IEC TS 62257-7-4:2019

IEC TS 62257-7-4 ®
Edition 1.0 2019-05
TECHNICAL
SPECIFICATION
Recommendations for renewable energy and hybrid systems for rural
electrification –
Part 7-4: Generators – Integration of solar with other forms of power generation
within hybrid power systems
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IEC TS 62257-7-4 ®
Edition 1.0 2019-05
TECHNICAL
SPECIFICATION
Recommendations for renewable energy and hybrid systems for rural

electrification –
Part 7-4: Generators – Integration of solar with other forms of power generation

within hybrid power systems
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-6823-0

– 2 – IEC TS 62257-7-4:2019 © IEC 2019
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 6
4 Overview . 6
5 Types of hybrid systems. 7
5.1 General . 7
5.2 Multi-master rotating machine dominated mini-grid . 7
5.2.1 General . 7
5.2.2 Design. 8
5.2.3 Design and selection of diesel generators . 8
5.2.4 Design and selection of renewable energy component. 9
5.2.5 Design and selection of batteries . 9
5.2.6 Control system . 9
5.3 Single switched master mini-grid . 10
5.3.1 General . 10
5.3.2 Design. 11
5.3.3 Design and selection of diesel generators . 12
5.3.4 Design and selection of renewable energy component. 12
5.3.5 5.2.4 Design and selection of batteries . 12
5.3.6 System control . 13
5.4 Multi-master inverter dominated mini-grid . 14
5.4.1 General . 14
5.4.2 Design. 15
5.4.3 Design and selection of diesel generators . 15
5.4.4 Design and selection of renewable energy component. 15
5.4.5 Design and selection of batteries . 15
5.4.6 Control . 15

Figure 1 – Typical multi-master rotating machine dominated mini-grid architecture . 8
Figure 2 – Single switched master mini-grid architecture . 11
Figure 3 – Multi-master inverter dominated mini-grid architecture . 14

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
RECOMMENDATIONS FOR RENEWABLE ENERGY
AND HYBRID SYSTEMS FOR RURAL ELECTRIFICATION –

Part 7-4: Generators – Integration of solar w ith other forms
of pow er generation w ithin hybrid power systems

FOREWORD
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The main task of IEC technical committees is to prepare International Standards. In
exceptional circumstances, a technical committee may propose the publication of a Techni c al
Specification when
• the required support cannot be obtained for the publication of an Internatio n a l S t a n d a r d ,
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 Specification are subject to review within three years of publication to decide
whether they can be transformed into International Standards.
IEC TS 62257-7-4, which is a Technical Specification, has been prepar ed by IE C t ec hni c al
committee 82: Solar photovoltaic energy systems.

– 4 – IEC TS 62257-7-4:2019 © IEC 2019
The text of this Technical Specification is based on the following documents:
Draf t TS Report on voting
82/1477/DTS 82/1545A/RVDTS
Full information on the voting for the approval of this Technical Specification can be found i n
the report on voting indicated in the above table.
This part of IEC 62257 is to be used in conjunction with IEC 62257 (all parts).
A list of all parts in the IEC 62257 series, published under the general title Recommendations
for renewable energy and hybrid systems for rural electrification, can be found on the IEC
website.
Future standards in this series will carry the new general title as cited above. Titles of existing
standards in this series will be updated at the time of the next edition.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related t o
the specific document. At this date, the document 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.

RECOMMENDATIONS FOR RENEWABLE ENERGY
AND HYBRID SYSTEMS FOR RURAL ELECTRIFICATION –

Part 7-4: Generators – Integration of solar w ith other forms
of pow er generation w ithin hybrid power systems

1 Scope
This part of IEC 62257, which is a technical specification, specifies the design and
implementation of hybrid off-grid solar systems, where solar energy provides energy to a l o a d
in conjunction with other sources of energy. Such sy stems may or may not include an energy
storage system. There are a variety of different system architectures and appl i c at ions , and
many ways in which these energy sources can be combined. Th i s doc um ent di s t inguis hes
between different sorts of hybrid system applications and gives guidance on t he des i gn and
integration of these systems.
It applies to single-phase and three-phase applications, and it covers situations where gri d i s
available as an additional source of power for charging batteries and maintaining system
reliability, but this document does not cover situations in which energy is fed back into a utility
grid, although such systems may incidentally possess this function.
2 Normative references
The following documents are referred to in the text in such a way the some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC TS 61836, Solar photovoltaic energy systems – Terms, definitions and symb ols
IEC TS 62257-7-2, Recommendations for renewable energy and hybrid systems for rural
electrification – Part 7-2: Generator set – Off-grid wind turb ines
IEC TS 62257-7-3, Recommendations for renewable energy and hybrid systems for rural
electrification – Part 7-3: Generator set – Selection of generator sets for rural e l e c t r ifi ca ti o n
systems
IEC TS 62257-9-7, Recommendations for renewable energy and hybrid systems for rural
electrification – Part 9-7: Selection of inverters
IEC 62509, Battery charge controllers for
...