IEC 61400-27-1:2015

Wind turbines - Part 27-1: Electrical simulation models - Wind turbines

IEC 61400-27-1:2015 specifies dynamic simulation models for generic wind turbine topologies/concepts/configurations on the market. It defines the generic terms and parameters with the purpose of specifying the electrical characteristics of a wind turbine at the connection terminals. The models are described in a modular way which can be applied for future wind turbine concepts. The dynamic simulation models refer to the wind turbine terminals. The validation procedure specified in IEC 61400-27-1 focuses on the IEC 61400-21 tests for response to voltage dips, reference point changes and grid protection.

Eoliennes - Partie 27-1: Modèles de simulation électrique - Eoliennes

L'IEC 61400-27-1:2015 spécifie des modèles de simulation dynamiques pour les topologies/concepts/configurations génériques d'éoliennes disponibles sur le marché. Elle définit les termes et paramètres génériques ayant pour objet de spécifier les caractéristiques électriques d'une éolienne au niveau des bornes de connexion. Les modèles sont décrits de manière modulaire et peuvent être appliqués aux futurs concepts d'éoliennes. Les modèles de simulation dynamiques se rapportent aux bornes de l'éolienne. La procédure de validation spécifiée dans l'IEC 61400-27-1 se concentre sur les essais de l'IEC 61400-21 pour la réponse aux creux de tension, les variations de la valeur de consigne et la protection du réseau.

General Information

• Status: Published
• Publication Date: 12-Feb-2015
• ICS: 27.180 - Wind turbine energy systems
• Technical Committee: TC 88 - Wind energy generation systems
• Drafting Committee: WG 27 - TC 88/WG 27
• Current Stage: DELPUB - Deleted Publication
• Start Date: 30-Jul-2020
• Completion Date: 26-Oct-2025

Relations

• Revised: IEC 61400-27-1:2020 - Wind energy generation systems - Part 27-1: Electrical simulation models - Generic models
• Effective Date: 05-Sep-2023

Overview

IEC 61400-27-1:2015 is an international standard published by the International Electrotechnical Commission (IEC) that defines electrical simulation models for wind turbines. This part 27-1 of IEC 61400 focuses on dynamic simulation models for a variety of generic wind turbine topologies and configurations available on the market. It establishes consistent generic terms and parameters to specify the electrical characteristics of wind turbines at their connection terminals. The standard employs a modular model structure designed to be adaptable and applicable to future wind turbine concepts, ensuring long-term relevance amid evolving technologies.

A key aspect of IEC 61400-27-1 is its validation procedure, which aligns with the test protocols specified in IEC 61400-21. These tests include wind turbine responses to grid voltage dips, reference point variations, and grid protection mechanisms to ensure reliable operation within electrical power systems.

Key Topics

• Dynamic Simulation Models
  Detailed dynamic models covering electrical and mechanical behavior of wind turbines, structured in modular components for ease of integration and future updates.

• Generic Wind Turbine Topologies
  Models address four main wind turbine types (Types 1 to 4), representing common configurations found in the industry:

  • Type 1: Fixed-speed, squirrel-cage induction generator
  • Type 2: Variable slip with rotor-side converters
  • Type 3: Doubly-fed induction generator (DFIG)
  • Type 4: Full converter-based turbines

• Modular Model Structure
  The standard specifies generic modular building blocks including aerodynamic models, mechanical drive train models, electrical generator sets, control systems, and protection devices.

• Model Interfaces and Parameters
  Uniform interfaces allow models to connect to grid simulations and wind power plant controllers. The standard defines parameter categories and initialization methods for accurate simulation alignment.

• Validation Procedures
  Specifies test methods for validating simulation model accuracy through:

  • Voltage dip response tests
  • Reference point change scenarios
  • Grid protection response tests

• Software Integration
  Guidelines for software interfaces facilitate model implementation across diverse simulation platforms for interoperability.

Applications

IEC 61400-27-1:2015 serves as a foundational reference for a variety of practical industry applications, including:

• Wind Turbine Design and Development
  Developers and manufacturers use validated dynamic models to analyze electrical behavior during transient events and optimize control strategies.

• Grid Integration Studies
  Power system engineers simulate wind turbine interaction with the electrical grid, evaluating grid stability, fault ride-through capabilities, and protection coordination.

• Wind Power Plant Modeling
  Aggregated turbine models support plant-level dynamic simulations for system planning, forecasting, and operational reliability assessments.

• Compliance and Certification Testing
  Testing bodies and certification authorities employ the standardized simulation models to verify turbine compliance with electrical performance requirements.

• Research and Educational Tools
  Academics and researchers utilize these generic models to study wind turbine dynamics, control system innovations, and grid code compliance, facilitating academic and industrial knowledge dissemination.

Related Standards

• IEC 61400-1: Wind Turbines – Part 1: Design Requirements – providing the fundamental mechanical and structural design standards for wind turbines.

• IEC 61400-21: Wind Turbines – Part 21: Measurement and Assessment of Power Quality Characteristics – specifying power quality tests, referenced for validation in IEC 61400-27-1.

• IEC 61400-27-2: Wind Turbines – Part 27-2: Electrical Simulation Models – Wind Power Plants – extending model definitions from individual turbines to plant-level aggregation.

• IEEE and CIGRE Grid Stability Standards: Providing supplementary terminology and stability classifications that complement model validation approaches.

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Keywords: IEC 61400-27-1, wind turbine simulation models, electrical characteristics, dynamic models, wind turbine topologies, grid integration, wind power plant models, voltage dip response, grid protection, modular modeling, wind turbine control, IEC standards, power system stability.

Standards Content (Sample)

IEC 61400-27-1 ®
Edition 1.0 2015-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Wind turbines –
Part 27-1: Electrical simulation models – Wind turbines

Eoliennes –
Partie 27-1: Modèles de simulation électrique – Eoliennes

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IEC 61400-27-1 ®
Edition 1.0 2015-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Wind turbines –
Part 27-1: Electrical simulation models – Wind turbines

Eoliennes –
Partie 27-1: Modèles de simulation électrique – Eoliennes

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.180 ISBN 978-2-8322-2226-3

– 2 – IEC 61400-27-1:2015  IEC 2015
CONTENTS
FOREWORD . 7
INTRODUCTION . 9
1 Scope . 12
2 Normative references . 12
3 Terms, definitions, abbreviations and subscripts . 12
3.1 Terms and definitions . 12
3.2 Abbreviations and subscripts . 17
3.2.1 Abbreviations . 17
3.2.2 Subscripts . 18
4 Symbols and units . 19
4.1 General . 19
4.2 Symbols (units) . 19
5 Specification of models . 21
5.1 Overview. 21
5.2 General specifications . 21
5.3 Model interface . 23
5.4 Parameters and initialisation . 24
5.4.1 General . 24
5.4.2 Parameter categories . 24
5.4.3 Global parameters . 24
5.4.4 Initialisation . 24
5.5 Modular structure of models . 25
5.5.1 Generic modular structure . 25
5.5.2 Type 1 . 26
5.5.3 Type 2 . 28
5.5.4 Type 3 . 30
5.5.5 Type 4 . 33
5.6 Module library . 37
5.6.1 Aerodynamic models . 37
5.6.2 Mechanical models . 38
5.6.3 Generator set models . 39
5.6.4 Electrical equipment . 44
5.6.5 Control models . 44
5.6.6 Grid protection model . 55
6 Specification of validation procedure . 57
6.1 Overview. 57
6.2 General specifications . 58
6.3 Validation procedure . 59
6.3.1 Voltage dips . 59
6.3.2 Reference point changes . 64
6.3.3 Grid protection . 64
Annex A (informative) Validation test documentation. 66
A.1 General . 66
A.2 Simulation model and validation setup information . 66
A.3 Template for validation test results . 66

A.3.1 General . 66
A.3.2 Voltage dips . 67
A.3.3 Reference point changes . 67
A.3.4 Grid protection . 68
Annex B (normative) Limits to possible model accuracy . 69
B.1 General . 69
B.2 Inevitable simulation errors . 69
B.3 Measurement errors . 69
nd
Annex C (normative) Digital 2 order critically damped low pass filter . 71
Annex D (informative) Simplified plant level model . 72
D.1 General . 72
D.2 Area of application . 72
D.3 Voltage and reactive power controller model description . 72
D.4 Frequency and active power controller model description. 74
Annex E (informative) Two-dimensional aerodynamic model . 76
E.1 Objective . 76
E.2 Model approach . 76
E.3 Model parameter fits . 77
E.4 Use cases . 80
E.4.1 General . 80
E.4.2 Stability study use cases . 80
E.4.3 Validation use cases . 80
E.5 Model initialisation at derated conditions . 80
Annex F (informative) Generic Software Interface for use of models in different
software environments . 81
F.1 Description of the approach . 81
F.2 Description of the Software interface . 82
F.2.1 Description of data structures . 82
F.2.2 Functions for communication through the ESE-interface . 83
F.2.3 Inputs, Outputs, Parameters . 85
Annex G (normative) Block symbol library . 86
G.1 General . 86
G.2 Time step delay . 86
G.3 Stand-alone ramp rate limiter . 86
G.4 First order filter with absolute limits, rate limits and freeze flag . 87
G.5 Lookup table . 88
G.6 Comparator . 88
G.7 Timer . 88
G.8 Anti windup integrator . 89
G.9 Integrator with reset . 90
G.10 First order filter with limitation detection . 90
G.11 Delay flag . 91
G.12 Raising edge detection . 91
Bibliography . 93

Figure 1 – Classification of power system stability according to IEEE/CIGRE Joint Task
Force on Stability Terms and Definitions . 9
Figure 2 – Example of step response. . 15

– 4 – IEC 61400-27-1:2015  IEC 2015
Figure 3 – General interface between WT model, grid model and WP model . 23
Figure 4 – General interface for initialisation of WT model, WP model and grid model. . 25
Figure 5 – Generic modular structure of WT models. 26
Figure 6 – Main electrical and mechanical components of type 1 WTs . 26
Figure 7 – Modular structure for the type 1A WT model. 27
Figure 8 – Modular structure for the type 1B WT model. 28
Figure 9 – Main electrical and mechanical components of type 2 WTs . 29
Figure 10 – Modular structure for the type 2 WT model . 29
Figure 11 – Modular structure for the type 2 control model . 30
Figure 12 – Main electrical and mechanical components of type 3 WTs . 31
Figure 13 – Modular structure for the type 3 WT model . 31
Figure 14 – Modular structure for the type 3 control models . 32
Figure 15 – Main electrical and mechanical components of type 4 WTs . 33
Figure 16 – Modular structure for the type 4A WT model . 34
Figure 17 – Modular structure for the type 4A control model . 34
Figure 18 – Modular structure for the type 4B WT model . 35
Figure 19 – Modular structure for the type 4B control model . 36
Figure 20 – Block diagram for constant aerodynamic torque model . 37
Figure 21 – Block diagram for one-dimensional aerodynamic model . 37
Figure 22 – Block diagram for two-dimensional aerodynamic model . 38
Figure 23 – Block diagram for two mass model . 39
Figure 24 – Block diagram for type 3A generator set model . 40
Figure 25 – Block diagram for type 3B generator set model . 42
Figure 26 – Block diagram for type 4 generator set model . 43
Figure 27 – Block diagram for the reference frame rotation model. 44
Figure 28 – Block diagram for pitch control power model . 45
Figure 29 – Block diagram for pitch angle control model . 46
Figure 30 – Block diagram for rotor resistance control model . 47
Figure 31 – Block diagram for type 3 P control model . 48
Figure 32 – Block diagram for type 3 torque PI . 49
Figure 33 – Block diagram for type 4A P control model . 49
Figure 34 – Block diagram for type 4B P control model . 50
Figure 35 – Block diagram for Q control model. 52
Figure 36 – Block diagram for current limiter . 54
Figure 37 – Block diagram for constant Q limitation model . 54
Figure 38 – Block diagram for QP and QU limitation model . 55
Figure 39 – Block diagram for grid protection system . 56
Figure 40 – Block diagram for u-f measurement . 57
Figure 41 – Signal processing structure with "play-back" method applied. . 60
Figure 42 – Signal processing structure with "full grid simulation" method applied. . 61
Figure 43 – Voltage dip windows. 63
Figure D.1 – Block diagram for WP reactive power controllers . 74
Figure D.2 – Block diagram for WP active power controller . 75

Figure E.1 – Aerodynamic power as function of blade angle Θ and wind speed v . 77
Figure E.2 – Partial derivative of power with respect to rotor speed change
∂p /∂ω as function of blade angle Θ and wind speed v . 77
aero WTR
Figure E.3 – Partial derivative of power with respect to blade angle dp as function of
θ
blade angle Θ . 78
Figure E.4 – Partial derivative of power with respect to rotor speed change dp as
ω
function of wind speed v for 1 p.u. (solid line) and 0,5 p.u. (dashed line) active power . 78
Figure E.5 – Approximation of aerodynamic power as function of wind speed . 79
Figure E.6 – Approximation of the blade angle as function of wind speed . 79
Figure F.1 – Sequence of Simulation on use of ESE-interface . 85
Figure G.1 – Block symbol for single integration time step delay . 86
Figure G.2 – Block symbol for stand-alone ramp rate limiter . 86
Figure G.3 – Block diagram for implementation of the stand-alone ramp rate limiter . 87
Figure G.4 – Block symbol for first order filter with absolute limits, rate limits and
freeze flag . 87
Figure G.5 – Block diagram for implementation of the first order filter with absolute
limits, rate limits and freeze state. 87
Figure G.6 – Block diagram for implementation of the freeze state without filter (T = 0) . 88
Figure G.7 – Block symbol for lookup table . 88
Figure G.8 – Block symbols for comparators . 88
Figure G.9 – Block symbol for timer . 89
Figure G.10 – Function of timer . 89
Figure G.11 – Block symbol for anti windup integrator . 89
Figure G.12 – Block diagram for implementation of anti windup integrator . 90
Figure G.13 – Block symbol for integrator with reset . 90
Figure G.14 – Block symbol for first order filter with limitation detection . 90
Figure G.15 – Block diagram for implementation of first order filter with limitation
detection . 91
Figure G.16 – Block symbol for delay flag . 91
Figure G.17 – Block diagram for implementation of delay flag . 91
Figure G.18 – Block symbol raising edge detection . 92
Figure G.19 – Block diagram for raising edge detection . 92

Table 1 – Global WT model parameters . 24
Table 2 – Initialisation variable used explicitly in model block diagrams . 25
Table 3 – Modules used in type 1A model . 27
Table 4 – Modules used in type 1B model . 28
Table 5 – Modules used in type 2 model . 30
Table 6 – Modules used in type 3 model . 32
Table 7 – Modules used in type 4A model . 35
Table 8 – Modules used in type 4B model . 36
Table 9 – Parameter list for one-dimensional aerodynamic model . 37
Table 10 – Parameter list for two-dimensional aerodynamic model . 37
Table 11 – Parameter list for two-mass model. 39
Table 12 – Parameter list for type 3A generator set model . 40

– 6 – IEC 61400-27-1:2015  IEC 2015
Table 13 – Parameter list for type 3B generator set model . 41
Table 14 – Parameter list for type 4 generator set model . 43
Table 15 – Parameter list for reference frame rotation model . 43
Table 16 – Parameter list for pitch control power model . 44
Table 17 – Parameter list for pitch angle control model . 45
Table 18 – Parameter list for rotor resistance control model . 46
Table 19 – Parameter list for p control model type 3 . 47
Table 20 – Parameter list for p control model type 4A . 49
Table 21 – Parameter list for p control model type 4B . 50
Table 22 – General WT Q control modes M . 50
qG
Table 23 – UVRT Q control modes M . 51
qUVRT
Table 24 – Parameter list for q control model . 51
Table 25 – Description of F flag values . 53
UVRT
Table 26 – Parameter list for current limiter model . 53
Table 27 – Parameter list for constant Q limitation model. 54
Table 28 – Parameter list for QP and QU limitation model . 55
Table 29 – Parameter list for grid protection model . 56
Table 30 – Windows applied for error calculations . 63
Table A.1 – Required information about simulation model and validation setup . 66
Table A.2 – Additional information required if full grid method is applied . 66
Table A.3 – Validation summary for voltage dips . 67
Table A.4 – Validation summary for reference point changes . 68
Table A.5 – Validation summary for grid protection . 68
Table D.1 – Parameters used in the voltage and reactive power control model . 73
Table D.2 – Parameters used in the frequency and active power control model . 74
Table E.1 – Points characterising the relation between the wind speed v and the partial
derivative dp . 78
ω
Table E.2 – Parameter list for the aerodynamics of a specific WT type . 79

INTERNATIONAL ELECTROTECHNICAL COMMISSION
_____________
WIND TURBINES –
Part 27-1: Electrical simulation models –
Wind turbines
FOREWORD
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International Standard IEC 61400-27-1 has been prepared IEC Technical Committee 88: Wind
turbines.
The text of this draft is based on the following documents:
Enquiry draft Report on voting
88/510/FDIS 88/529/RVD
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.

– 8 – IEC 61400-27-1:2015  IEC 2015
A list of all parts in the IEC 61400 series, published under the general title Wind turbines, can
be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
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• reconfirmed,
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INTRODUCTION
The IEC 61400-27 series specifies standard dynamic electrical simulation models for wind
power generation. IEC 61400-27-1 specifies wind turbine models and model validation
procedure. IEC 61400-27-2 will specify wind power plant models and model validation
procedure.
The increasing penetration of wind energy in power systems implies that Transmission
System Operators (TSOs) and Distribution System Operators (DSOs) need to use dynamic
models of wind power generation for power system stability studies. The models developed by
the wind turbine manufacturers reproduce the behaviour of their machines with a high level of
detail. Such level of detail is not suitable for stability studies of large power systems with a
huge number of wind power plants, firstly because the high level of detail increases the
complexity and thus computer time dramatically, and secondly because the use of detailed
manufacturer specific models requires a substantial amount of input data to represent the
individual wind turbine types.
The purpose of this standard is to specify generic dynamic models, which can be applied in
power system stability studies. The IEEE/CIGRE Joint Task Force on Stability Terms and
Definitions has classified power system stability in categories according to Figure 1.
Power System
Stability
Rotor Angle Frequency Voltage
Stability Stability Stability
Small-Disturbance Transient Large-Disturbance Small-Disturbance
Angle Stability Stability Voltage Stability Voltage Stability
Short Term Short Term Long Term
Short Term Long Term
© IEEE 2004
IEC
Figure 1 – Classification of power system stability according to IEEE/CIGRE Joint Task
Force on Stability Terms and Definitions
Referring to these categories, the models are developed to represent wind power generation
in studies of large-disturbance short term voltage stability phenomena, but they will also be
applicable to study other dynamic short term phenomena such as rotor angle stability,
frequency stability and small-disturbance voltage stability. Thus, the models are applicable for
dynamic simulations of power system events such as short-circuits (low voltage ride through),
loss of generation or loads, and system separation of one synchronous area into more
synchronous areas as specified in the scope.
The models have to be complete enough to represent the dynamic behaviour at the wind
turbine terminals, but must also be suitable for large-scale grid studies. Therefore simplified
wind turbine models are specified to perform the typical response of known wind turbine
technologies.
– 10 – IEC 61400-27-1:2015  IEC 2015
The wind turbine models specified in this standard are for fundamental frequency positive
sequence response . The models have the following limitations:
– The models are not intended for long term stability analysis.
– The models are not intended for investigation of sub-synchronous interaction phenomena.
– The models are not intended for investigation of the fluctuations originating from wind
speed variability in time and space. This implies that the models do not include
phenomena such as turbulence, tower shadow, wind shear and wakes.
– The models do not cover phenomena such as harmonics, flicker or any other EMC
emissions included in the IEC 61000 series.
– The models have not been developed explicitly with eigenvalue calculation (for small
signal stability) in mind .
– The models specified here apply only to wind turbines, and therefore do not include wind
power plant level controls and additional equipment such as SVCs, STATCOMs and other
devices which will be covered by IEC 61400-27-2. The wind turbine models interface to
the wind power plant controller models in IEC 61400-27-2.
– This standard does not address the specifics of short-circuit calculations.
– The models are not applicable to studies of extremely weak systems including situations
where wind turbines are islanded without other synchronous generation.
– The models are limited by the technical specifications in 5.2.
The validation procedure specified in this standard is intended to be applied to standard
models and other fundamental frequency wind turbine models. The validation procedure has
the following limitations:
– The validation procedure does not specify any requirements to model accuracy. It only
specifies measures to quantify the accuracy of the model .
– The validation procedure does not specify test and measurement procedures, as it is
based on tests specified in IEC 61400-21.
– The simulation model validation is not intended to justify compliance to any grid code
requirement, power quality requirements or national legislation.
– The test and measurement procedures introduce errors which limit the possible accuracy
as specified in the validation procedure.
– The validation procedure does not include steady state validation, but focuses on
validation of the dynamic performance of the model.
The following stakeholders are potential users of the models specified in this standard:
– TSOs and DSOs are end users of the models, performing power system stability studies
as part of the planning as well as the operation of the power systems.
– Wind plant owners are typically responsible to provide the wind power plant models to
TSO and/or DSO prior to plant commissioning.
– wind turbine manufacturers will typically provide the wind turbine models to the owner.
_______________
This standard is dealing with balanced as well as unbalanced faults, but for unbalanced faults, only the positive
sequence components are specified.
These wind generation systems are highly non-linear and simplifications have been made in the development of
the proposed models. Thus, linearisation for eigenvalue analysis is not trivial nor necessarily appropriate based
on these simplified models.
Clause 6 specifies a large number of measures for model accuracy. The importance of the individual measure
depends on the type of grid and type of stability study. Annex B describes limits to the possible accuracy of the
models.
– Developers of modern software for power system simulation tools will use the standard to
implement standard wind power models as part of the software library.
– Certification bodies in case of independent wind turbine model validation.
– Education and research communities, who can also benefit from the generic models, as
the manufacturer specific models are typically confidential.

– 12 – IEC 61400-27-1:2015  IEC 2015
WIND TURBINES –
Part 27-1: Electrical simulation models –
Wind turbines
1 Scope
IEC 61400-27 defines standard electrical simulation models for wind turbines and wind power
plants. The specified models are time domain positive sequence simulation models, intended
to be used in power system and grid stability analyses. The models are applicable for dynamic
simulations of short term stability in power systems. IEC 61400-27 includes procedures for
validation of the specified electrical simulation models. The validation procedure for
IEC 61400-27 is based on tests specified in IEC 61400-21.
IEC 61400-27 consists of two parts with the following scope:
– IEC 61400-27-1 specifies dynamic simulation models for generic wind turbine topologies/
concepts / configurations on the market. IEC 61400-27-1 defines the generic terms and
parameters with the purpose of specifying the electrical characteristics of a wind turbine at
the connection terminals. The models are described in a modular way which can be
applied for future wind turbine concepts. The dynamic simulation models refer to the wind
turbine terminals. The validation procedure specified in IEC 61400-27-1 focuses on the
IEC 61400-21 tests for response to voltage dips, reference point changes and grid
protection.
– IEC 61400-27-2 specifies dynamic simulation models for the generic wind power plant
topologies / configurations on the market including wind power plant control and auxiliary
equipment. In addition IEC 61400-27-2 specifies a method to create models for future wind
power plant configurations. The wind power plant models are based on the wind turbine
models specified in IEC 61400-27-1.
The electrical simulation models specified in IEC 61400-27 are independent of any software
simulation tool.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
u
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