Microgrid Planning and Design

A Concise Guide

Hassan Farhangi, Geza Joos

• Publisher: Wiley-IEEE Press
• Year: 2019
• ISBN:
  9781119453543
• Edition: 1
• Topic: Naturwissenschaften
• Subtopic: Energie

A practical guide to microgrid systems architecture, design topologies, control strategies and integration approaches

Microgrid Planning and Design offers a detailed and authoritative guide to microgrid systems. The authors - noted experts on the topic - explore what is involved in the design of a microgrid, examine the process of mapping designs to accommodate available technologies and reveal how to determine the efficacy of the final outcome. This practical book is a compilation of collaborative research results drawn from a community of experts in 8 different universities over a 6-year period.

Microgrid Planning and Design contains a review of microgrid benchmarks for the electric power system and covers the mathematical modeling that can be used during the microgrid design processes. The authors include real-world case studies, validated benchmark systems and the components needed to plan and design an effective microgrid system. This important guide:

• Offers a practical and up-to-date book that examines leading edge technologies related to the smart grid
• Covers in detail all aspects of a microgrid from conception to completion
• Explores a modeling approach that combines power and communication systems
• Recommends modeling details that are appropriate for the type of study to be performed
• Defines typical system studies and requirements associated with the operation of the microgrid

Written forgraduate students and professionals in the electrical engineering industry, Microgrid Planning and Design is a guide to smart microgrids that can help with their strategic energy objectives such as increasing reliability, efficiency, autonomy and reducing greenhouse gases.

1
Introduction

In the face of rising demand for electricity amid increasing costs and environmental impacts related to burning fossil fuels, utility companies must research ways to manage demand and integrate renewable sources of energy into the mainstream power system. North American utilities have begun setting targets to meet some of their future growth in electricity demand through energy conservation. Many utility companies have devised elaborate technology roadmaps and implementation plans to rejuvenate their aging infrastructure. The main barrier to moving forward for these and other power suppliers is the current antiquated nature of the electricity grid. Designed to cater to a centralized power generation, transmission, and distribution system, it does not readily lend itself to accommodating new technologies and solutions. It is the last remaining sector providing a critical service to customers without having real‐time feedback about how its services are utilized by its users. The electricity grid has traditionally operated as an open‐loop system where no real‐time data have been captured for such things as instantaneous demand, consumption profiles, or system performance. This open‐loop system cannot store energy, nor can it integrate renewable sources of energy, such as wind, solar, biomass, and wave/tide, with their intermittent behaviors or embrace pervasive control systems required to attain operational efficiencies and energy conservation.

Built in the last century, the electricity grid is a one‐way hierarchical system whereby power is generated and dispatched based on historical consumption data rather than on real‐time demand. As such, the system is over‐engineered by design to withstand peak loads, which might not be present at all times. This means that the system's expensive assets are not efficiently used at all times. Overall system control is achieved through an elaborate frequency regulation scheme. The control leverage is largely exercised at the production end through statistically planned responses to anticipated changes in system frequency. When the demand increases, the drop in system frequency is countered by increasing the system's production through leveraging spinning reserves until system frequency is back to normal. In contrast, when the demand decreases, resulting in a sudden rise in system frequency, the system responds by decreasing system production until system frequency is reduced to nominal values. However, this synchronous control is slow in nature and if variations in the forecasted demand happen faster than the system's intrinsic inertia can deal with, the system simply fails, resulting in brownouts and blackouts.

Electricity generation, transmission, and distribution are supported by an electricity grid, which forms the backbone of a typical power network. A grid may reference a sub‐network, such as a local utility's transmission grid or distribution grid, a regional transmission network, a whole country's or entire continent's electrical network. Conventional centralized grid systems tend to experience significant power loss due to inefficiencies. They are also being challenged by increasing demand, rising costs, tightening supply, declining reserve margins, and the need to minimize environmental impacts. At no time in its century‐long history has the global utility industry had to confront so many diverse and concurrent challenges as it does now. In the last few decades, electrical power providers have faced one or more of the following challenges:

• Aging infrastructure (more than 70% of utility assets in the USA are over 25 years old);
• Reliability (rampant blackouts in California, Northeast USA, and in Eastern Canada);
• Security (researchers in the USA have proven that the US electrical grid is prone to attacks);
• Market dynamics (various jurisdictions are moving toward industry deregulation);
• Rates and pricing (need to implement multi‐tariffs, time of use, smart metering, etc.);
• Distributed generation (DG) (the need to allow access to the grid by Independent Power Producers (IPPs) and Co‐Gens);
• Efficiency and optimization (need for demand response and peak control);
• Rising energy costs (related to rising oil prices and security of supply);
• Conservation (of the planet's limited source of energy);
• Mass electrification (meeting increasing demands on electricity);
• Renewable energy (integration of renewable sources of energy into the grid); and
• Green energy (minimizing the industry's carbon footprint).

At the core of the crisis is the inability of conventional electrical grids to respond to such challenges without major technological overhaul of their infrastructure. Among other things, this overhaul requires a layer of intelligent command and control to be placed on top of the electricity grid. Unfortunately, this level of intelligence cannot be introduced within the framework of utilities' existing electricity grids. A new and improved electrical grid is required. How this new grid, known as either an ‘intelligent grid’ or a ‘smart grid’ – in this book, ‘intelligent grid’ and ‘smart grid’, as well as ‘intelligent microgrid’ and ‘smart microgrid’ will be used interchangeably – differs from the current model as discussed here.

As Table 1.1 depicts, the next generation grid, is a convergence of information technology and communication technology with power system engineering. Smart grid is the focus of assorted technological innovations, which utility companies throughout North America and across the world plan to incorporate in many aspects of their operations and infrastructure. Given the sheer size of utility assets, the emergence of smart grid is more likely to follow an evolutionary trajectory rather than a drastic overhaul.

Table 1.1 Smart grid vis‐à‐vis the existing grid.

Existing grid	Smart grid
Electromechanical	Digital
One‐way communication	Two‐way communication
Centralized generation	Distributed generation
Hierarchical	Network
Few sensors	Sensors throughout
Blind	Self‐monitoring
Manual restoration	Self‐healing
Failures and blackouts	Adaptive and islanding
Manual check/test	Remote check/test
Limited control	Pervasive control
Few customer choices	Many customer choices

Smart grid will therefore materialize through strategic implants of distributed control and monitoring systems within and alongside existing electricity grids. Smart grids' functional and technological growth will mean that pockets of distributed intelligent systems emerge across diverse geographies. This organic growth will allow the utility industry to shift more of the old grid's load and functions onto the new grid, thus improving and enhancing their critical services. These smart grid embryos, known as intelligent or smart microgrids, will facilitate DG and co‐generation of energy. They will also provide for the integration of alternative sources of energy and management of the system's emissions and carbon footprint. They will enable utilities to make more efficient use of their existing assets through demand response, peak shaving, and service quality control.

However, the problem that most utility providers across the globe face is how to get to where they need to be as soon as possible, at the minimum cost, and without jeopardizing the critical services they are currently providing. Moreover, power companies must decide what strategies and along what pathways they should choose to ensure the highest possible return on the required investments for such major undertakings. At its core, the smart grid may emerge as an ad hoc integration of complementary components, subsystems, and functions under the pervasive control of a highly intelligent and distributed command and control system, developed by assimilating smart microgrids. As Figure 1.1 depicts, intelligent or smart microgrids form an interconnected network of distributed energy systems (loads and resources) that can function connected to, or separate from the overall electricity grid.

Figure 1.1 Topology of a smart microgrid.

Smart microgrids are therefore emerging as the basic building blocks of the future smart grid. Smart microgrids work on a smaller scale grid, where a variety of loads with different profiles could be supplied through a controlled distribution system integrated with various (often renewable) power generation sources.

As shown in Figure 1.2, it is the integration and interaction of smart microgrids that will form the smart grid of the future. One can readily see that the smart grid cannot replace the existing electricity grid, but must be an evolutionary complement to it. In other words, until such time as the existing electricity grid can be entirely replaced by the smart grid, the smart grid would and should co‐exist with the exiting electricity grid, adding to and/or enhancing its capabilities, functionalities, and capacities as it further develops. This, therefore, necessitates a strategic research program into technologies and standards for smart microgrids that allows for organic growth, inclusion of forward‐looking technologies and full backward compatibility with the existing legacy systems. The research program should therefore focus on three complementary areas:

• Operational issues of a smart microgrid, such as protection, switching, dispatching, control, management, etc.;
• Regulatory and standardization of the components, interfaces, and subsystems of a smart microgrid; and
• Communication, messaging, data networking, and automation of smart microgrid components and systems.

Figure 1.2 The evolution of smart grid..

Source Farhangi 2010 [1]

One major hurdle that has prevented utility companies from venturing into smart grid development is the need to test and validate technologies and solutions within a near‐real environment before such sub‐systems could be regarded as grid‐worthy. Given the fact that power companies must constantly provide a service critical to society, it is logical that successful lab tests or small‐scale pilots would not qualify such new technologies to be candidates for integration into such crucial infrastructure as the electricity grid. For that reason, there is a need for a microgrid environment where smart grid technologies at a sufficiently large scale could be developed, integrated as desired solutions, tested, an...

Table of contents

• Cover
• Table of Contents
• Copyright
• Dedication
• About the Authors
• Disclaimer
• List of Figures
• List of Tables
• Foreword
• Preface
• Acknowledgments
• Acronyms and Abbreviations
• 1 Introduction
• 2 Microgrid Benchmarks
• 3 Microgrid Elements and Modeling
• 4 Analysis and Studies Using Recommended Models
• 5 Control, Monitoring, and Protection Strategies
• 6 Information and Communication Systems
• 7 Power and Communication Systems
• 8 System Studies and Requirements
• 9 Sample Case Studies for Real‐Time Operation
• 10 Microgrid Use Cases
• 11 Testing and Case Studies
• 12 Conclusion
• References
• Index
• End User License Agreement