IEEE Std 421.1
™
-2007
(Revision of
IEEE Std 421.1-1986)
IEEE Standard Definitions
for Excitation Systems
for Synchronous Machines
I E E E
3 Park Avenue
New York, NY 10016-5997, USA
15 July 2007
IEEE Power Engineering Society
Sponsored by the
Energy Development and Power Generation Committee
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1™-2007
(Revision of
IEEE Std 421.1-1986)
IEEE Standard Definitions
for Excitation Systems
for Synchronous Machines
Sponsor
Energy Development and Power Generation Committee
of the
Power Engineering Society
Approved 8 March 2007
IEEE-SA Standards Board
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
Abstract: This standard defines elements and commonly used components in excitation systems
and contains definitions for excitation systems applied to synchronous machines. An included
annex contains one-line block diagrams of some typical excitation systems. These are presented
to illustrate the defined terminology referenced in this standard and clarify the understanding of
the excitation control system.
Keywords: definitions of excitation controls, excitation block diagrams, excitation control
systems, excitation systems terminology, synchronous generator controls
_________________________
The Institute of Electrical and Electronics Engineers, Inc.
3 Park Avenue, New York, NY 10016-5997, USA
Copyright © 2007 by the Institute of Electrical and Electronics Engineers, Inc.
All rights reserved. Published 15 July 2007. Printed in the United States of America.
IEEE is a registered trademark in the U.S. Patent & Trademark Office, owned by the Institute of Electrical and Electronics
Engineers, Incorporated.
Print: ISBN 0-7381-5535-7 SH95632
PDF: ISBN 0-7381-5536-5 SS95632
No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior
written permission of the publisher.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Standards documents are developed within the IEEE Societies and the Standards Coordinating Committees of
the IEEE Standards Association (IEEE-SA) Standards Board. The IEEE develops its standards through a consensus
development process, approved by the American National Standards Institute, which brings together volunteers
representing varied viewpoints and interests to achieve the final product. Volunteers are not necessarily members of the
Institute and serve without compensation. While the IEEE administers the process and establishes rules to promote
fairness in the consensus development process, the IEEE does not independently evaluate, test, or verify the accuracy
of any of the information contained in its standards.
Use of an IEEE Standard is wholly voluntary. The IEEE disclaims liability for any personal injury, property or other
damage, of any nature whatsoever, whether special, indirect, consequential, or compensatory, directly or indirectly
resulting from the publication, use of, or reliance upon this, or any other IEEE Standard document.
The IEEE does not warrant or represent the accuracy or content of the material contained herein, and expressly
disclaims any express or implied warranty, including any implied warranty of merchantability or fitness for a specific
purpose, or that the use of the material contained herein is free from patent infringement. IEEE Standards documents
are supplied “AS IS.”
The existence of an IEEE Standard does not imply that there are no other ways to produce, test, measure, purchase,
market, or provide other goods and services related to the scope of the IEEE Standard. Furthermore, the viewpoint
expressed at the time a standard is approved and issued is subject to change brought about through developments in the
state of the art and comments received from users of the standard. Every IEEE Standard is subjected to review at least
every five years for revision or reaffirmation. When a document is more than five years old and has not been
reaffirmed, it is reasonable to conclude that its contents, although still of some value, do not wholly reflect the present
state of the art. Users are cautioned to check to determine that they have the latest edition of any IEEE Standard.
In publishing and making this document available, the IEEE is not suggesting or rendering professional or other
services for, or on behalf of, any person or entity. Nor is the IEEE undertaking to perform any duty owed by any other
person or entity to another. Any person utilizing this, and any other IEEE Standards document, should rely upon the
advice of a competent professional in determining the exercise of reasonable care in any given circumstances.
Interpretations: Occasionally questions may arise regarding the meaning of portions of standards as they relate to
specific applications. When the need for interpretations is brought to the attention of IEEE, the Institute will initiate
action to prepare appropriate responses. Since IEEE Standards represent a consensus of concerned interests, it is
important to ensure that any interpretation has also received the concurrence of a balance of interests. For this reason,
IEEE and the members of its societies and Standards Coordinating Committees are not able to provide an instant
response to interpretation requests except in those cases where the matter has previously received formal consideration.
At lectures, symposia, seminars, or educational courses, an individual presenting information on IEEE standards shall
make it clear that his or her views should be considered the personal views of that individual rather than the formal
position, explanation, or interpretation of the IEEE.
Comments for revision of IEEE Standards are welcome from any interested party, regardless of membership affiliation
with IEEE. Suggestions for changes in documents should be in the form of a proposed change of text, together with
appropriate supporting comments. Comments on standards and requests for interpretations should be addressed to:
Secretary, IEEE-SA Standards Board
445 Hoes Lane
Piscataway, NJ 08854
USA
Authorization to photocopy portions of any individual standard for internal or personal use is granted by the Institute of
Electrical and Electronics Engineers, Inc., provided that the appropriate fee is paid to Copyright Clearance Center. To
arrange for payment of licensing fee, please contact Copyright Clearance Center, Customer Service, 222 Rosewood
Drive, Danvers, MA 01923 USA; +1 978 750 8400. Permission to photocopy portions of any individual standard for
educational classroom use can also be obtained through the Copyright Clearance Center.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
Introduction
This introduction is not part of IEEE Std 421.1-2007, IEEE Standard Definitions for Excitation Systems for
Synchronous Machines.
This standard defines elements and commonly used components in excitation systems and contains
definitions for excitation systems applied to synchronous machines. For general requirements of a
synchronous machine refer to IEEE Std C50.12™ and IEEE Std C50.13™.
a
A synchronous machine excitation control system operating under automatic control is a feedback control
system. Thus, the Terminology of the Excitation System Subcommittee Working Group of the Energy
Development and Power Generation (ED&PG) Committee adopted definitions that had a common basis to
excitation systems. Efforts were made not to conflict with terms found in the most recent edition of The
Authoritative Dictionary of IEEE Standards Terms
[B11], but to clarify or more fully define terms as
related specifically to excitation of synchronous machines.
b
Notice to users
Errata
Errata, if any, for this and all other standards can be accessed at the following URL: http://
standards.ieee.org/reading/ieee/updates/errata/index.html. Users are encouraged to check this URL for
errata periodically.
Interpretations
Current interpretations can be accessed at the following URL: http://standards.ieee.org/reading/ieee/interp/
index.html.
Patents
Attention is called to the possibility that implementation of this standard may require use of subject matter
covered by patent rights. By publication of this standard, no position is taken with respect to the existence
or validity of any patent rights in connection therewith. The IEEE shall not be responsible for identifying
patents or patent applications for which a license may be required to implement an IEEE standard or for
conducting inquiries into the legal validity or scope of those patents that are brought to its attention.
a
For more information on references, please refer to Clause 2.
b
The numbers in brackets correspond to those in the bibliography in Annex B.
iv
Copyright © 2007 IEEE. All rights reserved.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
Participants
At the time this standard was completed, the Definitions Working Group had the following membership:
A. Murdoch, Chair
J. C. Agee
Michael J. Basler
Roger Beaulieu
Roger Berube
Ken Bollinger
Sandro Corsi
Murray Coultes
Mel Crenshaw
Tom Eberly
Mike Fogarty
Pierre Fournaise
Jonathan D. Gardell
Irving Gibbs
George Girgis
Arjun Godhwani
Ram Gupta
James H. Gurney
Les Hajagos
Lou Hannett
David Harris
Joe Hurley
Prabha Kundur
Rod Lawson
Lawrence D. Long
Jim Luini
O. P. Malik
Daryl Maxwell
Georg Meier
Lorne Midford
John Morrow
Allan Morse
Rich Mummert
Larry Nettleton
Shawn E. Patterson
Marcel Racine
Manfred Reimann
Joe Ribeiro
Larry Rodland
Graham Rogers
Robert Rusch
Rich Schaefer
A. W. Schneider, Jr.
Paul Smulders
Jose Taborda
Arvind Tewari
John Undrill
Sundar Venkataraman
Larry Wall
Maroun Zakhour
The following members of the individual balloting committee voted on this standard. Balloters may have
voted for approval, disapproval, or abstention.
William J. Ackerman
J. C. Agee
Ali Al Awazi
G. J. Bartok
Michael J. Basler
Wallace B. Binder, Jr.
Thomas H. Blair
Steven R. Brockschink
Gustavo A. Brunello
James S. Case
Weijen Chen
Tommy P. Cooper
Luis M. Coronado
Matthew T. Davis
James H. Dymond
Gary R. Engmann
Robert E. Fenton
Jonathan D. Gardell
J. Travis Griffith
Robert Grondin
Randall C. Groves
James H. Gurney
Steve Hamilton
Ryusuke Hasegawa
Michael Henry
Gary A. Heuston
David A. Horvath
Dennis Horwitz
David W. Jackson
Innocent Kamwa
Jim Kulchisky
Saumen K. Kundu
Charles A. Lennon, Jr.
William E. Lockley
Lawrence D. Long
William Lumpkins
G. L. Luri
O. P. Malik
John W. Martin
Omar S. Mazzoni
Mark F. McGranaghan
Nigel P. McQuin
James R. Michalec
Gary L. Michel
Allan Morse
Karl N. Mortensen
Jerry R. Murphy
Michael S. Newman
Nils E. Nilsson
Lorraine K. Padden
Shawn E. Patterson
Julian E. Profir
Manfred Reimann
Frank H. Rocchio
Steven Sano
A. W. Schneider, Jr.
Ahmed M. El Serafi
Malcolm V. Thaden, Jr.
S. Thamilarasan
James W. Wilson, Jr.
v
Copyright © 2007 IEEE. All rights reserved.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
When the IEEE-SA Standards Board approved this standard on 8 March 2007, it had the following
membership:
Steve M. Mills, Chair
Robert M. Grow, Vice Chair
Donald F. Wright, Past Chair
Judith Gorman, Secretary
Richard DeBlasio
Alexander D. Gelman
William R. Goldbach
Arnold M. Greenspan
Joanna N. Guenin
Julian Forster*
Kenneth S. Hanus
William B. Hopf
Richard H. Hulett
Hermann Koch
Joseph L. Koepfinger*
John D. Kulick
David J. Law
Glenn Parsons
Ronald C. Petersen
Tom A. Prevost
Narayanan Ramachandran
Greg Ratta
Robby Robson
Anne-Marie Sahazizian
Virginia C. Sulzberger
Malcolm V. Thaden
Richard L. Townsend
Howard L. Wolfman
*Member Emeritus
Also included are the following nonvoting IEEE-SA Standards Board liaisons:
Satish K. Aggarwal, NRC Representative
Alan H. Cookson, NIST Representative
Jennie Steinhagen
IEEE Standards Program Manager, Document Development
Matthew J. Ceglia
IEEE Standards Program Manager, Technical Program Development
vi
Copyright © 2007 IEEE. All rights reserved.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
Contents
1. Overview .................................................................................................................................................... 1
1.1 Scope ................................................................................................................................................... 1
2. Normative references.................................................................................................................................. 1
3. Definitions.................................................................................................................................................. 2
Annex A (normative) Typical elements and components of excitation control systems.............................. 10
Annex B (informative) Bibliography............................................................................................................ 22
vii
Copyright © 2007 IEEE. All rights reserved.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Standard Definitions
for Excitation Systems
for Synchronous Machines
1.
1.1
2.
Overview
This standard contains definitions and terminology specifically related to elements and commonly used
components in excitation control systems for synchronous machines. Clause
1 is an overview of the
standard and provides an outline of the scope of the standard. Clause
2 lists references to other standards
that are relevant to definitions presented here. Clause
3 is a listing of the relevant definitions covered in this
standard.
This standard also has two annexes.
Annex A is an outline of some excitation system diagrams that are
referred to in some of the definitions.
Annex B provides bibliographical references.
Scope
This standard defines elements and commonly used components in excitation control systems and contains
definitions for excitation systems as applied to synchronous machines. These definitions should be useful in
the following areas:
⎯ Writing excitation systems specifications
⎯ Evaluating excitation system performance
⎯ Specifying methods for excitation system tests
⎯ Preparing related excitation system standards
⎯ Serving as an educational means for those becoming acquainted with excitation systems
⎯ Modeling excitation systems
Normative references
The following referenced documents are indispensable for the application of this standard. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments or corrigenda) applies.
1
Copyright © 2007 IEEE. All rights reserved.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
IEEE Std C50.12™, IEEE Standard for Salient-Pole 50 Hz and 60 Hz Synchronous Generators and
Generator/Motors for Hydraulic Turbine Applications Rated 5 MVA and Above.
1,
2
IEEE Std C50.13™, IEEE Standard for Cylindrical-Rotor 50 Hz and 60 Hz Synchronous Generators Rated
10 MVA and Above.
IEEE Std. 421.2™, IEEE Guide for Identification, Testing, and Evaluation of the Dynamic Performance of
Excitation Control Systems.
IEEE Std 421.3™, IEEE Standard for High-Potential Test Requirements for Excitation Systems for
Synchronous Machines.
IEEE Std 421.4™, IEEE Guide for the Preparation of Excitation System Specifications.
IEEE Std 421.5™-2005, IEEE Recommended Practice for Excitation System Models for Power System
Stability Studies.
3.
Definitions
For the purposes of this standard, the following terms and definitions apply. The Authoritative Dictionary
of IEEE Standards Terms
[B11]
3
should be referenced for terms not defined in this clause.
3.1 ac field breaker: A circuit breaker used to disconnect the excitation system from the power potential
transformer (PPT) or ac supply. See also: de-excitation.
3.2 ac regulator: See: voltage regulator.
3.3 adjuster: A device or function by which the set point is determined.
3.4 air-gap field voltage: The synchronous machine field voltage required to produce rated voltage on the
air-gap line of the synchronous machine with its field winding at 1) 75 °C for field windings designed to
operate at rating with a temperature rise of 60 °C or less; or 2) 100 °C for field windings designed to
operate at rating with a temperature rise greater than 60 °C.
NOTE—This defines one per unit excitation system voltage for use in computer representation of excitation systems.
4
3.5 air-gap line: The extended straight line part of the no-load saturation curve of the synchronous
machine.
3.6 alternator-rectifier exciter: An exciter whose energy is derived from an alternator and converted to
direct current by rectifiers. The exciter includes an alternator and power rectifiers that may be either
noncontrolled or controlled, including gate circuitry. It is exclusive of input control elements. The
alternator may be driven by any type of prime mover, most commonly the shaft of the synchronous
machine. The rectifiers may be stationary or rotating with the alternator shaft.
3.7 automatic control: In excitation control system usage, automatic control refers to maintaining
synchronous machine terminal voltage at a predetermined level without operator action, over the operating
range of the synchronous machine.
NOTE—Voltage regulation may be modified by the action of load current compensators, power factor or var
controllers, power system stabilizers, or may be constrained by the action of various limiters included in the excitation
system.
1
The IEEE publications listed in this document are trademarks of the Institute of Electrical and Electronics Engineers, 445 Hoes
Lane, Piscataway, NJ 08855-1331, USA (http://standards.ieee.org).
2
IEEE publications are available from the Institute of Electrical and Electronics Engineers, 445 Hoes Lane, Piscataway, NJ 08855-
1331, USA (http://standards.ieee.org).
3
The numbers in brackets correspond to those of the bibliography in Annex B.
4
Notes in text, tables, and figures of a standard are given for information only and do not contain requirements needed to implement
this standard.
2
Copyright © 2007 IEEE. All rights reserved.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
3.8 automatic voltage regulator (AVR): A term often used to designate either the voltage regulator alone
or the complete control system comprised of limiters, etc. See also: synchronous machine regulator.
3.9 autotracking: A function that causes the output of a control channel in the standby mode to follow the
action of an active control channel; for example, autotracking of the manual control to follow the automatic
control. Also called a follower.
3.10 auxiliary winding excitation system: An excitation system whose energy is derived from a separate
dedicated power winding in the main generator’s stator.
NOTE—See Figure A.10.
3.11 brushless exciter: An alternator-rectifier exciter employing rotating rectifiers with a direct connection
to the synchronous machine field, thus eliminating the need for brushes.
NOTE—See Figure A.6.
3.12 bumpless transfer: A transfer between two control modes that results in negligible change in
synchronous machine output. See also: null balance.
3.13 ceiling current: The maximum field current that the excitation system is designed to supply.
Typically, this is related to the thermal capability of the excitation system equipment or the synchronous
machine field circuit capability. See also: overexcitation limiter.
3.14 ceiling voltage: The maximum direct voltage that the excitation system is designed to supply from its
terminals under defined conditions.
NOTE 1— The no-load ceiling voltage is determined with the excitation system supplying minimal current.
NOTE 2— The ceiling voltage under load is determined with the excitation system supplying synchronous machine
rated field current.
NOTE 3— For an excitation system whose supply depends on the synchronous machine voltage and (if applicable)
current, the nature of power system disturbance and specific design parameters of the excitation system and the
synchronous machine influence the excitation system output. For such systems, the ceiling voltage is determined
considering a specified supply voltage (usually rated voltage) and (if applicable) synchronous machine current.
NOTE 4— For excitation systems employing a rotating exciter, the ceiling voltage is determined at rated speed.
3.15 compound source-rectifier exciter: An exciter whose energy is derived from the currents and
potentials of the ac terminals of the synchronous machine and converted to direct current by rectifiers. The
exciter includes the power transformers (current and potential), reactors (if required), and rectifiers that
may be either noncontrolled or controlled, including gate circuitry. It is exclusive of input control elements.
3.16 crowbar: In excitation system usage, a circuit designed to provide a conduction path for field current
flow to prevent excessive field voltage. Triggered semiconductors with series resistors or inductors are
commonly used. Non-linear resistors may alternatively provide this function.
NOTE—See Figure A.17b.
3.17 current boost: An excitation system auxiliary supply that acts to increase the available power
supplied to the field winding, typically during fault conditions where the terminal voltage is lower and
current is higher than normal.
3.18 current boost exciter: An exciter whose energy is derived from currents at the ac terminals of the
synchronous machine and converted to direct current by rectifiers. The current boost system output is
added directly with a potential source exciter rectifier as a separate rectifier system. The current boost
system may include power current transformers, and either noncontrolled rectifiers or controlled rectifiers,
with gate circuitry.
NOTE—See Figure A.14 and Figure A.15.
3
Copyright © 2007 IEEE. All rights reserved.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
4
Copyright © 2007 IEEE. All rights reserved.
Figure 1
3.19 dc field breaker: A circuit breaker used to disconnect the excitation system from the generator or
exciter field. See also: de-excitation.
3.20 dc generator-commutator exciter: An exciter whose energy is derived from a dc generator. The
exciter includes a dc generator with its commutator and brushes. It is exclusive of input control elements.
The exciter may be driven by a motor or any type of prime mover, most commonly by the shaft of the
synchronous machine.
3.21 dc regulator: See: manual control.
3.22 de-excitation: The removal of the excitation and field discharge of the synchronous machine, main
exciter, or pilot exciter.
NOTE—De-excitation may be accomplished by various means, such as a field discharge circuit breaker, dc field
breaker, ac field breaker, crowbar, free wheeling diode, phase-back control of controlled rectifiers, or a combination of
these.
3.23 digital excitation system: A common nomenclature for describing an excitation system for a
synchronous machine where some, if not all, of the functionality is implemented in a digital processor. As a
minimum, the AVR control function would be expected to be implemented digitally in such a system. It is
likely that the limiter functions and optional var/pf or PSS controls are also implemented in the same
digital-based control.
NOTE—See [B6].
3.24 discharge resistor: A resistor that, upon interruption of excitation source current, is connected across
the field winding of a synchronous machine or an exciter to limit the transient voltage in the field circuit
and to hasten the decay of field current of the machine.
3.25 discontinuous excitation control: A control function that acts to rapidly change synchronous
machine excitation to a level different than that called for by the voltage regulator and power system
stabilizer, for a period of time following a system fault or disturbance. Also known as discrete field forcing
or transient excitation boosting.
3.26 excitation control system: The feedback control system that includes the synchronous machine and
its excitation system. The term is used to distinguish the performance of the synchronous machine
and
excitation system in conjunction with the power system from that of the excitation system alone.
NOTE—See Figure 1.
EXCITATION SYSTEM
EXCITATION CONTROL SYSTEM
—Block diagram of excitation control system
3.27 excitation system: The equipment providing field current for a synchronous machine, including all
power, regulating, control, and protective elements.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
5
Copyright © 2007 IEEE. All rights reserved.
Figure 2
3.28 excitation system duty cycle: An initial operating condition and a subsequent sequence of events of
specified duration to which the excitation system will be exposed.
NOTE—The duty cycle usually involves a three-phase fault of specified duration that is located electrically close to the
synchronous machine. Its primary purpose is to specify the duty that the excitation system components can withstand
without incurring mis-operation or damage.
3.29 excitation system nominal response: The rate of increase of the excitation system output voltage
determined from the excitation system voltage response curve, divided by the rated field voltage. This rate,
if maintained constant (curve ac), would develop the same voltage-time area as obtained from the response
(curve ab) over the first half-second interval (unless a different time interval is specified).
NOTE 1— Refer to Figure 2.
NOTE 2— The excitation system nominal response shall be determined with the excitation system voltage initially
equal to the rated field voltage of the synchronous machine, after which the excitation system ceiling voltage is rapidly
attained by introducing a specified voltage error step.
NOTE 3— The excitation system nominal response shall be determined with the excitation system loaded with a
resistance equal to the field resistance under rated load conditions and adequate inductance so that voltage drop effects
and current and voltage waveforms are reasonably duplicated.
NOTE 4— For excitation systems whose supply depends on the synchronous machine voltage and (if applicable)
current, the nature of the power system disturbance and specific design parameters of the excitation system and the
synchronous machine influence the excitation system output. For such systems, the excitation system nominal response
shall be determined considering a specified supply voltage (usually rated voltage) and (if applicable) synchronous
machine current.
NOTE 5— If, for practical considerations, tests can only be made on individual components or the entire excitation
system but only at partial or no-load, analytical methods may be used to predict performance with rated field voltage
(see NOTE 1).
NOTE 6— For excitation systems employing a rotating exciter, the excitation system nominal response shall be
determined at rated speed.
NOTE 7— Not normally used in the specification of static excitation systems. There is a potential conflict if ceiling
voltage is also specified.
c
b
d
e
o
a
Nominal Response =
ce - ao
(ao)(oe)
where:
oe = 0.5 seconds
ao = synchronous machine
rated field voltage
Seconds
Exciter Voltage
—Excitation system nominal response
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
6
Copyright © 2007 IEEE. All rights reserved.
3.30 excitation system output terminals: The place of output from the equipment comprising the
excitation system. These terminals may be identical with the field winding terminals.
3.31 excitation system rated current: The direct current at the excitation system output terminals that the
excitation system can supply under defined conditions of its operation. This current is at least that value
required by the synchronous machine under the most demanding continuous operating conditions
(generally resulting from synchronous machine voltage, frequency, and power factor variations).
3.32 excitation system rated voltage: The direct voltage at the excitation system output terminals that the
excitation system can provide when delivering excitation system rated current under rated continuous load
conditions of the synchronous machine with its field winding at 1) 75 °C for field windings designed to
operate at rating with a temperature rise of 60 °C or less; or 2) 100 °C for field windings designed to
operate at rating with a temperature rise greater than 60 °C.
3.33 excitation system stabilizer: A function that serves to modify the voltage regulator forward signal by
either series or feedback compensation to improve the dynamic performance of the excitation control
system.
3.34 excitation system voltage response time: The time in seconds for the excitation voltage to attain 95%
of the difference between ceiling voltage and rated field voltage under specified conditions.
3.35 exciter: The equipment that provides the field current for the excitation of a synchronous machine.
3.36 fault current limiter: A function that acts to prevent the stator current from exceeding a preset value
during steady-state operation of the generator with a short-circuit applied to its output. The limiter acts to
limit fault current by decreasing excitation. Also known as line current limiter.
3.37 field current/voltage limiter: A control function that acts to prevent the field current or voltage from
exceeding a preset value. See also: overexcitation limiter.
3.38 field discharge circuit breaker: A circuit breaker having main contacts for energizing and de-
energizing the field of a synchronous machine or rotating exciter and having discharge contacts for short-
circuiting the field through a discharge resistor prior to the opening of the circuit breaker main contacts.
The discharge contacts also disconnect the field from the discharge resistor following the closing of the
main contacts.
NOTE 1— When used in the main field of a synchronous machine the circuit breaker is designated as a main field
discharge circuit breaker.
NOTE 2— When used in the field circuit of a rotating exciter of the main machine, the circuit breaker is designated as
an exciter field discharge circuit breaker. See
[B1].
3.39 field flashing: Momentary application of dc power to the field of a synchronous machine for the
purpose of building up terminal voltage.
3.40 field forcing: A control action that rapidly drives the field voltage of a synchronous machine in the
positive or in the negative direction.
3.41 field voltage/field current regulator: A regulator that functions to maintain the field voltage/field
current at a predetermined value.
3.42 field winding: A winding on either the stationary or the rotating part of a synchronous machine whose
sole purpose is the production of the main electromagnetic field of the machine.
3.43 field winding terminals: The place of input to the field winding of the synchronous machine. If there
are brushes and slip rings (collectors), these are considered to be part of the field winding.
3.44 freewheeling diode: A diode connected across the controlled bridge of a static excitation system to
provide a path for field current to flow if the normal bridge path is not available. Also called flyback diode.
NOTE—See Figure A.1c.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
7
Copyright © 2007 IEEE. All rights reserved.
3.45 high initial response: An excitation system capable of attaining 95% of the difference between
ceiling voltage and rated field voltage in 0.1 s or less under specified conditions.
3.46 impedance compensator: See: line drop compensator; reactive droop compensator.
3.47 large signal performance: Response of an excitation control system, excitation system, or elements
of an excitation system to signals that are large enough that nonlinearities must be included in the analysis
of the response to obtain realistic results.
3.48 line drop compensator: A function that modifies the machine terminal voltage to compensate for the
impedance drop to a fixed point external to the synchronous machine terminals.
3.49 load current compensator: A function that acts to influence the voltage regulator action to control
voltage at a point other than where the synchronous machine voltage is measured. Specific uses are reactive
droop compensation, reactive differential compensation, and line drop compensation.
3.50 manual control: In excitation system usage, manual control refers to direct control of the
synchronous machine excitation by operator action. See also: field voltage/field current regulator.
NOTE—Manual control may include open or closed loop control of the exciter output, or any other means that does not
directly control the synchronous machine output variables.
3.51 no-load field current: The direct current in the field winding of synchronous machine required to
produce rated voltage at no-load and rated speed.
3.52 no-load field voltage: The voltage required across the terminals of the field winding of the
synchronous machine under conditions of no-load, rated speed, and rated terminal voltage, and with the
field winding at 25 °C.
3.53 null balance: A circuit or action designed to match the output of the automatic voltage regulator and
the manual control to minimize the transient upon transfer of regulator control. See also: bumpless
transfer.
3.54 overexcitation limiter (OEL): A control function that limits the field current of the synchronous
machine or excitation equipment to permissible values with regard to thermal overload. Action may be
immediate or time delayed. Also called a maximum excitation limiter. See also: field current/voltage
limiter.
3.55 permanent magnet generator (PMG): An auxiliary synchronous machine with permanent magnet
field. Used to supply the power requirements of a portion of the excitation system. Also known as
permanent magnetic alternator (PMA).
NOTE—See Figure A.2, Figure A.4, and Figure A.6.
3.56 pilot exciter: The equipment providing the source of field power for the excitation of another exciter.
3.57 potential source-rectifier exciter: An exciter whose energy is derived from a stationary ac potential
source and converted to direct current by rectifiers. The exciter includes the power potential transformers
and power rectifiers that may be either noncontrolled or controlled, including gate circuitry. It is exclusive
of input control elements. The source of ac power may come from the machine terminals or from a station
auxiliary bus or a separate winding within the synchronous machine.
3.58 power current transformer: A transformer in a compound source-rectifier excitation system that
transfers electrical energy from the synchronous machine armature current to the excitation system at a
magnitude and phase relationship required by the excitation system. Also used in current boost
configuration.
NOTE—See Figure A.7 and Figure A.8.
3.59 power factor controller: A control function that acts through the adjuster to modify the voltage
regulator set point so as to maintain the synchronous machine steady-state power factor at a predetermined
value.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
8
Copyright © 2007 IEEE. All rights reserved.
3.60 power factor regulator: A synchronous machine regulator that functions to maintain the power factor
at a predetermined value. Commonly used on synchronous motors. See also: power factor controller.
3.61 power potential transformer (PPT): A transformer in a potential source-rectifier excitation system
that transfers electrical energy either from the machine terminals or from an auxiliary bus to the excitation
system at a magnitude level required by the excitation system. Also, a transformer in a compound source-
rectifier excitation system that transfers electrical energy from the synchronous machine armature terminals
to the excitation system at a magnitude and phase relationship required in the excitation system.
3.62 power system stabilizer (PSS): A function that provides an additional input to the voltage regulator
to improve the damping of power system oscillations.
NOTE—A number of different quantities may be used as input to the power system stabilizer, such as shaft speed,
frequency, electric power, etc., or a combination of these signals.
3.63 rated field current: The direct current in the field winding of the synchronous machine when
operating at rated voltage, current, power factor, and speed. Rated field current of any other rotating
exciters is based on the synchronous machine rated field current at a specified temperature.
3.64 rated field voltage: The voltage required across the terminals of the field winding under rated
continuous load conditions of the synchronous machine with its field winding at 1) 75 °C for field windings
designed to operate at rating with a temperature rise of 60 °C or less; or 2) 100 °C for field windings
designed to operate at rating with a temperature rise greater than 60 °C. Rated field voltage of any other
rotating exciter is based on the synchronous machine rated field current at a specified temperature.
3.65 reactive differential compensator: A function used to obtain reactive current sharing among
synchronous machines operating in parallel without causing reduction of terminal voltage. Requires
interconnection of voltage regulators or current transformers of the machines.
3.66 reactive droop compensator: A function that causes a reduction of terminal voltage proportional to
reactive current. Generally used to obtain reactive current sharing among synchronous machines operating
in parallel.
3.67 set point: The reference signal to which the controlled variable is to be compared.
3.68 shaft voltage suppressor: A filter device, usually consisting of a symmetrical RC network, connected
from each side of the field to ground. The filter is designed to eliminate common mode voltage that is
caused by power semiconductors used to supply the field circuit. The filter minimizes shaft voltages that
would otherwise lead to shaft currents, which could damage bearing surfaces.
3.69 small-signal performance: The response of an excitation control system, excitation system, or
elements of an excitation system to signals that are small enough that nonlinearities can be disregarded in
the analysis of the response, and operation can be considered to be linear.
3.70 stator current limiter: A function that acts to prevent the stator current from exceeding a preset
value. If the generator is operating overexcited, the limiter will decrease excitation, while in underexcited
operation the limiter increases excitation.
3.71 synchronous machine regulator: A general term applied to a regulator that couples the output
variables of a synchronous machine to control the exciter output through forward and feedback elements
for the purpose of regulating the synchronous machine output variables. See also: automatic voltage
regulator.
3.72 terminal voltage limiter: A function that acts to prevent the terminal voltage from exceeding a preset
level.
3.73 underexcitation limiter (UEL): A function that either overrides the voltage regulator action
(takeover type) or adds to terminal voltage setpoint (summing type), to maintain synchronous machine
excitation such that synchronous machine output remains above a preset level. Various terms have been
applied, often descriptive of the measured variable; minimum excitation limiter, underexcited reactive
ampere limit, and rotor angle limiter.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
9
Copyright © 2007 IEEE. All rights reserved.
3.74 var controller: A function that acts through the adjuster to modify the voltage regulator set point so as
to maintain the synchronous machine steady-state reactive power at a predetermined value.
3.75 var regulator: A synchronous machine regulator that functions to maintain the reactive component of
power at a predetermined value. Commonly used on synchronous motors. See also: var controller.
3.76 voltage regulation accuracy: The band or zone, expressed in percent of the rated value of the
regulated voltage, within which the excitation system will hold the regulated voltage of the synchronous
machine during steady or gradually changing conditions, in the absence of the action of any compensators
or limiters. Unless otherwise specified, the range will be assumed from no-load to rated kVA and power
factor.
3.77 voltage regulator: A synchronous machine regulator that functions to maintain the terminal voltage
of a synchronous machine at a predetermined value, or to vary it according to a predetermined plan.
3.78 volts per hertz limiter: A function that acts to prevent the ratio of terminal voltage to frequency from
exceeding a preset level. The purpose is to prevent excessive magnetic flux in the synchronous machine
and connected transformers.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
10
Copyright © 2007 IEEE. All rights reserved.
Annex A
(normative)
Typical elements and components of excitation control systems
The following figures are included only to aid in the understanding of the excitation control system and to
illustrate some typical systems terminology referenced and defined in this standard.
Figure A.1 is a generalized block diagram identifying excitation system control and protective elements.
The symbols used in
Figure A.1 are taken directly from IEEE Std 421.5-2005, “Computer Representation
of Excitation Systems”
[B15], and “Excitation System Models for Power System Stability Studies” [B16],
and are defined in
Table A.1.
Table A.2 shows the correlation between the diagrams of this standard and the excitation model types used
in IEEE Std 421.5-2005 and “Excitation System Models for Power System Stability Studies”
[B16]. Table
A.2
also shows a further breakdown of the three basic exciter types, as well as the source of exciter power.
Figure A.2 through Figure A.16 show typical configurations of the principal excitation systems currently in
use. These single line diagrams identify the source of the excitation power with control circuits shown for
clarity and general understanding.
Figure A.17a through Figure A.17d represent the typical three-phase rectifier bridge circuits that may be
used in excitation control systems. The rectifier bridge circuit is shown in
Figure A.3 and Figure A.6
through
Figure A.15 as a single rectifier or controlled rectifier in a block. These rectifiers are the main
source of the field current for an exciter or generator main field.
The potential source and compound source systems have power PTs and power CTs. These transformers
supply power to the rectifier bridge circuits; they should not be confused with the instrument transformers
supplying intelligence to the automatic control circuit, or used for protection and metering functions.
Table A.1—Nomenclature for Figure A.1
E
FD
– Exciter output voltage (generator field voltage)
I
FD
– Exciter output current (generator field current)
V
F
– Excitation system stabilizer signal
V
FE
– Signal proportional to exciter field current
V
L
– Limiters and protective elements feedback
V
R
– Regulator output
V
S
– Power system stabilizer output
V
SI
– Power system stabilizer inputs (shaft speed, frequency, synchronous machine
electric power, and others)
V
T
,I
T
– Generator terminal voltage and current, respectively
V
REF
– Voltage regulator, reference signal
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
11
Copyright © 2007 IEEE. All rights reserved.
Table A.2—Excitation system characteristics
Exciter
category
Type of
exciter
Exciter
power source
Figure High initial
response
Computer
model type*
DC DC generator commutator
exciter
Motor-generator set or synchronous
machine shaft
A.2, A.4
A.3
A.5
no
no
no
DC1A
DC2A
DC3A
AC Alternator-stationary
noncontrolled rectifier
Alternator-rotating
noncontrolled rectifier
(brushless)
Alternator-stationary
controlled rectifier
Synchronous machine shaft
Synchronous machine shaft
Synchronous machine shaft
A.7
A.6
A.8
no
no
yes
yes
AC3A
AC1A
AC2A
AC4A
ST
Potential source
controlled rectifier
Compound source
noncontrolled rectifier
Compound source
controlled rectifier
Synchronous machine voltage or
auxiliary bus voltage
Synchronous machine
voltage and current
Synchronous machine
voltage and current
A.9
A.10
A.11, A.14
A.12, A.13
A.15, A.16
yes
yes
no
yes
ST1A
ST3A
ST2A
ST3A
Figure A.1—Automatic control functions
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
Figure A.2—DC generator-commutator exciter with rotating amplifier
Figure A.3—DC generator-commutator exciter with static amplifier
12
Copyright © 2007 IEEE. All rights reserved.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
Regulator
Transfer
Station
Auxiliary
Power
Automatic
Control
Adjuster
Exciter Field
Rheostat
(Manual Control)
DC Exciter
Synchronous
Machine
CT
VT
PMG
MOT
Boost
Buck
Figure A.4—DC generator-commutator exciter with continuously acting regulator
employing static amplifiers
Figure A.5—DC generator-commutator exciter separately excited
with noncontinuously acting rheostatic regulator
13
Copyright © 2007 IEEE. All rights reserved.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
Synchronous
Machine
VT
N
S
AC Exciter
Exciter
Field
Adjuster
Automatic
Control
Manual
Control
Adjuster
CT
Regulator
Transfer
Gate
Control
PMG
Field Current or Voltage
N.O.
Figure A.6—Alternator-rectifier exciter employing rotating noncontrolled rectifiers
(brushless exciter)
Figure A.7—Alternator-rectifier exciter employing stationary noncontrolled rectifiers
14
Copyright © 2007 IEEE. All rights reserved.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
VT
Synchronous
Machine
CT
Automatic
Control
Adjuster
Adjuster
Manual
Control
Power
PT
AC Exciter
Power
CT
Field
Flashing
Gate
Control
Automatic
Control
Adjuster
Regulator
Transfer
Gate
Control
Figure A.8—Alternator-rectifier exciter employing controlled rectifiers
Figure A.9—Potential source-rectifier exciter employing controlled rectifiers
15
Copyright © 2007 IEEE. All rights reserved.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
Synchronous
Machine
Adjuster
Auxiliary Winding
in Generator
(Power PT)
Regulator
Transfer
Manual
Control
CT
Adjuster
VT
Automatic
Control
Gate
Control
Field
Flashing
Figure A.10—Potential source rectifier exciter employing controlled rectifiers
(with generator auxiliary power source)
CT
Adjuster
VT
Automatic
Control
Adjuster
Manual
Control
Saturable
Power
CT
Power
PT
Synchronous
Machine
Gate
Control
Field
Flashing
Regulator
Transfer
Figure A.11—Compund source-rectifier exciter employing noncontrolled rectifiers
16
Copyright © 2007 IEEE. All rights reserved.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
Figure A.12—Compund source-rectifier exciter employing controlled rectifiers
CT
Adjuster
VT
Gate
Control
Manual
Control
Field
Flashing
Synchronous
Machine
Adjuster
Automatic
Control
Reactor
Auxiliary Windings in
Generator (Power PT/CT)
Shunt
Control
F
P
C
Regulator
Transfer
Figure A.13—Compound source-rectifier exciter employing shunt controlled rectifiers
17
Copyright © 2007 IEEE. All rights reserved.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
CT
VT
Automatic
Control
Adjuster
Linear
Reactor
Power
CT
Synchronous
Machine
Field
Flashing
Saturable
Power
PT
Adjuster
Manual
Control
Figure A.14—Compound source-rectifier exciter employing noncontrolled rectifiers and
saturable potential transformers
Figure A.15—Rotating exciter rectifier with current boost excitation system
18
Copyright © 2007 IEEE. All rights reserved.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
Figure A.16—Potential source exciter with current boost excitation system
Figure A.17a—Three-phase full wave diode bridge (noncontrolled rectifier)
19
Copyright © 2007 IEEE. All rights reserved.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
AC
Input
DC
Output
(+)
(–)
Gate
Control
Control
Input
Optional
Figure A.17b—Three-phase full wave diode bridge (controlled rectifier)
Optional
AC
Input
DC
Output
(+)
(–)
Gate
Control
Control
Input
Figure A.17c—Three-phase full wave diode bridge (hybrid controlled rectifier)
20
Copyright © 2007 IEEE. All rights reserved.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
AC
Input
DC
Output
(+)
(–)
Gate
Control
Control
Input
Figure A.17d—Three-phase full wave diode bridge (shunt controlled rectifier)
21
Copyright © 2007 IEEE. All rights reserved.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
Annex B
(informative)
Bibliography
[B1] ANSI/IEEE C37.18-1979 (Reaff 1996), IEEE Standard Enclosed Field Discharge Circuit Breakers
for Rotating Electric Machinery.
[B2] Barnes, H. C., Oliver, J. A., Rubenstein, A. S., and Temoshok, M., “Alternator-Rectifier Exciter for
Cardinal Plant 724-MVA Generator,” IEEE Trans. Power App. Syst., vol. PAS-87, Apr. 1968, pp. 1189–
1198.
[B3] Chambers, G. S., Rubenstein, A. S., and Temoshok, M., “Recent Developments in Amplidyne
Regulator Excitation Systems for Large Generators,” AIEE Trans. Power App. Syst., vol. 80, 1961, pp.
1066–1072.
[B4] Cotzas, G. M., Crenshaw, M. L., and Richardson, G.L., “GENERREX-PPS (Potential Power Source)
Excitation System for Wisconsin Power and Light,” Edgewater 5, Proceedings of the Forty-Third
American Power Conference, Apr. 1981.
[B5] Cotzas, G. M., Drexler, K. F., Dvorscak, J. J., and Gerlitz, R. L., “Descriptions and Tests of the
GENERREX Excitation System for Large Steam Turbine-Generators,” IEEE Trans. Power App. Syst., vol.
PAS-95, May/June 1976, pp. 803–810.
[B6] Digital Excitation Applications Task Force of the Excitation System Subcommittee, “Digital
Excitation Technology—A Review of Features, Functions and Benefits,” IEEE Trans. Energy Convers.,
vol. 12, no. 3, Sept. 1997, pp. 255–258.
[B7] Digital Excitation Task Force of the Equipment Working Group, “Computer Models for
Representation of Digital-Based Excitation Systems,” IEEE Trans. Energy Convers., vol. 11, no. 3, Sept.
1996, pp. 609–615.
[B8] Dillman, T. L., Keay, F. W., Raczkowsi, C., Skooglund, J. W., and South, W. H., “Brushless
Excitation,” IEEE Spectrum, Mar. 1972, pp. 58–66.
[B9] Domeratzky, L. M., Rubenstein, A. S., and Temoshok, M., “A Static Excitation System for
Industrial and Utility Steam Turbine-Generators,” AIEE Trans. Power App. Syst., vol. 80, Feb. 1962, pp.
1072–1077.
[B10] Hurley, J. D, Bize, L. N., and Mummert, C. R., “The Adverse Effects of Excitation System Var and
Power Factor Controllers,” Paper PE-387-EC-0-12-1997.
[B11] IEEE 100, The Authoritative Dictionary of IEEE Standards Terms, Seventh Edition, New York,
Institute of Electrical and Electronics Engineers, Inc.
[B12] IEEE Task Force on Excitation Limiters, “Recommended Models for Overexcitation Limiting
Devices,” IEEE Trans. Energy Convers., vol. 10, no. 4, Dec. 1995, pp. 706–713.
[B13] IEEE Task Force on Excitation Limiters, “Underexcitation Limiter Models for Power System
Stability Studies,” IEEE Trans. Energy Convers., vol. 10, no. 3, Sept. 1995, pp. 524–531.
[B14] IEEE Tutorial Course, “Power System Stabilization Via Excitation Control,” 81-EHO 175-0 PWR.
22
Copyright © 2007 IEEE. All rights reserved.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
IEEE Std 421.1-2007
IEEE Standard Definitions for Excitation Systems for Synchronous Machines
[B15] IEEE Working Group of the Excitation Subcommittee, “Computer Representation of Excitation
Systems,” IEEE Trans. Power App. Syst., June 1968, pp. 1460–1464.
[B16] IEEE Working Group on Computer Modelling of Excitation Systems, “Excitation System Models
for Power System Stability Studies,” IEEE Trans. Power App. Syst., vol. PAS-100, no. 2, Feb. 1981, pp.
494–509.
[B17] Keay, F. W., and South, W. H., “A Solid-State Regulator for Electric Utility Applications,” IEEE
Trans. Power App. Syst., vol. PAS-90, no. 4, July/Aug. 1971, pp. 1527–1547.
[B18] Kundur, P., Klein, M., Rogers, G. J., and Zywno, M. S., “Application of Power System Stabilizers
for Enhancement of Overall System Stability,” IEEE Trans. Power Syst., vol. 4, no. 2, May 1989, pp. 614–
626.
[B19] Lane, L. J., Rogers, D. F., and Vance, P. A “Design and Tests of a Static Excitation System for
Industrial and Utility Steam Turbine-Generators,” AIEE Trans. Power App. Syst., vol. 80, Feb. 1962, pp.
1077–1085.
[B20] Lee, C. H., and Keay, F. W., “A New Excitation System and a Method of Analyzing Voltage
Response,” 1964 IEEE International Convention Record, vol. 12, pt. 3, pp. 5–14.
[B21] Lee, D. C., Beaulieu, R. E., Service, J. R. R., “A Power System Stabilizer Using Speed and
Electrical Power Inputs―Design and Field Experience,” IEEE Trans. Power App. Syst., PAS-100, no. 9,
Sept. 1981, pp. 4151–4157.
[B22] McClymont, K. R., Manchur, G., Ross, R. J., and Wilson, R. J., “Experience with High-Speed
Rectifier Excitation Systems,” IEEE Trans. Power App. Syst., vol. PAS-87, June 1968, pp. 1464–1470.
[B23] Murdoch, A., Owen, E. L., Sanchez-Gasca, J. J., D’Antonio, M. J., and Lawson, R. A., “Excitation
Systems―The Use of var/pf Control―A System Stability Perspective,” IEEE Paper 99-WM-025.
[B24] Rubenstein, A. S., and Temoshok, M., “Underexcitation Reactive Ampere Limit for Modern
Amplidyne Voltage Regulator,” AIEE Trans. Power App. Syst., PAS-15, vol. 73, Dec. 1954, pp. 1433–
1438.
[B25] Rubenstein, A. S., and Walkley, W. W., “Control of Reactive KVA with Modern Amplidyne
Voltage Regulators,” AIEE Trans. Power App. Syst., Dec. 1957.
[B26] Watson, W., and Manchur, G. S., “Experience with Supplementary Damping Signals for Generator
Static Excitation Systems,” IEEE Trans. Power App. Syst., Jan./Feb. 1973, pp. 199–203.
[B27] Whitney, E. C., Hoover, D. B., and Bobo, P. O., “An Electric Utility Brushless Excitation System”
AIEE Trans. Power App. Syst., vol. 78, 1959, pp. 1821–1824.
[B28] Woolridge, P. A. B., and Blythe, A. L., “Considerations Affecting the Design Philosophy of Solid-
State Exciters,” IEEE Trans. Power App. Syst., vol. PAS-87, May 1968, pp. 1288–1299.
23
Copyright © 2007 IEEE. All rights reserved.
Authorized licensed use limited to: Iowa State University. Downloaded on April 04,2018 at 01:22:38 UTC from IEEE Xplore. Restrictions apply.
