Overvoltage Protection and Insulation Coordination in Power System.pdf

Fachgebiet
Hochspannungstechnik
Overvoltage Protection and Insulation Coordination / Chapter 1 - 1 -
Overvoltage Protection
and
Insulation Coordination
in Power Systems
Prof. Dr.-Ing. Volker Hinrichsen
Dipl.-Ing. Simona Feier-Iova
Technische Universität Darmstadt
High Voltage Laboratories
© Siemens

Fachgebiet
What is Insulation Coordination?
Definition in IEC 60071-1
Definition in IEC 60071-1
Definition in IEEE 1313.1
Definition in IEEE 1313.1

Fachgebiet
Fundamentals of Insulation Coordination
Time duration of (over-)voltage
Possible voltages without arresters
Voltages limited by arresters
Withstand voltage of equipment
Lightning overvoltages
(Microseconds)
Switching overvoltages
(Milliseconds)
Temporary overvoltages
(Seconds)
Highest voltage of equipment
(Continuously)
Magnitude
of
(over-)voltage
/
p.u.
1
2
3
4
0
5

Fachgebiet
What is Insulation Coordination?
Procedure of insulation coordination [THI-01]
Three elements are involved in the insulation coordination discipline, namely:
• the study of the "stresses", both electrical and environmental, acting on the equipment
insulation. This is usually performed by calculations or field measurements;
• the study of the "strength" (dielectric withstand characteristics) of the insulation (both
new and aged) when submitted to such stresses, taking into account, when applicable,
the effect of the environmental stresses (pollution, rain, snow, ice, atmospheric
conditions at large altidudes), including the study of the "test and measurement
techniques" which are employed to assess such strength. The strength is determined
by calculations, based on suitable discharge models, and/or by laboratory/factory tests,
on-site tests and in-service measurements (diagnostics);
• the assessment of the insulation performance (usually expressed in terms of risk of
failure) in the considered situation of stresses and strength, including the selection and
application of "protective devices and techniques", to establish the final insulation
design fulfilling the specified requirements. This may be based on "deterministic" or
"statistical" approach.
Three elements are involved in the insulation coordination discipline, namely:
• the study of the "stresses", both electrical and environmental, acting on the equipment
insulation. This is usually performed by calculations or field measurements;
• the study of the "strength" (dielectric withstand characteristics) of the insulation (both
new and aged) when submitted to such stresses, taking into account, when applicable,
the effect of the environmental stresses (pollution, rain, snow, ice, atmospheric
conditions at large altidudes), including the study of the "test and measurement
techniques" which are employed to assess such strength. The strength is determined
by calculations, based on suitable discharge models, and/or by laboratory/factory tests,
on-site tests and in-service measurements (diagnostics);
• the assessment of the insulation performance (usually expressed in terms of risk of
failure) in the considered situation of stresses and strength, including the selection and
application of "protective devices and techniques", to establish the final insulation
design fulfilling the specified requirements. This may be based on "deterministic" or
"statistical" approach.

Fachgebiet
Literature (1)
[BAL-04-1] G. Balzer
Power Systems, Part 2
Chapter 4: Insulation coordination
Script TU Darmstadt, 2004
[BAL-04-2] G. Balzer
Elektrische Energieversorgung, Teil 2
Kapitel 4: Isolationskoordination
Skript der TU Darmstadt, 2004
[CIG-73] CIGRE W.G. 13-02
Switching overvoltages in EHV and UHV systems with special reference
to closing and reclosing transmission lines
ELECTRA 30 (1973) pp. 70-122
[CIG-79-1] CIGRE WG 33.02
Phase-to-phase Insulation Co-ordination:
Part 1: Switching overvoltages in three-phase systems
ELECTRA 64 (1979) pp. 138-158
Phase-to-phase Insulation Co-ordination
Part 2: Switching impulse strength of phase-to-phase external insulation
ELECTRA 64 1979, pp. 158-181

Fachgebiet
Literature (2)
Part 3: Design and testing of phase-to-phase insulation
ELECTRA 64 1979, pp. 182-210
[CIG-79-4] CIGRE TF 33-03.03
Part 4: The influence of non-standard conditions on the switching impulse strength
of phase-to-phase insulation
ELECTRA 64 1979, pp. 211-230
[CIG-91] CIGRE WG 33.01
Guide to procedures for estimating the lightning performance of
transmission lines, CIGRE technical brochure No. 63, 1991
buch_020.pdf
[CIG-92] CIGRE WG 33-07
Guidelines for the evaluation of the dielectric strength of external
insulation, CIGRE technical brochure No. 72, 1992
buch_019.pdf
[DOR-81] H. Dorsch
Überspannungen und Isolationsbemessung bei Drehstrom-Hochspannungsanlagen
Siemens AG, Erlangen, 1981 (ISBN 3-8009-1325-9)

Fachgebiet
Literature (3)
[ERI-88] A.J. Eriksson, K.-H. Weck
Simplified procedures for determining representative substation impinging lightning
overvoltages, CIGRE report 33-16, 1988
[ETG-93] ETG-Fachbericht 49
ETG-Tage '93: Isolationskoordination in Hoch- und Mittelspannungsanlagen
vde-Verlag GmbH Berlin, Offenbach (ISBN 0341-3934)
[FGH-78] FGH Technischer Bericht 1-240
Isolationskoordination auf der Grundlage der neuen DIN/VDE-Bestimmung 0111
FGH, Mannheim, Juli 1978
[HIL-99] A. R. Hileman
Insulation Coordination for Power Systems
Marcel Dekker, Inc., New York, Basel, 1999
[HIN-00] V. Hinrichsen
Metalloxidableiter: Grundlagen
Siemens AG Berlin, 1. Auflage 2000
AbleiterBuch.pdf
Metalloxidableiter: Grundlagen
Siemens AG Berlin, Edition 1, 2001
ArresterBook.pdf

Fachgebiet
Latest Designs and Service Experience with Station-Class Polymer Housed Surge Arresters
World Conference on Insulators, Arresters & Bushings
Marbella (Málaga), Spain, November 16-19, 2003, Proceedings pp. 85-96
pub_048.pdf
[KIN-05] V. Hinrichsen
Latest Testing Requirements and Emerging Standards for Transmission Line Arresters
World Conference on Insulators, Arresters & Bushings
Hong Kong, November 27-30, 2005
inmr_2005_paper.pdf
[KIS-84] I. Kishizima, K. Matsumoto, Y. Watanabe, New facilities for phase switching impulse
tests and some test results, IEEE PAS TO3 No. 6, June 1984 pp. 1211-1216.
[KOE-93-1] D. König, Y. N. Rao
Teilentladungen in Betriebsmitteln der Energietechnik
vde-Verlag, Berlin, Offenburg, 1993, ISBN 3-8007-1764-6
[KOE-93-2] D. König, Y. N. Rao
Partial discharges in Power Apparatus
vde-Verlag, Berlin, Offenburg, 1993, ISBN 3-8007-1760-3
Literature (4)

Fachgebiet
[PAR-68] L. Paris, R. Cortina
Switching and lightning impulse discharge characteristics of large air gaps and long insulation
strings, IEEE Trans on PAS, vol 87, No. 4, April 1968, p. 947-957
[RUD-99-1] R. Rudolph, B. Richter
Dimensioning, testing and application of metal oxide surge arresters in medium voltage networks
3rd Edition, 1999, ABB Switzerland, 26 pages (also available in German)
application_guide_medium_voltage_networks.pdf
[RUD-99-2] R. Rudolph, B. Richter
Bemessung, Prüfung und Einsatz von Metalloxid-Ableitern in Mittelspannungsnetzen
ABB Schweiz AG, Wettingen (CH), 3. Auflage 1999
Anwendungsrichtlinien_Mittelspannung.pdf
[THI-01] L. Thione
Insulation coordination in electrical power systems – theory and application
Tutorial, ALPI, Milan, 2001 (www.alpiass.com)
buch_018.pdf
Literature (5)

Fachgebiet
[WEC-07] K.-H. Weck
Standardization of insulation withstand levels for UHV systems in
IEC TC 28 „Insulation co-ordination”
IEC/CIGRE UHV Symposium Beijing 18-21 July 2007, report 5-4
5-4_KHWeck.pdf
Overview on CIGRE publications (very interesting!): Cigré Catalogue of Publications 01/07/2005
CATALOGUE_PUBLICATIONS_2005.pdf
Literature (6)

Fachgebiet
IEC 60071-1, Edition 8.0 (2006-01)
Insulation co-ordination – Part 1: Definitions, principles and rules
IEC 60071-2, Third Edition (1996-12)
Insulation co-ordination – Part 2: Application guide
IEC/TR 60071-4, First Edition (2004-06)
Insulation co-ordination - Part 4: Computational guide to insulation co-ordination and modelling of
electrical networks
IEC 60099-4, Ed. 2.1, 2006-07
Surge arresters – Part 4: Metal-oxide surge arresters without gaps for a.c. systems
IEC 60099-5, Ed. 1.1, 2000-03
Surge arresters – Part 5: Selection and application recommendations
DIN EN 60071-1, 1996-07
Isolationskoordination - Teil 1: Begriffe, Grundsätze und Anforderungen (IEC 60071-1:1993); Deutsche Fassung EN
60071-1:1995
DIN EN 60071-2, 1997-09
Isolationskoordination - Teil 2: Anwendungsrichtlinie (IEC 60071-2:1996); Deutsche Fassung EN 60071-2:1997
IEEE 1313.1-1996
IEEE Standard for Insulation Coordination—Definitions, Principles, and Rules
Standards (1)

Fachgebiet
IEEE 1313.2-1999
IEEE Guide for the Application of Insulation Coordination
IEEE C62.11-2005
IEEE Standard for Metal-Oxide Surge Arresters for AC Power Circuits (> 1 kV)
IEEE C62.22-1997
IEEE Guide for the Application of Metal-Oxide Surge Arresters for Alternating-Current Systems
Standards (2)

Fachgebiet
Organization
Lecture 13
31.01.2008
13
Test procedures; condition monitoring (life time aspects, partial
discharges, non-conventional approaches)
Lecture 12
24.01.2008
12
Calculation Examples
Lecture 11
17.01.2008
11
Insulation coordination
Lecture 10
10.01.2008
10
Christmas holidays
03.01.2008
Christmas holidays
27.12.2007
Insulation coordination
Lecture 9
20.12.2007
9
pollution, rain, parallel insulation, aging)
Lecture 8
13.12.2007
8
Dielectric strength (incl. gap factors,
Lecture 7
06.12.2007
7
Overvoltage protection incl. protective distance
Lecture 6
29.11.2007
6
Traveling waves
Lecture 5
22.11.2007
5
Lecture 4
15.11.2007
4
cancelled
08.11.2007
Lecture 3
01.11.2007
3 Voltage stresses
in power systems
Lecture 2
25.10.2007
2
Introduction
Lecture 1
18.10.2007
1

Fachgebiet
Organization
Examination
Examination
Exclusively oral
Exercises
Exercises
None; but calculation examples in the lecture
Script
Script
Slides will be available for download
www.hst.tu-darmstadt.de
User: studentiso
PW: isows0708

Fachgebiet
Insulation Coordination - Principles
Environment
System
System voltages
Dielectric
strength
Equipment
Overvoltage
protection devices
stress
versus
strength

Fachgebiet
• Voltages of the system
– Nominal voltage Un
» rounded value for characterizing the system
» 10 kV - 20 kV - 110 kV - 220 kV - 380 kV
– System voltage
» voltage at which the system is being operated
» around the nominal value, but not constant
– Highest system voltage Us
» highest operating voltage between phases under normal conditions
» 12 kV - 24 kV - 123 kV - 245 kV - 420 kV (IEC 60038)
• Voltages of equipment
– Highest voltage for equipment Um
» highest voltage between phases for which the insulation is designed
» 12 kV - 24 kV - 123 kV - 245 kV - 420 kV (IEC 60071-1)

Fachgebiet
• Overvoltages
– voltages exceeding the peak value of the highest system voltage
– various amplitudes and shapes depending on
» system configuration (grid size, degree of meshing, etc.)
» origin of overvoltage (failure, switching, lightning strike etc.)
• Dielectric strength of insulation
– verified by type test in the laboratory with the help of
» standardized test voltages (shape, amplitude)
» specified test setups
» specified environmental conditions
• Insulation coordination
– Determination of interdependence between voltages and
overvoltages of the system and necessary test voltages for the
equipment in the laboratory

Fachgebiet
Equipment in
the laboratory
Equipment in
the laboratory
Equipment in
the system
Equipment in
the system
Variety of amplitudes and
shapes of overvoltages
Variety of amplitudes and
shapes of overvoltages
Standardized amplitudes
and shapes of test voltages
Standardized amplitudes
and shapes of test voltages
Variety of operating
conditions and age
Variety of operating
conditions and age
Standardized setups
and conditions
Standardized setups
and conditions
Variety of
environmental conditions
Variety of
Standardized
Standardized

Fachgebiet
line
bb 1
bb 2
busbar disconnectors
Insulation phase - ground
stressed by voltages between one phase and ground
1
Insulation phase - phase
stressed by voltages between two phases
2
Longitudinal insulation
stressed by voltages between same phases of
two different systems
3
2
3
1

Fachgebiet
Insulation Coordination according to IEC 60071-1 (and 60071-2)

Fachgebiet

Fachgebiet
Procedure for
insulation
coordination
= 10 pages!
Procedure for
insulation
coordination
= 10 pages!
...39 pages in sum
...39 pages in sum

Fachgebiet

Fachgebiet
...125 pages in sum
...125 pages in sum

Fachgebiet
Procedure for Insulation Coordination - General
The procedure for insulation coordination consists of the selection of a set of
standard withstand voltages which characterize the insulation of the
equipment.
Range I Range II

Fachgebiet
Procedure for Insulation Coordination - General
Basic difference between ranges I and II
withstand
voltage
time duration of stress
peak
gap spacing 3 m
gap spacing 0.5 m
[FGH-78]
Minimum of withstand
voltage for switching
overvoltage
Minimum of withstand
voltage for switching
overvoltage
Withstand voltage
continuously
decreasing with time
duration of stress
Withstand voltage
continuously
decreasing with time
duration of stress
Range I
Range I
Range II
Range II

Fachgebiet
Procedure for Insulation Coordination in Four Steps
Determination of the representative overvoltages Urp
• The representative overvoltages are derived from real service conditions, but have
just standardized shapes.
• They are determined in amplitude, shape and duration by system analysis, taking
into account overvoltage limiting devices.
[IEC 60071-1]

Fachgebiet
Determination of the coordination withstand voltages Ucw
• The coordination withstand voltages are the lowest values of withstand voltages of
each overvoltage class, for which the expected low failure rate of the equipment is not
exceeded over its full lifetime.
• Derived from the representative overvoltages Urp by the coordination factor Kc.
[IEC 60071-1]
Typical for
Germany:
0.1% per year
1 failure in
1000 years

Fachgebiet
Deterministic approach
Deterministic approach Statistical approach
Statistical approach
Assumed maximum
of representative overvoltage
Assumed maximum
of representative overvoltage
Multiplication by coordination
factor based on
operating experience
Multiplication by coordination
factor based on
operating experience
Statistical distribution of
representative overvoltages
Statistical distribution of
representative overvoltages
Determination of
failure probability of insulation
Determination of
failure probability of insulation
Calculation of failure risk
depending on assumed
coordination withstand voltage
Calculation of failure risk
depending on assumed
coordination withstand voltage
Coordination withstand voltage
Assumed conventional Ucw (0% value) Statistical Ucw (10% value)
Coordination withstand voltage
Assumed conventional Ucw (0% value) Statistical Ucw (10% value)

Fachgebiet
Determination of the required withstand voltages Urw
• The required withstand voltages are determined by converting the coordination withstand
voltages to appropriate standard test conditions.
• Usually different from the coordination withstand voltages.
• Derived from the coordination withstand voltages Ucw by the safety factor Ks and the
atmospheric correction factor Kt or the altitude correction factor Ka.
[IEC 60071-1]

Fachgebiet
[IEC 60071-1]
Influences covered by the safety factor Ks
• Differences in equipment assembly
• Dispersion in product quality
• Quality of installation
• Aging of the installation during expected lifetime
• Other unknown influences

Fachgebiet
Determination of the required withstand voltages Urw
• The required withstand voltages are determined by converting the coordination withstand
voltages to appropriate standard test conditions.
• Usually different from the coordination withstand voltages.
• Derived from the coordination withstand voltages Ucw by the safety factor Ks and/or the
altitude correction factor Ka.
[IEC 60071-1]

Fachgebiet
Selection of the rated and of the standard insulation level
(set of standard rated withstand voltages Uw)
• Most economical set of standard withstand voltages Uw of the insulation to prove that all
the required withstand voltages are met.
• For each range (I or II) a combination of only two withstand voltages defined:
Range I: standard lightning impulse withstand voltage
standard short-duration power-frequency withstand voltage
Range II: standard switching impulse withstand voltage
standard lightning impulse withstand voltage
• For range I, only phase-to-earth standard withstand voltages are defined, which have to
cover phase-to-earth, phase-to-phase and longitudinal insulation.

Fachgebiet
[IEC 60071-1]
Definitions

Fachgebiet
Examples for…
... non-self-restoring insulation
(power transformers,
instrument transformers*))
*) mixed insulation
... self-restoring
insulation
(disconnectors,
insulators)

Fachgebiet
[IEC 60071-1]
List of standard short-duration power-frequency withstand voltages (r.m.s. values in kV)
630
570
510
480
460
395
360
325
275
230
185
140
95
70
50
38
28
20
10
1800
750
95
1950
850
125
1675
650
75
2100
950
145
2400
2250
1550
1425
1300
1175
1050
550
450
325
250
170
60
40
20
List of standard impulse withstand voltages (peak values in kV)

Fachgebiet
The standard voltage values are
all the same for
• phase-to-earth-,
• phase-to-phase-,
• longitudinal
insulation!
Range I:
Um = 1 kV up to and including Um = 245 kV
[IEC 60071-1]

Fachgebiet
Range II:
Um above 245 kV
Different standard voltage values for
• phase-to-earth-,
• phase-to-phase-,
• longitudinal
insulation!
[IEC 60071-1]

Fachgebiet
Outcome of insulation coordination
– For three types of insulation
» phase to ground
» phase to phase
» longitudinal
– and for 4 values each of required withstand voltages Urw
» required continuous operating voltage
» required short-duration power-frequency withstand voltage
» required switching impulse withstand voltage
» required lightning impulse withstand voltage

Standardization of tests for equipment
– Reduction of these 12 values to a necessary minimum number of
withstand voltages Uw of the insulation
– Determination of necessary withstand voltages from tables for two
ranges of highest voltage for equipment
twelve
voltages

Fachgebiet
[IEC 60071-1]
Procedure for Insulation Coordination in Four Steps - Summary
Flow chart acc. to IEC 60071-1
(Figure 1)
continued next slide

Fachgebiet
[IEC 60071-1]
Procedure for Insulation Coordination in Four Steps - Summary
Flow chart acc. to IEC 60071-1
(Figure 1) (continued)

Overvoltage Protection and Insulation Coordination in Power System.pdf

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