IEC TS 61400-26-3:2016

IEC TS 61400-26-3 ®
Edition 1.0 2016-08
TECHNICAL
SPECIFICATION
colour
inside
Wind energy generation systems –
Part 26-3: Availability for wind power stations

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IEC TS 61400-26-3 ®
Edition 1.0 2016-08
TECHNICAL
SPECIFICATION
colour
inside
Wind energy generation systems –

Part 26-3: Availability for wind power stations

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.180 ISBN 978-2-8322-3572-0

– 2 – IEC TS 61400-26-3:2016 © IEC 2016

CONTENTS
FOREWORD . 8

INTRODUCTION . 10

1 Scope . 12

2 Normative references. 12

3 Terms, definitions and abbreviations . 13

3.1 Terms and definitions . 13

3.2 Abbreviations for ‘Information available’ . 14
3.3 Abbreviations for ‘Information unavailable’ . 16
4 Information model for WPS . 17
4.1 General . 17
4.2 Services . 18
4.3 Information category priority . 20
4.4 Information model for BOP . 20
5 INFORMATION AVAILABLE (WPS) . 21
5.1 General . 21
5.2 OPERATIVE . 22
5.3 IN SERVICE . 23
5.3.1 General . 23
5.3.2 FULL PERFORMANCE . 24
5.3.3 PARTIAL PERFORMANCE . 25
5.3.4 READY STANDBY . 25
5.4 OUT OF SERVICE . 26
5.4.1 General . 26
5.4.2 TECHNICAL STANDBY . 27
5.4.3 OUT OF ENVIRONMENTAL SPECIFICATION . 28
5.4.4 REQUESTED SHUTDOWN . 29
5.4.5 OUT OF ELECTRICAL SPECIFICATION . 29
5.5 NON-OPERATIVE . 30
5.5.1 General . 30
5.5.2 SCHEDULED MAINTENANCE . 31
5.5.3 PLANNED CORRECTIVE ACTION . 32
5.5.4 FORCED OUTAGE . 32

5.5.5 SUSPENDED . 33
5.6 FORCE MAJEURE . 34
6 INFORMATION UNAVAILABLE (WPS) . 35
Annex A (informative) Entry and Exit condition overview . 37
Annex B (informative) Application scenarios – examples . 38
B.1 Overview. 38
B.2 Application scenarios . 38
B.2.1 Example 1: Normal operation – all WPS . 38
B.2.2 Example 2: Normal operation – part of WPS . 39
B.2.3 Example 3: Dirty WTGSs blades – all WPS . 40
B.2.4 Example 4: Dirty WTGSs blades – part of WPS . 41
B.2.5 Example 5: BOP limitations – all WPS . 42
B.2.6 Example 6: BOP limitations – part of WPS . 43

B.2.7 Example 7: ‘Spinning reserve’ – all WPS . 44

B.2.8 Example 8: ‘Spinning reserve’ – part of WPS . 46

B.2.9 Example 9: Noise restrictions – Warranty related . 47

B.2.10 Example 10: Noise restrictions – environmentally related . 48

B.2.11 Example 11: Ice storm on Grid – all WPS . 49

Annex C (informative) Balance of plant integration . 51

C.1 WPS functions and services . 51

C.2 Externally required functions and services . 51

C.3 Internally required functions and services . 51

C.4 Expansion of the Information Model for BOP functions and services . 51
Annex D (informative) Determination of potential production for a WPS – examples . 53
D.1 Overview. 53
D.2 Primary service . 53
D.3 Secondary services . 53
Annex E (informative) Service availability indicators – examples . 55
E.1 Overview. 55
E.2 Time based WPS availability . 55
E.2.1 General . 55
E.2.2 Operational service availability (“TSO’s view”) . 55
E.2.3 Operational service availability (“WPS operator’s view”) . 56
E.2.4 Technical service availability (“WPS maintenance provider’s view”) . 57
E.3 Production-based service availability indicators – examples . 58
E.3.1 Overview . 58
E.3.2 System operational production-based availability (“WPS operator’s
view”) . 58
E.3.3 System operational production-based availability (“TSO’s view”) . 59
E.3.4 System operational production-based availability (“WPS maintenance
provider’s view”) . 60
Annex F (informative) Examples of optional level 5 categories . 62
F.1 Overview. 62
F.2 Example of level 5 definitions . 62
F.2.1 General . 62
F.2.2 NOT CURTAILED . 64
F.2.3 NOT CURTAILED – WARNING . 65
F.2.4 UP-RATED . 66

F.2.5 DERATED – OTHER . 66
F.2.6 DERATED – GRID WPS OPERATOR . 67
F.2.7 DERATED – GRID TSO. 68
F.2.8 DERATED – GRID CONTROL . 69
F.2.9 DERATED – NOISE . 70
F.2.10 DERATED – TEMPERATURE . 71
F.2.11 DERATED – STRUCTURAL LOAD . 72
F.2.12 DERATED – WIND . 73
F.2.13 DEGRADED – OTHER . 74
F.2.14 DEGRADED – DIAGNOSTIC . 75
F.2.15 DEGRADED – NOISE . 76
F.2.16 DEGRADED – COMPONENT . 77
F.2.17 DEGRADED – TEMPERATURE . 78
F.2.18 DEGRADED – STRUCTURAL LOAD . 79

– 4 – IEC TS 61400-26-3:2016 © IEC 2016

F.2.19 OTHER READY STANDBY . 80

F.2.20 OTHER TECHNICAL STANDBY . 81

F.2.21 LUBRICATION . 81

F.2.22 DE-ICING . 82

F.2.23 DRY OUT . 82

F.2.24 CABLE UNTWIST . 83

F.2.25 OTHER ENVIRONMENTAL . 84

F.2.26 CALM WINDS . 84

F.2.27 HIGH WIND . 85

F.2.28 TEMPERATURE . 85

F.2.29 OTHER REQUESTED SHUTDOWN . 86
F.2.30 ENVIRONMENTAL . 86
F.2.31 GRID – WPS OPERATOR . 87
F.2.32 GRID – TSO . 88
F.2.33 NOISE . 88
F.2.34 FLICKER . 89
F.2.35 WILDLIFE . 90
F.2.36 STRUCTURAL LOAD . 90
F.2.37 OTHER OUT OF ELECTRICAL SPECIFICATION . 91
F.2.38 FREQUENCY . 92
F.2.39 VOLTAGE LEVEL LOW . 92
F.2.40 VOLTAGE LEVEL HIGH . 93
F.2.41 ASYMMETRY . 93
F.2.42 SCHEDULED MAINTENANCE . 94
F.2.43 OTHER CORRECTIVE ACTION . 94
F.2.44 UPGRADE . 95
F.2.45 INSPECTIONS . 95
F.2.46 RETROFIT . 96
F.2.47 REPAIR WORK . 96
F.2.48 OTHER FORCED OUTAGE . 97
F.2.49 FAILURE REPAIR . 97
F.2.50 DIAGNOSTIC . 98
F.2.51 LOGISTIC WPS MAINTENANCE PROVIDER . 99
F.2.52 LOGISTIC WPS OPERATOR . 99
F.2.53 RESPONSE WPS MAINTENANCE PROVIDER . 100

F.2.54 RESPONSE WPS OPERATOR . 101
F.2.55 OTHER SUSPENDED – SCHEDULED MAINTENANCE . 101
F.2.56 PERSONNEL SAFETY – SCHEDULED MAINTENANCE . 102
F.2.57 ENVIRONMENT – SCHEDULED MAINTENANCE . 103
F.2.58 IT ACCESS – SCHEDULED MAINTENANCE . 104
F.2.59 OTHER SUSPENDED – PLANNED CORRECTIVE ACTION . 105
F.2.60 PERSONNEL SAFETY – PLANNED CORRECTIVE ACTION . 106
F.2.61 ENVIRONMENT – PLANNED CORRECTIVE ACTION . 107
F.2.62 IT ACCESS – PLANNED CORRECTIVE ACTION . 108
F.2.63 OTHER SUSPENDED – FORCED OUTAGE . 109
F.2.64 PERSONNEL SAFETY – FORCED OUTAGE . 110
F.2.65 ENVIRONMENT – FORCED OUTAGE . 111
F.2.66 IT ACCESS – FORCED OUTAGE . 112
F.2.67 INACTIVE RESERVE . 113

F.2.68 MOTHBALLED . 114

F.2.69 RETIRED . 115

F.2.70 FORCE MAJEURE . 116

F.2.71 INFORMATION UNAVAILABLE . 117

Bibliography . 118

Figure 1 – Data stakeholders for a wind power station . 10

Figure 2 – Information category overview for a WPS . 17

Figure 3 – Example of a model split-up in active power, reactive power high and low

frequency compensation services . 19
Figure 4 – Information category priority for WPS . 20
Figure 5 – Mandatory INFORMATION AVAILABLE categories for WPS . 22
Figure 6 – OPERATIVE category . 23
Figure 7 – IN SERVICE category . 24
Figure 8 – FULL PERFORMANCE category . 24
Figure 9 – PARTIAL PERFORMANCE category . 25
Figure 10 – READY STANDBY category . 26
Figure 11 – OUT OF SERVICE category . 27
Figure 12 – TECHNICAL STANDBY category . 28
Figure 13 – OUT OF ENVIRONMENTAL SPECIFICATION category . 28
Figure 14 – REQUESTED SHUTDOWN category . 29
Figure 15 – OUT OF ELECTRICAL SPECIFICATION category . 30
Figure 16 – NON-OPERATIVE category . 31
Figure 17 – SCHEDULED MAINTENANCE category . 31
Figure 18 – PLANNED CORRECTIVE ACTION category . 32
Figure 19 – FORCED OUTAGE category . 33
Figure 20 – SUSPENDED category . 34
Figure 21 – FORCE MAJEURE category . 35
Figure 22 – INFORMATION UNAVAILABLE category . 36
Figure A.1 – Overview of the entry and exit conditions of all mandatory information
categories described in this document . 37

Table B.1 – Scenario, Example 1: Normal operation – all WPS . 38
Table B.2 – Scenario, Example 2: Normal operation – part of WPS . 39
Table B.3 – Scenario, Example 3: Dirty WTGSs blades – all WPS . 41
Table B.4 – Scenario, Example 4: Dirty WTGSs blades – part of WPS . 42
Table B.5 – Scenario, Example 5: BOP limitations – all WPS . 43
Table B.6 – Scenario, Example 6: BOP limitations – part of WPS . 44
Table B.7 – Scenario, Example 7: ‘Spinning reserve’ – all WPS . 45
Table B.8 – Scenario, Example 8: ‘Spinning reserve’ – part of WPS . 46
Table B.9 – Scenario, Example 9: Noise restrictions – all WPS . 47
Table B.10 – Scenario, Example 10: Noise restrictions – all WPS . 48
Table B.11 – Scenario, Example 11: Ice storm on Grid – all WPS . 49
Table D.1 – Examples on how to determine Potential production . 54

– 6 – IEC TS 61400-26-3:2016 © IEC 2016

Table F.1 – Example of level 5 definitions . 62

Table F.2 – NOT CURTAILED category . 65

Table F.3 – NOT CURTAILED – WARNING category . 65

Table F.4 – UP-RATED category . 66

Table F.5 – DERATED – OTHER category . 67

Table F.6 – DERATED – GRID WPS OPERATOR category . 68

Table F.7 – DERATED – GRID TSO category . 69

Table F.8 – DERATED – GRID CONTROL category . 70

Table F.9 – DERATED – NOISE category . 71
Table F.10 – DERATED – TEMPERATURE category . 72
Table F.11 – DERATED – STRUCTURAL LOAD category . 73
Table F.12 – DERATED – WIND category . 74
Table F.13 – DEGRADED – OTHER category . 75
Table F.14 – DEGRADED – DIAGNOSTIC category . 76
Table F.15 – DEGRADED – NOISE category . 77
Table F.16 – DEGRADED – COMPONENT category . 78
Table F.17 – DEGRADED – TEMPERATURE category . 79
Table F.18 – DEGRADED – STRUCTURAL LOAD category . 80
Table F.19 – OTHER READY STANDBY category . 81
Table F.20 – OTHER TECHNICAL STANDBY category . 81
Table F.21 – LUBRICATION category . 82
Table F.22 – DE-ICING category . 82
Table F.23 – DRY OUT category . 83
Table F.24 – CABLE UNTWIST category . 83
Table F.25 – OTHER ENVIRONMENTAL category . 84
Table F.26 – CALM WINDS category . 84
Table F.27 – HIGH WIND category . 85
Table F.28 – TEMPERATURE category . 85
Table F.29 – OTHER REQUESTED SHUTDOWN category . 86
Table F.30 – ENVIRONMENTAL category . 87
Table F.31 – GRID – WPS OPERATOR category . 87

Table F.32 – GRID – TSO category . 88
Table F.33 – NOISE category . 89
Table F.34 – FLICKER category . 89
Table F.35 – WILDLIFE category . 90
Table F.36 – STRUCTURAL LOAD category . 91
Table F.37 – OTHER OUT OF ELECTRICAL SPECIFICATION category . 91
Table F.38 – FREQUENCY category . 92
Table F.39 – VOLTAGE LEVEL LOW category . 92
Table F.40 – VOLTAGE LEVEL HIGH category . 93
Table F.41 – ASYMMETRY category . 93
Table F.42 – SCHEDULED MAINTENANCE category . 94
Table F.43 – OTHER CORRECTIVE ACTION category . 94

Table F.44 – UPGRADE category . 95

Table F.45 – INSPECTIONS category . 95

Table F.46 – RETROFIT category . 96

Table F.47 – REPAIR WORK category . 96

Table F.48 – OTHER FORCED OUTAGE category . 97

Table F.49 – FAILURE REPAIR category . 98

Table F.50 – DIAGNOSTIC category . 98

Table F.51 – LOGISTIC WPS MAINTENANCE PROVIDER category . 99

Table F.52 – LOGISTIC WPS OPERATOR category . 100
Table F.53 – RESPONSE WPS MAINTENANCE PROVIDER category . 100
Table F.54 – RESPONSE WPS OPERATOR category . 101
Table F.55 – OTHER SUSPENDED – SCHEDULED MAINTENANCE category . 102
Table F.56 – PERSONNEL SAFETY – SCHEDULED MAINTENANCE category . 103
Table F.57 – ENVIRONMENT – SCHEDULED MAINTENANCE category . 104
Table F.58 – IT ACCESS – SCHEDULED MAINTENANCE category . 105
Table F.59 – OTHER SUSPENDED – PLANNED CORRECTIVE ACTION category . 106
Table F.60 – PERSONNEL SAFETY – PLANNED CORRECTIVE ACTION category . 107
Table F.61 – ENVIRONMENT – PLANNED CORRECTIVE ACTION category . 108
Table F.62 – IT ACCESS – PLANNED CORRECTIVE ACTION category . 109
Table F.63 – OTHER SUSPENDED – FORCED OUTAGE category . 110
Table F.64 – PERSONNEL SAFETY – FORCED OUTAGE category . 111
Table F.65 – ENVIRONMENT – FORCED OUTAGE category . 112
Table F.66 – IT ACCESS – FORCED OUTAGE category . 113
Table F.67 – INACTIVE RESERVE category . 114
Table F.68 – MOTHBALLED category . 115
Table F.69 – RETIRED category . 116
Table F.70 – FORCE MAJEURE category . 117
Table F.71 – INFORMATION UNAVAILABLE category . 117

– 8 – IEC TS 61400-26-3:2016 © IEC 2016

INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
WIND ENERGY GENERATION SYSTEMS –

Part 26-3: Availability for wind power stations

FOREWORD
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

The main task of IEC technical committees is to prepare International Standards. In
exceptional circumstances, a technical committee may propose the publication of a technical
specification when
• the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts, or
• the subject is still under technical development or where, for any other reason, there is the
future but no immediate possibility of an agreement on an International Standard.
Technical specifications are subject to review within three years of publication to decide
whether they can be transformed into International Standards.
IEC TS 61400-26-3, which is a technical specification, has been prepared by IEC technical
committee 88: Wind energy generation systems.

The text of this technical specification is based on the following documents:

Enquiry draft Report on voting

88/571/DTS 88/588/RVC
Full information on the voting for the approval of this technical specification can be found in

the report on voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

A list of all parts of the IEC 61400 series, under the general title Wind turbines (previous title),
and Wind energy generation systems (new title), can be found on the IEC website.
Future standards in this series will carry the new general title as cited above. Titles of existing
standards in this series will be updated at the time of the next edition.
Mandatory information categories defined in this Technical Specification are written in capital
letters; optional information categories defined are written in capital letters and bold letters.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• transformed into an International standard,
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
– 10 – IEC TS 61400-26-3:2016 © IEC 2016

INTRODUCTION
The intention of this Technical Specification is to define a common basis for exchange of

information on availability indicators between owners, utilities, lenders, operators,

manufacturers, consultants, regulatory bodies, certification bodies, insurance companies and

other stakeholders in the wind power generation business. From this diverse group of

stakeholders a number of external and internal interfaces arise in the operation and delivery

of power. Some of these are energy related and many are informational. Since the intention

is for a common basis of informational exchange, many of these interfaces are illustrated in

Figure 1, which identifies external and internal elements related to energy production and

asset management and which also benefit from a defined set of terms. This is achieved by

providing an information model specifying how time designations shall be split into information
categories. The information model forms the basis for how to allocate time for reporting
availability indicators.
IEC
Figure 1 – Data stakeholders for a wind power station
This Technical Specification defines generic terms of wind turbine systems and environmental
constraints in describing system and component availability, lifetime expectancy, repairs and
criteria for determining overhaul intervals. The specification defines terminology and generic
terms for reporting energy based generating unit availability measurement. A generating unit
includes all equipment up to the point of interconnection . Availability measurements are
concerned with fractions of time and/or energy a unit is capable of providing service, taking
environmental aspects into account. Environmental aspects will be wind and other weather
conditions, as well as grid and substation conditions. The specification furthermore defines
terminology and terms for reporting availability indicators based on energy production.
_______________
Defined in IEC 60050-415:1999, 415-04-01.

The project scope is accomplished by separating the technical specification into three parts:

1) IEC TS 61400-26-1, which specifies terms for time based availability of a wind turbine

generating system;
2) IEC TS 61400-26-2, which specifies terms for production based availability of a wind

turbine generating system;
3) IEC TS 61400-26-3, which specifies terms for time based and production based

availability and services of a wind power station.

IEC TS 61400-26-3 is based on the models developed in IEC TS 61400-26-1 and

IEC TS 61400-26-2.
– 12 – IEC TS 61400-26-3:2016 © IEC 2016

WIND ENERGY GENERATION SYSTEMS –

Part 26-3: Availability for wind power stations

1 Scope
This part of IEC 61400, which is a technical specification, provides a framework from which

time-based and production-based availability indicators of a wind power station can be
derived. It unambiguously describes how data is categorised and provides examples of how
the data can be used to derive availability indicators.
The approach is to apply the terms and definitions for the applied information models
introduced in IEC TS 61400-26-1 and IEC TS 61400-26-2 to a wind power station.
The basic approach is based on the assumption that a wind power station may be modelled
as one 'WTGS' representing a complete wind power station. The wind power station is made
up of all WTGSs, functional services and balance of plant elements as seen from the point of
common coupling.
It is not the intention of this specification to define how time-based and production-based
availability shall be calculated. Nor is it the intention to form the basis for power curve
performance measurements – which is the objective of IEC 61400-12. However, the annexes
should be regarded as examples and guidelines for developing methods for calculation of
availability indicators.
This document also includes informative annexes with:
• examples of how to expand the model to more services,
• examples of how to determine the information category for the wind power station,
• examples of how to expand the model to balance of plant elements,
• examples of determination of lost production,
• examples of availability algorithms for production based indicators,
• examples of other availability indicators,
• examples of application scenarios.

2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 60050 (all parts), International Electrotechnical Vocabulary (available at
IEC 60050-415, International Electrotechnical Vocabulary – Part 415 : Wind turbine generator
systems (available at IEC TS 61400-26-1:2011, Wind turbines – Part 26-1: Time-based availability for wind turbine
generating systems
IEC TS 61400-26-2:2014, Wind turbines – Part 26-2: Production-based availability for wind

turbines
3 Terms, definitions and abbreviations

3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC TS 61400-26-1,

IEC TS 61400-26-2 and IEC 60050-415 and the following apply.

3.1.1
actual service
actual level of a Service provided by the WPS as measured at the network connection point
Note 1 to entry: Actual service can only be assigned to measureable Services.
3.1.2
balance of plant
BOP
infrastructural components of the WPS with the exception of the WTGS(s) and its internal
components and subsystems
Note 1 to entry: The infrastructure normally consists of site electrical facilities, monitoring and control (often
called SC
...