EN IEC 61970-456:2018

SLOVENSKI STANDARD
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Energy management system application program interface (EMS-API) - Part 456: Solved
power system state profiles
Schnittstelle für Anwendungsprogramme für Netzführungssysteme (EMS-API) - Teil 456:
Globale Stabilitätsbeurteilung
Interface de programmation d'application pour système de gestion d'énergie (EMS-API) -
Partie 456: Profils d'état de réseaux électriques résolus
Ta slovenski standard je istoveten z: EN IEC 61970-456:2018
ICS:
29.240.30 Krmilna oprema za Control equipment for electric
elektroenergetske sisteme power systems
35.200 Vmesniška in povezovalna Interface and interconnection
oprema equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 61970-456

NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2018
ICS 33.200 Supersedes EN 61970-456:2013
English Version
Energy management system application program interface
(EMS-API) - Part 456: Solved power system state profiles
(IEC 61970-456:2018)
Interface de programmation d'application pour système de Schnittstelle für Anwendungsprogramme für
gestion d'énergie (EMS-API) - Partie 456: Profils d'état de Netzführungssysteme (EMS-API) - Teil 456: Globale
réseaux électriques résolus Stabilitätsbeurteilung
(IEC 61970-456:2018) (IEC 61970-456:2018)
This European Standard was approved by CENELEC on 2018-04-23. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden,
Switzerland, Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61970-456:2018 E

European foreword
The text of document 57/1951/FDIS, future edition 2 of IEC 61970-456, prepared by IEC/TC 57
"Power systems management and associated information exchange" was submitted to the
IEC-CENELEC parallel vote and approved by CENELEC as EN IEC 61970-456:2018.

The following dates are fixed:
• latest date by which the document has to be (dop) 2019-01-23
implemented at national level by
publication of an identical national
standard or by endorsement
(dow) 2021-04-23
• latest date by which the national
standards conflicting with the
document have to be withdrawn
This document supersedes EN 61970-456:2013.

Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.

This document has been prepared under a mandate given to CENELEC by the European Commission
and the European Free Trade Association.

Endorsement notice
The text of the International Standard IEC 61970-456:2018 was approved by CENELEC as a
European Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:

IEC 61970-1 NOTE Harmonized as EN 61970-1.
IEC/TS 61790-2 NOTE Harmonized as CLC/TS 61790-2.
IEC 61790-301 NOTE Harmonized as EN 61790-301.
IEC 61790-501 NOTE Harmonized as EN 61790-501.
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

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.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 61970-452 2017 Energy management system application EN 61970-452 2017
program interface (EMS-API) - Part 452:
CIM static transmission network model
profiles
IEC 61970-453 2014 Energy Management System Application EN 61970-453 2014
Program Interface (EMS-API) -- Part 453:
Diagram Layout Profile
IEC 61970-552 2016 Energy management system application EN 61970-552 2016
program interface (EMS-API) - Part 552:
CIMXML Model exchange format
IEC 61970-456 ®
Edition 2.0 2018-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Energy management system application program interface (EMS-API) –

Part 456: Solved power system state profiles

Interface de programmation d'application pour système de gestion d'énergie

(EMS-API) –
Partie 456: Profils d'état de réseaux électriques résolus

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.200 ISBN 978-2-8322-5440-0

– 2 – IEC 61970-456:2018 © IEC 2018
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Profile information . 8
5 Overview . 8
6 Use cases . 13
6.1 Overview. 13
6.2 EMS network analysis integration . 15
6.3 Power flow based network analysis . 16
7 Data model with CIMXML examples . 21
7.1 Use of the interfaces . 21
7.1.1 Overview . 21
7.1.2 Network model boundaries . 21
7.1.3 Bus-branch and node-breaker models . 24
7.2 Topology (TP) interface . 27
7.3 State Variables (SV) interface . 29
7.4 Steady State Hypothesis (SSH) interface . 31
8 Profiles . 31
8.1 Comments and notes . 31
8.2 SteadyStateHypothesis profile . 32
8.2.1 General . 32
8.2.2 Concrete Classes . 33
8.2.3 Abstract Classes. 46
8.2.4 Data Types . 53
8.3 Topology profile . 55
8.3.1 General . 55
8.3.2 Concrete Classes . 55
8.3.3 Abstract Classes. 57
8.4 StateVariables profile . 58
8.4.1 General . 58
8.4.2 Concrete Classes . 58
8.4.3 Abstract Classes. 64
8.4.4 Data Types . 65
Bibliography . 67

Figure 1 – Relations between MAS, profile and dataset . 9
Figure 2 – Profile relationships . 11
Figure 3 – Connectivity model example . 12
Figure 4 – The European power system with regions . 14
Figure 5 – Information exchange in power flow and sharing of results . 15
Figure 6 – EMS datasets to an external client . 16
Figure 7 – Node-breaker power flow Integration architecture . 17

IEC 61970-456:2018 © IEC 2018 – 3 –
Figure 8 – Bus-branch power flow Integration architecture . 17
Figure 9 – Boundary injection model . 18
Figure 10 – Alternate boundary modelling . 19
Figure 11 – Assembled model alternatives . 20
Figure 12 – Line boundary dataset example . 22
Figure 13 – Substation boundary dataset example . 22
Figure 14 – Power Flow on an assembledd model . 23
Figure 15 – Power Flow on a regional network part . 24
Figure 16 – CIM relation between ConnectivityNode and TopologicalNode . 25
Figure 17 – Bus-branch modeling of bus coupler and line transfer . 26
Figure 18 – CIM topology model . 27
Figure 19 – Topology solution interface . 28
Figure 20 – CIM state variable solution model . 29
Figure 21 – State solution interface example . 30

Table 1 – Profiles defined in this document . 8

– 4 – IEC 61970-456:2018 © IEC 2018
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ENERGY MANAGEMENT SYSTEM APPLICATION
PROGRAM INTERFACE (EMS-API) –
Part 456: Solved power system state profiles

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 itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
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
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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.
International Standard IEC 61970-456 has been prepared by IEC technical committee 57:
Power systems management and associated information exchange.
This second edition cancels and replaces the first edition published in 2013 and Amendment
1:2015. This edition constitutes a technical revision. It is based on the IEC 61970 UML CIM16
version 33.
This edition includes the following significant technical changes with respect to the previous
edition:
a) The Steady State Hypothesis (SSH) profile has been added in new Subclause 8.2.
b) Clause 5 "Overview" has been extended to better describe the relation between different
profiles and aligned with the current nomenclature used with profiles, e.g. "data set" and
"network part".
IEC 61970-456:2018 © IEC 2018 – 5 –
c) The former Clause 6 "Architecture" has been shrunk and merged with Clause 6 "Use
cases".
d) The former Clause 7 "Applying the standard to business problems" has been split and
merged with Clause 6 "Use cases" and Clause 7 "Data model with CIMXML examples".
e) Clause 6 "Use cases" description of the use cases has been extended.
f) The former Clause 8 "Data model with CIMXML examples" has become section 7 "Data
model with CIMXML examples".
g) The CIMXML document examples in Clause 7 "Data model with CIMXML examples" has
been updated to match with IEC 61970-552:2016.
h) Clause 8 "Profiles" describe the actual profile data.
i) Subclause 8.1 "Comments and notes" gives additional information on the use some profile
data.
The text of this International Standard is based on the following documents:
FDIS Report on voting
57/1951/FDIS 57/1963/RVD
Full information on the voting for the approval of this International Standard 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 in the IEC 61970 series, published under the general title Energy
management system application program interface (EMS-API), can be found on the IEC
website.
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 to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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 – IEC 61970-456:2018 © IEC 2018
INTRODUCTION
This document is one of several parts of the IEC 61970 series that defines common
information model (CIM) datasets exchanged between application programs in energy
management systems (EMS).
The IEC 61970-300 series specifies the common information model (CIM). The CIM is an
abstract model that represents the objects in an electric utility enterprise typically needed to
model the operational aspects of a utility.
This document is one of the IEC 61970-400 series of component interface standards that
specify the semantic structure of data exchanged between components (or applications)
and/or made publicly available data by a component. This document describes the payload
that would be carried if applications are communicating via a messaging system, but the
standard does not include the method of exchange, and therefore is applicable to a variety of
exchange implementations. This document assumes and recommends that the exchanged
data is formatted in XML based on the resource description framework (RDF) schema as
specified in IEC 61970-552 CIM XML model exchange standard.
IEC 61970-456 specifies three profiles:
• The Steady State Hypothesis (SSH) profile that describe power flow application input
variables such as voltage set points, switch statuses etc.
• The topology profile that describe a bus-branch model. A topology model may be created
by a network model builder from a node-breaker model and SSH inputs or by a tool where
a user interactively builds a topology model. A topology model is input to power flow
applications.
• State variables solution from a power system case such as is produced by power flow or
state estimation applications.
IEC 61970-456 describes the dynamic value inputs and solutions with reference to a power
system model that conforms to IEC 61970-452 in this series of related standards. The
separation of information into profiles also enables separation of data into documents
corresponding to the profiles. In this way the profiles defined in this document generate small
data documents compared with traditional bus-branch or node-breaker formats that include
the network, the initial conditions and the result.

IEC 61970-456:2018 © IEC 2018 – 7 –
ENERGY MANAGEMENT SYSTEM APPLICATION
PROGRAM INTERFACE (EMS-API) –
Part 456: Solved power system state profiles

1 Scope
This part of IEC 61970 belongs to the IEC 61970-450 to IEC 61970-499 series that, taken as
a whole, define at an abstract level the content and exchange mechanisms used for data
transmitted between power system analyses applications, control centers and/or control
center components.
The purpose of this document is to rigorously define the subset of classes, class attributes,
and roles from the CIM necessary to describe the result of state estimation, power flow and
other similar applications that produce a steady-state solution of a power network, under a set
of use cases which are included informatively in this standard.
This document is intended for two distinct audiences, data producers and data recipients, and
may be read from those two perspectives. From the standpoint of model export software used
by a data producer, the document describes how a producer may describe an instance of a
network case in order to make it available to some other program. From the standpoint of a
consumer, the document describes what that importing software must be able to interpret in
order to consume power flow cases.
There are many different use cases for which use of this document is expected and they differ
in the way that the document will be applied in each case. Implementers are expected to
consider what use cases they wish to cover in order to know the extent of different options
they must cover. As an example, this document will be used in some cases to exchange
starting conditions rather than solved conditions, so if this is an important use case, it means
that a consumer application needs to be able to handle an unsolved state as well as one
which has met some solution criteria.
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 61970-452:2017, Energy management system application program interface (EMS-API) –
Part 452: CIM static transmission network model profiles
IEC 61970-453:2014, Energy management system application program interface (EMS-API) –
Part 453: Diagram layout profile
IEC 61970-552:2016, Energy management system application program interface (EMS-API) –
Part 552: CIMXML Model exchange format
3 Terms and definitions
No terms and definitions are listed in this document.

– 8 – IEC 61970-456:2018 © IEC 2018
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
4 Profile information
The profiles defined in this document are based on the UML version CIM16v33.
The profiles are listed in Table 1.
Table 1 – Profiles defined in this document
Name Version URI
SteadyStateHypothesis 1 http://iec.ch/TC57/2013/61970-456/SteadyStateHypothesis/1
(SSH)
Topology (TP) 4 http://iec.ch/TC57/2013/61970-456/Topology/4
StateVariables (SV) 4 http://iec.ch/TC57/2013/61970-456/StateVariables/4

5 Overview
This document describes an interface standard in which XML payloads are used to transfer
initial conditions and results created during typical steady-state network analysis processes
(e.g. state estimation or power flow solutions). Major requirements/objectives driving the
design of this document include:
• Power flow solution algorithms and outputs are virtually the same whether run in
operations or planning contexts. State estimator output shares a common core with power
flow. A single standard is desired so as to minimize software development and enable use
cases that cross between environments.
• While some users of this standard might only be interested in the output state, the more
general situation is that users continue to perform follow-on analyses (e.g. security
analysis, voltage stability) and require both the input on which the solution was based and
the output result.
• Real life analytical processes often involve a series of solutions in which most of the input
data remains the same from one solution to the next, and the standard must support these
processes in a way that does not repeat data unnecessarily.
• Power flow solutions tend to drift if the result from a power flow run is used as input to a
subsequent power flow run. By preserving the initial conditions between power flow runs
the solutions do not drift.
In order to meet these requirements, this document depends on modularizing the potentially
voluminous overall input and output data into subsets that would each be realized as smaller,
XML payloads. An instance of one of these subsets is referred to herein as a ‘dataset’. Data
set payloads are typically compressed to a zip archive.
Two types of partitioning into datasets are utilized. In the first, the data is modularized
according to what kind of data is produced (which generally corresponds with what kind of
application produces the data). CIM ‘profiles’ (subsets of the complete CIM) define the
classes and attributes that make up of each kind of modularization. The second type of
partitioning is by network parts, which divides data into sets of instances according to which
utility or entity in an interconnection is responsible for the data. The party responsible for data
is called the Model Authority of the data and the network parts are defined by Model Authority
Sets (MAS). This partitioning occurs at the instance level and produces multiple datasets

IEC 61970-456:2018 © IEC 2018 – 9 –
governed by a profile and network part. Datasets from different MAS combine to form the
complete set of data for that profile, Figure 1 illustrates this.
MAS BE
(Belgium)
MAS NL
(Netherlands)
MAS
BE-NL
Boundary
Profiles
EQ
SSH TP SV
A dataset or xml payload
IECI
Figure 1 – Relations between MAS, profile and dataset
Different IEC 61970 profiles are listed along the horizontal axis:
• EQ for equipment as described in IEC 61970-452.
• SSH for power flow initial data as described in this document.
• TP for topology data as described in this document.
• SV for state variables data as described in this document.
A few example Model Authority Sets are listed along the vertical axis:
• MAS BE represent a regional Model Authority Set for Belgium that is a network part
defined by a Model Authority BE, e.g. the Belgian TSO.
• MAS NL represent a regional Model Authority Set for Netherlands that is a network part
defined by another Model Authority NL, e.g. the Netherlands TSO.
• MAS BE-NL Boundary represent a Model Authority Set that is a network part for the
boundary between MAS BE and MAS NL. The boundary network part is typically agreed
mutually between Model Authority BE and NL.
The document symbol in Figure 1 describe a dataset packaged as a payload, e.g. a CIMXML
document as described in IEC 61970-552.
The Model Authority Sets along the vertical axis in Figure 1 define parts of a network.
Datasets belong to a Model Authority Set and this is indicated in Figure 1 by the horizontally
aligned datasets at each MAS.
Network parts
– 10 – IEC 61970-456:2018 © IEC 2018
The profiles along the horizontal axis in Figure 1 describe a subset of the CIM canonical data
used for a particular purpose. A dataset Figure 1 contain data for a specific profile and this is
indicated in Figure 1 by the vertically aligned datasets at each profile.
At each crossing point between a Model Authority Set and profile there is a stack of datasets
meaning that for this particular Model Authority Set and profile there may be many datasets
e.g. representing different points in time or different study cases. The ways datasets can be
created and combined is dependent on the use case. Specifications that better support use
cases on how to combine datasets an explicit CIM model for Model Authority Sets is being
developed and will be released in the future.
This document is flexible and designed to satisfy a wide range of analytical scenarios in the
planning and operating business environments. We expect that where parties are using it to
collaborate in some business process, those parties will often want to create additional
business agreements that describe any restrictions and customizations of the document that
are deemed necessary for their process. In most cases, these additional agreements will be
local agreements and will not be IEC industry standards.
This document does not specify a serialization format on its own but does so in companion
with specification for CIMXML payloads is defined in IEC 61970-552. This method of
serialization has the several useful characteristic
• The serialization format for a profile is defined by rules in IEC 61970-552 that describe the
format based on the semantic model from the profile.
• Valid XML describing a complete model could be achieved simply by concatenating the
CIMXML documents for each partial or profile document. Thus ‘merge’ and ‘extract’ of
pieces of the modeling require no separate ‘stitching’ instructions and is conceptually a
very simple process.
• IEC 61970-552 also describes how payload headers provide information as to how
payloads fit together.
Figure 2 shows some of the profiles that are covered by the IEC 61970-450 to IEC 61970-499
series and depicts the relationships between them. The profiles are defined in different
IEC 61970-450 specifications where each specification defines a group of profiles:
• Static network model profiles defined in IEC 61970-452
– Equipment profile. The static modelling information describing power system physical
elements and their electrical connections;
– Measurement profile that defines the existence of measurements and their relations to
power system equipment.
• Schematic display layout exchange profiles defined in IEC 61970-453
– Schematic layout exchange profile. Describe the elements of schematic or geographic
displays that typically shall be amended when new elements are added to a network
model.
• Initial and solved power system state profiles defined in IEC 61970-456 (this document)
– Steady State Hypothesis profile that provide the initial conditions to power flow. This
profile have numerous sources, e.g. State Estimator or cases set up in a study;
– Topology profile. The topology result as is produced by a network model builder;
– State Variables profile. The result of a power flow calculation.

IEC 61970-456:2018 © IEC 2018 – 11 –

IEC 61970-456 IEC 61970-451
profiles profiles
Steady
Discrete
State
State
measurements
Variables
Hypotesis
(SV)
(SSH)
Analog
Topology
measurements
(TP)
IEC 61970-452
Equipment
model
profiles
(EQ)
IEC 61970-453
Display
profiles
layouts
(DL)
IEC
Figure 2 – Profile relationships
These modules satisfy the needs of network analysis business processes used in operations,
in planning studies, as well as for transfers between operations and planning. The
IEC 61970-451 profiles that support transfer of SCADA measurements to EMS applications do
not yet exist and is planned work.
Network models used in operations include detailed descriptions of measurements and their
location in the network and switching devices, such models are called node-breaker models.
Network models used in planning may not have this level of detail and typically exclude
measurements and switching devices. Instead of computing the power flow buses
(TopologicalNodes) from switching device statuses the power flow buses are maintained
manually.
It assumed that node-breaker and bus-branch models will be combined in the future to enable
sharing of the same models between operations and planning.
In Figure 2, an arrow between profiles indicates that there are relationships defined between
classes in the two profiles. The directionality indicates that classes in the “from” profile
depend on classes in the “to” profile. For data this means that “from” class data refers to or
depends on “to” class data. Example: a dataset of an equipment model may have many
Topology, State Variable and Steady State Hypothesis datasets that refer to it.
In IT-systems, datasets corresponding to the profiles in Figure 2, are exchanged between
functions and/or applications. Some examples of applications and their dataset exchange are
described in Clauses 6 and 7.
The equipment model has equipment connectivity described by the ConnectivityNode and
Terminal classes, refer to Figure 3. The Terminal class is central in that it support Equipment,
Topology, State Variables, Steady State Hypothesis and Diagram Layout profiles. Within the
Equipment profile the Terminal associate ConnectivityNodes with ConductingEquipment and

– 12 – IEC 61970-456:2018 © IEC 2018
provide multi Terminal equipment (e.g. Switches, ACLinesegments etc.) with well-defined
equipment “sides”.
The Equipment and Steady State Hypothesis profiles are the basis for network model building
and power flow calculation. The Topology profile describe power flow busses,
TopologicalNodes that are used as input by a power flow calculation. TopologicalNodes are
created in a step preceding the actual power flow solution and can be the result of a network
model builder using ConnectivityNodes as input or by manual editing in a bus-branch model
editor. The state variables profile describes the result of a power flow application, refer to
Figure 3.
Equipment & connectivity
SteadyState Equipment profile
Hypotesis profile
Connectivity
Node
Conducting
BNM
Terminal
equipment
Bus-branch connectivity
SvPowerFlow
Topological
Node
SvInjection
SvVoltage
Topology profile State variable profile

IEC
Figure 3 – Connectivity model example
The arrows in Figure 3 describe references between the CIM objects. For a node-breaker
model the TopologicalNodes are computed from switching devices connecting
ConnectivityNodes and for a bus-branch model the TopologicalNodes are manually
maintained.
A node-breaker model use ConnectivityNodes to describe how conducting equipment are
connected. In topology processing all conducting equipment connected with each other
through closed Switches are identified and conducting equipment Terminals are assigned to a
TopologicalNode.
A bus-branch model use TopologicalNodes to describe how conducting equipment are
connected. In this case the TopologicalNodes are manually maintained and the assignment of
conducting equipment Terminals to TopologicalNodes is also manually maintained. The
manually maintained TopologicalNodes have well known identifiers or “Bus numbers” that
enables comparison of different studies on the same network.

IEC 61970-456:2018 © IEC 2018 – 13 –
In the case of a node-breaker models the TopologicalNodes are created by topology
processing. BusNameMarkers (BNM) are used to avoid an arbitrary naming of
TopologicalNodes resulting from topology processing, as described in 7.1.1. The
TopologicalNodes in a bus-branch model imply that the Switches in a corresponding node-
breaker model have specified Switch statuses (Switch.open). By creating BusNameMarkers
for one or more such sets of Switch statuses and use the BusNameMarker names to name the
TopologicalNodes generated by topology processing it is possible to preserve the
TopologicalNode names. Variations in Switch statuses is managed by adding as many
BusNameMarkers as needed to support the wanted variations.
This use of BusNameMarkers preserve TopologicalNode names but not the mRID (the
rdf:ID/rdf:about in IEC 61970-552). Hence TopologicalNode mRIDs will vary between different
topology processing runs. In version 17 of the canonical UML the information model has been
modified to support preserving the TopologicalNode mRIDs (this version of the profile is
based on version 16 of the canonical UML).
An equipment model using ConnectivityNodes may not necessarily have any switches. A
simplified equipment model can initially be created without switches similar to a bus-branch
model. This enables mixing detailed node-breaker models having switches with simplified
bus-branch style models without switches as both describe connectivity using
ConnectivityNodes. This is useful when operational models are to be combined with planning
models to verify that the planned extensions work with existing operational models.
6 Use cases
6.1 Overview
This clause describes how the standard should be applied in business problems and gives
examples of some scenarios.
Network applications use a bus-branch model in the basic power flow calculation where the
branches are non-zero impedance elements. Real power systems have measurements and
switching devices that are not described in bus-branch models but in node-breaker-models.
So, to run network calculations on a node-breaker model a bus-branch model where all zero
impedance elements have been removed is created. In many study situations, it is impractical
to deal with all the details in a node-breaker model, hence studies often use a bus-branch
model for building study cases. The Steady State Hypothesis profile describes the data, e.g.
switch statuses, needed to transform a node-barker model into a bus-branch model.
A large interconnected power network is typically divided into regions with a system operator
that is responsible for operating the power network within a region. With increased and
stronger interconnections between the regions the mutual dependency between the regions
increases. A consequence is that a power flow set up for a particular region must also include
a substantial part of the neighboring regions including both EQ and SSH data. Figure 4 shows
an example from Europe.
– 14 – IEC 61970-456:2018 © IEC 2018

Figure 4 – The European power system with regions
The Case building process includes many sources of SSH data, as shown in Figure 5.

IEC 61970-456:2018 © IEC 2018 – 15 –

EQ DL
Diagram Layout Datasets
Described by
Network As-Built
- Equipment GL
Geo Locations
CIM Profiles
- Containment
Model Parts
Physical Model - Connectivity
- Controls DY
Dynamics Select / Edit
- SIPS
- Equipment Rating
- Normal operations CL
Contingency List
- Energy allocation
Planned
Construction
Model Parts
Projects
Node-
TP
State Estimation breaker
SSH
- TopologyNodes
- association to
- Status
conducting equipm
- Switch status
Measurement Outage   - In Service
Device Status
- Branch end
Sources Schedules Initialization/Edit Bus-
SV
- Tap positions
branch
- Control settings
- Voltage regulation
- Flow regulation - Energized State
Control Setting
Topology & - Island Topology
- SIPS
Energy
External Initialization/Edit - BusVoltage
- Monitoring
Network Solution
- Bus Injections
- Operating limits
Forecasts &
Sources
Algorithm
- Other - Terminal flows
Schedules
- Controls
- Energy Injections
Monitoring
- Violations
- Bulk generation
Initialization/Edit  - Solar
- Wind
- Storage
- Traditional Load
Energy Injection
- DR
Case Parts
- etc,
Initialization/Edit
Repository Case Parts
IEC
Figure 5 – Information exchange in power flow and sharing of results
Figure 5 describes how input to Power Flow calculation has many different possible sources.
State Estimation and measurements create SSH data as input to Power Flow calculations.
Case building includes selecting and combining data from different sources to form a
complete input to a Power Flow study. The Steady State Hypothesis (SSH), Topology (TP)
and State Variables (SV) are in scope of this specification. Other interfaces indicated in
Figure 5are outside the scope of this specification.
6.2 EMS network analysis integration
An architecture for transfer of data from a SCADA/EMS to other applications is shown in
Figure 6.
– 16 – IEC 61970-456:2018 © IEC 2018

Analog
AM
measurements
SCADA
Discrete
DM
measurements
Data Equipment
EQ
model
modeler
Network
Model
TP
Topology
builder
Steady state
SSH
hypothesis
State
State
estimator
SV
variables
Schedule
Schedule
values
updater
IEC
Figure 6 – EMS datasets to an external client
The following interfaces are shown in Figure 6:
– EQ: Equipment model data as described in IEC 61970-452;
– DM: network discrete measurements dataset;
– AM: network analog measurements dataset;
– TP: Topology dataset from Network model builder;
– SV: State Variables dataset from state estimator;
–
...