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Electrical Power Systems Quality, Second Edition
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Electrical Power Systems Quality, Second Edition
What is Power Quality?
Power Quality -- Voltage Quality
Why Are We Concerned About Power Quality?
The Power Quality Evaluation Procedure
Who Should Use This Book
Overview of the Contents
Need for a Consistent Vocabulary
General Classes of Power Quality Problems
Transients
Long-Duration Voltage Variations
Short-Duration Voltage Variations
Voltage Imbalance
Waveform Distortion
Voltage Fluctuation
Power Frequency Variations
Power Quality Terms
Ambiguous Terms
CBEMA and ITI Curves
References
Sources of Sags and Interruptions
Estimating Voltage Sag Performance
Fundamental Principles of Protection
Solutions at the End-User Level
Evaluating the Economics of Different Ride-Through Alternatives
Motor-Starting Sags
Utility System Fault-Clearing Issues
References
Sources of Transient Overvoltages
Principles of Overvoltage Protection
Devices for Overvoltage Protection
Utility Capacitor-Switching Transients
Utility System Lightning Protection
Managing Ferroresonance
Switching Transient Problems with Loads
Computer Tools for Transients Analysis
References
Harmonic Distortion
Voltage versus Current Distortion
Harmonics versus Transients
Harmonic Indexes
Harmonic Sources from Commercial Loads
Harmonic Sources from Industrial Loads
Locating Harmonic Sources
System Response Characteristics
Effects of Harmonic Distortion
Interharmonics
References
Bibliography
Harmonic Distortion Evaluations
Principles for Controlling Harmonics
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Where to Control Harmonics
Harmonic Studies
Devices for Controlling Harmonic Distortion
Harmonic Filter Design: A Case Study
Case Studies
Standards of Harmonics
References
Bibliography
Principles of Regulating the Voltage
Devices for Voltage Regulation
Utility Voltage Regulator Application
Capacitors for Voltage Regulation
End-User Capacitor Application
Regulating Utility Voltage with Distributed Resources
Flicker
References
Bibliography
Introduction
Benchmarking Process
RMS Voltage Variation Indices
Harmonics Indices
Power Quality Contracts
Power Quality Insurance
Power Quality State Estimation
Including Power Quality in Distribution Planning
References
Bibliography
Resurgence of DG
DG Technologies
Interface to the Utility System
Power Quality Issues
Operating Conflicts
DG on Distribution Networks
Siting DGDistributed Generation
Interconnection Standards
Summary
References
Bibliography
Resources
Definitions
Reasons for Grounding
Typical Wiring and Grounding Problems
Solutions to Wiring and Grounding Problems
Bibliography
Monitoring Considerations
Historical Perspective of Power Quality Measuring Instruments
Power Quality Measurement Equipment
Assessment of Power Quality Measurement Data
Application of Intelligent Systems
Power Quality Monitoring Standards
References
Index
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Source: Electrical Power Systems Quality
1
Introduction
Both electric utilities and end users of electric power are becoming
increasingly concerned about the quality of electric power. The term
power quality has become one of the most prolific buzzwords in the
power industry since the late 1980s. It is an umbrella concept for a mul-
titude of individual types of power system disturbances. The issues
that fall under this umbrella are not necessarily new. What is new is
that engineers are now attempting to deal with these issues using a
system approach rather than handling them as individual problems.
There are four major reasons for the increased concern:
1. Newer-generation load equipment, with microprocessor-based con-
trols and power electronic devices, is more sensitive to power qual-
ity variations than was equipment used in the past.
2. The increasing emphasis on overall power system efficiency has
resulted in continued growth in the application of devices such as
high-efficiency, adjustable-speed motor drives and shunt capacitors
for power factor correction to reduce losses. This is resulting in
increasing harmonic levels on power systems and has many people
concerned about the future impact on system capabilities.
3. End users have an increased awareness of power quality issues.
Utility customers are becoming better informed about such issues as
interruptions, sags, and switching transients and are challenging
the utilities to improve the quality of power delivered.
4. Many things are now interconnected in a network. Integrated
processes mean that the failure of any component has much more
important consequences.
1
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Chapter
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Introduction
2
Chapter One
The common thread running though all these reasons for increased
concern about the quality of electric power is the continued push for
increasing productivity for all utility customers. Manufacturers want
faster, more productive, more efficient machinery. Utilities encourage
this effort because it helps their customers become more profitable and
also helps defer large investments in substations and generation by
using more efficient load equipment. Interestingly, the equipment
installed to increase the productivity is also often the equipment that
suffers the most from common power disruptions. And the equipment
is sometimes the source of additional power quality problems. When
entire processes are automated, the efficient operation of machines and
their controls becomes increasingly dependent on quality power.
Since the first edition of this book was published, there have been
some developments that have had an impact on power quality:
1. Throughout the world, many governments have revised their laws
regulating electric utilities with the intent of achieving more cost-com-
petitive sources of electric energy. Deregulation of utilities has compli-
cated the power quality problem. In many geographic areas there is no
longer tightly coordinated control of the power from generation
through end-use load. While regulatory agencies can change the laws
regarding the flow of money, the physical laws of power flow cannot be
altered. In order to avoid deterioration of the quality of power supplied
to customers, regulators are going to have to expand their thinking
beyond traditional reliability indices and address the need for power
quality reporting and incentives for the transmission and distribution
companies.
2. There has been a substantial increase of interest in distributed
generation (DG), that is, generation of power dispersed throughout the
power system. There are a number of important power quality issues
that must be addressed as part of the overall interconnection evalua-
tion for DG. Therefore, we have added a chapter on DG.
3. The globalization of industry has heightened awareness of defi-
ciencies in power quality around the world. Companies building facto-
ries in new areas are suddenly faced with unanticipated problems with
the electricity supply due to weaker systems or a different climate.
There have been several efforts to benchmark power quality in one part
of the world against other areas.
4. Indices have been developed to help benchmark the various
aspects of power quality. Regulatory agencies have become involved in
performance-based rate-making (PBR), which addresses a particular
aspect, reliability, which is associated with interruptions. Some cus-
tomers have established contracts with utilities for meeting a certain
quality of power delivery. We have added a new chapter on this subject.
Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com)
Copyright © 2004 The McGraw-Hill Companies. All rights reserved.
Any use is subject to the Terms of Use as given at the website.
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