IEC TS 62600-100:2012

IEC/TS 62600-100 ®
Edition 1.0 2012-08
TECHNICAL
SPECIFICATION
colour
inside
Marine energy – Wave, tidal and other water current converters –
Part 100: Electricity producing wave energy converters – Power performance
assessment
IEC/TS 62600-100:2012(E)
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IEC/TS 62600-100 ®
Edition 1.0 2012-08
TECHNICAL
SPECIFICATION
colour
inside
Marine energy – Wave, tidal and other water current converters –

Part 100: Electricity producing wave energy converters – Power performance

assessment
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
V
ICS 27.140 ISBN 978-2-83220-330-9

– 2 – TS 62600-100 © IEC:2012(E)
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Symbols and units . 8
4 Sequence of work . 10
5 Test site characterization . 10
5.1 General . 10
5.2 Measurements . 10
5.2.1 Wave measurement for wave power . 10
5.2.2 Current measurement . 11
5.2.3 Tidal measurement . 11
5.2.4 Bathymetric survey . 11
5.2.5 Calculation of wave spatial transfer model . 11
5.2.6 Modelling of the test site . 11
6 Methodology . 12
6.1 General . 12
6.2 Sample duration and frequency . 12
6.3 Simultaneity . 13
6.4 Data recording. 13
6.4.1 Amount of data to be recorded . 13
6.4.2 Data format and retaining . 13
7 Measurement and data collection for wave data . 13
7.1 General . 13
7.2 WMI and calibration . 13
7.3 Instrumentation location . 13
7.3.1 General . 13
7.3.2 Direct measurement . 13
7.3.3 Measures with spatial transfer model . 14
7.3.4 Correction for WEC interference . 14
7.4 Metocean data . 14
7.5 Procedure for the calculation of derived parameters . 14
8 WEC power output measurements . 15
8.1 WEC output terminals . 15
8.2 Power measurement point . 15
8.3 Power measurements . 16
8.3.1 General . 16
8.3.2 Limitations on power production . 16
8.4 Instruments and calibration . 16
9 Determination of power performance . 17
9.1 General . 17
9.2 Structure of the normalized power matrix . 17
9.2.1 Core structure . 17
9.2.2 Sub-division of the normalized power matrix . 17
9.2.3 Calculation of the capture length . 17

TS 62600-100 © IEC:2012(E) – 3 –
9.2.4 Representation of the capture length matrix. 17
9.3 Calculation of power matrix . 18
10 Calculation of mean annual energy production (MAEP) . 18
10.1 General . 18
10.2 Standard methodology. 18
10.3 Alternative methodology . 19
10.4 Completeness of the capture length matrix for MAEP . 19
Annex A (informative) Example production of a normalized power matrix . 20
Annex B (normative) Method for power loss compensation where the measurement
point is located on shore . 28
Annex C (normative) Evaluation of uncertainty . 31
Annex D (normative) Error analysis of the wave spatial transfer model . 33
Bibliography . 35

Figure 1 – Timeline of assessment . 10
Figure 2 – Data flow diagram . 12
Figure A.1 – Power scatter. 21
Figure B.1 – Location options for metering equipment . 28
Figure B.2 – Positive sequence cable model . 29

Table 1 – Symbols and units . 8
Table A.1 – Sample data . 20
Table A.2 – Average capture length . 22
Table A.3 – Standard deviation of capture length . 23
Table A.4 – Maximum capture length . 24
Table A.5 – Minimum capture length . 25
Table A.6 – Number of data samples . 26
Table A.7 – Power matrix . 27
Table C.1 – List of uncertainty components . 31

– 4 – TS 62600-100 © IEC:2012(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MARINE ENERGY –
WAVE, TIDAL AND OTHER WATER CURRENT CONVERTERS –

Part 100: Electricity producing wave energy converters –
Power performance assessment
FOREWORD
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indispensable for the correct application of this publication.
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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 62600-100, which is a technical specification, has been prepared by IEC technical
committee 114: Marine energy – Wave, tidal and other water current converters.

TS 62600-100 © IEC:2012(E) – 5 –
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
114/87/DTS 114/95/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 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.
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
related to the specific publication. At this date, the publication 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.
The contents of the corrigendum of April 2017 have been included in this copy.

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.
– 6 – TS 62600-100 © IEC:2012(E)
INTRODUCTION
This part of IEC 62600, which is a Technical Specification, provides performance assessment
methods for Wave Energy Conversion Systems (WECS). A Wave Energy Converter (WEC) is
a device which generates electricity using the action of water waves and delivers electricity to
an electrical load.
Wave energy industry development is transitioning from preliminary stages to commercial
production stages. Validated data gathering and processing techniques are important to
improve existing technologies. This technical specification will be subject to changes as data
are collected and processed from testing of WECS.
The expected users of the specification include:
• device developers who want to validate the performance of their WEC;
• investors who want to assess the performance of a device developer’s WEC;
• project developers who want to assess the performance of their project against
manufacturer’s claims;
• surveyors contracted to carry out the assessment.

TS 62600-100 © IEC:2012(E) – 7 –
MARINE ENERGY –
WAVE, TIDAL AND OTHER WATER CURRENT CONVERTERS –

Part 100: Electricity producing wave energy converters –
Power performance assessment
1 Scope
This part of IEC 62600, which is a Technical Specification, provides a method for assessing
the electrical power production performance of a Wave Energy Converter (WEC), based on
the performance at a testing site.
The scope of this Technical Specification includes:
a) all WECs that produce electrical power from wave energy;
b) all sea resource zones (near and offshore, deep and shallow water);
c) the specification applies to commercial scale WECs that are:
1) compliantly moored,
2) tautly moored,
3) bottom mounted,
4) shore mounted.
The scope of this Technical Specification does not include:
a) WECs that produce other forms of energy unless this energy is converted into electrical
energy;
b) resource assessment;
c) scaled devices in test facilities (tank or scaled sea conditions) where any scaling would
need to be carried out to extrapolate results for a full scale device;
d) power quality issues;
e) environmental issues;
f) power matrix transposition from one location to another.
This Technical Specification provides a systematic method which includes:
– measurement of WEC power output in a range of sea states;
– WEC power matrix development;
– an agreed framework for reporting the results of power and wave measurements.
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
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60044-1, Instrument transformers – Part 1: Current transformers

– 8 – TS 62600-100 © IEC:2012(E)
IEC 60688, Electrical measuring transducers for converting a.c. electrical quantities to
analogue or digital signals
IEC 61000-3 (all parts), Electromagnetic compatibility (EMC) – Part 3: Limits
IEC 61869-3, Instrument transformers – Part 3: Additional requirements for inductive voltage
transformers
ISO/IEC Guide 98-1:2009, Uncertainty of measurement – Part 1: Introduction to the
expression of uncertainty in measurement
ISO/IEC Guide 98-3:2008, Uncertainty of measurement – Part 3: Guide to the expression of
uncertainty in measurement (GUM:1995)
ISO 8601, Data elements and interchange formats – Information interchange –
Representation of dates and times
EquiMar: Protocols for the equitable assessment of marine energy converters, Part II,
Chapters I.A.1 through I.A.5., Editors: David Ingram, George Smith, Claudio Bittencourt
Ferreira, Helen Smith. European Commission 7th framework programme grant agreement
number 213380, First Edition 2011
NDBC:2009, Technical Document 09-02, Handbook of automated data quality control checks
and procedures. National Data Buoy Center, August 2009
3 Symbols and units
For the purposes of this document, the symbols and units listed in Table 1 apply.
Table 1 – Symbols and units
Symbol Definition Units
th
fcell
Frequency of occurrence in the i bin
Hz
i
C
Total positive sequence line-to-line capacitance of subsea cable farad
cable
c
Group velocity m/s
g
f Frequency Hz
f
Frequency at component i Hz
i
Energy at f distributed with angle θ
+π
G(θ,f) 1/rad
NOTE
G(θ, f )⋅ dθ= 1
∫
−π
h Water depth m
H
Spectral estimate of significant wave m

m0
H
Significant wave height m
s
I
Line current
meas
A
J
Omnidirectional measured wave energy flux
W/m
J
Omnidirectional measured wave energy flux per bin
i
W/m
L Capture length m
L
Capture length per bin m
i
TS 62600-100 © IEC:2012(E) – 9 –
Symbol Definition Units
M Number of data sets in a bin -

MAEP Mean Annual Energy Production Wh
th
m
Frequency n order moments of the variance spectrum -
n
n Number of sea states -
N
Number of bins -
P Measured power output W
P
Measured power output per bin W
i
P
Real power W
meas
PF
Power factor -
meas
Q
Reactive power W
meas
R
Total positive sequence resistance of subsea cable Ω
cable
m
S Spectral density
Hz
m
S(f) Spectral density as function of frequency

Hz
Spectral density at WEC 2
m
S(f)
WEC
T ( f , t,θ , h,.)⋅ S( f )
Equals WMI
Hz
m
S(f) Spectral density at WMI
WMI
Hz
Directional spectrum
m
S(f, θ)
S( f )⋅ G(θ , f )
Hz⋅ rad
m
S
Spectral density at frequency component i
i
Hz
S
Standard deviation -
p
t Time lag or shift between the WMI and the WEC s
T Operational hours per record h
T
Energy period s
e
Spatial transfer model, for correction of the spectral density measured at the
WMI to the WEC
T(f, t, θ, h,.)
-
NOTE Not all the variables are listed. The correction depends on the test site.
U Line-to-line voltage V
U
Line-to-line r.m.s. voltage
meas
V
V , V
WEC side positive sequence voltage V
p1+ p1–
V , V
Shore side positive voltage V
p2 p2–
X
Total positive sequence reactance of subsea cable Ω
cable
Δf
Frequency spacing Hz
i
g
ρ Fluid density
m
θ Wave direction °
φ Phase angle °
– 10 – TS 62600-100 © IEC:2012(E)
4 Sequence of work
Figure 1 shows the sequenced of work for the assessment as described in this technical
specification. The pre-test sections shall be conducted prior to the testing period. Following
the testing period the post-test sections shall be conducted.
Test site characterisation
PRE-TEST
Methodology
TESTING
Measurement and Wave energy
PERIOD
data collection for conversion power
wave data output measurement
Determination of power performance
POST-TEST
Calculation of mean annual energy

Figure 1 – Timeline of assessment
5 Test site characterization
5.1 General
An analysis of the prospective test site shall be undertaken to ensure that it is suitable for
power assessment of a WEC. The incident wave climate shall be evaluated to ensure the
power performance matrix can be populated. In order to infer the incident wave power at the
location of a WEC, the effect of bathymetry and marine currents on the incident wave climate
shall be sufficiently analyzed to determine whether a transfer model between the Wave
Measurement Instrument (WMI) and WEC will be required. If a transfer model is required, the
analysis shall support the development of a suitable transfer model.
5.2 Measurements
5.2.1 Wave measurement for wave power
A WMI shall be deployed at the proposed WEC location prior to WEC deployment. A second
WMI shall be deployed simultaneously at the proposed post-deployment wave measurement
location. The WMIs shall be deployed for a minimum of 3 months prior to WEC deployment
and it is recommended the WMIs record data for 12 months prior to WEC deployment to
account for seasonal variations.
The spectral data shall be calculated from WMI time series data. Estimates of the significant
wave height estimate and energy period shall be calculated from the spectral data. The
following parameters, to be used to determine the power matrix, shall be included in the
determination of the power matrix:
a) spectral shape;
b) directionality of waves;
c) directional frequency spectrum;
d) water depth including tidal effect;

TS 62600-100 © IEC:2012(E) – 11 –
e) tidal and marine current, direction and velocity;
f) wind speed and direction;
g) density of water;
h) occurrence and thickness of ice.
Parameters from the above list that have not been recorded, and thus not included in the
development the power matrix, shall be identified and the rationale for their exclusion
justified.
5.2.2 Current measurement
Marine currents at the test site shall be recorded and documented. The current speed and
direction data shall be measured simultaneously with the wave measurement and shall extend
over a minimum of 30 days. The sampling period shall be a maximum of 10 minutes. At least
one current speed and direction record will be taken from the upper half of the water column
during the deployment period. The primary purpose of current records is to facilitate the
development of a marine current model of the area. Tidal and non-tidal currents shall be
estimated and differentiated.
It is recommended, however, to measure current velocity and directions at different points of
the water column in order to adequately describe the velocity profile at the site.
5.2.3 Tidal measurement
Tidal heights shall be recorded at the test site. The measurements shall extend over at least
30 days and shall be analysed to estimate tidal ranges.
5.2.4 Bathymetric survey
The boundary of the test site shall be defined and documented. A bathymetric survey of the
area shall be undertaken and documented. The resolution of the bathymetric survey shall be
as needed to support the wave spatial transfer model, see 5.2.5.
The survey should provide the details on the bottom profile.
5.2.5 Calculation of wave spatial transfer model
The sea state at the location of the WMI shall be representative of the sea state at the
location of the WEC. If the difference between the energy flux at the WMI and the WEC – as
determined by the deployment of a minimum of two WMIs, one at the wave measurement
location and one at the WEC location – is less than 10,0 % for 90,0 % of the records then it
can be assumed that the wave field is statistically equivalent.
NOTE It is expected that this will be the case for a well-chosen deep-water test site.
If the above condition is not met then a spatial transfer model shall be generated and
validated. The spatial transfer model can either be an existing modelling program or a custom
modelling program. The modelling program shall be validated. The accuracy of the model
shall be determined as shown in Annex D.
5.2.6 Modelling of the test site
The spatial transfer model shall predict the spectrum at the WEC based on the spectrum at
the WMI. The test site should be modelled to assist in the development of a spatial transfer
model. The spatial transfer model shall be acceptable if it predicts the energy flux at the WEC
to within 10,0 % of the measured energy flux for 90,0 % of the of the data recorded according
to 5.2.1.
NOTE The spatial transfer model would generally be in the form:

– 12 – TS 62600-100 © IEC:2012(E)
(1)
S( f ,θ ) = T( f ,t,θ,h,.)⋅ S( f ,θ )
WEC WMI
6 Methodology
6.1 General
This technical specification governs the methodology for measurement, analysis and
presentation of data to assess the power performance of an electricity generating WEC.
The sea state incident at the WEC shall be measured to the accuracy specified in Clause 7.
The sea state measurements shall be analysed to give the parameters for each sample
sufficient to describe the sea state as specified in Clause 7.
The electrical power production at the WEC shall be measured to the accuracy specified in
Clause 8. The electrical power production measurements shall be analysed to give the
parameters for each sample sufficient to describe the electrical power production as specified
in Clause 8.
A power matrix shall be compiled as specified in Clause 9 which compares the parameters of
the sea state samples and the electrical power production samples (see Figure 2).
Sea state Electrical power Measurement
measurement measurement description
Meta data
Sea state Electrical power
header
parameters parameters
Aggregated data Performance
records database
Power matrix
Figure 2 – Data flow diagram
6.2 Sample duration and frequency
The parameters describing the sea state and electrical power production for each sample
shall be recorded as specified in this Clause 6. The minimum sample duration shall be
20 min. It shall be reported at least every hour.
The minimum sample frequency shall be 1,0 Hz.
NOTE Sample duration will affect the accuracy of the measurement. A short sampling duration can result in the
poor characterization of the sea state.

TS 62600-100 © IEC:2012(E) – 13 –
6.3 Simultaneity
The measurements from a WMI and WEC power output shall be measured at the same time to
provide correlation between sea state and WEC output power. WMI and WEC data shall be
synchronized so that the sea-state incident at the WEC can be correlated with WMI records. It
is recommended that WMI data be recorded simultaneously with WEC power data for a
minimum of one half of the sample duration.
NOTE The spatial transfer model shall be used to correct any time delay between the measurements taken at the
WMI and the location of the WEC. The correction for the time delay will not affect the simultaneity of the
measurements.
6.4 Data recording
6.4.1 Amount of data to be recorded
The minimum amount of data recorded shall be based on the design operating envelope of
interest. This shall define the amount of testing that is required to develop a power matrix.
The minimum testing duration shall be six months and be representative of the deployment
location.
NOTE Spectral shape can vary with seasons leading to variations in the power matrix.
6.4.2 Data format and retaining
The data shall provide a record of sea state and electrical power production over time. Each
aggregated data record shall be date and time stamped using ISO 8601. The records shall be
annotated with quality control flags giving the results of the quality control checks carried out
during the recording and analysis path. The records shall be recoverable in ASCII format with
a descriptive header for each data record.
7 Measurement and data collection for wave data
7.1 General
The purpose of this Clause 7 is to specify the wave and environmental data required to
produce a power matrix for a WEC. This Clause 7 shall also provide the methodology for
analyzing the wave data in order to characterise the environmental conditions. The minimum
sample frequency shall be 1,0 Hz.
7.2 WMI and calibration
The calibration, accuracy, and limitation of the WMI shall be documented to reference
NDBC:2009 Technical Document 09-02.
7.3 Instrumentation location
7.3.1 General
WMI deployment location or locations shall be selected to best represent the sea state at the
WEC. The WMI location will be selected to minimize its effect on the WEC and the WEC on
the WMI. The effects of reflection, radiation, diffraction, and shadowing shall be considered
when selecting the WMI location effects.
7.3.2 Direct measurement
Direct measurement can be used if the site investigations as specified in Clause 5 have not
revealed any significant variations in the sea states between the WEC and WMI. The WMI
data will be representative of the sea state at the WEC. The WMI and WEC data can be
processed and analysed directly.

– 14 – TS 62600-100 © IEC:2012(E)
7.3.3 Measures with spatial transfer model
A spatial transfer model shall be used to account for the changes occurring between the
position of the WMI and the WEC. The spatial transfer function will provide the sea state data
to be analysed with the WEC data.
7.3.4 Correction for WEC interference
The WMI shall be positioned to reduce the amount of interference from the WEC. A model
shall be developed to estimate the waves from radiation and refraction. The WMI shall be
placed in a location where the average radiated wave energy has decayed by at least 90 %.
7.4 Metocean data
It is recommended to measure and record all relevant parameters believed to have an
influence on power production. Since there are several factors that may affect the
performance of a WEC, depending on its type, awareness of any correlation between power
and a specific parameter should be sought and reported. A listing of the parameters is
included in 5.2.1. As a minimum requirement, the significant wave height estimate H , the
m0
wave energy period T , and the wave energy flux J shall be calculated using the measured
e
wave data and reported.
Other parameters that have a significant effect on the power production of the WEC shall also
be recorded and calculated. The calculation of any additional parameters shall be defined and
reported in sufficient detail to allow for repeatability (see Annex C). The accuracy of the
calculated parameters shall be given, according to the uncertainty estimation defined by
ISO/IEC Guide 98-1 and ISO/IEC Guide 98-3.
Directly measured parameters will be expressed with indication of absolute error.
Specifications on the type, location, calibration, and accuracy of the measurement instrument
shall be given.
7.5 Procedure for the calculation of derived parameters
Wave data shall be described by wave spectra which provides information on how the wave
elevation variance is distributed with frequency.
a) Frequency f : A range of frequencies will be selected for spectral analysis depending on
i
the measurement instrument and sampling rate. The spectral frequency range used for
calculation should be between 0,033 Hz and 0,50 Hz with the number of frequency bins
determined from data analysis. Frequency bin width should not exceed 0,015 Hz.
b) The frequencies shall be defined using either a geometric progression where the ratio
between two adjacent frequencies is constant, or a fixed frequency spacing. In either case
the maximum frequency bin width shall not exceed 0,015 Hz.
NOTE 1 Currents may have a significant effect on wave and power parameters due to Doppler shift. Refer to
ISO 19901-1:2005 for the correction procedure. If the ratio of intrinsic to apparent wave frequency is between
0,9 and 1,1, corrections are not required. Any corrections from apparent to intrinsic wave shall be clearly
noted.
c) Frequency moments of the variance spectrum m . The moments of the spectrum from
n
n = –1 and n = 0 shall be calculated from
N
n
(2)
m = S f Δf
n ∑ i i i
i=1
d) The spectral significant wave height estimate H is defined as:
m0
H = 4,00 m (3)
m0 0
TS 62600-100 © IEC:2012(E) – 15 –
e) The energy period T is defined as:
e
m
−1
T = (4)
e
m
f) The wave energy flux J (omnidirectional) is defined as:
J=ρg S c Δf
(5)
i gi i
∑
i
where
g is the gravitation constant equal to 9,8 m/s .
g) The group velocity is defined as:
 
1 2⋅ k ⋅ h
i
c = ⋅c ⋅ 1+ (6)
gi pi  
2 sinh(2⋅ k ⋅ h)
 i 
g
c = ⋅ tanh(k⋅ h) (7)
pi i
k
i
NOTE 2 In deep water conditions this simplifies to:
ρg
(8)
J= H T
m0 e
64π
NOTE 3 The directionality of the sea state is important when the WEC is directionally sensitive. The Metocean
data will be recorded as a parameter. The directionality of the waves can be described as a mean direction and a
parameter representing the spreading.
8 WEC power output measurements
8.1 WEC output terminals
In the case of an AC grid-connected WEC its output terminals shall be at the point where the
output power is in the form of AC at the network frequency.
In the case of a non-grid connected WEC, its output terminals shall be at the point where the
power is connected directly to the load. The output power shall be in the form of AC at a
commonly used network frequency (e.g. 50 Hz, 60 Hz), and at a commonly used grid
connection voltage level (e.g. 400 V, 6,6 kV). These details shall be clearly stated.
The output terminal point shall be clearly stated.
8.2 Power measurement point
The power measurement point should be at the electrical output terminals of the WEC.
When this is not possible the power measurement point shall be at a point where other effects
(such as losses due to cables or other electrical components) between the measurement point
and the output terminals may be determined. In this case the methodology for these
corrections shall be fully detailed. Power loss correction is only permitted for transmission
equipment that is required for measuring the electrical power at the WEC output terminal. The
power measurement point shall be clearly stated. In the case where the power measurement
point differs from the output terminals the justification shall be made.

– 16 – TS 62600-100 © IEC:2012(E)
NOTE Annex B contains a method for cable loss compensation where the measurement point is located on shore.
8.3 Power measurements
8.3.1 General
The net electric power of the WEC shall be measured, inclusive of any reduction due to
system energising power and necessary ancillary loads on board the WEC. The power shall
be recorded at minimum of 2 Hz, the power signal having been subjected to a suitable anti-
aliasing filter.
The mean, standard deviation, maximum and minimum of the digitized values which occur in
each sample shall be recorded.
8.3.2 Limitations on power production
In the case of an AC grid connected WEC, an assessment shall be made of any potential
limitations imposed on WEC power export capacity due to the grid connection. These may
include the capacity of the connection itself or the requirement for significant reactive power
export, resulting in constraints on the WEC power output under certain conditions. In the case
where such constraints can occur, a method to identify when the WEC is operating under
constrained output power conditions shall be put in place. Output power data during these
conditions shall be identified and may be excluded for use in the power performance matrix.
It is recommended in this circumstance that an external dump load be installed in order to
eliminate the WEC power output constraint.
8.4 Instruments and calibration
The net electric power of the WEC shall be measured using a power measurement device
such as a transducer and be based upon measurements of current and voltage on a minimum
of two phases.
Electrical transducers and the power measurement device used in the electrical
measurements should be class 0,5 or better, should be calibrated to traceable standards and
shall meet the requirements of the following standards:
• power transducers : IEC 60688;
• current transformers: IEC 60044-1;
• voltage transformers: IEC 61869-3.
The operating range of the power measurement device shall be sufficient to include all
positive peaks corresponding to net generation and all negative peaks corresponding to net
imported power. As a guide, the full-scale working range of the power measurement device
and transducers should be at least:
• export: 1 % to 200 % of rated power;
• import: –1 % to –50 % of rated power.
At the low power range of ±1 % of the device’s rated capacity, where the working range of the
power measurement device does not allow for class 0,5 measurements, the power recorded
should be zero. At the low power range where the working range of the transducer does allow
for class 0,5 measurements, their measured values shall be recorded.
NOTE It is important that current transformers are specified correctly as they become non-linear for low currents
(≤ 5 % of their range or thereabouts).

TS 62600-100 © IEC:2012(E) – 17 –
9 Determination of power performance
9.1 General
The power performance of the WEC shall be presented using a normalized power matrix. The
normalization shall be calculated using the capture length and the average bin power. The
power performance of a WEC can be determined for two distinct purposes. The first purpose
is to define the power performance of a WEC so that it can subsequently be used to predict
energy yield at a different site. In this case the capture length matrix should be produced as
detailed in 9.2.
NOTE The capture length matrix is preferred over the power matrix because it is less sensitive to sea-state
parameters and thus less affected by the method of bins. However, the calculation of the power matrix is specified
in 9.3 to enable its calculation where appropriate.
The second purpose is to assess the power performance of a WEC to determine if it meets the specified power
performance claims. If a capture length matrix for the WEC exists then this can be achieved by comparing the
measured power performance to the capture length matrix.
9.2 Structure of the normalized power matrix
9.2.1 Core structure
The normalized power matrix shall be constructed by applying the “method of bins” to the
capture lengths (see 9.3). The bins shall be defined by at least the significant wave height
estimate, H and energy period, T . The bins for significant wave height shall have a
m0 e
maximum width of 0,5 m and the bins for the energy period shall have a maximum width of
1,0 s.
9.2.2 Sub-division of the normalized power matrix
Additional indices, such as the mean wave direction or spectral bandwidth, may be added to
the normalized power matrix to reduce the variability of capture length in each bin.
NOTE It is advantageous to sub-divide the normalized power matrix if by doing so it reduces the variability of the
performance prediction, thereby giving greater confidence in the estimation of WEC energy production.
9.2.3 Calculation of the capture length
The capture length is equal to the net electrical power capture divided by the wave energy
flux.
P
(9)
L=
J
9.2.4 Representation of the capture length matrix
In cases where only significant wave height, H and energy period, T are used to define the
e
m0
capture length matrix a table can be used to fully represent the capture length matrix. Where
more indices are used to define the capture length matrix the significant wave heigh
...