- Shopping Bag ( 0 items )
"At a time when bulk power systems operate close to their design limits, the restructuring of the electric power industry has created vulnerability to potential blackouts. Prompt and effective power system restoration is essential for the minimization of downtime and costs to the utility and its customers, which mount rapidly after a system blackout.
Power System Restoration meets the complex challenges that arise from the dynamic capabilities of new technology in areas such as large-scale system analysis, communication and control, data management, artificial intelligence, and allied disciplines. It provides an up-to-date description of the restoration methodologies and implementation strategies practiced internationally. The book opens with a general overview of the restoration process and then covers:
* Techniques used in restoration planning and training
* Knowledge-based systems as operational aids in restoration
* Issues associated with hydro and thermal power plants
* High and extra-high voltage transmission systems
* Restoration of distribution systems
Power System Restoration is essential reading for all power system planners and operating engineers in the power industry. It is also a valuable reference for researchers, practicing power engineers, and engineering students."
IEEE Power Engineering Society
"...covers all aspects of restoration strategies and techniques by analyzing the pre-disturbance conditions & status of post-disturbance target systems...explains how to minimize blackout duration...an essential reference."
I. General Discussion
This part presents papers that offer excellent overviews of the power system restoration process. They provide background and introductory material for those who want to become familiar with the key aspects of restoration. More importantly, they also include in-depth discussions of the overall restoration process. They help to illustrate the careful balance that will be required between different objectives, components, constraints, and operations to ensure a successful restoration.
II. Discussion of Reprints
1.01 Power System Restoration-A Task Force Report, 1987, p. 3
The first paper offers a comprehensive discussion of the restoration process by first introducing the essential steps in restoration. It then examines restoration considerations for systems with specific types of generation, as well as considerations that are common to all systems such as switching operations timing and cold load inrush. To help address these concerns and plans for restoration, the paper discusses database requirements for generators, particularly with respect to hot restarts. It also provides background on generator mechanical, electrical, and frequency control systems; and how they impact restoration. The paper also discusses the importance of balancing reactive power and controlling voltage during restoration. It goes on to illustrate how load and generation need to be balanced as restoration proceeds, and how controlled islanding and generation isolation may develop. Finally, the paper compares the philosophies of sequential versus parallel restoration in terms of backup power supply problems, blackstart capability, and sectionalizing subsystems.
1.02 Power System Restoration-The Second Task Force Report, 1987, p. 10
This paper investigates specific restoration problems that occurred following major disturbances. These 19 studies identified such problems as faulty synchronization equipment, resynchronization failures, lightning arrester failures due to switching overvoltages, lack of adequate data, and switching errors. The paper then distills these problems into seven general restoration problem categories: (1) reactive power imbalance, (2) load-generation imbalance, (3) lack of load-generation coordination, (4) lack of communication, (5) impediments caused by protective systems, (6) loss of emergency backup power, and (7) lack of restoration plans. Each of these is followed by suggested solutions and then by overall suggestions to help enhance restoration.
1.03 Analytical Tools for Power System Restoration-Conceptual Design, 1988, p. 17
The paper looks at the restoration process as a series of analyses and decisions to meet a set of operating constraints. It proposes a conceptual framework for computeraided monitoring and assessment during restoration. It also describes a knowledge-based or expert system to help guide restoration. That system would evaluate monitored conditions; suggest an appropriate sequence of actions for assessment; define the problem and select software to be used in an analysis; and then validate the results of the analysis. Based on these results, the system could modify the suggested sequence of actions to help arrive at an improved restoration.
1.04 System Operation Challenges, 1988, p. 24
This paper includes a set of five reports that address various problems that can impact the restoration process. The first involves the general issue of Energy Management System (EMS) software and hardware slowly progressing towards obsolescence, which affects normal operations as well as restoration. The second deals with the difficulty involved in determining EMS requirements. The third raises the concern that EMS alarm systems are designed for normal and limited emergency conditions, and therefore, may need to be modified for restoration conditions. Under these circumstances, only essential alarms should be activated to avoid overwhelming the system. The fourth addresses restoration training concerns such as instructional design, development of performance standards, and inadequacy of resources. Finally, the fifth lists a series of restoration problems in the context of restoration planning, actions during system degradation, and restoration of a stabilized system.
1.05 Power System Restoration Issues, 1991, p. 31
This paper lists major considerations that need to be dealt with during restoration, such as switching transients, remote cranking power, damage assessment versus cause identification, phase angle differences, and generator startup times. The paper then lists the fundamental steps that need to be included in the development of a restoration plan. It goes on to discuss exploration of more advanced methods such as expert systems to aid in restoration and operator training.
1.06 Special Considerations in Power System Restoration, 1992, p. 37
This detailed paper addresses several important restoration issues. It discusses the problem of excessive alarms that may occur, and it suggests that a more confined set of alarms should be used during restoration. It then reviews restoration switching problems and strategies, including the need to consider backup power systems and cold weather problems. In addition, the optimal sequencing of generator startups is discussed in detail. Next, the special problems associated with underground transmission cable are illuminated. Finally, the paper lists the capabilities and limitations of both public and private telecommunication systems during restoration.
1.07 New Approaches in Power System Restoration, 1992, p. 46
This paper looks at how the computer can be used to aid the restoration process. What are the strengths and weaknesses of restoration that is fully computer automated, computed aided, or simply shared cooperatively by both computer and operator? What are the key steps in developing and implementing an expert system? What are the requirements for an Operator Training Simulator (OTS) for use in restoration preparation, and for what typical restoration scenarios would OTS be applicable?
1.08 A Hierarchical Interactive Approach to Electric Power System Restoration, 1992, p. 52
This paper begins with the argument that the use of general guidelines for restoration lacks specificity. It proposes that these guidelines be framed more tightly in terms of multiple, albeit conflicting, objectives; variables that can be controlled; and constraints that need to be honored. The paper recommends a hierarchical interactive control approach such that restoration control actions are decomposed into direct (or localized), optimizing (centralized and global), and adaptive (alternative strategy) layers. The paper then proceeds to explain these concepts to illustrate how they can be used to improve the restoration process.
1.09 Special Consideration in Power System Restoration-The Second Working Group Report, 1994, p. 61
This paper details four restoration issues. The first discusses different types of loads and addresses modeling of cold load pickup both heuristically and through use of physical models. The second looks at variations that may occur in cold load pickup on low-voltage networks. The third discusses the unique role that gas turbines can play in contributing to rapid system restoration. The fourth describes reactive power balancing from the perspectives of transmission line charging, generator capabilities, power-plant auxiliary requirements, and voltage control techniques.
1.10 Steam Plant Startup and Control in System Restoration, 1994, p. 68
This paper indicates the complexity of steam plant restarts following a major system shutdown. It first discusses normal steam unit startups and shutdowns in detail. It then explains how this orderly controlled process differs markedly from a unit that trips and abruptly shuts down following a major disturbance. Finally, it offers methods to improve generator operation during major disturbances through changes in design and operator training.
1.11 An AGC Implementation for System Islanding and Restoration Conditions, 1994, p. 75
This paper begins with an excellent background description of Automatic Generation Control (AGC). From that base, it describes the development of an Island AGC system on the Virginia power system to help improve the restoration process by maintaining a constant frequency. It then shows options that would be available to operators if Island AGC were invoked. It concludes with an analysis of actual test results from the Virginia power system.
1.12 Analytical Tool Requirements for Power System Restoration, 1994, p. 86
This work presents an overview of restoration analytical tools (AT) and serves as a valuable reference because it also addresses practical issues pertaining to restoration. It explains the need for AT in preparing restoration plans and training, but it also implies the need for general restoration guidelines that do not rely on AT. For each type of AT restoration software, the authors indicate: (1) what needs to be studied; (2) specific restoration features needed; (3) recommended preparatory work; (4) study procedures; and (5) why restoration studies are needed.
1.13 A Framework for Power System Restoration Following a Major Power Failure, 1995, p. 96
The last paper in Part I is an organized summary of many of the other restoration papers. As such, it can serve as a general restoration guide for operators, an outline to help prepare a more specific restoration plan, and a guide to help evaluate and improve restoration preparedness. The paper provides a framework for restoration by outlining: (1) recommended goals and objectives of restoration; (2) responses that should be initiated at the onset of abnormal conditions; (3) the sequence of restoration actions that should be taken; and (4) steps that can be taken to enhance restoration preparedness.
POWER SYSTEM RESTORATION - A TASK FORCE REPORT
Contributing Members: M. Adibi (Chairman), P. Clelland, L. Fink, H. Happ, R. Kafka, J. Raine, D. Scheurer, and F. Trefny
Abstract - The IEEE PES System Operation Subcommittee has established the Power System Restoration Task Force to: review operating practices, conduct a literature search, prepare relevant glossaries and bibliographies, and promote information exchange through technical papers. This is the first report of the Task Force.
The problem of bulk power system restoration following a complete or partial collapse is practically as old as the electric utility industry itself. Many electric utilities have developed over the years system restoration schemes that meet the needs of their particular systems. These plans provide a great deal of insight into how the restorative process is viewed by operating and planning personnel and what concerns and constraints any plan must operate under.
The body of the report consists of notes prepared by members of the Task Force. It should not be inferred that a complete reporting on Power System Restoration is undertaken here. The intent is to report upon work of the Task Force to date. The report also reviews several different restoration plans and shows their common concerns and constraints.
Today's bulk power systems provide a highly reliable supply of electric power. However, due to a combination of unforeseen circumstances, there is the remote possibility of a system wide outage. It is therefore prudent to be prepared for such an unlikely eventuality by developing an up-to-date, readily accessible, and easily understood power system restoration plan to allow a quick and orderly recovery from a system outage, with resultant minimum impact on the public.
The bulk power supply major disturbances are primarily caused by transient faults and mainly originate in the transimission systems. A very large number of these initiating causes of supply interruptions are due to temporary faults, such as lightning, which are immediately cleared by fast and selective protective relays, leaving the system in an unfaulted condition. In many cases, however, these temporary initiating causes produce subsequent effects which are "permanent," including loss of generation, load and interconnections. These subsequent effects result in a partial to complete collapse of unfaulted power systems. Thus, searching for the originating fault in power failures may be futile, although identifying the status of the collapsed system components would enhance restoration.
The major portion of the initial effort in restoring bulk supply is in restart and reintegration procedures for generation and transmission systems. Load pick-up during these initial phases, i.e. restart and reintegration, is necessary for (a) bringing generators to their stable, minimum generation levels and (b) maintaining satisfactory voltage conditions.
This paper first reviews three different restoration plans. It then describes the power system characteristics relevant to restoration. This is followed by power system considerations. Finally, it provides a bibliography covering 1940 to 1984.
II. REVIEW OF RESTORATION PLANS
1. Thermal Systems
The system restoration plan developed for all thermal systems serving metropolitan areas is based on:
Sectionalization of the system into two or more subsystems and simultaneous reintegration of generation and transmission in each subsystem. Selection of subsystems is based on black-start capability within each subsystem and steam generators with hot restart capability, and any transmission and loads required to interconnect them.
Division of the restoration procedure into restart, reintegration, load pick-up and interconnection phases. The restart phase begins with providing station service for the restart of steam units within each subsystem. In the reintegration phase generating stations are interconnected. During these two phases only the necessary loads are picked-up as dictated by generation and transmission requirements. These two phases end when the subsystems are synchronized and firmly interconnected. During the load pick-up phase loads are picked-up in small increments to avoid excessive underfrequency deviations. Due consideration is given to reactive power balance, voltage conditions and stability of the system. With the start of large steam units and availability of ample reactive absorbing capabilities, the EHV lines are energized and the interconnections are reestablished.
2. Hydro-Thermal Systems
The system restoration plan developed for hydrothermal systems serving metropolitan areas is based on energizing the entire bulk power transmission system in one step and providing station service to all thermal generating stations. This approach uses the ability of large hydro stations to absorb the charging currents of the complete transmission system, and it is an attempt to avoid the time consuming line sectionalization and switching operations which are normally required in system restoration. The high voltages at the receiving end of lines are avoided by manual operation of hydro's voltage regulators far below normal.
With the availability of large hydros, the interconnection phase can also precede the load pick-up phase.
3. Primarily Hydro Systems
The system restoration plan developed for all hydro or primarily hydro systems emphasize the switching operation and the response of prime movers to a sudden load pickup. In this plan, due consideration is given to the time it takes to isolate and energize the necessary lines by using central control systems to execute the switching operation programs. The off-line dynamic programs are used to determine responses of the system and provide guidelines for load pick-up based on the prevailing generation on-line, transmission configuration and system loading.
4. Common Characteristics of Restoration
Review of the above and several other system restoration plans show a number of common concerns even though their strategies are different:
1. Immediate resupply of station service.
2. Time consuming nature of switching operation.
3. Start-up timings of thermal units.
4. Voltage rise problems of energizing unloaded transmission lines.
5. Frequency response of prime movers to a sudden load pick-up.
6. Cold load inrush, power factors and coincident demand factors.
Excerpted from Power System Restoration Excerpted by permission.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.
SPECIFIC SYSTEM RESTORATION.
DISTRIBUTION SYSTEM RESTORATION.
About the Editor.
About the Authors.
In the interim, a number of excellent papers on the subject have been written. This book responds to the continued interest in restoration by including all the original papers of the first publication along with 73 additional papers. To enhance the organization of the work, the papers are now sorted into seven main parts and, for the sake of continuity, papers in each part are arranged in the order of their original publication date. Also for convenience, a General Discussion and Discussion of Reprints are provided at the beginning of each part. Part 1 is on Restoration Overview edited by J.J. Ancona. It covers major power system disturbances, power system restoration issues, special considerations in restorations, new approaches in power system restoration, steam plant start-up and control, analytical tools requirements, and a framework for power system restoration. It offers excellent overviews of the power system restoration process, and it provides background and introductory material for those wishing to familiarize themselves with the key aspects of restoration. More importantly, they also include in-depth discussions of the overall restoration process. This helps to illustrate the different objectives, components, constraints, and operations to ensure a successful restoration.
Part 2 is on Restoration Techniques edited by M. M. Adibi. It covers real and reactive power control, sustained and transient overvoltage controls, reactive capability of generators, frequency response of prime movers, protective system issues and line asymmetries, remote cranking of steam electric units, and nuclear plant requirements. It offers various techniques used in planning, simulating, field testing, and verifying different aspects of power system restoration. The models and procedures developed address steady-state, transient, and dynamic behaviors of the power system and its major components. In addition, it provides guidelines and recommendations for development of an efficient restoration plan and its safe execution.
Part 3 is on Restoration Planning edited by L. H. Fink. It covers pre-disturbance conditions and post-disturbance status, post- restoration target system and restoration stages, physical, scheduling, and policy constraints, build-up and build-down tactics and strategies, generic restoration actions and specific building blocks, system modeling, simulation and validation, and estimation of restoration duration. These papers follow the major blackout of 1977 in the northeastern United States. They represent serious reconsideration of system restoration problems and of the need to develop and maintain adequate restoration plans. Part 4 is on Restoration Training edited by M. Rafian. It covers conventional methods of operator training, development of an operator training simulator (OTS), verification of the restoration plan using OTS, evaluation of restoration tools using OTS, conduct and evaluation of restoration drills, experience using the OTS as a training tool, and restoration training techniques. These papers deal with the use of OTS in system restoration, and they discuss the actual experiences and broad issues surrounding the area of power system restoration training.
Part 5 is on Specific System Restoration edited by R. J. Kafka. It covers the restoration plan for the Pacific Northwest power system, system restoration at Ontario-Hydro, service restoration on the Hydro-Quebec power system, restoration of the French, Italian, Greek, and Swedish systems, interactive long-term simulation for restoration, optimum restoration with interactive graphics, and policies for restoration of power system. This group of papers deals with the specific restoration plans of various organizations. Although each plan is different, there are many common characteristics. With respect to restoration planning, we see an evolution from plans based on the experience and expertise of system planning and operations personnel to heuristic trial and error simulations, to computer-guided and optimized simulations.
Part 6 is on Knowledge-Based Systems edited by C. C. Liu. It covers information beyond breaker and relay operations, inconsistent information on the status of breakers and switches, determination of the generator start-up sequence, transmission path findings, determination of the switching sequence, optimal field crew dispatch, and integration of Energy Management System and analytical tools. Power system restoration is one of the important applications for knowledge-based systems (KBSs). This group of papers primarily covers the bulk power system and subtransmission systems, and addresses numerous sub-problems due to the complexity and scope of restoration.
Part 7 is on the Distribution System Restoration edited by A. J. Monticelli. It covers physically based load models, cold load pickup of large secondary networks, feeder reconfiguration for service restoration, restoration and loss reduction of distribution systems, restoration in subcontrol center, power network restoration support systems, and optimal distribution design for cold load pickup. This group of papers includes models for cold load pickup, transformer thermal behavior, and methods (both combinatorial and analytical) used for determining optimal energization order. Finally, for quick reference, both an author and a subject index are included at the end of the book.
Though significantly expanded, this edition is not intended as an exhaustive treatment of the subject. Hopefully, however, it will serve as an excellent reference source for those interested in restoration study, planning, and preparation. The PSR-WG welcomes your continued interest and future papers.