft “squishiness” as a spring Turbine models model shaft “squishiness” as a spring High-pressure turbine shaft dynamics
Steam chest time delay High-pressure turbine shaft dynamics
For rigid shaft (no twist)
Speed governor model
Steam valve control Steam valve limits R = .05 (5% droop)
Example – no load to full load by governor action only (not be commanded power). (5% drop in speed)
A complete dynamic model Stator transients
d-axis rotor transients
q-axis rotor transients
Rotor shaft dynamics
Magnetic circuit algebraic equations (linear)
Excitation system (Exciter + Automatic Voltage Regulator)
Turbine/Governor
3 stator 1 field 3 dampers 2 shaft 1 exciter 2 VR 1 turbine 1 governor 14 14th order model
Terminal constraints How are Vd, Vq, Vo and Id, Iq, Io related? Open circuit: Id = Iq = Io = 0 Short circuit: Vd = Vq = Vo = 0
Balanced 3 resistive load: Substitute for Vd, Vq, Vo and eliminate Id, Iq, Io using the 3 magnetic circuit algebraic equations
Infinite bus
Substitute for Vd, Vq, Vo and eliminate Id, Iq, Io using the 3 magnetic circuit algebraic equations
Line impedance plus infinite bus Note: These flux linkages are not independent states. They are in “series” with the synchronous machine flux linkages. They do not increase the order of the model.
An infinite bus By definition, an infinite bus has:
How can we create one from our synchronous machine model? Infinitely slow field Infinitely slow 1q damper No 1d damper No 2q damper Infinite inertia No stator resistance Negligible transient reactances