oSIST prEN IEC 61400-16:2026

Wind energy generation systems - Part 16: Standard format for sharing power curves and associated information

Sistemi za proizvodnjo energije na veter - 16. del: Standardna oblika za izmenjavo krivulj moči in pripadajočih informacij

General Information

• Status: Not Published
• Public Enquiry End Date: 31-May-2026
• ICS: 27.180 - Wind turbine energy systems
• Technical Committee: IEHT - Electrotechnics - Hydraulic turbins
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 31-Mar-2026
• Due Date: 18-Aug-2026
• Ref Project: prEN IEC 61400-16:2026 - Wind energy generation systems - Part 16: Standard format for sharing power curves and associated information

Overview

oSIST prEN IEC 61400-16:2026 - Wind Energy Generation Systems - Part 16: Standard Format for Sharing Power Curves and Associated Information sets a unified, machine-readable standard for sharing wind turbine power curves and supporting data. Developed by the International Electrotechnical Commission (IEC) and maintained by CENELEC (CLC), this standard aims to streamline digital data exchange in the wind energy industry. By specifying content, terminology, and data structure, oSIST prEN IEC 61400-16:2026 makes sharing power curve data between wind turbine manufacturers (OEMs), developers, and stakeholders more efficient, reliable, and less error-prone.

Efficient and accurate sharing of wind turbine performance characteristics-especially power curves and associated parameters like thrust, noise emissions, and operational modes-is critical for energy production modeling, project development, and site suitability assessments. This standard moves the industry toward greater digitalization and enables improved automation and risk management.

Key Topics

• Standardized Data Format: Defines a common, JSON-based structure (Power Curve Schema) for exchanging wind turbine power curve data and associated information.
• Ease of Integration: Enables easier integration into energy modeling tools, digital workflows, and asset management systems by promoting machine-readability and consistency.
• Comprehensive Data Coverage: Includes document metadata, turbine model information, design basis, operating modes, power and thrust curves, and optional data (e.g., acoustic emissions).
• Flexibility: Accounts for different OEM practices, optional properties, and varying data requirements, while enabling both basic and complex power curve representations.
• Validation and Automation: Promotes automated data validation using JSON Schema, reducing human error and supporting robust data handling practices.
• Terminology and Structure: Ensures harmonized use of technical terms and data organization, supporting clarity and international compatibility.

Applications

The oSIST prEN IEC 61400-16:2026 standard delivers significant value to various wind energy stakeholders:

• Wind Turbine OEMs: Streamline internal processes and standardize external communications by providing power curves and associated data in a universally accepted, structured format. Accelerates time-to-market for new turbine models and supports local and global sales efforts.
• Project Developers & Planners: Improves the quality and speed of wind farm energy yield analysis, site assessments, and risk evaluation. Facilitates reliable comparison of different turbines and rapid financial close for new projects.
• Software Vendors and Data Analysts: Enables seamless integration of power curve datasets into digital tools for energy modeling, asset management, or reporting. Reduces manual data processing and fosters automated workflows.
• Consultants and Financial Stakeholders: Minimizes technical, commercial, and reputational risks by ensuring that project decisions are based on consistent, validated turbine performance data.
• Regulators and Certification Bodies: Supports regulatory compliance, certification reviews, and technical documentation by providing a clear, standardized framework for data submission and review.

Related Standards

• ISO/IEC 21778:2017: Specifies the JSON data interchange syntax used as the basis for the power curve data format in oSIST prEN IEC 61400-16:2026.
• EN IEC 61400-1:2019: Outlines general design requirements for wind energy generation systems, referenced for structural and environmental parameters.
• IEC 61400-12: Covers wind turbine power performance measurements, relevant for understanding the background and contextual use of power curve data.
• IEC Power Curve Schema: The JSON schema and associated resources are available to support implementation and validation.

Adoption of oSIST prEN IEC 61400-16:2026 promises to improve interoperability, enhance digital workflows, and support global best practices in wind energy project development and operations. This standard is an essential resource for any organization engaged with wind turbine performance data and its applications.

Standards Content (Sample)

SLOVENSKI STANDARD
01-maj-2026
Sistemi za proizvodnjo energije na veter - 16. del: Standardna oblika za izmenjavo
krivulj moči in pripadajočih informacij
Wind energy generation systems - Part 16: Standard format for sharing power curves
and associated information
Ta slovenski standard je istoveten z: prEN IEC 61400-16:2026
ICS:
27.180 Vetrne elektrarne Wind turbine energy systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

88/1161/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 61400-16 ED1
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2026-03-27 2026-06-19
SUPERSEDES DOCUMENTS:
88/1057/CD, 88/1149/CC
IEC TC 88 : WIND ENERGY GENERATION SYSTEMS
SECRETARIAT: SECRETARY:
Denmark Mrs Christine Weibøl Bertelsen
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):
ASPECTS CONCERNED:
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft for
Vote (CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.
This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of which they
are aware and to provide supporting documentation.
Recipients of this document are invited to submit, with their comments, notification of any relevant “In Some Countries”
clauses to be included should this proposal proceed. Recipients are reminded that the CDV stage is the final stage for
submitting ISC clauses. (SEE AC/22/2007 OR NEW GUIDANCE DOC).
TITLE:
Wind energy generation systems – Part 16: Standard format for sharing power curves and associated
information.
PROPOSED STABILITY DATE: 2028
NOTE FROM TC/SC OFFICERS:
There was a mistake on the URL in clause 5. The schema (with associated examples, tests and resources) is available on GitHub at
https://github.com/IEC-61400/power-curve-schema”
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IEC CDV 61400-16 ED1 © IEC 2026 88/1161/CDV

CONTENTS
CONTENTS . 1
FOREWORD . 3
Introduction. 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
3.1 Defined terms . 7
3.2 Abbreviations . 12
4 The Power Curve Schema . 12
4.1 Overview . 12
4.2 Other considerations . 13
4.2.1 Units . 13
4.2.2 Casing . 13
4.2.3 Normalisation . 13
4.2.4 Arrays . 14
4.2.5 Required values. 14
4.3 The "document" property. 14
4.3.1 Purpose . 14
4.3.2 Contents . 14
4.3.3 Example of the "document" property . 15
4.3.4 Special considerations . 15
4.4 The "turbine" property . 15
4.4.1 Purpose . 15
4.4.2 Contents . 15
4.4.3 Example of the "turbine" property . 18
4.5 The "design_bases" property . 19
4.5.1 Purpose . 19
4.5.2 Contents . 19
4.5.3 Examples of the "design_bases" property . 24
4.6 The "power_curves" property . 26
4.6.1 Scope . 26
4.6.2 Purpose . 26
4.6.3 Contents . 27
4.6.4 Example of the "power_curves" property . 33
4.7 The "additional" property . 33
4.7.1 Purpose . 33
4.7.2 Contents . 34
4.7.3 Example of the "additional" property . 34
5 Schema publication and change management . 34
Annex A (informative) Background to power curves and associated information . 36
Annex B (informative) Creation of JSON documents . 37
Bibliography . 38

Table 1 – Document sub-properties . 14
Table 2 – Turbine sub-properties . 16
IEC CDV 61400-16 ED1 © IEC 2026 88/1161/CDV

Table 3 – Sub-properties for "turbine" > "thermal_regulation" . 17
Table 4 – Sub-properties for "turbine" > "thermal_regulation" > "cold" . 17
Table 5 – Sub-properties for "turbine" > "thermal_regulation" > "hot" . 17
Table 6 – Sub-properties for "turbine" > "thermal_regulation" > "derating" . 17
Table 7 – Sub-properties of items within design_bases . 19
Table 8 – Certification details . 20
Table 9 – IEC design class details (standard classes) . 20
Table 10 – Design class details (classes additional parameters) . 21
Table 11 – Sub-properties for standard turbulence categories. 21
Table 12 – Sub-properties for 1D Normal and Extreme Turbulence Models . 22
Table 13 – Sub-properties for 2D Normal and Extreme Turbulence Models . 23
Table 14 – Sub-properties for each "climate" property . 24
Table 15 – Sub-properties for "power_curves" . 27
Table 16 – Properties of each Operating mode . 27
Table 17 – Properties of each object in the cuts array . 28
Table 18 – Properties of each object in the parameters array . 29
Table 19 – Properties of acoustic emissions . 30
Table 20 – Properties of `overrides` . 32
Table 21 – Properties of "wind_speed_reference" . 32
Table 22 – Additional sub properties . 34

IEC CDV 61400-16 ED1 © IEC 2026 88/1161/CDV

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Wind energy generation systems –
Part 16: Standard format for sharing power curves and associated
information.
FOREWORD
a) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical
Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt
with may participate in this preparatory work. International, governmental and non-governmental organizations
liaising with the IEC also participate in this preparation. IEC collaborates closely with the International
Organization for Standardization (ISO) in accordance with conditions determined by agreement between the two
organizations.
b) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
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any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
e) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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services carried out by independent certification bodies.
f) All users should ensure that they have the latest edition of this publication.
g) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
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h) 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.
i) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC has no notice of (a) patent(s), which may be
required to implement this document. However, implementers are cautioned that this may not represent the latest
information, which may be obtained from the patent database available at https://patents.iec.ch and/or
www.iso.org/patents . IEC shall not be held responsible for identifying any or all such patent
rights.
IEC 61400-16 was prepared by IEC technical committee 88: Wind energy generation systems.
It is an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
IEC CDV 61400-16 ED1 © IEC 2026 88/1161/CDV

The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs . The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications .
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IEC CDV 61400-16 ED1 © IEC 2026 88/1161/CDV

Introduction
Wind turbine power curves and associated information (3.1.17) (thrust curves, acoustic
emissions, turbine model characteristics (3.1.25) , design bases and operating modes) are
necessary for the accurate and efficient modelling of energy production, environmental impact,
and turbine suitability. To facilitate adoption of the standard, data other than basic power curve
(3.1.16) information is considered optional.
Prior to this standard, power curve (3.1.16) information was communicated in many different
ways with varying degrees of completeness. Often the necessary information was spread
across multiple documents requiring human interaction and error-prone manual transcription.
Furthermore, power curves were becoming more complex with different operating modes,
ranges of air density (3.1.2) and turbulence intensity (3.1.26) , thermal de-rates, thrust settings,
and more. The growing complexity and lack of automation made data management quite
challenging.
This standard is intended to enable progress toward digitalisation, especially seamless data
interchange, to enable improved:
– time-to-market for new wind turbine sales (e.g. by accelerating turnaround for OEMs’ local
sales teams),
– time-to-financial-close for new wind farms,
– automation and workflow between internal and external teams, and
– management of technical, commercial and reputational risk (e.g. from human error in Energy
Yield Analysis and other processes).
IEC CDV 61400-16 ED1 © IEC 2026 88/1161/CDV

1 Scope
The Scope of the IEC 61400-16 standard is to establish a common content, terminology and
structure applicable to all wind turbine OEMs for the sharing of wind turbine power curves and
associated information (3.1.17) (for background, see Annex A) in a machine-readable format.
Throughout the remainder of this document, this common structure is defined by a Power Curve
Schema. A JSONSchema (3.1.11) defines how to structure and populate a specific JSON
(3.1.10) document (for more detail, see Annex B), and can be used for automated data
validation.
The power curves and associated information (3.1.17) communicated within a JSON (3.1.10)
document (which is compliant with the Power Curve Schema) covers:
– Document metadata
– The turbine model characteristics (3.1.25)
– Design basis information
– Operating mode information, where each mode contains
• Power (as a function of wind speed and optionally other parameters)
• Thrust (as a function of wind speed and optionally other parameters)
• Optional acoustic emissions (as a function of wind speed and other parameters)
– Power de-rating details
JSON documents containing power curves and associated information shall be based on the
JavaScript Object Notation ("JSON") format ISO/IEC 21778:2017 and shall follow the
specifications in this document (i.e. conform to the Power Curve Schema).
Security, document integrity (e.g. digital signing) and distribution of data rests with the authors
and users of the data and is outside the scope of the standard.
Measured power curves can be represented using the Power Curve Schema but details relating
to the measurement configuration, statistics of the measurement results and other details
specific to power performance measurements cannot be captured.
This standard does not specify document generation, display, checking or publishing processes
which may be achieved using third party or custom tools (e.g. automated PDF report generation
from the JSON data).
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.
ISO/IEC 21778:2017, Information technology - The JSON data interchange syntax
EN IEC 61400-1:2019, Wind energy generation systems - Part 1: Design requirements
3 Terms and definitions
The Terms and definitions clause is a mandatory element of the text.
For rules on the drafting of the Terms and definitions, refer to the ISO/IEC Directives, Part
2:2018, Clause 16 .
IEC CDV 61400-16 ED1 © IEC 2026 88/1161/CDV

To insert a new terminological entry, go to the Structure tab and click on Insert Term entry .
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1 Defined terms
3.1.1
acoustic emission
sound power emitted by a wind turbine at source, described as a function of frequency and/or
wind speed for a specific turbine operating mode
Note 1 to entry: Typically, the frequency data are provided as one-third octave bands.
Note 2 to entry: Typically, wind speed data are provided with respect to hub height or a 10 m reference height.
3.1.2
air density
the mass of air molecules within a given volume, measured in kilograms per cubic meter
3.1.3
application programming interface
or API, is a set of rules allowing software applications to communicate with other software
applications
3.1.4
available hub heights
selection or range of hub heights at which the turbine may be constructed
3.1.5
Bulk Richardson Number (BRN)
a dimensionless ratio in meteorology related to the dissipation of turbulence divided by the
shear production (the generation of turbulence kinetic energy caused by wind shear) of
turbulence.
Note 1 to entry: Bulk Richardson Number is an approximation of the Gradient Richardson number.
Note 2 to entry: High values indicate unstable and/or weakly-sheared environments; low values indicate weak
instability and/or strong vertical shear.
3.1.6
characteristic turbulence intensity
Value of turbulence intensity I15 as defined in IEC61400-1 Ed2.
Note 1 to entry: This value, I , is used in IEC61400-1 Ed 2 and should not be mistaken for the reference turbulence
intensity (3.1.19), I used in IEC61400-1 Eds. 3 and 4.
ref,
3.1.7
cut
condition under which a wind turbine is switched on or off when wind speed exceeds or falls
below a specified threshold, based on a specified averaging time period
IEC CDV 61400-16 ED1 © IEC 2026 88/1161/CDV

3.1.7.1
low-cut-in
type of cut representing the transition from not generating to generating, as wind speed
increases from below the cut threshold
3.1.7.2
low-cut-out
type of cut representing the transition from generating to not generating, as wind speed
decreases from above the cut threshold
3.1.7.3
high-cut-out
type of cut representing the transition from generating to not generating, as wind speed
increases from below the cut threshold
3.1.7.4
high-cut-in
type of cut representing the transition from not generating to generating, as wind speed
decreases from above the cut threshold
3.1.8
design basis
the specific criteria against which a wind turbine has been designed for safe operation, including
permissible environmental conditions and operational ranges
Note 1 to entry: The plural form, design bases, is used extensively in the schema.
3.1.9
hub height
height of the centre of the wind turbine rotor above the terrain surface
Note 1 to entry: For a vertical axis wind turbine the hub height is the height of the equator plane.
Note 2 to entry: For an offshore wind turbine hub height is referenced to mean sea level
[SOURCE: IEC60050 415-05-06, modified note 2 has been added]
3.1.10
JSON
shorthand for JavaScript Object Notation, an open and widely used syntactic framework for data
interchange and storage, as defined by ISO/IEC 21778:2017
3.1.10.1
JSON key
string enclosed in quotation marks which is the name of the variable to which a value will then
be assigned within the JSON data-interchange format
[SOURCE: ISO/IEC 21778:2017]
3.1.10.2
JSON property
in the context of JSON, a property is a key-value pair in an object, binding the value to the key
3.1.10.3
JSON value
string, number, boolean expression, array or object value within the JSON data-interchange
format
[SOURCE: ISO/IEC 21778:2017]
IEC CDV 61400-16 ED1 © IEC 2026 88/1161/CDV

3.1.11
JSON Schema
declarative language for annotating and validating JSON documents' structure, constraints, and
data types
[SOURCE: https://json-schema.org/draft/2020-12]
3.1.12
metadata
set of data that describes and gives information about other data
3.1.13
Monin-Obukhov stability
a dimensionless variable used to describe the stability of the atmospheric boundary layer
3.1.14
inverse Monin-Obukhov length
inverse of the height at which turbulence is generated more by buoyancy than by wind shear
[m^-1]
3.1.15
operating mode
configuration of the turbine control system for an operational strategy that is designed to
achieve a specific outcome (e.g. restricting the noise emission to a certain value, or setting the
rated power to a higher or lower value than defined in turbine property 4.4 )
Note 1 to entry: See also Table 15 for definition of a "default operating mode".
3.1.16
power curve
tabular representation of the electrical power output of a wind turbine, typically presented as a
function of air density and wind speed
3.1.17
power curves and associated information
group of data comprising (principally) a power curve, but including closely associated
information such as thrust, acoustic emissions and other contextual data related to the power
curve
3.1.18
power curve parameters
parameters against which values of power and thrust are tabulated
Note 1 to entry: Each given parameter represents a dimension of the power curve (although the dimension may be
singleton).
Note 2 to entry: Parameters can be given as single values (representing a singleton dimension), ranges
(representing a singleton dimension in the power curve valid in that range), value lists (corresponding to non-
singleton dimensions in the tabulated power curve) and range lists (each list item representing a validity range, or
'bin')
3.1.18.1
air-density parameter
value of air density (3.1.2) for which a power curve is tabulated
3.1.18.2
bulk-richardson-number parameter
value of the Bulk Richardson Number (BRN) (3.1.5) at the turbine location for which a power
curve is tabulated
IEC CDV 61400-16 ED1 © IEC 2026 88/1161/CDV

3.1.18.3
turbulence-intensity parameter
value of turbulence intensity (3.1.26) at hub height for which a power curve is tabulated
3.1.18.4
turbulence-lengthscale parameter
value of turbulence lengthscale (3.1.23) at hub height for which a power curve is tabulated
3.1.18.5
reference-turbulence-intensity parameter
value, range, or values of reference turbulence intensity (3.1.19) at the turbine location for
which a power curve is tabulated
Note 1 to entry: The IEC 61400-1 standard gives the Normal Turbulence Model, relating Turbulence Intensity I to
the reference value I where I = I * (0.75*V +5.6)/V . Since turbulence intensity drops considerably as a
ref ref hub hub
function of speed (like a 1/x curve), the reference turbulence intensity can be a useful value for interpreting the site
turbulence across a wide range of wind speeds - in essence, I is a measure of turbulence which is somewhat
ref
independent of wind speed. Thus, I may be more useful than the turbulence-intensity parameter (3.1.18.3) in simply
ref
characterising performance in broader buckets of low, medium, high turbulence, without the complexity of determining
power and thrust performance for the extreme wide range of raw turbulence intensity values at a site.
3.1.18.6
vertical-shear-exponent parameter
value, range, or values of vertical shear exponent (3.1.27) at the turbine location for which a
power curve is tabulated
3.1.18.7
wind-speed parameter
value of wind speed (3.1.28) at hub height for which a power curve is tabulated
3.1.18.8
wind-veer parameter
value, range, or values of wind veer (3.1.29) at hub height for which a power curve is tabulated
Note 1 to entry: Wind veer at hub height may be approximated by the change in wind direction between the max
and min blade tip height locations, divided by the rotor diameter.
3.1.18.9
monin-obukhov-stability parameter
value of Monin-Obukhov stability parameter (3.1.13) at the turbine location for which a power
curve is tabulated
3.1.18.10
inverse-monin-obukhov-length parameter
value of inverse Monin-Obukhov length (3.1.14) at the turbine location for which a power curve
is tabulated
3.1.19
reference turbulence intensity
reference value of turbulence intensity I corresponding to the 70th quantile at 15m/s wind
ref
speed at hub height
Note 1 to entry: As defined in IEC61400-1
3.1.20
rotor speed
rotational speed of a wind turbine rotor about its axis
[SOURCE: IEC 60050 415-01-18]
IEC CDV 61400-16 ED1 © IEC 2026 88/1161/CDV

3.1.21
sound power level
a measure of the strength of acoustic emissions in decibels (dB)
3.1.22
temperature derating
tabular representation of the conditions under which the maximum power output of the turbine
is restricted
Note 1 to entry: Maximum power can be a function of a combination of some or all of temperature, altitude, air
density or wind speed
3.1.23
turbulence lengthscale
a characteristic length [m] associated with the peak of the streamwise velocity spectrum,
representing the energy-containing sub-range of turbulent velocity fluctuations
3.1.24
thrust curve
tabular representation of the thrust coefficient or thrust force of a wind turbine as a function of
parameters such as air density and wind speed
3.1.25
turbine model characteristics
information describing the main features of a turbine model, including its rotor diameter, rated
power, model name, manufacturer name, etc.
3.1.26
turbulence intensity
ratio of wind speed standard deviation to the mean wind speed, determined from the same set
of measured data samples of wind speed, and taken over a specific period of time
Note 1 to entry: Where numeric values are given, turbulence intensity is expressed as a factor in the range 0,1
rather than a percentage.
Note 2 to entry: In the context of wind turbines, the turbulence intensity is specified over a 10-minute averaging
period.
[SOURCE: IEC 60050 415-03-25, modified - Note 1 has been added.]
3.1.27
vertical shear exponent
exponent of a power law often used to describe the shape of a vertical wind profile
Note 1 to entry: Modified the term 'shear exponent' to clarify that the vertical component is used.
[SOURCE: IEC 60050 415-03-18]
3.1.28
wind speed
free-stream wind speed [m/s]
Note 1 to entry: Definition of free-stream wind speed is according to IEC 61400-12.
3.1.29
wind veer
rate of change of wind direction with height [degrees/m], which may vary in time and location
(positive clockwise about the vertical axis, independent of hemisphere)
IEC CDV 61400-16 ED1 © IEC 2026 88/1161/CDV

3.2 Abbreviations
3.2.1
API
application programming interface
3.2.2
CC
term representing cold climate conditions found in IEC 61400-1:2019 [1] design requirements
3.2.3
OEM
original equipment manufacturer
3.2.4
S
term representing special IEC wind turbine class found in IEC 61400-1:2019 [1] design
requirements
3.2.5
T
term representing a design class for areas subject to tropical cyclones found inIEC 61400-
1:2019 [1] design requirements
3.2.6
TI
turbulence intensity
4 The Power Curve Schema
4.1 Overview
The Power Curve Schema defines the data structure and semantics of machine-readable
documents for interchange of power curves and associated information.
Documents for interchange of power curves and associated data shall use JSON, and shall
validate against any Power Curve Schema in the version range >=1.0.0, <2.0.0 (see Clause 5).
Specifics of data interchange protocol are outside the scope of this document: typically, a form
trivially convertible to JSON will be used in transmission (e.g. Binary JSON or other compressed
format). Where necessary, the form and conversion requirements shall be specified.
The Schema divides data into four main areas (or "properties", in JSON terminology):
– The "document" property contains information related to the document itself such as author,
identifiers, provenance, etc.
– The "turbine" property contains information related to the physical turbine hardware such as
rotor size, available hub heights, etc.
– The optional "design_bases" property contains information related to the environmental
conditions and certification pertaining to the power curves.
___________
This standard does not impose any requirement on the structure or format in which data is stored or otherwise
used (e.g. by an organisation or application).
The Power Curve Schema uses JSON Schema (3.1.11) draft 2020-12.
IEC CDV 61400-16 ED1 © IEC 2026 88/1161/CDV

– The "power_curves" property contains specification of the set of operational modes
available for the turbine. Each mode data object contains metadata (e.g. the name and
purpose of the mode) and associated power, thrust and optional acoustic emission curves.
– The optional "additional" property contains extra or manufacturer-specific data.
The standard recognizes that individual OEMs may have different ways of differentiating
between power curves and their associated thrust curves. The Schema has been designed to
provide flexibility to accommodate variations in practice across all major turbine OEMs.
A document compliant with the Power Curve Schema shall be structured as follows:
{
"document": {
// See examples of the "document" property in clause 4.3.3  },
"turbine": {
// See examples of the "turbine" property in clause 4.4.3  },
"design_bases": [
// Optional. See examples of "design_bases" property items in clause 4.5.3  ],
"power_curves": {
// See examples of the "power_curves" property in clause 4.6.4  },
"additional": {
// Optional. See examples of "additional" property in clause 4.7.3
}
4.2 Other considerations
4.2.1 Units
Where dimensional quantities are required, values shall always be given in their basic SI units,
e.g. power in Watts, and force in Newtons, except where explicitly stated.
This is an intentional choice to avoid ambiguity and eliminate likelihood of conversion errors. It
is appreciated that units are often selected for presentational purposes in power curve (3.1.16)
documents. For example, power as 12600 kW is easier to read than 12600000W. However, this
standard addresses data interchange, not presentation. There are many ways (e.g. web
applications, automated reporting, dashboards) that this data can be presented and such visual
choices should be made at the presentational layer.
Where human-readability (or size) of the raw JSON data is of concern, scientific notation may
be used for serialisation of data to text. For example, 12.6E+06 represents 12600000 in a way
that is both human-readable and unambiguous.
4.2.2 Casing
There are different casing conventions for variable naming in computer science, such as
"snake_case" (lower case words separated with underscores), "camelCase" (word breaks
indicated by capitalization), "compressedcase" (word breaks removed) and others.
Data conforming to the Power Curve Schema shall be defined using "snake_case" for property
naming throughout. The schema is designed to enforce this convention.
4.2.3 Normalisation
Data normalisation refers to the structure in which data is recorded - i.e. 'flat' data records that
may refer to one another via an identifier, versus 'nested' data records which contain other
records instead of referring to them.
The choice of whether to store 'normalised' versus 'denormalised' data depends on
considerations outside of the scope of this standard (such as access patterns and
searchability). The data structure adopted here is a pragmatic compromise of both. In particular:
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– each mode refers to one or more entries in the "design_bases" property (a normalised
pattern) to prevent many repeats of the same data item; and
– each mode may contain overrides of elements from the turbine property (a denormalised
pattern), since mode-specific overrides are rare and it was felt advantageous to have a
single definition of the top level turbine model data to avoid the confusion of multiple
definitions.
4.2.4 Arrays
Where properties or sub-properties contain arrays, the notation [idx] is used throughout the
standard to indicate an item in that array, particularly in clause titles. For example,
"power_curves" > "operating_modes[idx]" refers to an item in the operating_modes, since
"power_curves" > "operating_modes" is of type array.
4.2.5 Required values
To facilitate adoption of the standard, a number of properties (e.g. `design_bases`) are optional,
to account for situations where only basic power curve information is provided.
For subproperties of optional objects, the 'required' value given in table headers determines
whether subproperties are required given the presence of all parent objects.
4.3 The "document" property
4.3.1 Purpose
The purpose of the document property is to facilitate search, identification, audit, and other
workflows associated with data and document management. Additional notes and contextual
information may be included.
4.3.2 Contents
Table 1 – Document sub-properties
Sub- Description Type Required
property
metadata A list of metadata items according to the Dublin Core Metadata Initiative array[object] yes
(DCMI) elements/1.1. See
https://www.dublincore.org/specifications/dublin-core/dcmi-
terms/#section-3 for detailed information on each element.
4.3.2.1 The "document" > "metadata" property
The metadata property allows the publisher to include metadata that facilitate search,
identification and audit, or provide additional notes and contextual information.
A system of labelling documents with metadata is already well established by the Dublin Core
Metadata Initiative (DCMI) (https://www.dublincore.org/specifications/dublin-core/dcmi-terms/).
The DCMI specifies a set of 'terms', which are kinds of metadata that may be applied to online
documents. Each term conveys a particular meaning about what an item of metadata is for (e.g.
'abstract', 'created' and 'identifier'). The metadata property shall comprise a list of those items,
where each item consists of a `term_name` (the name of the DCMI term conveying purpose)
and the corresponding `value` of that item.
See also the special considerations in 4.3.4.
4.3.2.2 Other properties
The document property contains no sub-properties other than metadata; however, future
revisions of the standard may introduce additional properties at this level.
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4.3.3 Example of the "document" property
{
"metadata": [
{
"term_name": "identifier",
"value": "126b9e41-722f-49ab-9586-b55188adf420"
},
{
"term_name": "format",
"value": "IEC61400-16-1"
},
{
"term_name": "source",
"value": "https://your-documents.your-domain.com/Doc12345Rev01.pdf"
}
]
}
4.3.4 Special considerations
At least one `identifier` term shall be added. The first such term shall contain a globally unique
identifier for this document (i.e. two documents shall never exist with the same global identifier
but different contents). For example, this may comprise a generated universally unique
identifier, or may comprise a more human-readable value (so long as it is guaranteed to be
globally unique, e.g. by namespacing to a manufacturer) encapsulating document and revision
ID.
The `source` term (or multiples of it) shall be used to reference the source material(s) or
document(s), for example a manufacturer-issued PDF. Whilst not required, it is recommended
that this reference be a URI to the original document (which may be hosted behind a
permissions system) rather than containing simply a document number.
A `format` term shall be added containing the value `IEC61400-16`. This allows readers to
determine the nature of the document containing a power curve as per this standard.
A `type` term shall be added containing the value `Dataset`. This indicates that the contents of
the document comprise "Data encoded in a defined structure" according to the DCMI Type
Vocabulary https://www.dublincore.org/specifications/dublin-core/dcmi-type-vocabulary/
The background rationale for these considerations is discussed in detail at
https://github.com/octue/power-curve-schema/issues/18.
4.4 The "turbine" property
4.4.1 Purpose
The purpose of the turbine property is to provide top-level information about the turbine model
characteristics (3.1.25).
The turbine property contains data applicable across all operating modes, with the exception
that some operating modes may override certain values (e.g. some operating modes may have
a different rated power or be applicable only to a subset of the available hub heights). See
mode-specific overrides in 4.6.3.1.6 and comments on data normalisation in 4.2.3 for more
details.
4.4.2 Contents
Each sub-property is described in the following table and through examples of associated JSON
content. Properties labelled as required shall be populated. Properties not labelled as required
may be included if available and inclusion is encouraged for completeness.
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Table 2 – Turbine sub-properties
Sub-property Description Type Required
manufacturer_name Full name of the manufacturer (e.g. a legal entity) string yes
manufacturer_display_name Shortened or informal name of the manufacturer (for string yes
display purposes). See also manufacturer_name.
model_name Name of the turbine model as stated on certification string yes
documents
model_description General description about the turbine model, e.g. for string yes
giving a brief overview in a turbine selection tool.
platform_name Optional name of the platform on which this turbine string optional
model is based
platform_description Optional general description of the platform on string optional
which this turbine model is based.
rotor_diameter Nominal rotor diameter of the turbine [m] number yes
rotor_tilt Shaft angle relative to horizontal used for number optional
calculation of inflow losses [degrees]
number_of_blades Number of blades (typically 3, occasionally 2) number yes
rated_power Nominal rated power of the turbine in W. Used for number yes
preliminary sizing and search. This value may be
overridden on a per-mode basis (see section
4.6.3.1.6).
cut_in_rpm Nominal rotational speed at cut-in (specify 0 for number optional
stall-regulated devices) [RPM]. This value may be
overridden on a
...