Embedded Generation

by N. Jenkins, Ron Allan, Peter Crossley, David Kirschen, G. Strbac

Overview

The use of combined heat and power (CHP) plants and renewable energy sources reduces the amount of greenhouse gases released into the atmosphere and helps to alleviate the consequent climate change. The policies of many governments suggest that the proportion of electrical energy produced by these sources will increase dramatically over the next two decades. Unlike traditional generating units, these new types of power plant are usually 'embedded' in the distribution system or 'dispersed' around the network. As a result, conventional design and operating practices are no longer applicable; for example, power protection principles have to be revised and complex economic questions need to be resolved. This book, intended for both students and practising engineers, addresses all the issues pertinent to the implementation of embedded generation. Much of the material was originally developed for the UMIST MSc/CPD course in Electrical Power Engineering so there is a strong tutorial element. However, since this subject is evolving very rapidly, the authors also discuss the technical and commercial consequences of the very high penetration of embedded generation that are to be expected in the years ahead.

Product Details

ISBN-13:	9780852967744
Publisher:	The Institution of Engineering and Technology
Publication date:	10/01/2000
Series:	Power and Energy Ser.
Pages:	292
Product dimensions:	6.12(w) x 9.25(h) x 0.90(d)

About the Author

G. Strbac

Table of Contents

Preface Contributors Glossary 1. Introduction 1.1 - Embedded or dispersed generation 1.2 - Reasons for embedded generation 1.3 - Extent of embedded generation 1.4 - Issues of embedded generation 1.5 - Technical impacts of embedded generation on the distribution system 1.5.1 - Network voltage changes 1.5.2 - Increase in network fault levels 1.5.3 - Power quality 1.5.4 - Protection 1.5.5 - Stability 1.5.6 - Network operation 1.6 - Economic impact of embedded generation on the distribution system 1.7 - Impact of embedded generation on the transmission system 1.8 - Impact of embedded generation on central generation 1.9 - References 2. Embedded generation plant 2.1 - Combined Heat and Power plants 2.2 - Renewable energy generation 2.2.1 - Small-scale hydro-generation 2.2.2 - Wind power plants 2.2.3 - Offshore wind energy 2.2.4 - Solar photovoltaic generation 2.3 - Summary 2.4 - References 3. System studies 3.1- Introduction 3.2 - Types of system studies 3.3 - Power flow studies 3.3.1 - Power flow in a two-bus system 3.3.2 - Relation between flows and voltages 3.3.3 - Power flow in larger systems 3.3.4 - Solving the power flow equations 3.3.5 - Application to an embedded generation scheme 3.4 - Fault studies 3.4.1 - Balanced fault calculations 3.4.2 - Concept of fault level 3.4.3 - Application to an embedded generation scheme 3.4.4 - Unbalanced faults 3.4.5 - Application to an embedded generation scheme 3.4.6 - Standards for fault calculations 3.5 - Stability studies 3.5.1 - A simple dynamic model of the mechanical subsystem 3.5.2 - Power transfer in a two-bus system 3.5.3 - Electro-mechanical transientsfollowing a fault 3.5.4 - The equal area criterion 3.5.5- Stability studies in larger systems 3.5.6 - Stability of induction generators 3.5.7 - Application to an embedded generation scheme 3.6 - Electromagnetic transient studies 3.7 - References 3.8 - Appendix: Equal area criterion 4. Generators 4.1 - Synchronous generators 4.1.1 - Steady-state operation 4.1.2 - Excitation systems 4.1.3 - Operation during network disturbances 4.2 Induction generators 4.2.1 - Steady-state operation 4.2.2 - Connection of an induction generator 4.2.3 - Self-excitation 4.2.4 - Operation during network disturbances 4.2.5 - Advanced shunt compensation for induction generators 4.3 - Power electronic converters 4.3.1 - Voltage source converters 4.4 - References 5. Power quality 5.1 - Voltage flicker 5.2 - Harmonics 5.3 - Voltage unbalance 5.4 - Summary 5.5 - References 6. Protection of embedded generators 6.1 - Introduction 6.2 - Protection schemes for isolated and embedded generators 6.2.1 - Single generator on an isolated network 6.2.2 - Generator operating in parallel with other generators on an isolated network 6.2.3 - Generator embedded into utility network 6.2.4 - Protection requirements 6.3 - Overcurrent protection 6.3.1 - Overcurrent protection of the generator intertie 6.3.2 - Example of how overcurrent protection can be applied to an LV connected generator 6.3.3 - Negative sequence overcurrent 6.3.4 - Directional control of overcurrent elements 6.4 - Earth fault overcurrent protection 6.4.1 - Methods of earthing the generator 6.4.2 - Time-delayed earth fault overcurrent 6.4.3 - Earthing of transformer connected generators 6.4.4 - Earthing of directly connected generators 6.5 - Differential protection of the stator winding 6.5.1 - Operating principle 6.5.2 - High-impedance differential 6.5.3 - Low-impedance biased differential protection 6.6 - Phase and interturn faults on the stator windings 6.7 - Under/overvoltage protection 6.8 - Under/overfrequency protection 6.9 - Reverse power relay 6.10 - Loss of excitation 6.11 - Unbalanced loading 6.12 - Generator stator thermal protection 6.13 - Overexcitation 6.14 - Loss of mains protection 6.14.1 - Rate of change of frequency 6.14.2 - Vector shift 6.15 - Rotor protection 6.16 - References 7. Reliability concepts and assessment 7.1 - Introduction 7.2 - HLI - generation capacity 7.3 - HLII - composite generation and transmission systems 7.4 - HLIII - distribution systems without embedded generation 7.4.1 - Conceptual requirements 7.4.2 - Probabilistic criteria and indices 7.4.3 - Historical evaluation techniques 7.4.4 - Basic reliability assessments 7.5 - Distribution systems with embedded generation 7.5.1 - Concepts of embedded generation 7.5.2 - Types and impact of energy sources 7.6 - Historical reliability assessment approaches 7.7 - Simplified case studies 7.7.1 - Basic radial systems 7.7.2 - Embedded generation vs. network expansion 7.8 - Generation reliability modelling 7.8.1 - Modelling assumptions and considerations 7.8.2 - Concepts of modelling 7.8.3 - Energy source model 7.8.4 - Generation model 7.8.5 - Generation plant model 7.8.6 - Solution of the plant model 7.9 - Network reliability model 7.10 - Reliability and production indices 7.10.1 - Capacity credit 7.10.2 - Reliability indices 7.10.3 - Production indices 7.11 - Study cases 7.12 - Conclusions 7.13 - References 8. Economics of embedded generation 8.1 - Introduction 8.2 - Connection costs and charges 8.2.1 - Concept 8.2.2 - Voltage level related connection cost 8.2.3 - Deep v. shallow connection charges 8.3 - Distribution use of system charges and embedded generation 8.3.1 - Current practice 8.3.2 - Contribution of embedded generation to network security 8.4 - Allocation of losses in distribution networks with EG 8.5 - An alternative framework for distribution tariff development 8.5.1 - Stage 1: Optimal network capacity for transport 8.5.2 - Stage 2: Security driven network expenditure 8.5.3 - Stage 3: Pricing - allocation of costs 8.6 - Conclusions 8.7 - References 9. Concluding remarks

Editorial Reviews

Embedded Generation is an important book, collating a variety of useful information based on...broad industrial and academic experience...an interesting read rather than just a dry academic text. Researchers in energy policy as well as electrical engineering students will find that the issues raised in Embedded Generation show that this is an exciting field in the industry and a necessary area for further research.

A working group apparently from the University of Manchester have developed this text for a course in electrical power engineering, which can also be a reference or tutorial for practicing engineers. They explain the features of electricity generating plants that are embedded in the distribution system or dispersed around it. Such plants, mothballed in Britain since the 1970s, are being reactivated as combined heat and power plants using renewable energy. Conventional design and operating practices do not apply to them; for example power protection principles have to be revised and complex economic questions need to be resolved. Annotation c. Book News, Inc., Portland, OR (booknews.com)

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