Distributed Generation – Induction and Permanent Magnet Generators

Distributed power generation is a technology that could help to enable efficient, renewable energy production both in the developed and developing world. It includes all use of small electric power generators, whether located on the utility system, at the site of a utility customer, or at an isolated site not connected to the power grid. Induction generator (IG) is the most commonly used and cheapest technology, compatible with renewable energy resources. Permanent magnet (PM) generators have traditionally been avoided due to high fabrication costs; however, compared with IGs they are more reliable and productive. Distributed Generation thoroughly examines the principles, possibilities and limitations of creating energy with both IGs and PM generators. It takes an electrical engineering approach in the analysis and testing of these generators, and includes diagrams and extensive case study examples to better demonstrate how the integration of energy sources can be accomplished. The book also provides the practical tools needed to model and implement new techniques for generating energy through isolated or grid-connected systems. Besides a chapter introducing the technical, economic and environmental impacts of distributed generation, this book includes: * an examination of various phase-balancing schemes for a three-phase IG operating on a single-phase power system;* a coupled circuit 2-D finite element analysis of a grid-connected IG, with Steinmetz connection;* a study of self-excited induction generator (SEIG) schemes for autonomous power systems, and the voltage and frequency control of SEIG with a slip-ring machine (SESRIG);* a report on a PM synchronous generator with inset rotor for achieving a reduced voltage regulation when supplying an autonomous power system, and an analysis of its performance using a two-axis model and finite element method;* experimental work on various IG and SEIG schemes. This book is a must-read for engineers, consultants, regulators, and environmentalists involved in energy production and delivery, helping them to evaluate renewable energy sources and to integrate these into an efficient energy delivery system. It is also a superior reference for undergraduates and postgraduates. Designers, operators, and planners will appreciate its unique contribution to the literature in this field.

Table of Contents:
Foreword. Preface. Acknowledgements. About the Authors. 1. Distributed Generation. 1.1 Introduction. 1.2 Reasons for DG. 1.3 Technical Impacts of DG. 1.3.1 DG Technologies. 1.3.2 Thermal Issues. 1.3.3 Voltage Profile Issues. 1.3.4 Fault-Level Contributions. 1.3.5 Harmonics and Interactions with Loads. 1.3.6 Interactions Between Generating Units. 1.3.7 Protection Issues. 1.4 Economic Impact of DG. 1.5 Barriers to DG Development. 1.6 Renewable Sources of Energy. 1.7 Renewable Energy Economics. 1.8 Interconnection. 1.8.1 Interconnection Standardization. 1.8.2 Rate Design. 1.9 Recommendations and Guidelines for DG Planning. 1.10 Summary. References. 2. Generators. 2.1 Introduction. 2.2 Synchronous Generator. 2.2.1 Permanent Magnet Materials. 2.2.2 Permanent Magnet Generator. 2.3 Induction Generator. 2.3.1 Three-Phase IGs and SEIGs. 2.3.2 Single-Phase IGs and SEIGs. 2.4 Doubly Fed Induction Generator. 2.4.1 Operation. 2.4.2 Recent Work. 2.5 Summary. References. 3. Three-Phase IG Operating on a Single-Phase Power System. 3.1 Introduction. 3.2 Phase Balancing Using Passive Circuit Elements. 3.2.1 Analysis of IG with Phase Converters. 3.2.2 Phase-Balancing Schemes. 3.2.3 Case Study. 3.2.4 System Power Factor. 3.2.5 Power and Efficiency. 3.2.6 Operation with Fixed Phase Converters. 3.2.7 Summary. 3.3 Phase Balancing using the Smith Connection. 3.3.1 Three-Phase IG with the Smith Connection. 3.3.2 Performance Analysis. 3.3.3 Balanced Operation. 3.3.4 Case Study. 3.3.5 Effect of Phase-Balancing Capacitances. 3.3.6 Dual-Mode Operation. 3.3.7 Summary. 3.4 Microcontroller-Based Multi-Mode Control of SMIG. 3.4.1 Phase Voltage Consideration. 3.4.2 Control System. 3.4.3 Practical Implementation. 3.4.4 Experimental Results. 3.4.5 Summary. 3.5 Phase Balancing using a Line Current Injection Method. 3.5.1 Circuit Connection and Operating Principle. 3.5.2 Performance Analysis. 3.5.3 Balanced Operation. 3.5.4 Case Study. 3.5.5 Summary. References. 4. Finite Element Analysis of Grid-Connected IG with the Steinmetz Connection. 4.1 Introduction. 4.2 Steinmetz Connection and Symmetrical Components Analysis. 4.3 Machine Model. 4.4 Finite Element Analysis. 4.4.1 Basic Field Equations. 4.4.2 Stator Circuit Equations. 4.4.3 Stator EMFs. 4.4.4 Rotor Circuit Model. 4.4.5 Comments on the Proposed Method. 4.5 Computational Aspects. 4.6 Case Study. 4.7 Summary. References. 5. SEIGs for Autonomous Power Systems. 5.1 Introduction. 5.2 Three-Phase SEIG with the Steinmetz Connection. 5.2.1 Circuit Connection and Analysis. 5.2.2 Solution Technique. 5.2.3 Capacitance Requirement. 5.2.4 Computed and Experimental Results. 5.2.5 Capacitance Requirement on Load. 5.2.6 Summary. 5.3 SEIG with Asymmetrically Connected Impedances and Excitation Capacitances. 5.3.1 Circuit Model. 5.3.2 Performance Analysis. 5.3.3 Computed and Experimental Results. 5.3.4 Modified Steinmetz Connection. 5.3.5 Simplified Steinmetz Connection. 5.3.6 Summary. 5.4 Self-regulated SEIG for Single-Phase Loads. 5.4.1 Circuit Connection and Analysis. 5.4.2 Effect of Series Compensation Capacitance. 5.4.3 Experimental Results and Discussion. 5.4.4 Effect of Load Power Factor. 5.4.5 Summary. 5.5 SEIG with the Smith Connection. 5.5.1 Circuit Connection and Operating Principle. 5.5.2 Performance Analysis. 5.5.3 Balanced Operation. 5.5.4 Results and Discussion. 5.5.5 Summary. References. 6. Voltage and Frequency Control of SEIG with Slip-Ring Rotor. 6.1 Introduction. 6.2 Performance Analysis of SESRIG. 6.3 Frequency and Voltage Control. 6.4 Control with Variable Stator Load. 6.5 Practical Implementation. 6.5.1 Chopper-Controlled Rotor External Resistance. 6.5.2 Closed-Loop Control. 6.5.3 Tuning of PI Controller. 6.5.4 Dynamic Response. 6.6 Summary. References. 7. PMSGs For Autonomous Power Systems. 7.1 Introduction. 7.2 Principle and Construction of PMSG with Inset Rotor. 7.3 Analysis for Unity-Power-Factor Loads. 7.3.1 Analysis Using the Two-Axis Model. 7.3.2 Design Considerations. 7.3.3 Computed Results. 7.3.4 Experimental Results. 7.3.5 Summary. 7.4 A Comprehensive Analysis. 7.4.1 Basic Equations and Analysis. 7.4.2 Conditions for Zero Voltage Regulation. 7.4.3 Extremum Points in the Load Characteristic. 7.4.4 Power-Load Angle Relationship. 7.4.5 The Saturated Two-Axis Model. 7.4.6 Summary. 7.5 Computation of Synchronous Reactances. 7.5.1 Analysis Based on FEM. 7.5.2 Computation of Xd and Xq. 7.5.3 Computed Results. 7.5.4 Summary. 7.6 Analysis using Time-Stepping 2-D FEM. 7.6.1 Machine Model and Assumptions. 7.6.2 Coupled Circuit and Field Analysis. 7.6.3 Magnetic Saturation Consideration. 7.6.4 Computed Results. 7.6.5 Experimental Verification. 7.6.6 Summary. References. 8. Conclusions. 8.1 Accomplishments of the Book. 8.2 Future Work. Reference. Appendix A. Analysis for IG and SEIG. A.1 Symmetrical Components Equations for IG. A.2 Positive-Sequence and Negative-Sequence Circuits of IG. A.3 Vp and Vn for IG with Dual-Phase Converters. A.4 Derivation of Angular Relationship. A.5 Input Impedance of SEIG with the Steinmetz Connection. References. Appendix B. The Method of Hooke and Jeeves. Reference. Appendix C. A Note on the Finite Element Method [1] . C.1 Energy Functional and Discretization. C.2 Shape Functions. C.3 Functional Minimization and Global Assembly. Reference. Appendix D. Technical Data of Experimental Machines. D.1 Machine IG1. D.2 Machine IG2. D.3 Prototype PMSG with Inset Rotor. Index.

About the Author :
Loi Lei Lai graduated from Aston University in Birmingham with a BSc and a PhD. He was awarded a DSc by City University London. He is also an honrorary graduate of City University. In 1984, he was appointed Senior Lecturer at Staffordshire Polytechnic. From 1986 to 1987, he was a Royal Academy of Engineering Industrial Fellow to both GEC Alsthom Turbine Generators Ltd and the Engineering research Centre. He is currently Head of Energy Systems Group and Chair in Electrical Engineering at City University London. In the last decade, Professor Lai has authored/co-authored 200 technical publications. He has also written a book entitled Intelligent System Applications in Power Engineering - Evolutionary Programming and Neural Networks and, in 2001, edited the book Power System Restructuring and Deregulation - Trading, Performance and Information Technology, both published by John Wiley & Sons, Ltd. He was award the IEEE Third Millennium Medal and won the IEEE Power Engineering Society, United Kingdom and Republic of Ireland (UKRI), chapter, Outstanding Engineer Award in 2003. In 1995, he received a high-quality paper prize from the International Association of Desalination, USA and in 2006 he was awarded a Prize paper by the IEEE Power Generation Committee. He is a Fellow of the IEEE and the IET (Institution of Engineering and Technology). Among his professional activities, he is a Founder and was the Conference Chairman of the international Conference on Power Utility Deregulation, Restructuring man of the International Conference on Power Utility Deregulation, Restructuring and Power Technologies (DRPT) 2000, co-sponsored by the IEEE (now IET) and Power Technologies (DRPT) 2000, co-sponsored by the IEE (now IET) and IEEE. He reviews grant proposals regularly for the EPSRC, Australian Research Council and Hong Kong research Grant Council. In 2001, he was invited by the Hong Kong Institution of Engineers to be Chairman of an Accreditation Visit Team to accredit the BEng (Hons) degree in Electrical Engineering. Since 2005, Professor Lai has been invited as a judge for the Power/Energy Category in the IET Innovation in Engineering Awards. He was also Student Recruitment Office of the IEEE UKRI Section Executive Committee. He is a member of the Intelligent Systems Subcommittee in Power System Analysis, Computing and Economic Committee, IEEE Power Engineering Society; a Member of the Executive Team of the Power Trading and Control Technical and Professional Network, IET; an Editor of the IEE Proceedings - Generation, Distribution and Generation (now IET Generation, Distribution and Generation); an Editorial Board Member of the International Journal of Electrical Power & Energy Systems published by Elsevier Science Ltd, UK; International Advisor, Hong Kong Institution of Engineers (HKIE) Transactions and an Editorial Board Member of the European Transactions on Electrical Power published by John Wiley & Sons, Ltd. He was a research Professor at Tokyo Metropolitan University, is also Visiting professor at Southeast University Nanjing and Guest Professor at Fudan University, Shanghai. He has also been invited to deliver keynote addresses and plenary speeches to several major international conferences sponsored by the IET and IEEE. Tze Fun Chan received his BSc (Eng) and MPhil degrees in electrical engineering from the University of Hong Kong in 1974and 1980, respectively. He received his PhD in electrical engineering from City University London in 2005. Currently, Dr Chan is an Associate Professor in the Department of Electrical Engineering, Hong Kong Polytechnic University, where he has been since 1978. His research interests are self-excited AC generators, brushless AC generators and permanent magnet machines. In June 2006, he was awarded a Prize Paper by the IEEE Power Engineering Society Energy Development and Power Generation Committee.