1. Multi-machine systems Starrett Mini-Lecture #4

2. In multi-machine systems l No Equal Area Criterion l Visualize multiple springs & masses that are interconnected by horizontal springs

3. Multi-Machine Diagram l System of coupled, nonlinear differential equations l Block diagram

4. Detailed generator models l Include affects of varying flux linkages, generator internal voltages, & the field voltage l More differential equations! l More variable transformations (Parks) & circuit equations

5. Block diagrams

6. NOTE: Before you can include models for excitation systems, you need to include the detailed machine models!

7. Excitation system l Modulates the field voltage of the synchronous machines l Supplies DC voltage yDC Exc. = DC generator yAC Exc. = AC generator (rectified) yStatic Exc. = stationary DC supply

8. Elements of an excitation system (Kundur) l Exciter - DC power supply for field l Regulator - amplifies, stabilizes exciter l Voltage transducer & load compensator - senses terminal voltage, remote l Power system stabilizer - additional signal for damping (speed, P acc or f) l Limiters and protection - limit voltages & currents

9. Excitation System Components

10. How it all goes together