Dr. A. M. Sharaf; Bo Yin Electrical and Computer Engineering Department

1. Torsional Oscillation Stabilization Using A Low Cost Detuning PWM-GTO Switched Filter Dr. A. M. Sharaf; Bo Yin Electrical and Computer Engineering Department University of New Brunswick February 15, 2005

2. PRESENTATION OUTLINE • Introduction • Background review of SSR • Modeling details for -Synchronous generators -Induction motors • Sample dynamic simulation results • Conclusions

3. Introduction What is Subsynchronous Resonance (SSR)? Subsynchronous Frequency: • Subsynchronous resonance is an electric power system condition where the electric network exchanges energy with a turbine generator at one or more of the natural frequencies of the combined electrical and mechanical system below the synchronous frequency of the system. • Example of SSR oscillations: • SSR was first discussed in 1937 • Two shaft failures at Mohave Generating Station (Southern Nevada, 1970’s) Where: - Synchronous Frequency = 60 Hz - Electrical Frequency - Inductive Line Reactance - Capacitive Bank Reactance

4. Background Review of SSR • Categories of SSR Interactions: • Torsional interaction • Induction generator effect • Shaft torque amplification • Combined effect of torsional interaction and induction generator • Self-excitation • Torsional natural frequencies and mode shapes • Other sources for excitation of SSR oscillations • Power System Stabilizer (PSS) • HVDC Converter • Static Var Compensator (SVC) • Variable Speed Drive Converter

5. Modeling for Synchronous Generator Sample Study System Figure 1. Sample Series Compensated Turbine-Generator and Infinite Bus System Figure 2. Turbine-Generator Shaft Model Table 1. Mechanical Data

6. Modeling for Synchronous Generator Figure 3. Matlab/Simulink Unified System Model for the Sample Turbine-Generator and Infinite Bus System

7. The Intelligent Shaft Monitor (ISM) Scheme Figure 4. Proposed Intelligent Shaft Monitoring (ISM) Scheme

8. The Intelligent Shaft Monitor (ISM) Scheme - The result signal of (LPF, HPF, BPF) = 377 –Radians/Second T0 = 0.15 s, T1 = 0.1 s, T 2 = 0.1s, T3 = 0.02 s Figure 5. Matlab Proposed Intelligent Shaft Monitoring (ISM) Scheme with Synthesized Special Indicator Signals ( )

9. The Dynamic Filter Compensator (DFC) Scheme -Shunt Modulated Power Filter -Series Capacitor -Fixed Capacitor Figure 6. Facts Based Dynamic Filter Compensator Using Two GTO Switches S1, S2 Per Phase

10. Control System Design Figure 7. Dynamic Error Tracking Control Scheme for the DFC Compensator

11. Control System Design Figure 8. DFC Device Using Synthesized Damping Signals ( ) Magnitudes

12. Simulation Results for Synchronous Generator without DFC Compensation without DFC Compensation Figure 9. Monitoring Synthesized Signals ( ) Under Short Circuit Fault Condition

13. Simulation Results for Synchronous Generator with DFC Compensation with DFC Compensation Figure 11. Monitoring Synthesized Signals ( ) Under Short Circuit Fault Condition

14. Simulation Results for Synchronous Generator without DFC Compensation without DFC Compensation Figure 10. SSR Oscillatory Dynamic Response Under Short Circuit Fault Condition

15. Simulation Results for Synchronous Generator with DFC Compensation with DFC Compensation Figure 12. SSR Oscillatory Dynamic Response Under Short Circuit Fault Condition

16. Modeling for Induction Motor Figure 13. Induction Motor Unified System Model

17. The Dynamic Power Filter (DPF) Scheme Figure 14. Novel Dynamic Power Filter Scheme with MPF/SCC Stages

18. Control System Design - 1 Figure 15. Tri-loop Dynamic Damping Controller

19. Control System Design -2 Figure 16. Tri-loop Error-Driven Error-Scaled Dynamic Controller Using a Nonlinear Tansigmoid Activation Function

20. Control System Design –2 Cont. Figure 17. Proposed Tansigmoid Error-Driven Error-Scaled Control Block

21. Synthesized Monitoring Signals Where: Figure 18. Voltage Transformed Synthetic Signals Figure 19. Current Transformed Synthetic Signals

22. Simulation Results for Induction Motor Without Damping DPF Device With Damping DPF Device Figure 20. Monitoring Signals P & Q Figure 21.Monitoring Signals P & Q

23. Simulation Results for Induction Motor Without Damping DPF Device With Damping DPF Device Figure 22. Shaft Torque Oscillatory Dynamic Response Figure 23. Load Power versus Current, Voltage Phase Portrait

24. Summery: Three Cases Comparison Case 1 Case 2 Case 3 With SSR Modes But Without DPF With SSR Modes And With DPF Without SSR Modes Figure 26. Monitoring Signals Figure 25. Monitoring Signals Figure 24. Monitoring Signals

25. Summery: Three Cases Comparison Case 1 Case 2 Case 3 With SSR ModesAnd With DPF With SSR Modes But Without DPF Without SSR Modes Figure 27. Monitoring Signals Figure 28. Monitoring Signals Figure 29. Monitoring Signals

26. Summery: Three Cases Comparison Case 1 Case 2 Case 3 without SSR Modes with SSR Modes But without DPF with SSR Modes And with DPF Figure 30. Shaft Torque and Speed Dynamic Response Figure 31. Shaft Torque and Speed Dynamic Response Figure 32. Shaft Torque and Speed Dynamic Response

27. Conclusions • For both synchronous generators and induction motor drives, the SSR shaft torsional oscillations can be monitored using the online Intelligent Shaft Monitor (ISM) scheme. • The ISM monitor is based on the shape of these 2-d and 3-d phase portraits recognition and polarity of synthesized signals • The proposed Dynamic Power Filter (DPF) scheme is validated for SSR torsional modes damping

28. Thank You & Question ?