IEC TS 62600-202:2022

IEC TS 62600-202 ®
Edition 1.0 2022-04
TECHNICAL
SPECIFICATION
colour
inside
Marine energy – Wave, tidal and other water current converters –
Part 202: Early stage development of tidal energy converters – Best practices
and recommended procedures for the testing of pre-prototype scale devices
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IEC TS 62600-202 ®
Edition 1.0 2022-04
TECHNICAL
SPECIFICATION
colour
inside
Marine energy – Wave, tidal and other water current converters –

Part 202: Early stage development of tidal energy converters – Best practices

and recommended procedures for the testing of pre-prototype scale devices

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.140 ISBN 978-2-8322-1095-9

– 2 – IEC TS 62600-202:2022 © IEC 2022
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 9
2 Normative references . 9
3 Terms and definitions . 10
4 Symbols and abbreviated terms . 11
5 Staged development approach . 11
5.1 General . 11
5.2 Stage 1 . 14
5.2.1 Scope . 14
5.2.2 Stage gate . 14
5.3 Stage 2 . 15
5.3.1 Scope . 15
5.3.2 Stage gate . 15
5.4 Stage 3 . 16
5.4.1 Scope . 16
5.4.2 Stage gate . 16
6 Test planning . 17
6.1 TEC similitudes . 17
6.1.1 General . 17
6.1.2 Reynolds scaling . 18
6.1.3 Temperature and salinity effects on Reynolds number . 21
6.2 Power take off (PTO) similitude . 21
6.3 Design statement . 21
6.4 Facility selection and outline plan . 23
6.4.1 General . 23
6.4.2 Stage 1 and Stage 2 . 23
6.4.3 Stage 3 . 25
6.5 Physical model considerations . 26
6.5.1 General . 26
6.5.2 Stage 1 . 26
6.5.3 Stage 2 . 27
6.5.4 Stage 3 . 27
6.5.5 Methods for applying torque . 27
6.5.6 Methods for controlling angular velocity . 28
6.6 Additional test procedures. 28
6.6.1 Dry run . 28
6.6.2 Natural frequency . 28
6.7 Uncertainties and repeat tests . 28
7 Reporting requirements . 29
7.1 Overview. 29
7.2 General . 29
7.3 Test conditions and goals . 29
7.3.1 General . 29
7.3.2 Facility selection report . 29
7.3.3 Physical model report . 30

7.3.4 Measurement procedure report . 30
7.4 Presentation of results . 30
8 Data acquisition . 31
8.1 Signal conditioning . 31
8.2 Sample rate . 32
8.3 Analogue to digital conversion and DAQ system . 32
8.4 Frequency response . 32
8.5 Data synchronization . 32
8.6 Data recording . 33
8.7 Recording of supplementary test data . 33
8.8 Calibration factors/Physical units . 33
8.9 Instrument response functions . 33
8.10 Health monitoring and verification of signals . 33
8.11 Special data acquisition requirements for Stage 3 open ocean trials . 34
9 Testing environment characterization . 34
9.1 General . 34
9.2 Environmental measurements . 34
9.3 Inflow/ Onset velocity . 35
9.3.1 General . 35
9.3.2 Inferred inflow velocity . 36
9.3.3 Point measurement . 36
9.4 Velocity shear profile . 36
9.4.1 General . 36
9.4.2 Measuring a velocity shear profile. 36
9.4.3 Presenting velocity shear profile . 37
9.5 Wave climate . 37
9.5.1 General . 37
9.5.2 Measuring waves . 38
9.6 Turbulence . 38
9.6.1 General . 38
9.6.2 Turbulence intensity . 38
9.6.3 Integral length and time scales . 39
9.6.4 Other considerations . 39
9.7 Temperature, salinity, density and viscosity . 39
10 Turbine rotor performance characterization . 39
10.1 Testing goals . 39
10.2 Performance indicators . 40
10.2.1 General . 40
10.2.2 Power, torque and angular velocity . 40
10.2.3 Turbine rotor drag (thrust) . 40
10.3 Non-dimensional performance indicators . 40
10.3.1 General . 40
10.3.2 Torque performance characterization . 40
10.3.3 Power performance characterization . 40
10.3.4 Thrust performance characterization . 41
10.3.5 Presentation of non-dimensional results . 41
11 Motions and loads under operational conditions . 41
11.1 Testing goals . 41

– 4 – IEC TS 62600-202:2022 © IEC 2022
11.2 Testing similitude . 41
11.3 Platform motions . 42
11.4 Local loads, cross-sectional loads and mooring or global loads . 43
11.5 Test conditions . 44
11.5.1 Stage 1 andand 2 . 44
11.5.2 Stage 3 . 45
11.5.3 Fatigue measures . 45
12 Motions and loads under survival conditions . 45
12.1 Testing goals . 45
12.2 Testing similitude . 46
12.3 Signal measurements . 47
12.4 Environmental Input parameters . 47
12.4.1 General . 47
12.4.2 Stage 1 and 2 . 47
12.4.3 Stage 3 . 48
12.5 Performance indicators . 48
13 Testing of arrays. 48
Annex A (informative) Stage gates . 49
A.1 General . 49
A.2 Design statements . 49
A.3 Stage gate criteria . 49
A.4 Uncertainty factors . 50
A.5 Third party review . 50
Annex B (informative) Device type . 51
B.1 General . 51
B.2 Axial flow turbines . 51
B.3 Cross-flow turbines . 51
B.4 Hydrofoil devices . 52
B.5 Other . 52
B.5.1 Ducted devices . 52
B.5.2 Oscillating devices . 52
B.5.3 Underwater kites. 52
Annex C (informative) Facilities selection. 53
C.1 General . 53
C.2 Towing tank . 53
C.3 Re-circulating water channel/flume . 53
C.4 Open water push test . 54
C.5 Tidal test site . 54
C.6 Cavitation tunnel . 55
C.7 Other facilities . 55
C.7.1 General . 55
C.7.2 Other specialized basins and tanks . 55
C.7.3 Wind tunnel . 55
C.7.4 Rotating arm facility . 55
C.8 Facilities comparison . 55
Annex D (informative) Instruments . 57
D.1 General . 57
D.2 Flow characteristics . 57

D.2.1 General . 57
D.2.2 Acoustic techniques . 57
D.2.3 Optical techniques . 57
D.2.4 Other techniques . 58
D.3 Wave measurement . 58
D.4 Structural characteristics . 58
D.5 Measurement and control of turbine shaft angular velocity . 58
D.6 Measuring torque . 59
D.7 Measuring thrust . 59
D.8 Mooring force measurement . 59
D.9 Model motion . 59
D.9.1 Optical multi camera six degree of freedom measurement system . 59
D.9.2 Gyroscope, accelerometer, compass, GPS . 60
Bibliography . 61

Figure 1 – Power and drag (thrust) coefficients for the US Department of Energy’s
Reference Model vertical-axis cross-flow turbine (RM2) tested in a towing tank
(Bachant et al. 2016) . 20
Figure 2 – Effect of Reynolds number on performance – Power (left) and thrust (right)
coefficient for reference model RM2 at λ = 3,1 plotted versus turbine diameter and
approximate average turbine blade root chord Reynolds number (Bachant et al. 2016) . 20
Figure 3 – Effect of Reynolds number on performance – Power coefficient versus tip
speed ratio (left) and power coefficient at λ = 1,9 plotted versus turbine diameter and
approximate average turbine blade root chord Reynolds number (right), both for UNH-
RVAT turbine (Bachant and Wosnik 2016) . 20

Table 1 – Staged development approach . 13
Table 2 – Scaling considerations . 18
Table 3 – Presentation of continuously measured indicators . 31
Table 4 – Presentation of discrete measured indicators . 31
Table 5 – Environmental measurements . 35
Table 6 – Instruments suitability for velocity profiling . 37
Table 7 – Environmental performance indicators . 38
Table 8 – Geometric similitude requirements (operational environments) . 42
Table 9 – Structural similitude requirements (operational environments) . 42
Table 10 – Kinematic signal measurements (operational environments) . 43
Table 11 – Dynamic signal measurements (operational environments) . 44
Table 12 – Current parameters for kinematics and dynamics testing (operational
conditions) . 45
Table 13 – Geometric similitude requirements (survival environments) . 46
Table 14 – Structural similitude requirements (survival environments) . 47
Table C.1 – Pros and cons of testing in towing tanks . 53
Table C.2 – Pros and cons of testing in recirculating water channels/flumes . 54
Table C.3 – Pros and cons of open water push tests . 54
Table C.4 – Pros and cons of testing at tidal test sites . 55
Table C.5 – Comparison of facilities . 56

– 6 – IEC TS 62600-202:2022 © IEC 2022
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MARINE ENERGY – WAVE, TIDAL AND OTHER WATER
CURRENT CONVERTERS –
Part 202: Early stage development of tidal energy converters –
Best practices and recommended procedures for the
testing of pre-prototype scale devices

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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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.
IEC TS 62600-202 has been prepared by IEC technical committee 114: Marine energy – Wave,
tidal and other water current converters. It is a Technical Specification.
The text of this Technical Specification is based on the following documents:
Draft Report on voting
114/407/DTS 114/414A/RVDTS
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Specification is English.
A list of all parts in the IEC 62600 series, published under the general title Marine energy –
Wave, tidal and other water current converters, can be found on the IEC website.

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/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.
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.

– 8 – IEC TS 62600-202:2022 © IEC 2022
INTRODUCTION
To further develop the tidal energy industry, Stage Gates, best practices and recommended
procedures for the testing of pre-prototype scale devices must be well understood. This
document is a collaborative effort from technology developers, academic researchers and test
facility managers.
The purpose of this document is to provide a structured approach in testing and evaluating Tidal
Energy Converters. By following a standardised design path, risk will be reduced and
stakeholder confidence increased. Through best practise guidance and applicable
methodologies this document will ensure consistent, appropriate and comparable data is
collected for the characterization and analysis required in the development of a Tidal Energy
Converter. Furthermore, the reporting procedures will ensure that the results can be replicated
by others.
The core of this document follows a Stage Gate approach; for each stage the program of work
is outlined and supporting information relating to test planning and reporting presented. The
specific recommendations are provided in a holistic manner guiding the process with respect to
test planning, reporting requirements, data acquisition, test environment characterization, and
characterization of both rotor and device (motion) performance. Annexes provide the reader
with further information on facility selection and instrumentation.
The overall goal of this document is to accommodate the majority of technology developers and
facilitate a coherent and structured approach that will accelerate the tidal energy sector in
fulfilling its market potential as a renewable energy contributor. However, it is recognised that
this document will not cover every eventuality that may be relevant for all users. Therefore, this
document assumes that the user is familiar with the subject matter and has access to, and
reviews relevant literature, including the literature cited herein.
NOTE This document presently does not describe testing under wave-current interaction, effects of turbulence on
tidal energy converters beyond a basic introduction to some turbulence parameters typically reported, and
quantification of uncertainty which is covered in other referenced documents.
+
MARINE ENERGY – WAVE, TIDAL AND OTHER WATER
CURRENT CONVERTERS –
Part 202: Early stage development of tidal energy converters –
Best practices and recommended procedures for the
testing of pre-prototype scale devices

1 Scope
This document specifies the development stages of Tidal Energy Converters up to the pre-
prototype scale (Stages 1 to 3). It includes the hydraulic laboratory test programs, where
environmental conditions are controlled so they can be scheduled, and the first scaled system
open-water trials, where combinations of tidal currents, wind and waves occur naturally and the
programs are adjusted and flexible to accommodate these conditions. Full-scale prototype
(Stages 4 and 5) development is not covered in this document.
This document describes the minimum test programs that form the basis of a structured
technology development schedule. For each testing campaign, the prerequisites, goals and
minimum test plans are specified. This document addresses:
a) Planning an experimental program, including a design statement, technical drawings,
selection of scale and facility based on physical laws, site data and other inputs;
b) Device representation and characterization, including the physical device model, power-
take-off components, foundation and mooring arrangements where appropriate;
c) Energy resource and environment characterization, concerning either the tank testing facility
or the open-water deployment site, depending on the stage of development;
d) Specification of explicit test goals, including power conversion performance and device
loads.
Guidance on the measurement sensors and data acquisition packages is included, but not
dictated. Providing that the specified parameters and tolerances are adhered to, the device
developer is free to select the components and instrumentation.
An important element of testing is to define the limitations and accuracy of the raw data and,
more specifically, the results and conclusions drawn from the trials. A methodology of
addressing these limitations is presented with each goal so the plan always produces
defendable results of defined uncertainty.
It is anticipated that this document will serve a wide audience of tidal energy stakeholders,
including device developers and their technical advisors; government agencies and funding
councils; test centers and certification bodies; private investors; and environmental regulators
and non-governmental organizations.
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 TS 62600-1, Marine energy – Wave, tidal and other water current converters – Part 1:
Vocabulary
IEC TS 62600-101, Marine energy – Wave, tidal and other water current converters – Part 101:
Wave energy resource assessment and characterization

– 10 – IEC TS 62600-202:2022 © IEC 2022
IEC TS 62600-103:2018, Marine energy – Wave, tidal and other water current converters – Part
103: Guidelines for the early stage development of wave energy converters – Best practices
and recommended procedures for the testing of pre-prototype devices
IEC TS 62600-200, Marine energy – Wave, tidal and other water current converters – Part 200:
Electricity producing tidal energy converters – Power performance assessment
IEC TS 62600-201:2015, Marine energy – Wave, tidal and other water current converters – Part
201: Tidal energy resource assessment and characterization
IEC TS 62600-300:2019 Marine energy – Wave, tidal and other water current converters – Part
300: Electricity producing river energy converters – Power performance assessment
ISO/IEC Guide 98-3, Uncertainty of measurement – Part 3: Guide to the expression of
uncertainty in measurement (GUM:1995)
ISO/IEC 17025:2017, General requirements for the competence of testing and calibration
laboratories
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC TS 62600-1 and the
following apply:
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
blockage
ratio of the tidal energy
converter projected area to the facility test section cross-sectional area
Note 1 to entry: There is a constraining effect exaggerating performance data when this ratio is too high, which is
typically observed for ratios greater than 5 %.
3.2
Stage 1
small-scale testing in the laboratory
Note 1 to entry: Stage 1 is equivalent to Technology Readiness Level (TRL) 2-3.
3.3
Stage 2
medium-scale testing in the laboratory
Note 1 to entry: Stage 2 is equivalent to Technology Readiness Level (TRL) 4.
3.4
Stage 3
large-scale testing in open water
Note 1 to entry: Stage 3 is equivalent to Technology Readiness Level (TRL) 5-6.
3.5
turbulence intensity
ratio of the tidal current speed standard deviation to the mean tidal current
speed.
Note 1 to entry: It is also referred to as turbulence level, and is a very simplified description of how turbulent the
flow at a tidal site or in a facility is.
Note 2 to entry: Turbulence intensity is to be determined from the same set of measured data samples of tidal
current speed, and taken over a specified period of time.

4 Symbols and abbreviated terms
ADCP Acoustic Doppler Current Profiler
ADV Acoustic Doppler Velocimeter
AEP Annual Energy Production as defined in IEC TS 62600-1
AD Analogue to Digital
CoG Centre of Gravity
COTS Commercial off-the-shelf
DAQ Data Acquisition
DoF Degrees of Freedom as defined in IEC TS 62600-1
EEP Energy Extraction Plane as defined in IEC TS 62600-1
FMECA Failures Mode, Effects and Criticality Analysis
MLW Mean Low Water
MHW Mean High Water
PDF Probability Density Function
RAO Response Amplitude Operator
PTO Power-Take-Off as defined in IEC TS 62600-1.
SCADA Supervisory Control and Data Acquisition System
TEC Tidal Energy Converter as defined in IEC TS 62600-1
TEOS-10 The Thermodynamic Equation of Seawater – 2010
TRL Technology Readiness Level
TSR Tip Speed Ratio
ULS Ultimate Limit State in the context of structural engineering
5 Staged development approach
5.1 General
This clause introduces the staged development approach to the design and evaluation of a TEC
through physical model testing. Each stage of development is motivated by risk reduction. The
primary goals for each stage address elements that should be completed before proceeding
through the user’s pre-defined Stage Gate for that stage. Each stage corresponds to technology
readiness levels (TRL) that measure the progress of technology advancement.
Scaled tidal flow conditions produced in the test tank should be representative of anticipated
full-scale tidal flow conditions at the expected deployment sites; namely depth-limited turbulent
open channel flows, such as those produced in large flumes. Departures from these conditions
due to test facility limitations or differences, e.g., absence of velocity gradients, ambient
turbulence and other unsteady flow characteristics over the energy extraction plane, for
example in towing tanks, should be documented, and the anticipated effects on test results
should be described.
Table 1 shows an overview of the Stage Gate framework and process from the early design
concept to the deployment of the first limited device number array, Stage 1 to 5. For each Stage
Gate, Table 1 includes the relevant model-test description, typical geometric scale range, test
objectives, and Stage Gate success metrics used in the go/no-go analysis.
This Stage Gate framework is designed to be consistent with TEC development and evaluation
guidance and protocols developed by the International Energy Agency, Ocean Energy Systems
(IEA OES) under Annex II (Bahaj, Blunden, and Anwar 2008; Nielsen 2010).

– 12 – IEC TS 62600-202:2022 © IEC 2022
Each stage is based on a different physical scale range carefully selected to achieve a set of
specific design objectives prior to advancing the device trials to the next stage. This clause
outlines the scope and Stage Gates for Stages 1, 2 and 3, guiding the development process
from TRL 1 to 6. Stages 4 and 5 concern full scale (or near full scale) testing and are not
covered in this document.
This document does not dictate a scale for each of the Stages 1-3. The model testing scale
heavily depends on the test objective, size of full-scale TEC, governing scaling laws to achieve
dynamic similitude, and the fidelity of the available instrumentation. The scales provided in
Table 1 are included as indicators based on previous TEC development efforts.
Every type of TEC will have slightly different requirements so a customized program should be
drawn up around these basic testing requirements. Different physical models may be prepared
to evaluate specific subsystems or design features. The necessary and recommended goals
and experimental activities for Stages 1 to 3 are described in detail in Clauses 6 through 13.
Activities are to be defined in the context of best engineering practice, where factors of safety,
reliability or other design philosophies are followed.
A Stage Gate process shall be applied after each set of trials to evaluate if the TEC has
achieved the required experimental objectives before advancing to the next stage.
A set of Stage Gate criteria for the evaluation of the TEC response and performance at the end
of each testing period are defined for Stages 1 to 3 in 5.2 to 5.4. These criteria shall be
addressed before advancing to the next stage. These criteria (5.2 to 5.4 ) are currently defined
as a general framework and allow for a high degree of flexibility to suit the design requirements.
At Stage 1, it should be anticipated that several iterations of a device would be required to
optimize its performance, reliability, safety and economics. More than one iteration may still be
required at Stage 2, and a single implementation should normally suffice at Stage 3.

Table 1 – Staged development approach
Stage Model test TRL Typical Test objectives Go/No-Go
description range
analysis
of
Stage Gate success
scales
thresholds
1 Concept model 2-3 1:15- Concept verification: Rotor power conversion
100 demonstrated.
Turbine rotor: Demonstrate
power energy conversion Loads characterized for
normal o
...