IEC TR 63282:2024

IEC TR 63282 ®
Edition 2.0 2024-08
TECHNICAL
REPORT
LVDC systems – Assessment of standard voltages and power quality
requirements
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IEC TR 63282 ®
Edition 2.0 2024-08
TECHNICAL
REPORT
LVDC systems – Assessment of standard voltages and power quality

requirements
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.020  ISBN 978-2-8322-9130-6

– 2 – IEC TR 63282:2024 © IEC 2024
CONTENTS
FOREWORD . 7
INTRODUCTION . 9
1 Scope . 10
2 Normative references . 10
3 Terms and definitions . 10
4 Structure of LVDC systems . 14
4.1 General . 14
4.2 Architecture . 14
4.3 Operation modes . 15
4.3.1 Passive DC systems . 15
4.3.2 Active DC systems. 15
5 LVDC voltage division . 16
5.1 General . 16
5.2 Voltage bands . 16
5.3 Operation ranges with respect to DC voltage and time . 18
5.4 States . 19
6 Power quality phenomena relevant to LVDC networks . 19
6.1 General . 19
6.2 Relationships between voltage band and power quality in LVDC systems . 20
6.3 Relationship between oscillation and power quality in LVDC systems . 20
6.4 Supply voltage deviation . 21
6.5 Ripple and high frequency interference . 22
6.6 Voltage swell . 23
6.7 Voltage dip . 24
6.8 Voltage supply interruption . 25
6.9 Rapid voltage change (RVC) . 25
6.10 Voltage surges . 26
6.11 Voltage unbalance . 27
7 Guidance for voltages and power quality in LVDC system. 28
7.1 Considerations for voltages in distribution DC networks . 28
7.1.1 General . 28
7.1.2 Factors considered to define voltage values . 28
7.1.3 DC voltages . 30
7.2 EMC, compatibility and testing of equipment . 31
7.3 Considerations for DC power quality . 33
7.4 Measurement methods . 34
7.4.1 General . 34
7.4.2 DC system electric value integration time . 35
7.4.3 Frequency ranges of ripple spectral analysis . 35
7.4.4 DC power quality measurement methods . 35
7.4.5 DC system electric power measurements . 35
7.5 DC power quality standardization framework . 35
Annex A (informative) PQ waveforms collected from a certain LVDC project . 36
Annex B (informative) A LVDC oscillation typical example . 38
Annex C (informative) Supply radius in DC distribution systems . 40
Annex D (informative) Electric power and power quality computation in DC system . 41

D.1 DC mean and RMS values of voltage or current . 41
D.2 General electric power system: decomposition of a general electric load . 41
D.3 Computation of electric powers and PQ indices . 42
D.3.1 Computation of electric values in time domain . 42
D.3.2 Computation of electric values in frequency domain . 43
D.3.3 Total harmonic distortion T used in AC system . 44
hd
D.3.4 The relation of different electric powers . 45
D.4 Representation of electric powers in AC system . 46
D.5 Representation of electric powers in DC system . 46
D.6 Power quality indices in DC system . 47
D.6.1 General . 47
D.6.2 DC peak-peak ripples . 47
D.6.3 Ripple spectra . 47
D.6.4 DC RMS ripple or ripple distortion. 48
D.7 Illustration example of distortion power in DC system . 50
D.8 Main conclusions on electric value computation in DC system . 50
D.9 Need of characteristics of DC voltage . 51
Annex E (informative) District LVDC system demonstration project in Tongli, China. 52
E.1 Project overview . 52
E.2 Voltage level selection principle . 52
E.3 System operation . 53
Annex F (informative) A typical MV&LVDC distribution system in Wujiang, China . 54
F.1 Project overview . 54
F.2 Voltage selection . 55
Annex G (informative) An office building with general building utilities and office
workplaces . 58
G.1 Sustainable circular building . 58
G.2 Zone system . 61
G.3 Aspects regarding the DC zone classification in DC installation . 67
Annex H (informative) An example of configurations for active DC systems . 68
H.1 General . 68
H.2 Structure . 68
H.3 State of grid (SOG) . 68
Annex I (informative) Preferred voltage in different countries . 73
I.1 Preferred voltage in China . 73
I.2 Preferred voltage in the Netherlands . 75
I.3 Preferred voltage in Germany . 75
Annex J (informative) Voltage with respect to earth . 77
Annex K (informative) CIGRE approaches for DC systems . 80
Annex L (informative) Voltage level in Current OS . 81
L.1 Introduction to the organization . 81
L.2 Voltages used in Current OS . 81
Annex M (informative) Voltage level in DC-INDUSTRY and open DC alliance . 85
M.1 General . 85
M.2 Operating range of the components . 85
M.3 Regulated feeders . 86
M.4 Uncontrolled feeders . 86
M.5 Typical DC loads . 86

– 4 – IEC TR 63282:2024 © IEC 2024
M.6 Converters for energy storage or photovoltaic . 87
M.7 DC breakers . 87
M.8 Nominal voltage . 87
M.9 Voltage bands and limits . 87
M.10 Operating status of the DC grid . 89
M.10.1 General . 89
M.10.2 Duration for the operating statuses . 89
M.10.3 Examples for the operating statuses . 90
M.10.4 Description of operating statuses . 90
Bibliography . 92

Figure 1 – Unipolar, balanced and bipolar DC systems . 15
Figure 2 – Voltage bands in DC systems . 16
Figure 3 – DC Voltage areas for safe interoperability . 18
Figure 4 – Relationships between voltage band and power quality in LVDC systems . 20
Figure 5 − Oscillation example . 21
Figure 6 – Voltage swell example . 24
Figure 7 – Voltage dip example . 25
Figure 8 – RVC event: example of a change in average voltage that results in an RVC
event . 26
Figure 9 – Example of voltage surge . 27
Figure 10 – A schematic of a bipolar system (the CIGRE B4 DC test system) . 28
Figure 11 – LVDC distribution domain and installation domain . 29
Figure 12 – Relation between disturbance levels (schematic significance only) . 31
Figure 13 – LVAC voltage compatibility and immunity levels . 32
Figure A.1 – Voltage deviation caused by load switching . 36
Figure A.2 – Voltage ripple in steady state . 36
Figure A.3 – Voltage dip caused by the start-up of motor load . 37
Figure B.1 – Equivalent topology of the substation . 38
Figure B.2 – The voltage and current oscillation waveform on ±375 V bus . 39
Figure D.1 – Equivalent model of a general electric load . 42
Figure D.2 – Representation of electric powers in AC system . 46
Figure D.3 – Representation of electric powers in DC system . 46
Figure D.4 – Ripples of output DC voltage of positive of a PWM AC/DC converter . 47
Figure D.5 – Spectral analysis of DC voltage and current measured at the input of an

electronic load . 48
Figure D.6 – DC powers caused by intermittent DC current . 50
Figure D.7 – LVAC compatibility level measured in differential mode values . 51
Figure E.1 – Architecture of the district LVDC system in Tongli . 52
Figure F.1 – Location map of the typical MV&LVDC system . 55
Figure F.2 – The structure of the MV&LVDC system in China . 55
Figure G.1 – Office building with general building utilities and office work places . 59
Figure G.2 – Example of zone 0 and zone 1 . 62
Figure G.3 – Example of zone 0, 1 and 2 . 63
Figure G.4 – Example of zone 2 system . 63

Figure G.5 – Purely zone 3 system with the protection devices of distributed sources . 64
Figure G.6 – Example of a zone 4 system with a single source . 64
Figure G.7 – Current OS system overview and safety zones . 65
Figure G.8 – DC zones label . 65
Figure G.9 – Examples of DC zones labels . 66
Figure H.1 – Active DC distribution system . 68
Figure H.2 – DC distribution system with one load and one source . 70
Figure H.3 – DC distribution system with more than one load and a source and
increasing source power . 71
Figure H.4 – Distribution system with more than one load and a source and dump load
active . 71
Figure H.5 – Distribution system with more than one load and source in overloaded
mode . 72
Figure J.1 – DC voltage definitions . 77
Figure J.2 – DC voltage bands relative to earth . 78
Figure J.3 – DC voltages to earth – examples . 79
Figure K.1 – Temporary DC pole to ground voltage profiles in DC systems . 80
Figure L.1 – Threshold of ventricular fibrillation . 81
Figure L.2 – Voltage used in Current OS . 83
Figure L.3 – Voltage bands of different levels . 84
Figure M.1 – Operating ranges of the components (line-to-line voltage) . 85
Figure M.2 – DC voltage of uncontrolled rectifiers (line-to-line) . 86
Figure M.3 – Voltage bands and limits in DC-INDUSTRY . 88
Figure M.4 – Operating status depending on voltage and duration . 90

Table 1 – Voltage between lines (unipolar systems) or line and mid-point (bipolar
systems) for installation domain . 29
Table 2 – Voltage between lines (unipolar systems) or line and mid-point (bipolar
systems) for distribution domain . 30
Table 3 – Immunity test requirements for DC input and output power ports of devices
meant to be used in residential, commercial and light industrial environment . 32
Table 4 – Immunity test requirements for DC input and output power ports of devices
meant to be used in industrial environment . 33
Table 5 – Ripple on DC input power port immunity test . 33
Table C.1 – 1,5 (±0,75) kV typical supply radius of overhead DC lines . 40
Table C.2 – 750 (±375) V, 220 (±110) V typical section supply radius of
overhead DC lines . 40
Table D.1 – Different powers . 50
Table F.1 – The current carrying capacity of medium voltage AC and DC cables . 56
Table F.2 – The voltage level corresponding relationship between AC and DC with the
same transmission capacity . 56
Table F.3 – DC voltage range with modulation ratio limit . 57
Table G.1 – Safety zones and labels . 66
Table G.2 – Functions for different DC zone classification . 67
Table H.1 – Examples in case of 350/700 V DC systems . 69
Table H.2 – Allowed cable voltage drop . 70

– 6 – IEC TR 63282:2024 © IEC 2024
Table I.1 – Nominal voltage in LVDC distribution system . 73
Table I.2 – Nominal voltage in ELVDC equipment . 74
Table I.3 – Comparison between DC and AC system voltages . 75
Table I.4 – Overview of the DC voltage classes (VC) and the corresponding U and
U values . 76
Table M.1 – Nominal voltage in DC-INDUSTRY . 87

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LVDC SYSTEMS –
ASSESSMENT OF STANDARD VOLTAGES
AND POWER QUALITY REQUIREMENTS

FOREWORD
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
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shall not be held responsible for identifying any or all such patent rights.
IEC TR 63282 has been prepared by IEC technical committee 8: System aspects of electrical
energy supply. It is a Technical Report.
This second edition cancels and replaces the first edition published in 2020. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Optimized terms and definitions in Clause 3:
Introduction of new terms and definitions and refining of existing ones.
b) Modified the definition of voltage bands:
In Clause 5, the definition of voltage limits in voltage bands is added, from U to U . The
1 6
definition of voltage bands, from B4 to B7, is modified.

– 8 – IEC TR 63282:2024 © IEC 2024
c) Distinguished the difference between oscillation and power quality phenomenon:
In Clause 3, the definition of oscillation is added based on IEV 103-05-04. In 6.3, relationship
between oscillation and power quality is clarified. Annex B gives a LDC oscillation typical
example which has really happened in a MV&LVDC system in China.
d) Modified the recommended voltage for distribution DC network:
The factors considered in voltage values definition is clarified. And the voltage is divided in
two domains, distribution domain and installation domain. The voltage recommendation in
LVDC is listed corresponding to voltage bands.
e) Modified the voltage immunity level assessment:
It is mentioned in 7.2 that the assessment of voltage immunity levels of mass LVDC power
electronic devices need to be further discussed, ripple as an example is introduced.
f) Added DC power quality measurement methods:
In 7.3, DC power quality measurement methods is introduced based on AC methodologies.
And some additional DC power quality indices are recommended to assess the DC system.
DC electric power and power quality measurement methods are introduced in 7.4, defining
the electric value integration time and frequency ranges.
Typical electric power and power quality computation methods are modified in Annex D.
g) Added an annex on MVDC system:
A use case of a typical MV&LVDC distribution system is added in Annex F, to support
developments of TS of 8A and 8B on DC microgrids.
h) Added an annex on Current OS voltage level:
The voltage level applied in Current OS is introduced in Annex L to give more information
on the LVDC voltage level recommendation.
The text of this Technical Report is based on the following documents:
Draft Report on voting
8/1695/DTR 8/1704/RVDTR
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 Report is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/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, or
• revised.
IMPORTANT – The "colour inside" logo on the cover page of this document 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
LVDC (low voltage direct current) distribution systems have recently been recognized by a
number of stakeholders as an alternative approach to provide efficient power supply to the
consumers. LVDC covers a wide range of power applications from USB-C up to megawatts for
aluminium melting. LVDC is seen as a solution for greener and more sustainable energy
systems in developed economies as well as an alternative option for electricity access in
developing countries.
In industrial applications, LVDC is utilized where processing of resources results in the
production, distribution and storage of physical goods, especially in a factory or special area of
a factory.
The standardization of DC voltages is a key issue, and urgent work is needed. Existing LVAC
systems have different standard voltages, depending on the geography and application. LVDC
distribution voltages are optimized to provide a good context for industries that import and
export equipment but also for general travellers. Appropriate international LVDC voltage ranges
will provide a basis for design and testing of electrical equipment and systems and ease of
transition for equipment from AC to DC supply.
LVDC voltages meet the range of use cases where LVDC systems can make a difference. The
list of standard voltages is as short as possible and allow for cost-effective and safe operation.
The PQ (power quality) issues in DC power systems are not identical to those in AC systems,
but there are some common issues. Power quality considerations are well studied and
standardized on AC power systems, but many power quality phenomena and EMC have not yet
been fully identified and evaluated for DC distribution systems.
Power electronic converters/inverters add further demands. Power quality phenomena in LVDC
distributed systems can be related to the structure of the entire system, and the operating
condition of sources and loads. At the same time, the DC output performance of a single
converter and the coordination among several converters can also result in different power
quality issues and grid stability.
Requirements for power quality and EMC in LVDC distribution are established in order to
provide a solid basis for the planning and operation of LVDC distribution systems. In addition,
the design and configuration of the protection system is addressed with the objective of
enhancing the availability of the source, the reliability, and the lifetime of the system.
Generally, the standardization of voltage level and PQ phenomena of LVDC distribution greatly
stimulate the wide adoption of LVDC.
This document provides information on the following topics: standard voltages, EMC
requirements, power quality, and measurement methods.

– 10 – IEC TR 63282:2024 © IEC 2024
LVDC SYSTEMS –
ASSESSMENT OF STANDARD VOLTAGES
AND POWER QUALITY REQUIREMENTS

1 Scope
The purpose of this document is to collect information and report experience for the
standardization of voltage levels and related aspects (power quality, EMC, measurement, etc.)
for LVDC systems (systems with nominal voltage up to and including 1 500 V DC).
Rationale for the proposed voltage values is given. Variation of parameters for the voltage
(power quality) for their boundaries are defined. Nevertheless, some of the technical items are
not exhaustively explained in this document and some gaps are identified for future work.
Attention is paid to the definition of DC voltage.
Systems in which a unipolar voltage is interrupted periodically for certain purposes, e.g. pulse
voltage, are not considered.
Traction systems are excluded from this document.
This document gives technical inputs to TCs in charge of the standardization of different issues
and coordinated by SyC LVDC.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
nominal system voltage
suitable approximate value of voltage used to designate or identify a system
[SOURCE: IEC 60050-601:1985, 601-01-21, modified − The term has been changed from
"nominal voltage of a system" to "nominal system voltage".]
3.2
DC supply voltage
line-to-line or line-to-mid-point voltage at the supply terminals
3.3
bipolar DC system
DC system comprising a positive and negative line, and a mid-point, distributed or not

3.4
unipolar DC system
DC system comprising a positive or a negative line, and a mid-point
3.5
DC system nominal voltage
U
n
value of the voltage by which the electrical installation or part of the electrical installation is
designated and identified
Note 1 to entry: The DC system nominal voltage U is within the nominal band [U ; U ] but not always half-way
n 2 3
between U and U . In all cases
2 3
U ≤ U ≤ U
2 n 3
Note 2 to entry: For a bipolar system, it is recommended to use a dual notation, for example, "±U " or "U / U ".
L-M L-M L-L
3.6
DC voltage deviation
voltage deviation due to the slow change in power system operation state
Note 1 to entry: Voltage deviation is the difference between actual voltage and nominal system voltage when the
change rate of the average DC voltage is in the appropriate speed in order to limit the deviation in an acceptable
range.
3.7
voltage unbalance
condition in a bipolar system in which the line to mid-point voltages are not equal
3.8
ripple
set of unwanted periodic deviations with respect to the average value of the measured or
supplied quantity, occurring at frequencies which can be related to that of the mains supply, or
of some other definite source, such as a chopper or load changes
Note 1 to entry: Ripple is determined under specified conditions and is a part of PARD (Periodic and/or random
deviation). It may be assessed by instantaneous value or RMS value.
Note 2 to entry: Sources of ripple may include, but are not limited to, voltage regulation instability of the DC power
source, commutation/rectification within the DC power source, and load variations within utilization equipment.
Note 3 to entry: Ripple is determined as well in percentage to the DC component and in RMS value computed in
line with CISPR for conducted disturbances. Ripple can be hundreds of kHz.
[SOURCE: IEC 60050-312:2001, 312-07-02, modified – "or load changes" has been added at
the end of the definition, a sentence has been added to Note 1 to entry; Notes 2 and 3 to entry
have been added.]
3.9
over-voltage
voltage the value of which exceeds a specified limiting value
[SOURCE: IEC 60050-151:2001,151-15-27]
3.10
under-voltage
voltage the value of which is lower than a specified limiting value
[SOURCE: IEC 60050-151:2001,151-15-29]

– 12 – IEC TR 63282:2024 © IEC 2024
3.11
voltage swell
sudden increase of the voltage at a point in the electrical supply system followed by voltage
recovery after a short period of time
Note 1 to entry: Application: for the purpose of this document, the swell start threshold is equal to the 110 % of the
reference voltage (see CLC/TR 50422: 2013, Clause 3, for more information).
Note 2 to entry: For the purpose of this document, a voltage swell is a two-dimensional electromagnetic disturbance,
the level of which is determined by both voltage and time (duration).
3.12
voltage dip
sudden decrease of the voltage at a point in the electrical supply system followed by voltage
recovery after a short period of time
Note 1 to entry: The residual voltage can be expressed as a value in volts, or as a percentage or per unit value
relative to the reference voltage.
[SOURCE: IEC 60050-614:2016, 614-01-08, modified – "Reduction" has been changed to
"decrease", " electric power system" has been changed to "electrical supply system", "time
interval" has been changed to "period of time", reference to sinusoidal voltage has been
removed.]
3.13
voltage surge
transient voltage wave propagating along a line or a circuit and characterized by a rapid
increase followed by a slower decrease of the voltage
[SOURCE: IEC 60050-161:1990, 161-08-11]
3.14
voltage supply interruption
disappearance of the supply voltage for a time interval whose duration is between two specified
limits
[SOURCE: IEC 60050-161:1990, 161-08-20, modified – In the term, "short interruption (of
supply voltage)" has been changed to "voltage supply interruption", the note has been deleted.]
3.15
rapid voltage change
RVC
quick transition in voltage occurring between two steady-state conditions, and during which the
voltage does not exceed the under-voltage/over-voltage thresholds
3.16
oscillation
physical phenomenon characterized by one or more alternately increasing and decreasing
quantities
Note 1 to entry: Oscillation in LVDC system is characterized by an electromagnetic parameter (voltage current,
power, etc.) in the system alternately increasing and decreasing. The phenomenon can be caused by interference,
parameter mismatch or control stability issues.
[SOURCE: IEC 60050-103:2019,103-05-04, modified – Note 1 to entry has been completely
changed.]
3.17
DNO
distribution network operator
party operating a distribution network

3.18
DSO
distribution system operator
party extending the function of a DNO to incorporate active management of some power
resources
3.19
U
+
positive voltage
voltage between the positive line and the mid-point
Note 1 to entry: Only defined for bipolar DC systems.
3.20
U
−
negative voltage
voltage between the negative line and the mid-point
Note 1 to entry: Only defined for bipolar DC systems.
3.21
balanced voltage
U
b
average of the positive and the negative voltage
Note 1 to entry: U = (|U | + |U |)/2.
b − +
Note 2 to entry: Only defined for bipolar DC systems.
3.22
unbalanced voltage
U
u
average difference of the positive and the negative voltage
Note 1 to entry: U = (U − U )/2.
u + −
Note 2 to entry: Only defined for bipolar DC systems.
3.23
mid-point
common point between two symmetrical circuit elements the opposite ends of which are
electrically connected to different line conductors of the same circuit
Note 1 to entry: Only defined for bipolar DC systems.
[SOURCE: IEC 60050-195:2021, 195-02-04, modified – "of which the opposite ends" has been
changed to "the opposite ends of which" and the note to entry has been added.]
3.24
under-voltage ride through
capability of equipment to stay connected and continue functioning during voltage dips
3.25
DC voltage
voltage equal to its average value during a defined time interval
3.26
over-voltage ride through
capability of equipment to stay connected and continue functioning during voltage swells

– 14 – IEC TR 63282:2024 © IEC 2024
4 Structure of LVDC systems
4.1 General
The low-voltage DC systems described consist of loads, applications, electricity generation
devices, and storage devices that are connected with each other with a direct current (DC)
system/installation. Thus, as far as the recommended voltages and power qualities of certain
LVDC systems are concerned, different analysis dimensions and elements are taken into
consideration, including different architectures, operation modes, etc.
NOTE A LVDC system includes publ
...