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SMART GRID ARCHITECTURAL DESIGNS
1.1 INTRODUCTION
Todayâs electric grid was designed to operate as a vertical structure consisting of generation, transmission, and distribution and supported with controls and devices to maintain reliability, stability, and efficiency. However, system operators are now facing new challenges including the penetration of RER in the legacy system, rapid technological change, and different types of market players and end users. The next iteration, the smart grid, will be equipped with communication support schemes and real-time measurement techniques to enhance resiliency and forecasting as well as to protect against internal and external threats. The design framework of the smart grid is based upon unbundling and restructuring the power sector and optimizing its assets. The new grid will be capable of:
- Handling uncertainties in schedules and power transfers across regions
- Accommodating renewables
- Optimizing the transfer capability of the transmission and distribution networks and meeting the demand for increased quality and reliable supply
- Managing and resolving unpredictable events and uncertainties in operations and planning more aggressively.
1.2 TODAYâS GRID VERSUS THE SMART GRID
As mentioned, several factors contribute to the inability of todayâs grid to efficiently meet the demand for reliable power supply. Table 1.1 compares the characteristics of todayâs grid with the preferred characteristics of the smart grid.
TABLE 1.1. Comparison of Todayâs Grid vs. Smart Grid [4]
|
Active Consumer Participation | Consumers are uninformed and do not participate | Informed, involved consumersâdemand response and distributed energy resources |
Accommodation of all generation and storage options | Dominated by central generationâmany obstacles exist for distributed energy resources interconnection | Many distributed energy resources with plug-and-play convenience focus on renewables |
New products, services, and markets | Limited, poorly integrated wholesale markets; limited opportunities for consumers | Mature, well-integrated wholesale markets; growth of new electricity markets for consumers |
Provision of power quality for the digital economy | Focus on outagesâslow response to power quality issues | Power quality a priority with a variety of quality/price optionsârapid resolution of issues |
Optimization of assets and operates efficiently | Little integration of operational data with asset managementâbusiness process silos | Greatly expanded data acquisition of grid parameters; focus on prevention, minimizing impact to consumers |
Anticipating responses to system disturbances (self-healing) | Responds to prevent further damage; focus on protecting assets following a fault | Automatically detects and responds to problems; focus on prevention, minimizing impact to consumers |
Resiliency against cyber attack and natural disasters | Vulnerable to malicious acts of terror and natural disasters; slow response | Resilient to cyber attack and natural disasters; rapid restoration capabilities |
1.3 ENERGY INDEPENDENCE AND SECURITY ACT OF 2007: RATIONALE FOR THE SMART GRID
The Energy Independence and Security Act of 2007 (EISA) signed into law by President George W. Bush vividly depicts a smart grid that can predict, adapt, and reconfigure itself efficiently and reliably. The objective of the modernization of the U.S. grid as outlined in the Act is to maintain a reliable and secure electricity [2] infrastructure that will meet future demand growth. Figure 1.1 illustrates the features needed to facilitate the development of an energy-efficient, reliable system.
The Act established a Smart Grid Task Force, whose mission is âto insure awareness, coordination and integration of the diverse activities of the DoE Office and elsewhere in the Federal Government related to smart-grid technologies and practicesâ [1]. The task forceâs activities include research and development; development of widely accepted standards and protocols; the relationship of smart grid technologies and practices to electric utility regulation; the relationship of smart grid technologies and practices to infrastructure development, system reliability, and security; and the relationship of smart grid technologies and practices to other facets of electricity supply, demand, transmission, distribution, and policy. In response to the legislation, the U.S. research and education community is actively engaged in:
1. Smart grid research and development program
2. Development of widely accepted smart grid standards and protection
3. Development of infrastructure to enable smart grid deployment
4. Certainty of system reliability and security
5. Policy and motivation to encourage smart grid technology support for generation, transmission and distribution
As Figure 1.2 shows, there are five key aspects of smart grid development and deployment.
1.4 COMPUTATIONAL INTELLIGENCE
Computational intelligence is the term used to describe the advanced analytical tools needed to optimize the bulk power network. The toolbox will include heuristic, evolution programming, decision support tools, and adaptive optimization techniques.
1.5 POWER SYSTEM ENHANCEMENT
Policy-makers assume that greatly expanded use of renewable energy [4,5] resources in the United States will help to offset the impacts of carbon emissions from thermal and fossil energy, meet demand uncertainty, and to some extent, increase reliability of delivery.
1.6 COMMUNICATION AND STANDARDS
Since planning horizons can be short as an hour ahead, the smart gridâs advanced automations will generate vast amounts of operational data in a rapid decision-making environment. New algorithms will help it become adaptive and capable of predicting with foresight. In turn, new rules will be needed for managing, operating, and marketing networks.
1.7 ENVIRONMENT AND ECONOMICS
Based on these desired features, an assessment of the differences in the characteristics of the present power grid and the proposed smart grid is needed to highlight characteristics of the grid and the challenges. When fully developed the smart grid system will allow customer involvement, enhance generation and transmission with tools to allow minimization of system vulnerability, resiliency, reliability, adequacy and power quality. The training tools and capacity development to manage and operate the grids and hence crate new job opportunities is part of the desired goals of the smart grid evolution which will be tested using test-bed. To achieve the rapid deployment of the grids test bed and research centers need to work across disciplines to build the first generation of smart grid.
By focusing on security controls rather than individual vulnerabilities and threats, utility companies and smart-grid technology vendors can remediate the root causes that lead to vulnerabilities. However, security controls are more difficult and sometimes impossible to add to an existing system, and ideally should be integrated from the beginning to minimize implementation issues. The operating effectiveness of the implemented security controls-base will be assessed routinely to protect the smart grid against evolving threats.
1.8 OUTLINE OF THE BOOK
This book is organized into 10 chapters. Following this chapterâs introduction, Chapter 2 presents the smart grid concept, fundamentals, working definitions, and system architecture. Chapter 3 describes the tools using load flow concepts, optimal power flows, and contingencies and Chapter 4 describes those using voltage stability, angle stability, and state estimation. Chapter 5 evaluates the computational intelligence approach as a feature of the smart grid. Chapter 6 explains the pathways design of the smart grid using general purpose dynamic stochastic optimization. Chapter 7 reviews renewable supply and the related issues of variability and probability distribution functions, followed by a discussion of storage technologies, capabilities, and configurations. Demand side managemen (DSM) and demand response, climate change, and tax credits are highlighted for the purpose of evaluating the economic and environmental benefit of renewable energy sources. Chapter 8 discusses the importance of developing national standards, followed by a discussion of interoperability such that the new technologies can easily be adapted to the legacy system without violating operational constraints. The chapter also discusses cyber security to protect both RER and communication infrastructure. Chapter 9 explains the significant research and employment training for attaining full performance and economic benefits of the new technology. Chapter 10 discusses case studies on smart grid development and testbeds to aid deployment. The chapter outlines the grand challenges facing researchers and policy-makers before the smart grid can be fully deployed, and calls for investment and multidisciplinary collaboration. Figure 1.3 is a schematic of the chapters.
1.9 GENERAL VIEW OF THE SMART GRID MARKET DRIVERS
To improve efficiency and reliability, several market drivers and new opportunities suggest that the smart grid must:
1. Satisfy the need for increased integration of digital systems for increased efficiency of the power system. In t...