IEC TS 62600-30:2018

Marine energy - Wave, tidal and other water current converters - Part 30: Electrical power quality requirements

IEC TS 62600-30:2018(E) includes: definition and specification of the quantities to be determined for characterizing the power quality of a marine energy (wave, tidal and other water current) converter unit; measurement procedures for quantifying the characteristics of a marine energy (wave, tidal and other water current) converter.
The measurement procedures are valid for a single marine energy converter (MEC) unit (or farm) with three-phase grid or an off-grid connection. The measurement procedures are valid for any size of MEC unit.

General Information

• Status: Published
• Publication Date: 28-Aug-2018
• ICS: 27.140 - Hydraulic energy engineering
• Technical Committee: TC 114 - Marine energy - Wave, tidal and other water current converters
• Drafting Committee: PT 62600-30 - TC 114/PT 62600-30
• Current Stage: PPUB - Publication issued
• Start Date: 29-Aug-2018
• Completion Date: 13-Sep-2018

Standards Content (Sample)

IEC TS 62600-30 ®
Edition 1.0 2018-08
TECHNICAL
SPECIFICATION
colour
inside
Marine energy – Wave, tidal and other water current converters –
Part 30: Electrical power quality requirements

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IEC TS 62600-30 ®
Edition 1.0 2018-08
TECHNICAL
SPECIFICATION
colour
inside
Marine energy – Wave, tidal and other water current converters –

Part 30: Electrical power quality requirements

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.140 ISBN 978-2-8322-5978-8

– 2 – IEC TS 62600-30:2018  IEC 2018
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 9
3 Terms and definitions . 9
4 Symbols and units . 10
5 Abbreviated terms . 12
6 Marine energy converter power quality characteristic parameters . 12
6.1 Overview. 12
6.2 Marine energy converter specification . 12
6.3 Voltage fluctuations (continuous operations) . 13
6.3.1 General . 13
6.3.2 Continuous operation: MV connected systems . 13
6.3.3 Continuous operation: LV connected system . 14
6.4 Current harmonics, interharmonics and higher frequency components . 14
6.5 Response to voltage drops . 15
6.6 Active power . 16
6.6.1 Maximum measured power . 16
6.6.2 Ramp rate limitation . 16
6.6.3 Set-point control . 16
6.7 Reactive power . 17
6.7.1 Reactive power capability . 17
6.7.2 Set-point control . 17
7 Test procedures . 17
7.1 General . 17
7.1.1 Overview . 17
7.1.2 Test validity . 18
7.1.3 Test conditions . 18
7.1.4 Test equipment . 19
7.2 Voltage fluctuations (continuous operation) . 23
7.2.1 MV connected marine energy converters . 23
7.2.2 Fictitious grid . 23
7.2.3 Continuous operation – MV connected marine energy converters . 25
7.2.4 Continuous operation – LV connected marine energy converters . 26
7.3 Current harmonics, interharmonics and higher frequency components . 26
7.4 Response to temporary voltage drop . 27
7.5 Active power . 29
7.5.1 General . 29
7.5.2 Maximum measured power . 29
7.5.3 Ramp rate limitation . 30
7.5.4 Set point control . 30
7.6 Reactive power . 30
7.6.1 General . 30
7.6.2 Reactive power capability . 30
7.6.3 Set point control . 31

8 Determination of power quality . 32
8.1 General . 32
8.2 Voltage fluctuations (continuous operation) . 32
8.2.1 MV connected marine energy converter units . 32
8.2.2 LV connected marine energy converter . 33
8.3 Current harmonics, interharmonics and higher frequency components . 34
Annex A (informative) Sample report format . 36
A.1 General . 36
A.2 Marine energy converter rated data at terminals . 37
A.3 Voltage fluctuations (continuous operation) . 37
Annex B (informative) Voltage fluctuations and flicker . 39
B.1 Medium voltage (MV) connected converters . 39
B.2 Low voltage (LV) connected converters . 40
Annex C (informative) Measurement of active power, reactive power and voltage . 41
Bibliography . 43

Figure 1 – Adjustment of active power set-point . 16
Figure 2 – Adjustment of reactive power set-point . 17
Figure 3 – Assumed elements of measurement system (MV-connected marine energy
converter unit) . 19
Figure 4 – Assumed elements of measurement system (LV-connected marine energy
converter) . 20
Figure 5 – Assumed elements of wave energy converter power quality measurement
system . 21
Figure 6 – Assumed elements of tidal energy converter unit power quality
measurement system . 22
Figure 7 – Fictitious grid for simulation of fictitious voltage . 23
Figure 8 – System with short circuit emulator for testing MEC unit response to
temporary voltage drop . 28
Figure 9 – Tolerance of voltage drop. 29
Figure B.1 – Measurement and assessment procedures for flicker during continuous
operation of the marine energy converter (MV-connected converter) . 39
Figure B.2 – Measurement and assessment procedures for flicker during continuous
operation of the marine energy converter (LV-connected converter). 40

Table 1 – Marine energy – resource classification . 14
Table 2 – Specification of per unit voltage drops (the specified magnitudes, duration
and shape are for the voltage drop occurring as if the MEC under test is not
connected, i.e. without contribution from the installation) . 15
Table 3 – Measurement ranges to be excluded . 18
Table 4 – General specification of requirements for measurement equipment . 20
Table 5 – Specification of requirements for wave measurement equipment . 21
Table 6 – Specification of requirements for tidal velocity measurement equipment . 22
Table 7 – Specification of exponents according to IEC TR 61000-3-6 . 34
Table A.1 – General marine energy converter information . 36
Table A.2 – Marine energy converter nameplate ratings . 36
Table A.3 – Test information . 37

– 4 – IEC TS 62600-30:2018  IEC 2018
Table A.4 – Marine energy converter rated data at terminals . 37
Table A.5 – Reactive set-point control. 37
Table A.6 – Flicker index (coefficient or disturbance factor) data . 38
Table A.7 – Flicker coefficient as a function of resource conditions . 38

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MARINE ENERGY –
WAVE, TIDAL AND OTHER WATER CURRENT CONVERTERS –

Part 30: Electrical power quality requirements

FOREWORD
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The main task of IEC technical committees is to prepare International Standards. In
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• the required support cannot be obtained for the publication of an International Standard,
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• the subject is still under technical development or where, for any other reason, there is the
future but no immediate possibility of an agreement on an International Standard.
Technical specifications are subject to review within three years of publication to decide
whether they can be transformed into International Standards.
IEC TS 62600-30, which is a technical specification, has been prepared by IEC technical
committee 114: Marine energy – Wave, tidal and other water current converters.

– 6 – IEC TS 62600-30:2018  IEC 2018
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
114/238/DTS 114/253A/RVDTS
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 document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the IEC 62600 series, 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 website 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.

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.
INTRODUCTION
Marine energy conversion systems, as viable electric power sources for utility and community-
based applications, require close attention to the quality of the power produced. Poor power
quality has negative impacts on both the electrical power source and the load. Therefore,
guidance is needed for the manufacturer, developer and user on how to mitigate power quality
issues during the design of the device. Electrical system planners also need to identify the
requirements for grid integration of such variable and intermittent energy sources, while
maintaining high reliability and power quality standards.
Conceptually, except for wave energy convertors, many marine energy converter unit devices
operate in a manner similar to wind turbines. As power quality is a mature topic within other
renewable and conventional power generation schemes, there are numerous standards,
codes, and guidelines in existence. In contrast, there are no standards or technical
specifications for marine power generation systems that deal with the power quality issues
and the associated integration needs. Therefore, this knowledge-gap needs to be addressed
through incremental, detailed and collaborative standards development.
This technical specification aims at:
• identifying power quality issues and parameters (non-device specific and non-prescriptive)
for single/three-phase, grid-connected/off-grid (including micro-mini grid) marine wave,
tidal and other water current converter-based power systems;
• establishing the measurement methods, application techniques and result-interpretation
guidelines.
In addition to containing the associated definitions, normative references, symbols and units,
forms, annexes, as well as other supporting material, the core of this technical specification
would contain the following key items:
• identify characteristic parameters, define and specify the quantities required to
characterize the power quality impacts of marine energy conversion devices,
• develop measurement procedures as pertains to marine energy devices,
• outline standardized procedures for measuring the characteristic parameters, including
test and measurement conditions, and test equipment requirements.
It is expected that this technical specification will provide evaluation guidelines for device
developers and applied researchers.
Assessment of power quality for utilities will be part of a separate, future technical
specification that is currently being developed under IEC TC 8 SC 8A.

– 8 – IEC TS 62600-30:2018  IEC 2018
MARINE ENERGY –
WAVE, TIDAL AND OTHER WATER CURRENT CONVERTERS –

Part 30: Electrical power quality requirements

1 Scope
This part of IEC 62600 includes:
• definition and specification of the quantities to be determined for characterizing the power
quality of a marine energy (wave, tidal and other water current) converter unit;
• measurement procedures for quantifying the characteristics of a marine energy (wave,
tidal and other water current) converter.
The measurement procedures are valid for a single marine energy converter (MEC) unit (or
farm) with three-phase grid or an off-grid connection. The measurement procedures are valid
for any size of MEC unit, though this document only requires MEC unit types intended for
PCC (Point of Common Coupling) at Medium Voltage (MV) or High Voltage (HV) to be tested
and characterized. In addition, a simplified measurement and reporting procedure is outlined
for MEC units connected at Low Voltage (LV) networks. MV–connected and LV-connected
devices are defined as:
• MV connected units – typically multiple three-phase MEC units operating as a marine
power farm and delivering power through a HV or MV network;
• LV connected units – typically single-phase or three-phase units deployed in isolated,
hybrid or micro-grid type systems supplying small-scale loads.
Considering the nascent status of the marine energy sector, the following limitations of this
document are to be recognized:
• voltage fluctuations under switching operation – the current revision only considers
voltage fluctuations under continuous operation;
• resource classifications – to categorize the measured flicker quantities, various resource
classes are suggested only as guidelines. The user is advised to use these resource
classes judiciously.
The measurement procedures are designed to be as non-site-specific as possible so that
power quality characteristics measured at a test site, for example, can be considered valid at
other sites also providing the same MEC unit configuration and operation modes (for example
control parameters). If the configuration or operation mode is changed in any way that might
cause the MEC unit to behave differently with respect to power quality, the power quality
measurement procedures must be repeated.
This document is for testing of wave, tidal and other water current energy converter units,
though it contains information that may also be useful for testing of MEC farms. The cases
described are not intended for Ocean Thermal Energy Conversion (OTEC) systems.
NOTE This document uses the following terms for system voltage:
– low voltage (LV) refers to U <= 1 kV;
n
– medium voltage (MV) refers to 1 kV < U <= 35 kV;
n
– high voltage (HV) refers to U > 35 kV.
n
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 TR 61000-3-6:2008, Electromagnetic compatibility (EMC) – Part 3-6: Limits – Assessment
of emission limits for the connection of distorting installations to MV, HV and EHV power
systems
IEC TR 61000-3-7:2008, Electromagnetic compatibility (EMC) – Part 3-7: Limits – Assessment
of emission limits for the connection of fluctuating installations to MV, HV and EHV power
systems
IEC 61000-4-7:2002, Electromagnetic compatibility (EMC) – Part 4-7: Testing and
measurement techniques – General guide on harmonics and interharmonics measurements
and instrumentation, for power supply systems and equipment connected thereto
IEC 61000-4-7:2002/AMD1:2008
IEC 61000-4-15:2010, Electromagnetic compatibility (EMC) – Part 4-15: Testing and
measurement techniques – Flickermeter – Functional and design specifications
IEC 61400-21, Wind turbines – Part 21: Measurement and assessment of power quality
characteristics of grid connected wind turbines
IEC 61800-3:2017, Adjustable speed electrical power drive systems – Part 3: EMC
requirements and specific test methods
IEC 61869-1:2007, Instrument transformers – Part 1: General requirements
IEC 61869-2:2012, Instrument transformers – Part 2: Additional requirements for current
transformers
IEC 61869-3:2011, Instrument transformers – Part 3: Additional requirements for inductive
voltage transformers
IEC 62008:2005, Performance characteristics and calibration methods for digital data
acquisition systems and relevant software
IEC TS 62600-100:2012, Marine energy – Wave, tidal and other water current converters –
Part 100: Electricity producing wave energy converters – Power performance assessment
IEC TS 62600-101:2015, Marine energy – Wave, tidal and other water current converters –
Part 101: Wave energy resource assessment and characterization
IEC TS 62600-201:2015, Marine energy – Wave, tidal and other water current converters –
Part 201: Tidal energy resource assessment and characterization
3 Terms and definitions
For purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
– 10 – IEC TS 62600-30:2018  IEC 2018
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
flicker
impression of unsteadiness of visual sensation induced by a light stimulus whose luminance
or spectral distribution fluctuates with time
Note 1 to entry: Flicker is caused by rapid, regular changes to the voltage level of the electrical supply caused by
devices connected to the electrical system. The voltage variations are caused by fluctuating power consumed or
generated by a load or particularly renewable generator, more severely for reactive power fluctuations.
[SOURCE: IEC 60050-161:1990,161-08-13, modified – The note to entry has been added]
3.2
network impedance phase angle
phase angle of network short-circuit impedance:
ψ = arctan(X / R )
k k k
where
X is the network short-circuit reactance;
k
R is the network short-circuit resistance.
k
3.3
point of common coupling
PCC
point in an electric power system, electrically nearest to a particular load, at which other loads
are, or may be, connected
Note 1 to entry: These loads can be either devices, equipment or systems, or distinct network users’ installations.
[SOURCE: IEC 60050-161:1990,161-07-15, modified – " Power supply network" has been
replaced by "electric power system"; in note 1 to entry, "customer" has been replaced by
"user" and note 2 to entry has been deleted]
3.4
total harmonic distortion
ratio of the RMS value of the harmonic content to the RMS value of the fundamental
component or the reference fundamental component of an alternating quantity
[SOURCE: IEC 60050-551:1998,551-20-13, modified – Notes to entry have been deleted ]
4 Symbols and units
is the electrical angle at t = 0
α
o
β exponent with a numerical value to be selected to determine I
hΣ
α (t) electrical angle of the fundamental component of the measured voltage (°)
m
ψ network impedance phase angle (°)
k
∆d fractional change in voltage
dyn
c(ψ ) flicker coefficient for continuous operation
k
c (ψ ) flicker coefficient of an individual marine energy converter
i k
time-series data of flicker coefficient (synthesized)
c(ψ )(t)
k
d relative voltage change (%)
E long-term flicker emission limits for the PCC under consideration
plti
E short-term flicker emission limits for the PCC under consideration
psti
f supply/grid frequency (Hz)
g
f (t)
time-varying frequency
f (V ) device flicker characteristics (graphical, tabular/look-up or best-fit formula)
MEC
H significant wave height (m)
m0
I subgrouped RMS current harmonic of harmonic order h
h
th
I h order harmonic current distortion at the PCC
hΣ
th th
I h order harmonic current distortion of the i converter
h,i
measured instantaneous current (A)
i (t)
m
I
rated phase current (A)
r
L inductance of fictitious grid (H)
fic
th
n ratio of the transformer at the i converter
i
N number of marine energy converters connected to the PCC
mec
600 s average value of maximum measured active power of the marine energy
P
converter
P 60 s average value of maximum measured active power of the marine energy
converter
P 0,2 s average value of maximum measured active power of the marine energy
0,2
converter
P long-term flicker disturbance factor
lt
P long-term flicker emission from the sum of marine energy converters
lt∑
P rated active power of marine energy converter (W)
r
P short-term flicker disturbance factor
st
P flicker emission from the marine energy converter unit on the fictitious grid
st,fic
P flicker disturbance factor of an individual marine energy converter
st,i
time-series data of flicker disturbance factor (synthesized)
P (t)
st
P short-term flicker emission from the sum of marine energy converters
st∑
Q reactive power
Q maximum reactive power
max
Q minimum reactive power
min
R resistance of fictitious grid (Ω)
fic
network short-circuit resistance (Ω)
R
k
S short-circuit apparent power of the grid under specified conditions (VA)
k
S short-circuit apparent power of the fictitious grid (VA)
k,fic
– 12 – IEC TS 62600-30:2018  IEC 2018
S
rated apparent power of the marine energy converter (VA)
r
S rated apparent power of the individual marine energy converter unit of a farm (VA)
r,i
T energy period (s)
_e
u (t) instantaneous phase-to-neutral voltage of an ideal voltage source (V)
o
u (t) instantaneous phase-to-neutral voltage simulated at fictitious grid (V)
fic
u (t) measured instantaneous voltage (V)
m
U nominal phase-to-phase voltage (V)
n
v average tidal speed (m/s)
ta
v average water current velocity (m/s)
wa
time varying marine resource (typically synthesized or measured) for a given site
V (t)
MEC
V marine resource (wave, tidal or water current)
MEC
X network short-circuit reactance (Ω)
k
X reactance of fictitious grid (Ω)
fic
5 Abbreviated terms
HV high voltage (> 35 kV)
LV low voltage (< 1 kV)
MV medium voltage (> 1 kV and < 35 kV)
PCC point of common coupling
RMS root mean square
MEC marine energy converter
SCR short circuit ratio
VD voltage drop
6 Marine energy converter power quality characteristic parameters
6.1 Overview
Clause 6 gives the quantities that shall be stated for characterizing the power quality of a
MEC unit, i.e. MEC unit specifications (6.2), voltage fluctuations (6.3), harmonics (6.4),
voltage drop response (6.5), and power control (6.6 to 6.7). A sample report format is given in
Annex A.
Generator sign convention shall be used, i.e. the positive direction of the power flow is
defined to be from the MEC unit to the grid. If the MEC unit is replaced with a resistor and an
inductor, both active and reactive power will be negative.
6.2 Marine energy converter specification
The rated data of the MEC unit (referred to the MEC unit terminals) shall be specified,
including P , S , and U .
r r r
NOTE The rated data are used only for normalizing purposes in this document.

6.3 Voltage fluctuations (continuous operations)
6.3.1 General
The voltage fluctuations caused by the MEC unit shall be characterised as described in 6.3.2
and 6.3.3 for continuous operations, (i.e. no switching voltage fluctuations) for MV and LV
connected systems respectively.
6.3.2 Continuous operation: MV connected systems
th
The MEC unit flicker coefficient for continuous operation, c(ψ ), shall be stated as the 95
k
percentile for the network impedance phase angles ψ = 30°, 50°, 70° and 85° in a table,
k
preferably for three different resource levels. The flicker coefficient for continuous operation
refers to the normalised measure of the flicker emission during continuous operation of the
MEC unit:
S
k,fic
c(ψ )= P ×
k st,fic
S
r
where
P is the flicker emission from the MEC unit on the fictitious grid;
st,fic
S is the rated apparent power of the MEC unit;
r
S is the short-circuit apparent power of the fictitious grid.
k,fic
NOTE The flicker coefficient for continuous operation is the same for a short-term (10 min) and long-term period
(2 h).
These resource levels should represent low, medium and high resource levels at the specific
location. Sample low, medium and high resource levels are given for wave, tidal and water
current converters in Table 1. These values are indicative only as it is acknowledged that the
resources can vary from location to location. The following guidelines apply. For tidal and
current devices, the three resource ranges should be between the cut-in and cut-out flow
velocities. For wave energy devices, it should be ensured that the three sea states chosen
reflect the full operating range of the wave energy device.
Measured flicker coefficients should be reported (in tabular, graphical and/or formula format)
for the whole range of the MEC unit’s operation, i.e. the high resource level selected should
allow specified rated active power output of the MEC unit. Annex A contains a template of the
report.
___________
A flicker coefficient value below which 95 % of the observed values fall.

– 14 – IEC TS 62600-30:2018  IEC 2018
Table 1 – Marine energy – resource classification
2 3
Converter Water current
Wave Tidal
Definition Scatter table/chart of the annual Annual average tidal speed Flow speed information
occurrence of the significant (10 min average, v ) presented in duration curves,
ta
wave height H , energy period where 90 % probability that the
m0 experienced at the rotor whether
flow velocity (annual data with
T ducted/un-ducted, or uni/bi-
–10
10 min average, v ) would
directional
wa
exceed a given threshold
Low v ≤ 1,00 m/s v ≤ 1,00 m/s
ta wa
Medium 1,00 m/s < v <1,75 m/s 1,00 m/s < v <1,75 m/s
ta wa
High 1,25 m/s < v 1,75 m/s < v
ta wa
The characteristics shall be stated for the MEC unit operating with reactive power as close as
possible to zero, i.e. if applicable, the reactive set-point control shall be set to Q = 0. If any
other operational mode is used, this shall be clearly stated.
6.3.3 Continuous operation: LV connected system
The MEC unit short term flicker disturbance factor for continuous operation, P , shall be
st
th
stated as the 95 percentile for the measured condition in a table, preferably for three
different resource levels, as before. Also measured flicker disturbance factor should be
reported (in tabular, graphical and/or formula format) for the whole range of MEC unit’s
operation. Annex A contains a template of the report.
6.4 Current harmonics, interharmonics and higher frequency components
The emission of current harmonics, interharmonics and higher frequency components during
continuous operation shall be measured and recorded. This document considers steady-state
harmonic emissions only, i.e. fault free operation.
The values of the individual current components (harmonics, interharmonics and higher
frequency components) and the total harmonic current distortion shall be given in tables in
percentage of I and for operation of the MEC unit within the active power bins 0 %, 10 %,
n
20 %…, 100 % of P . 0 %, 5 %, 15 %, …, 95 % are the bin midpoints.
r
The individual harmonic current components shall be specified as subgrouped values for
frequencies up to 50 times the fundamental grid frequency, and the total harmonic current
distortion shall be stated as derived from these.
The interharmonic current components shall be specified as subgrouped values for
frequencies up to 2 kHz in accordance to Annex A of IEC 61000-4-7:2002/AMD1:2008.
The higher frequency current components shall be specified as subgrouped values for
frequencies between 2 kHz and 9 kHz in accordance to Annex B of
IEC 61000-4-7:2002/AMD1:2008.
The current harmonics, interharmonics and higher frequency components shall be stated for
the MEC unit operating with reactive power as close as possible to zero, i.e. if applicable the
___________
IEC TS 62600-101:2015, Marine energy – Wave, tidal and other water current converters – Part 101: Wave
energy resource assessment and characterization
IEC TS 62600-201:2015, Marine energy – Wave, tidal and other water current converters – Part 201: Tidal
energy resource assessment and characterization

reactive set-point control shall be set to Q = 0. If another operational mode is used, this shall
be clearly stated.
6.5 Response to voltage drops
The response of the MEC unit to the voltage drops specified in Table 2 shall be stated for the
MEC unit operating between 0,1 P and P . The stated response shall include results from 2
r r
consecutive tests of each case (VD1-VD6) by time series of active power, reactive power,
active current, reactive current and voltage at the MEC unit for the time shortly prior to the
voltage drop and until the effect of the voltage drop has abated. The MEC operational mode
shall be specified.
The test is for verifying the MEC unit response to voltage drops (due to grid faults) and
providing a basis for the MEC numerical simulation model validation. Optional tests and
measurements (for example pitch angle and rotational speed tests in the case of tidal turbines,
or tests using different damping coefficients in the case of wave energy converters) may be
carried out and reported for more detailed assessment of simulation models and compliance
with specific grid code requirements.
Table 2 – Specification of per unit voltage drops (the specified magnitudes,
duration and shape are for the voltage drop occurring as if the MEC under
test is not connected, i.e. without contribution from the installation)
Case Magnitude of voltage Magnitude of positive Duration s Shape
phase to phase (as a sequence voltage
fraction of voltage (as a fraction of
immediately before voltage immediately
the drop occurs) before the drop
occurs)
----- ----
VD1 – symmetrical three-phase 0,90 ± 0,05 0,90 ± 0,05 0,5 ± 0,02 |__|
voltage drop
----- ----
VD2 – symmetrical three-phase 0,50 ± 0,05 0,50 ± 0,05 0,5 ± 0,02 |__|
voltage drop
----- ----
VD3 – symmetrical three-phase 0,20 ± 0,05 0,20 ± 0,05 0,2 ± 0,02 |__|
voltage drop
----- ----
VD4 – two-phase voltage drop 0,90 ± 0,05 0,95 ± 0,05 0,5 ± 0,02 |__|
----- ----
VD5 – two-phase voltage drop 0,50 ± 0,05 0,75 ± 0,05 0,5 ± 0,02 |__|
----- ----
VD6 – two-phase voltage drop |__|
0,20 ± 0,05 0,60 ± 0,05 0,2 ± 0,02

A voltage drop may cause a MEC unit to cut-out for many reasons, not only related to the
electrical drive train but also due to mechanical vibrations or ancillary system low voltage
capabilities. It is therefore necessary to do the test on the complete MEC unit where possible
rather than relying on drive train testing only.
NOTE The purpose of VD1 and VD4 is for testing of MEC units that have no capabilities to ride through any deep
voltage drops, and the tests are generally relevant as basis for validation of numerical simulation models.
The measurements in 6.5 relate to characterizing a MEC unit’s response to a voltage drop
caused by a grid fault. Grid operators can have different requirements for low voltage ride
through (LVRT). While these measurements go somewhat to characterizing an installation’s
LVRT capability they may not meet grid operators grid code compliance requirements. It is
advised that consultation is undertaken with the relevant grid operator to ensure this test is to
their requirements.
– 16 – IEC TS 62600-30:2018  IEC 2018
6.6 Active power
6.6.1 Maximum measured power
The maximum measured active power of the MEC unit shall be specified as a 600 s average
value, P , a 60 s average value, P and as a 0,2 s average value, P . For each
600 60 0,2
measurement, the input resource conditions shall be stated.
6.6.2 Ramp rate limitation
If available, the ability of the MEC unit to operate in ramp rate limitation control mode shall be
characterised by test results presented in a graph. The graph shall show available and
measured active power output during a ramping operation. The ramp rate value achievable by
the MEC shall be presented as a percentage of rated power per minute for a test period of at
least 10 min.
The test results shall be reported as 0,2 s average data.
6.6.3 Set-point control
If available, the ability of the MEC to operate in active power set-point control mode shall be
characterized by test results presented in a graph. The graph shall show available
(extrapolated from resource conditions) and measured active power output during operation at
set point values being adjusted from 100 % down to 20 % of rated power in steps of 20 % with
2 min operation at each set-point value, i.e. according to Figure 1.
The test results shall be reported as 0,2 s average data.
NOTE The ability of a MEC to participate in an automatic frequency control scheme is closely linked to its ability
to operate in active power set-point control mode. Participation in automatic frequency con
...