Development of a vertical oscillator energy harvester: design and testing of a novel renewable resource power conversion system

Thesis (M.S.) University of Alaska Fairbanks, 2020Remote Alaska communities have historically dealt with elevated electric power expenses due to high cost of transporting diesel fuel for power generation. To offset this cost, the installation of various renewable resources have been utilized, particularly wind and solar power. Hydrokinetic generation by harnessing river flows is an emerging and less commonly implemented renewable resource that offers great potential for power generation. Specifically, this study investigates the behavior of a novel concept for harnessing vertical oscillation that occurs when a bluff body is inserted into a flow path. Unlike traditional rotating turbines used in hydrokinetic energy, this particular device utilizes the fluid structure interactions of vortex-induced-vibration and gallop. Due to the unique characteristics of this vertical motion, a thorough examination of the proposed system was conducted via a three-pronged approach of simulation, emulation, and field testing. Using a permanent magnet synchronous generator as the electrical power generator, an electrical power conversion system was simulated, emulated, and tested to achieve appropriate power smoothing for use in microgrid systems present in many Alaskan rural locations.Alaska Center for Energy and Power (ACEP) at the University of Alaska Fairbanks (UAF)Chapter 1. Introductory material -- 1.1. Introduction -- 1.2. Research problem and objectives -- 1.3. Hydrokinetic power advantages -- 1.4. Hydrokinetic power difficulties -- 1.5. Vertical oscillator dynamics -- 1.6. Generator considerations -- 1.7. Generation stability -- 1.8. Power conversion -- 1.9. Harmonics -- 1.10. Thesis organization. Chapter 2. Literature review of relevant topics -- 2.1. Introduction -- 2.2. Generators -- 2.2.1. Synchronous generators -- 2.2.2. Induction generators -- 2.2.3. DC generators -- 2.3. Power conversion -- 2.3.1. rectifiers -- 2.3.2. DC converters -- 2.3.3. Inverters -- 2.3.4. Conversion efficiency -- 2.4. Microgrids -- 2.4.1. Distributed energy resources -- 2.4.2. Loads (demand) -- 2.4.3. Energy storage -- 2.4.4. Microgrid frequency response -- 2.5. Hydrokinetic power smoothing -- 2.5.1. Energy storage power smoothing -- 2.6. Maximum power point tracking (MPPT) -- 2.7. Conclusion. Chapter 3. Generator selection and modeling -- 3.1. Introduction -- 3.2. PMSG physical construction -- 3.3. Generator operating characteristics -- 3.4. Generator manufacturer's data -- 3.5. Model development -- 3.5.1. Permanent magnet synchronous generator block -- 3.5.2. Diode rectifier -- 3.5.3 DC link smoothing components -- 3.5.4. Inverter -- 3.6 Simulink® simulations -- 3.7. Model verification -- 3.8.Conclusion. Chapter 4. Test bench construction and experimental results -- 4.1. Introduction -- 4.2. Laboratory power supply -- 4.3. Prime mover -- 4.4. Variable frequency drive and circuit breaker -- 4.5. Transformer -- 4.6. load banks -- 4.7. Instrumentation -- 4.7.1. Precision power analyzer -- 4.7.2. LEM module -- 4.7.3. Current transformers (CTs) -- 4.7.4. Torque sensor -- 4.7.5. Power supply -- 4.7.6. Oscilloscope -- 4.7.7. multimeter -- 4.7.8. Tachometer -- 4.8. Miscellaneous supplies -- 4.9 Test bench design summary -- 4.10. Test bench experimental results -- 4.11. Conclusion. Chapter 5. Vertical oscillator design, construction, and field testing -- 5.1. Introduction -- 5.2. Vertical oscillator design and construction -- 5.2.1. Debris diverter -- 5.2.2. Bluff body -- 5.2.3. Power take-off system -- 5.2.4. Field testing electrical system -- 5.2.5. Mechanical system instruments -- 5.3. Field testing results -- 5.4. Field testing difficulties -- 5.5. Conclusion. Chapter 6. Power signal conditioning -- 6.1. Introduction -- 6.2. Power conditioning topologies -- 6.2.1. AC-DC-DC-AC topology -- 6.2.2. PMSG VFD with regenerative capability topology -- 6.2.3. Battery charge controller topology -- 6.3. Power converter design considerations -- 6.3.1. Power conversion -- 6.3.2. Inverter selection -- 6.3.3. Battery charging pulsations -- 6.4. Battery charging system simulation -- 6.4.1. Battery charging and DC load modeling -- 6.4.2. Battery charging topology with single-phase inverter -- 6.4.3. Battery charging topology with three-phase inverter -- 6.5. Conclusion. Chapter 7. Conclusion, future work, and lessons learned -- 7.1. Conclusion -- 7.1.1. Generator selection & modeling conclusions -- 7.1.2. Laboratory testing conclusions -- 7.1.3. Field testing conclusions -- 7.1.4. Power conditioning design conclusions -- 7.1.5. Final conclusions -- 7.2. Future work -- 7.3. Final thoughts -- References -- Appendices