SIST-TS IEC/TS 62257-9-1:2009

SLOVENSKI STANDARD
SIST-TS IEC/TS 62257-9-1:2009
01-marec-2009
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Recommendations for small renewable energy and hybrid systems for rural electrification
- Part 9-1: Micropower systems
Ta slovenski standard je istoveten z: IEC/TS 62257-9-1
ICS:
27.190 Biološki viri in drugi Biological sources and
alternativni viri energije alternative sources of energy
SIST-TS IEC/TS 62257-9-1:2009 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TS IEC/TS 62257-9-1:2009

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SIST-TS IEC/TS 62257-9-1:2009
IEC/TS 62257-9-1
Edition 1.0 2008-09
TECHNICAL
SPECIFICATION

Recommendations for small renewable energy and hybrid systems for rural
electrification –
Part 9-1: Micropower systems


INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XA
ICS 27.160; 27.180 ISBN 2-8318-9996-6
® Registered trademark of the International Electrotechnical Commission

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CONTENTS
FOREWORD.5
INTRODUCTION.7
1 Scope.8
2 Normative references .9
3 Terms and definitions .9
4 General .11
4.1 Boundary of a micropower plant .11
4.2 Composition of a micropower plant.12
4.3 General functional layout of a micropower plant .12
5 Design.13
5.1 Design criteria .13
5.2 Power generation mix.14
5.2.1 General .14
5.2.2 Internal combustion generator sets.15
5.3 Electrical design.15
5.3.1 System voltage selection .15
5.3.2 Interconnection of generators .15
5.4 Mechanical and civil works .16
5.4.1 Civil works.16
5.4.2 Technical room.16
5.4.3 Battery room.17
5.4.4 Specific requirements .17
6 Safety issues.17
6.1 Electrical issues .17
6.1.1 General .17
6.1.2 Specific requirements .17
6.2 Mechanical issues .21
6.3 Thermal and fire issues .22
6.4 Noise issues.22
6.5 Access security .22
7 Erection of equipment.22
7.1 Siting.22
7.1.1 Photovoltaic array.22
7.1.2 Wind turbine .23
7.1.3 Micro-hydro turbine .23
7.1.4 Generator set .23
7.1.5 Technical room.23
7.2 Equipment installation .24
7.2.1 Mechanical .24
7.2.2 Electrical .24
8 Acceptance process .26
8.1 General .26
8.2 Phase 1: Preparation.27
8.3 Phase 2: Documentation .27
8.4 Phase 3: Commissioning .27

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8.4.1 Step 1: Evaluation of the conformity of the installed system with the
accepted design .27
8.4.2 Step 2: Evaluation of qualification of the installation .27
8.4.3 Step 3: Preliminary tests.27
8.4.4 Step 4: Performance testing .28
8.5 Phase 4: Agreement.28
8.6 Commissioning records .28
9 Operation, maintenance and replacement.28
10 Marking and documentation.29
10.1 Marking .29
10.1.1 Information for emergency services .29
10.1.2 Information for maintenance .29
10.1.3 Information for batteries .29
10.1.4 Information for sockets .29
10.1.5 Signs .29
10.2 Documentation .30
Annex A (informative) Selectivity of protection .31
Annex B (informative) Risk assessment of lightning stroke.32
Annex C (normative) Voltage domains .35
Annex D (informative) Battery room .36
Annex E (informative) Energy fraction calculations .39
Annex F (informative) Noise control .41
Annex G (informative) Commissioning record sheet (examples).43
Bibliography.53

Figure 1 – Micropower system limits .11
Figure 2 – Example of functional layout for a micropower plant supplying a.c. energy.13
Figure 3 – Interconnection configuration with d.c. bus and a.c. bus.16
Figure 4 – Interconnection configuration with a.c. bus only .16
Figure 5 – Example of protection against effects of lightning and over-voltage for
generators with two live conductors output (d.c. or a.c.) TNS P+N .18
Figure 6 – Example of protection against effects of lightning over-voltage for three
phase generators with four live a.c. conductors (TNS P+N scheme) – Generator side.19
Figure 7 – Example of a simplified lightning protection including a crow’s foot earth
termination.20
Figure 8 – Protection of a photovoltaic array.21
Figure 9 – Wiring arrangement for equipotential link .21
Figure A.1 – Example of the selectivity of protection .31

Table 1 – Minimum dimensions for lightning protection wires .20
Table 2 – Cross-section of 230 V a.c. power cables .24
Table 3 – Fuse ratings for protection from short-circuiting in 230 V/400 V a.c. circuits .25
Table 4 – Fuse ratings for protection from short-circuiting in 120 V/208 V a.c. circuits .26
Table 5 – Circuit-breaker ratings for protection from short-circuiting .26
Table B.1 – Stake index values.32
Table B.2 – Construction index values .33

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Table B.3 – Height index values.33
Table B.4 – Situation index values .33
Table B.5 – Lightning prevalence index values .33
Table B.6 – Assessment of risk and need for protection.34
Table C.1 – Voltage domains .35

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

RECOMMENDATIONS FOR SMALL RENEWABLE ENERGY AND
HYBRID SYSTEMS FOR RURAL ELECTRIFICATION –

Part 9-1: Micropower systems


FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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.
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 62257-9-1, which is a technical specification, has been prepared by IEC technical
committee 82: Solar photovoltaic energy systems.
This technical specification is based on IEC/PAS 62111 (1999); it cancels and replaces the
relevant parts of IEC/PAS 62111.

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This technical specification is to be used in conjunction with the IEC 62257 series and with
future parts of this series as and when they are published.
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
82/501/DTS 82/526/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 the parts of the IEC 62257 series, under the general title Recommendations for
small renewable energy and hybrid systems for rural electrification, can be found on the IEC
web site.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result 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.

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INTRODUCTION
The IEC 62257 series of documents intends to provide to the different players involved in
rural electrification projects (such as project implementers, project contractors, project
supervisors, installers, etc.) documents for the setting-up of renewable energy and hybrid
systems with a.c. nominal voltage below 500 V, d.c. nominal voltage below 750 V and nominal
power below 100 kVA.
These documents are recommendations:
• to choose the right system for the right place;
• to design the system;
• to operate and maintain the system.
These documents are focused only on rural electrification concentrating on, but not specific
to, developing countries. They must not be considered as all-inclusive to rural electrification.
The documents try to promote the use of renewable energies in rural electrification; they do
not deal with clean mechanisms developments at this time (CO emission, carbon credit,
2
etc.). Further developments in this field could be introduced in future steps.
This consistent set of documents is best considered as a whole with different parts
corresponding to items for safety, sustainability of systems and at the lowest life-cycle cost as
possible. One of the main objectives is to provide the minimum sufficient requirements,
relevant to the field of application, that is, small renewable energy and hybrid off-grid
systems.

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RECOMMENDATIONS FOR SMALL RENEWABLE ENERGY AND
HYBRID SYSTEMS FOR RURAL ELECTRIFICATION –

Part 9-1: Micropower systems



1 Scope
Decentralized Rural Electrification Systems (DRES) are designed to supply electric power for
sites which are not connected to a large interconnected system, or a national grid, in order to
meet basic needs.
The majority of these sites are
• isolated dwellings;
• village houses;
• community services (public lighting, pumping, health centres, places of worship or
cultural activities, administrative buildings, etc.);
• economic activities (workshops, micro-industry, etc.).
The DRES fall into the following three categories:
• process electrification systems (for example, for pumping);
• individual electrification systems (IES) for single users;
• collective electrification systems (CES) for multiple users.
Process or individual electrification systems exclusively consist of two subsystems:
• an electric energy generation subsystem;
• the user's electrical installation.
Collective electrification systems, however, consist of three subsystems:
• an electric energy generation subsystem;
• a distribution subsystem, also called microgrid;
• user’s electrical installations including interface equipment between the installations
and the microgrid.
This technical specification applies to a micropower plant which is the electric energy
generation subsystem associated with a decentralized rural electrification system.
It provides general requirements for the design, erection and operation of micropower plants
and general requirements to ensure the safety of persons and property.
The micropower plants covered by this specification are low-voltage a.c., three-phase or
single-phase, with rated capacity less than, or equal to, 100 kVA. They do not include voltage
transformation.
The low-voltage levels covered under this specification are
• the 230 V 1-Ø/400 V 3-Ø, the 220 V 1-Ø/380 V 3-Ø, and the 120 V 1-Ø/208 V 3-Ø
systems at 60 Hz or 50 Hz;
• the ELV d.c. systems.

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The requirements cover “centralized” micropower plants for application in
– process electrification;
– individual electrification systems and collective electrification systems.
It does not apply to distributed generation on microgrids.
2 Normative references
The following referenced documents are indispensable for the application 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 60364 (all parts), Low-voltage electrical installations
IEC 60364-5-53:2001, Electrical installations of buildings – Part 5-53: Selection and erection
of electrical equipment – Isolation, switching and control
IEC 60529 (all parts), Degrees of protection provided by enclosures (IP Code)
IEC/TS 62257-2:2004, Recommendations for small renewable energy and hybrid systems for
rural electrification – Part 2: From requirements to a range of electrification systems
IEC/TS 62257-4:2005, Recommendations for small renewable energy and hybrid systems for
rural electrification – Part 4: System selection and design
IEC/TS 62257-5:2005, Recommendations for small renewable energy and hybrid systems for
rural electrification – Part 5: Protection against electrical hazards
IEC/TS 62257-6:2005, Recommendations for small renewable energy and hybrid systems for
rural electrification – Part 6: Acceptance, operation, maintenance and replacement
IEC/TS 62257-7-1:2006, Recommendations for small renewable energy and hybrid systems
for rural electrification – Part 7-1: Generators – Photovoltaic arrays
IEC/TS 62257-7-3:2008, Recommendations for small renewable energy and hybrid systems
for rural electrification – Part 7-3: Generator set – Selection of generator sets for rural
electrification systems
IEC/TS 62257-9-2:2006, Recommendations for small renewable energy and hybrid systems
for rural electrification – Part 9-2: Microgrids
IEC/TS 62257-9-4:2006, Recommendations for small renewable energy and hybrid systems
for rural electrification – Part 9-4: Integrated system – User installation
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
generator set
equipment producing electricity from a fossil fuel; it consists basically of an internal
combustion engine producing mechanical energy and a generator which converts the
mechanical energy into electrical energy and mechanical transmission, support and assembly
components

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3.2
reference earth
reference ground (US)
conductive part of the earth, considered as conductive, the electric potential of which is
conventionally taken as zero, being outside the zone of influence of any earthing arrangement
[IEV 826-13-01]
3.3
skilled person
person with relevant education or experience to enable him/her
• to perceive risks and to avoid hazards which electrical, chemical or mechanical equipment
may create;
• to perform or supervise correctly the required task.
3.4
instructed person
person adequately advised or supervised by skilled persons to enable him/her
• to perceive risks and to avoid hazards which electrical, chemical or mechanical equipment
may create;
• to perform correctly the required task.
3.5
ordinary person
person who is neither a skilled person nor an instructed person
3.6
licenced person
person who is authorized to perform electrical work under the appropriate state or territory
statutes and regulations (only skilled or instructed persons can be licenced)
3.7
microgrid
subsystem of a DRES intended for power distribution of which the capacity does not exceed
100 kVA, the prefix “micro” being intended to express the low level of transmitting capacity
3.8
micropower plant
subsystem of a DRES for power generation up to 100 kVA, the prefix “micro” being intended
to express the low power level generated (from a few kVA to a few tens of kVA)
3.9
protective conductor (identification: PE)
conductor provided for purposes of safety, for example protection against electric shock
[IEV 826-13-22]
3.10
PEN conductor
conductor combining the functions of both a protective earthing conductor and a neutral
conductor
[IEV 826-13-25]

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3.11
power line
overhead or underground line installed to convey electrical energy for any purpose other than
communication
3.12
renewable energy
RE
energy generated from natural resources such as sunlight, wind, rain, waves, tides,
geothermal heat (list not exhaustive), which are renewable (naturally replenished). Renewable
energy technologies include solar power, wind power, hydroelectricity, micro hydro, biomass,
biofuels (list not exhaustive)
3.13
selectivity of protection
ability of a protection to identify the faulty section and/or phase(s) of a power system
[IEV 448-11-06]
3.14
lightning arrester
surge diverter
surge arrester
device intended to protect the electrical apparatus from high transient overvoltages and to
limit the duration and frequently the amplitude of the follow-on current
[IEV 811-31-09]
3.15
technical room/cabinet
room or cabinet in which are located devices and apparatus dedicated to inter-connection of
the different generators, protection of the different circuits, monitoring and control of the
micropower plant and interfacing with the application
4 General
4.1 Boundary of a micropower plant
The micropower plant is defined as illustrated in Figure 1.
    Electrification system
Energy production Distribution Demand
subsystem subsystem subsystem
Microgrid For example, user’s
Micropower
installation
system
Loads
Other
User interface
Generators
equipment
IEC  1530/08

Figure 1 – Micropower system limits

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The physical limits of the micropower plant are the upstream terminals of the main switch
between the micropower plant and the microgrid.
4.2 Composition of a micropower plant
A micropower plant includes:
• one or several generators;
• storage devices (if needed) and associated charge controller;
• other equipment, such as
– energy management device;
– energy converter;
– telecommunication equipment (if any);
– main board;
– interfaces:
– between generators;
– between the micropower plant and the microgrid or the application;
– between the micropower plant and the operator;
– switches;
– protection devices;
• equipotential bonding;
• earthing system;
• civil works.
4.3 General functional layout of a micropower plant
Figure 2 illustrates an example of the general functional layout of a micropower plant
combining the different equipment listed in 4.2.

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TS 62257-9-1 © IEC:2008(E) – 13 –


Generator set room Storage room
Technical room

AC AC DC DC


Battery Charge
Generator Generator Generator Generator
bank controller
Energy manager
1 set 1 2






Energy

converter
Board



To microgrid
or application

IEC  1531/08

Figure 2 – Example of functional layout for a micropower plant supplying a.c. energy
5 Design
5.1 Design criteria
The design of any system should be guided by a number of criteria, determined by the project
implementer (for example, user’s affordable needs, lowest economic life-cycle cost, lowest
environmental impact, site constraints). Some of the major areas to be considered are:
• average daily design d.c. load energy and average daily design a.c. load energy;
• m
...