Multi-machine systems

Starrett Mini-Lecture #4

In multi-machine systems

No Equal Area Criterion Visualize multiple springs & masses that are

interconnected by horizontal springs

Multi-Machine Diagram

System of coupled, nonlinear differential equations

Block diagram

Detailed generator models

Include affects of varying flux linkages, generator internal voltages, & the field voltage

More differential equations! More variable transformations (Parks) & circuit

equations

Block diagrams

NOTE: Before you can include models for excitation systems, you need to

include the detailed machine models!

Excitation system

Modulates the field voltage of the synchronous machines

Supplies DC voltage DC Exc. = DC generator AC Exc. = AC generator (rectified) Static Exc. = stationary DC supply

Elements of an excitation system (Kundur)

Exciter - DC power supply for field Regulator - amplifies, stabilizes exciter Voltage transducer & load compensator -

senses terminal voltage, remote Power system stabilizer - additional signal for

damping (speed, Pacc or f) Limiters and protection - limit voltages &

currents

Excitation System Components

How it all goes together