Electric thermal storage in isolated wind diesel power systems: use of distributed secondary loads for frequency regulation
AuthorJanssen, Nicholas T.
ChairWies, Richard W.
Peterson, Rorik A.
KeywordHybrid power systems
Diesel electric power-plants
Wind power plants
Heat storage devices
MetadataShow full item record
AbstractIsolated coastal utilities in Arctic villages commonly use a mix of diesel and wind power to provide electrical service to their consumers. It is common for such communities to experience periods of high wind generation for which no immediate demand exists and either waste, curtail, or poorly utilize the surplus. The objective of the present work is to explore (through mathematical and numerical modelling) the technical feasibility of and optimization strategies for distributing this excess wind energy as domestic space heat for use as a cleaner, more economical alternative to fossil fuels. Autonomously controlled Electric Thermal Storage (ETS) devices are considered as a solution to decouple the supply of excess wind power with domestic heat demand without the need for communication infrastructure or a second distribution circuit. First, using numerical heat transfer analysis, it is shown that the performance of an ETS heater core can be generalized and expressed in terms of its physical properties and simple geometric dimensions in such a way as to inform system sizing and economic performance studies for prospective applications. Furthermore, a collection of autonomous ETS units is shown (using a full-scale lab-validated mathematical model) to possess the ability to assume the role of partial and/or sole frequency regulator on a hybrid wind-diesel system. Several design changes are proposed, which render the commercially-available units more amenable to frequency regulation. Ultimately, ETS is shown to be a promising alternative means of utilizing excess renewable energy for domestic space heat while providing additional stability to the electrical grid.
DescriptionThesis (Ph.D.) University of Alaska Fairbanks, 2017
Table of ContentsChapter 1 Introduction -- 1.1 Hybrid Wind-Diesel Systems -- 1.2 Frequency Regulation -- 1.3 Voltage Regulation -- 1.4 Energy Storage -- 1.5 Secondary Loads -- 1.6 Electric Thermal Storage -- 1.7 Summary and Organization of Subsequent Chapters -- 1.8 Nomenclature -- 1.9 References -- Chapter 2 Summary of Measurement and Modeling Methodologies -- 2.1 Numerical Heat Transfer - Measurement -- 2.2 Numerical Heat Transfer - Physical Modeling -- 2.3 Electromechanical Dynamics - Measurement -- 2.3.1 Field Measurements -- 2.3.2 Raw Data -- 2.3.3 Post Processing: RMS Values -- 2.3.4 Post Processing: Frequency and Power Factor -- 2.3.5 Post Processing: Impedance, Real Power, and Reactive Power -- 2.4 Electromechanical Dynamics - Modeling -- 2.4.1 Model Structure -- 2.4.2 Equivalent Circuit Simulation Process -- 2.4.3 Solution of Nonlinear Ordinary Differential Equations (ODEs) -- 2.5 References -- Chapter 3 Generalized Heat Flow Model of a Forced Air Electric Thermal Storage Heater Core -- 3.1 Abstract -- 3.2 Introduction -- 3.3 Model -- 3.3.1 Definitions -- 3.3.2 Structure -- 3.3.3 Governing Equations -- 3.3.4 Boundary Conditions -- 3.3.5 Material Properties -- 3.4 Analysis -- 3.4.1 Solution Linearization and Air Velocity Profile -- 3.4.2 Thermal Gradients -- 3.4.3 Parameter Sweep -- 3.5 Results and Discussion -- 3.5.1 One-parameter Model -- 3.5.2 Two-parameter Model -- 3.5.3 Core Energy Balance -- 3.5.4 Stove Modelling -- 3.6 Conclusions -- 3.7 Acknowledgements -- 3.8 Funding -- 3.9 Nomenclature -- 3.10 References -- Chapter 4 Development of a Full-Scale-Lab-Validated Dynamic Simulink© Model for a Stand-Alone -- Wind-Powered Microgrid -- 4.1 Abstract -- 4.2 Introduction -- 4.3 Mathematical Model -- 4.3.1 Diesel Engine/Governor Model -- 4.3.2 Synchronous Generator Model -- 4.3.3 Excitation System Model -- 4.3.4 Induction Generator Model -- 4.4 Data Collection -- 4.5 Results -- 4.5.1 Data Processing -- 4.5.2 Diesel Only (DO) Mode - Laboratory Results -- 4.5.3 Diesel Only (DO) Mode - Simulation Results -- 4.5.4 Wind-Diesel (WD) Mode -- 4.6 Conclusions -- 4.7 Future Work -- 4.8 Acknowledgements -- 4.9 References -- Chapter 5 Frequency Regulation by Distributed Secondary Loads on Islanded Wind-Powered Microgrids -- 5.1 Abstract -- 5.2 Introduction -- 5.3 Mathematical Model -- 5.3.1 Wind-Diesel Hybrid System -- 5.3.2 Individual ETS Units Response -- 5.3.3 Aggregate DSL Response -- 5.4 Analysis -- 5.4.1 Invariant Model Inputs (Machine Parameters) -- 5.4.2 Variable Model Inputs -- 5.4.3 Model Outputs -- 5.5 Results and Discussion -- 5.5.1 Synchronized Switching -- 5.5.2 Staggered Switching -- 5.5.3 Additional Observations and Discussion -- 5.6 Conclusion and Future Work -- 5.7 References -- Chapter 6 Modelling Integration Strategies for Autonomous Distributed Secondary Loads on High Penetration Wind-Diesel Microgrids -- 6.1 Abstract -- 6.2 Introduction -- 6.3 Model -- 6.3.1 System Requirements -- 6.3.2 System Components -- 6.3.3 Control Strategy -- 6.4 Results and Discussion -- 6.4.1 Ramp Simulation -- 6.4.2 Representative Simulation -- 6.4.3 Design Considerations -- 6.5 Conclusions -- 6.6 Acknowledgements -- 6.7 References -- Chapter 7 Results and Observations -- 7.1 Result and Observations of Chapter 3 -- 7.2 Results and Observations of Chapter 4 -- 7.3 Results and Observations of Chapter 5 -- 7.4 Results and Observations of Chapter 6 -- Chapter 8 Conclusions -- 8.1 Conclusions for Generalized Heat Flow Model of a Forced Air Electric Thermal Storage Heater Core -- 8.2 Conclusions for Development of a Full-Scale-Lab-Validated Dynamic Simulink© Model for a Stand-Alone Wind-Powered Microgrid -- 8.3 Conclusions for Frequency Regulation by Distributed Secondary Loads (DSLs) on Islanded Wind-Powered Microgrids -- 8.4 Conclusions for Modeling Integration Strategies for Autonomous Distributed Secondary Loads on High Penetration Wind-Diesel Microgrids -- 8.5 Suggestions for Future Research -- 8.6 Overall Conclusions -- 8.7 Acknowledgements.
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