Draft Technical Report

Draft Technical Report – AHWG07 - Harmonization Issues

IEC 61970 and IEC 61850 Harmonization Issues

1.Introduction

This report lists and categorizes the issues concerned with harmonization of the 61970 (CIM) and 61850 standards. However, the resolution of these issues affects all TC57 standards that reference or build on the CIM, such as the 61968 standards.

1.1Background

The list presented here is based on meetings in Las Vegas on February 5, 2003, between George Schimmel and Terry Saxton (conveners for WG10 and 13, respectively); A list of issues deferred to AHWG07 by WG13 that were raised as comments from recent voting to approve 61970 Part 301 CIM Base for circulation as an FDIS. Since the vote was positive, only relatively minor changes could be made to the First edition of Part 301, with the rest deferred to a future amendment; Proposals from WG 10-12 generated at a meeting in Pittsburgh in May 2002.

The TC57 Reference Architecture paper provides background on the models represented by the TC57 standards and points to some of the differences, while not proposing any specific resolutions. An important perspective is presented here, that harmonization does not require all models to be made the same (i.e., there is not only a single representation for a breaker object used by all TC57 standards) using the same modeling notation. While this is a desirable objective, it may not be realistic in every case given the maturity and existing deployment of the current draft standards. Also, there may be valid reasons for having different models for different domains of application. Further, there may also exist natural seams between these domains in the real world of utility operations, where direct sharing of objects is neither implemented nor desirable. For example, raw SCADA received by SCADA master stations is typically processed (e.g., smoothed, interpolated, and converted to engineering units) prior to use by EMS applications, such as topology processors, state estimation, and other advanced network applications. Of course, this perspective must be balanced by future planned uses and system architectures, which may be different from current practices. The main point to keep in mind is that there must be a balance maintained between what seems desirable from a modeling perspective and what is practical from a deployment perspective in the real world.

2.Terminology

The use of normal terminology needs to be refined in order to avoid ambiguous term usage.

Note: One such example is “Network Topology”. This term can mean Power System Network Topology/Connectivity or Communication Network Topology/Connectivity.

Therefore it is suggested that the following terms be used throughout this document:

PowerSystemResource / As defined in IEC 61970
Function / The real-time behavior of a PowerSystemResource(s) in the case of devices
Data / Represents the instances of attribute values
Class / This is the abstract definition of PowerSystemResource or Function definitions.
PowerSystem Topology / Shall be used in regards to issues of power system network topology or connectivity.
Communication Topology / Shall be used in regards to issues of communication network topology or connectivity.

3.Identifying harmonization issues

3.1Use Cases

Use Cases are used to clearly show how utilities exchange information. A Use Case shows who all the actors are, what systems are involved, the current/desired format for data on each interface, etc. It should address real-time operations, initial configuration of IEDs in substations, model maintenance, and incremental changes to models and configuration, after-the-fact analysis of events, collection and use of historical data, etc.

A pictorial overview representation of the actors and processes involved in the implementation and operation of a substation is shown here in Figure 1.

Two Use Cases identified as being important in identifying key harmonization issues include:

‘Retrofit of the equipment in a substation (with addition of a new line and transformer)’

‘Real-Time information exchange between 61850 devices and the Control Center / Office’

Use Case 1 (described in section?) points out in step 8 that the functional model exchange is performed via SCL files or 61850 device browsing, as well as changes to the Power System Model via CIM model changes requiring communicating CIM model changes between the Substation and Control Center. Use Case 2 will deal with real-time information exchange issues. Use Case 2 is yet to be completed, but discussions indicate that CIM data model exchange issues may be (at least partially) addressed by adding support of the Logical Node, via harmonized XML tags (between the CIM and SCL) and real-time information exchange issues may be resolved via use of the CIM AliasName in the MeasurementType table.

Figure 1: Use Case: Enterprise and Substation Information Exchange Overview

These Use Cases show interaction between 61970 and 61850 and the need for harmonization between their respective model schemas.

A primary objective of this effort is to show the “Scope of Information” used by different systems. This would show where natural seams might occur.

3.2XML – How It Is Used

The eXtensible Markup Language (XML) is being used by several IEC TC57 working groups. It is preferable that a common information model be used to create the XML to ensure all XML schemas are consistent and use the same tags with the same name and meaning.

61968 and 61970 share a common XML schema for all XML that is based on the CIM. It is recommended that the Substation Configuration Language (SCL) in 61850 and all other XML uses also be based on this same model, wherever objects that are needed are already represented in the CIM. This should start with the hierarchical relationships for containers and inheritance in the CIM (i.e., ControlArea, Substation, VoltageLevel, Bay, Transformer, etc.). At some more detailed level in the hierarchy, it may then make sense to specialize one of the existing classes in the CIM to embrace existing 61850 models, if the CIM does not adequately represent the device properties needed. However, even here the CIM can be extended to add needed specializations, as WG14 has done with that portion of the 61968 standards that needed specialized device models or other specialized objects used in distribution applications.

If the SCL is intended to be an external view of configuration data to be archived and made available to other applications, then it would be most helpful if the XML schema used by the SCL were based on the same information model used by those applications.

3.3Process for Starting New Work in TC57

There is a need for guidelines on how to extend the work of TC57. The guidelines should describe the process to follow for each new work item to ensure compatibility with existing work. This would permit an evaluation to be made of the impact on existing standards and on the CIM. In particular, this process would help to bridge the language gaps that may exist between those with an IT-orientation and view of the world (WG13/14) and those with a device-orientation and view of the world (WG10-12). Often times these different perspectives make it difficult to see how to apply existing standards developed by another working group, whereas a dialog at the time of formation of the NWIP may uncover areas where collaboration would be beneficial to the end user of the standards produced as well as save time spent in “reinventing the wheel.”

The guidelines should also include a common document structure to be used wherever possible by all working groups to make it easier to read, understand, and use standards produced in TC57, regardless of which working group produced them. By document structure is meant how to define the different parts, not the clauses/sections within a document, which are already addressed in the IEC Guidelines documents for producing standards. An example used in WG13 is as follows:

Guidelines and General Requirements

Glossary

Data/Information Models

Interface Standards

Technology Mappings

3.4Work Item proposal

It is recommended that a proposal be made to the SPAG to define this process for adding new standards. This proposal would point out the need and benefits to following this procedure to be able to evaluate the impact on the CIM and other existing standards. Perhaps if such a procedure had been in place, the need for after-the-fact harmonization could have been largely avoided.

4.Specific Harmonization Issues

4.1SI Units

Some people have recommended the use of Base SI units for the CIM. This would require a change from current practice. However, there are many factors to consider before making such a change. It may be that the current CIM approach is preferable for many applications, with simple transformations to Base SI units done where needed. There are different views on this which need to be heard before final decisions are made. The current CIM first edition will not include any changes in this area, except to add units where none existed at all.

4.2Topology

The addition of a Logical Node object to the CIM has been proposed as a way to permit 61850 standards to use the topology model in the CIM to model PowerSystem topology. It is also feasible to model the Communication Network Topology with this same approach.

4.3Other Issues

Impact on 61968 (WG 14’s use of the CIM)

Impact on RTU configuration data 60 870-5

Tase.2 Block 8 vs. CIM 302 vs. WG 16 ebXML

Single place to define objects throughout TC57

oCould be distributed based on major owner, or centrally in a 4xx series document in 61970, a new TC57 global document, or a registry, etc.

oIdentify how often changes might be needed to not be restricted by rapid and frequent changes

oAsset Management

4.4Additional Harmonization Issues Deferred to AHWG7

This section references specific comments received from the voting on the 61970-301 57/578/CDV, which is the Part 301 CIM Base document with the majority of the Transmission and Generation models, as well as other related CIM Packages. The Attachments B-D contain the comments with the WG13 resolutions from the USA, Sweden, and Japan which were deferred to AHWG7.

5.Harmonization proposal

Lars-Ola Österlund and Wolfgang Wimmer have jointly made a proposal which is being presented by AHWG07 to working groups 10-12 and WG13. This is shown in Attachment B.

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Draft Technical Report – AHWG07 - Harmonization Issues

Attachment A

Use Cases

1.Introduction

This is an annex to the Harmonization issues document produced by the IEC TC57 working group AHWG07.

Use Case 1: Network ExtensionRetrofit of the equipment in a substation

(with addition of a new line and transformer)

1.1.11.Summary:

Add a new line and transformer and Rreplace the old control and protection system with a new automated system based on 61850 standards. Consider then:

• how to reuse the data from the old system, e.g. tag-names, parameters, connectivity.
• the addition of new measurements, control functions, protection etc.
• implications of emergency replacement

1.1.22.Actor(s):

Name / Role description
Network Planner, company 1 (builds a new substation) / Make studies of the line parameters to properly design the line. Works within the planning department at the ISC (ISO).
Network Planner, company 2 (builds a new bay) / Make studies of the line parameters to properly design the line. Works within the planning department at the ISC (ISO).
Line Engineer company 1 / Engineer the line on company 1 territory. System operator engineering department.
Line Engineer company 2 / Engineer the line on company 2 territory. System operator engineering department.
Substation Engineer company 1 / Engineer the new substation primary and secondary equipment. System operator engineering department. This includes substation layout, protection, control, and metering.
Substation Engineer company 2 / Engineer the new bay primary and secondary equipment. System operator engineering department. This includes bay layout, protection, control, and metering. A large number of people from various departments are cooperating in this.
Communication Network Engineer company 1 / Engineer the Communication Network in company 1 territory. System operator engineering, communications, or IT department.
Communication Network Engineer company 2 / Engineer the Communication Network in company 2 territory. System operator engineering, communications, or IT department.
Vendors / Build and/or install equipment.
System Operator company 1 / Upgrades the Control Center (CC) with new data reflecting the new line and data exchange. Prepares the data exchange with other Control Centers. Company specific rules are used to decide what data is exchanged and how (ICCP, 101/104 etc.)
System Operator company 2 / Upgrades the Control Center (CC) with new data reflecting the new line and data exchange. Prepares the data exchange with other Control Centers.

1.1.33.Probable Participating Systems:

System / Services or information provided
Power System Network planning tool / Calculate network parameters based on Load Flow and/or dynamic stability programs.
Communication Network planning / Determine communication technology and connectivity that will be required to exchange information to/from and within the substation.
Line engineering tool / Used to design the transmission line
Substation engineering tool / Used to design substation lay out (CAD-tool)
Protection design tool / Used to calculate protection schemes
Substation automation configuration tool (System configurator in 61850-6) / Used to design the substation protection, control and metering. Overall design independent of vendor.
IED configuration tool (IED configurator in 61850-6) / Vendor and product specific configuration and implementation of substation automation configuration.
Substation control system (IED hardware) / The actual substation control system running the IED instances.
Communication NetworkData communication concentrator configuration/configurator / Used to describe the data exchange between systems.
Metering system Function Data Engineering / Collect energy metering and performs billing. Includes configuration of metering subsystem.
ControlCenter Data Engineering / Used to configure and load the ControlCenter database.
Note: This is Power System and Communication Network configuration
ControlCenter / The actual CC performing supervision, control, (SCADA) on-line network calculations, Load frequency control, ...

1.1.44.Pre-conditions:

Existing system without substation automation.

1.1.55.Assumptions / Design Considerations:

New IEC 61850 devices are being added to an existing substation. Assume no substation automation in existing system, so that part of this use case is replace existing protection and control equipment with new substation automation based on 61850.

Variations on this use case for future consideration:

1. Existing substation is already 61850 automated, so this is just an addition of a new line and transformer with extension of existing substation automation equipment.

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Draft Technical Report – AHWG07 - Harmonization Issues

New IEC 61850 devices are being added to an existing substation.

1.1.66.Normal Sequence:

Step / Description of actor activity / Input to this step / Processing / Output from this step
1 / Network planner plans transmission line.
Network planning tool / Order from manager at the company. Requested line capacity. / High level planning for new line and transformer / Planned line parameters (in the CIM model), e.g. tentative impedance values, approx length, substations at endpoints.
Format: Plan as Incremental CIM/XML model export or less formally.
Action – define parameters involved
2 / Line engineer designs the line.
Line engineering tool / Planned line parameters from step 1. / Select towers, patterns of lines, catalog lookup, calculate exact line length, - , tower placement, mutual coupling, etc. / Actual line parameters updated (in the CIM model), e.g. impedance values, length, cable characteristics, geometries, line right of way, geometry,
Format: CIM/XML
Additional data not currently in CIM for planning
Action – Terry contact Lauris Arnold, LIPA, Planning – could get answers.
Action – Frances to contact Greg Congleton about getting this information from planning.
3 / Design the substation layout and specify primary equipment (includes both planning and design).
Substation engineering tool – will need interfaces,
Need list of vendors and tools used in this step to identify applications involved in information exchange and specific parameters.
Action – Christoph provide links to references and presentations from CIGRE conf,
See 61850 part 6 for flow diagram.
Action – Put 61850 and CIM FDIS in SS-CC folder in WG19 eroom so we can have access for this project. Also put on CIMug when permission granted from TC57 / Actual line parameters from step 2.
Availability and capacity requirements. / Add breakers, switches, bus extension, to existing CIM model.
Name all new equipment (line, transformer, other) / Primary equipment specifications, names (on drawings) and Power System connectivity (topology).
Produce partial SSD (output of system spec tool file (topology)
Partial SCL files and CIM-based network model updates with topology, instance data, and names.
Described in SCL and/or CIM model.
Action – Grant, post summary of 4 different SCL file formats based on same schema.
4 / Plan protection.
Protection design tool / Substation diagrams and primary equipment specifications from step 3. / Provide all new SS protection equipment, IEDs, etc. to bring in 61850 automation. / Protection functions and parameters. Described in SCL. May be passed to CIM.
5 / Plan metering.
Metering design tool / Substation diagrams and primary equipment specifications from step 3. / Metering functions and parameters. Described in SCL. May be passed to CIM.
6 / Design substation functions.
Substation automation configuration tool / Protection and metering functions and parameters from steps 4 and 5.
Substation diagrams and primary equipment specifications from step 3. / Control functions (including also load shed etc.), protection, and metering. Described in SCL. May be passed to CIM.
7 / Allocate functions (includes protection and metering) to IEDs.
IED configuration tool. / Control, protection, and metering functions from step 6. / Defined IEDs including the configuration of parameters and signal points.
8 / Deploy functions to IEDs.
IED configuration tool. / Defined IEDs from step 7 / Complete configured IED deployed to hardware
9 / Design Communication Network topology. / Complete configured IED configurations from steps 3 thru 8. / Communication parameters associated with ISO/OSI reference model layers 1 thru 6 including security parameters.
This step also includes the configuration of a substation information concentrator if used (e.g. a sub-SCADA master or RTU or IED/distributed IEDs).
In CIM and SCL.
10 / Configure Substation Communication Information Exchange Model (communication front end).
Data communication concentrator or configurator. / Complete configured IED deployed to hardware from step 8. Old point definitions, any new points available. / Functional Model (in SCL – or through the browsing of active devices): names, reporting groups, periodicity, etc. Pass to CIM.
11 / Configure control center including Power System model and SCADA data points (measurements)
ControlCenter Data Engineering / Substation diagrams and topology from step 3.
Communication Network topology and Functional Model from steps 9 and 10. / Operational CC
12 / Configure metering system function.
Metering system Data Engineering / Communication Network topology and Functional Model from steps 9 and 10. / Operational metering system
13 / Take data into operation
ControlCenter and/or metering system / Operational systems from steps 10, 11, and 12. / Test protocols documenting verified data points.

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