1. Flywheels and Power System Stability Michael Breuhl Mentors: Horacio Silva Dr. Héctor Pulgar-Painemal

2. Renewables in the Grid More renewables in grid Depletion of fossil fuels Global warming Issues Low inertia due to renewables Variability in generation and loading Need a method to help regulate the grid 5-2

3. Energy Storage Systems Can store energy within devices for later use Can be built almost anywhere Help system by injecting or removing power Ex. batteries, capacitors, flywheels 5-3

4. Flywheels and Power System Stability Our focus is analyzing the small signal stability of the electromechanical mode Many of the disturbances deal with this mode The disturbances affect the system quickly They occur in the range of 1 Hz to 3 Hz Desire to dampen the disturbances quickly Flywheels are optimal Injects power quickly Long lifespan 5-4

5. Modified 9 Bus System 5-5 1 163 MW 6.7 MVAR 20 MW 0 MVAR 90 MW 30 MVAR 125 MW 50 MVAR 100 MW 35 MVAR FESS Slack Bus 72 MW 0 MVAR 27 39 8 5 6 4 10

6. Case Study Perform sensitivity analysis with flywheels Used DigSilent software for analysis Case 1: Analyzed changes in system based on inertia Case 2: Analyzed changes in system based on loads 5-6

7. Results 5-7 Bus 4 Bus 7 Bus 9

8. Dynamic Simulation 5-8 Simulated changes in power with a short circuit at 1 second

9. Conclusions Dampening with flywheel increases with higher inertia values of generator Proper placement of flywheel can increase dampening further The trend seen in this small system is: If the flywheel is placed on the same bus with the generator of lower inertia, the dampening should be higher 5-9

10. Future Work See impact of flywheels on a bigger Compare with our findings from this system See how generators interact with one another Look into correlations with participation of generators and dampening 5-10

11. Acknowledgements This work was supported primarily by the ERC Program of the National Science Foundation and DOE under NSF Award Number EEC-1041877. Other US government and industrial sponsors of CURENT research are also gratefully acknowledged. 11

12. Questions and Answers 12