Doing a CIM Project

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CIM Design Center A rule I learned about applying technology:

Understand the design center of the technology.

Use extreme caution if trying to apply the technology outside its design center.

CIM Design Center CIM standards aim to simplify integration of components and expand options for supply of

components by standardizing information exchanges. Reduce complexity with clear consistent semantic modeling across the enterprise. Data sources: achieve a clear picture of data mastership in the enterprise. Data consumers: make ‘data of record’ available on demand to qualified users.

CIM employs a canonical data model (CDM) strategy for standardizing interfaces in the power system operations and planning domain.

The CIM CDM is partitioned into sub-domains by IEC WGs. These groups work hard to maintain a unified semantic model over the whole domain.

The interfaces defined under CIM are organized into profiles. A profile specifies the information structure of exchanged information by creating contextual semantic models.

- Contextual semantic models are a subset of the CIM CDM. i.e. They inherit their structure from the CIM CDM.

- Contextual semantic models could contain information not modeled in the CIM CDM.

•This is not current CIM practice for standard interfaces. There is typically a family of related interfaces defined within a profile. Products implement support for profiles. Testing occurs against profiles. CIM compliance is defined against profiles.

- There is no such thing as just ‘CIM compliant’. You have to specify the profile.

Do not expect CIM to make sense outside its design center. If its not needed in a CIM interface, don’t expect it to be in the model.

Don’t expect that CIM is a good database schema.

Don’t expect CIM to make a good class design for your application.

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What is a Canonical Data Model?

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Overview of CIM Standards Methodology

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WG13 CIM Standards

Instance Data

Contextual Semantic Model

Topology

State Variables

Measurement Specification

Equipment Model

modeler

scada

Equip model

Meas Spec

topology&

scheduling

Analog Set

Topology

State Var

state estimation

State Var

contingency analysis

State Var

State Var

State Var

AnalogMeas Set

StatusMeas Set

Status Set

CDM Semantic Model

CIM CDM

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Versions

CIM is designed to achieve consistent, high quality models across a large domain.

This mission requires that CIM is able to change as new interfaces are added.

Typically it is not possible to preserve semantic quality if changes are restricted to additions.

At the global CDM level, change is embraced as long as it makes a significant contribution to semantic quality.

This is clearly different from normal situation, where standards are expected to be stable.

Stability may be addressed as appropriate at profile levels. Profiles are where the investment is made.

Implementation and testing of interfaces is at the profile level, based on a contextual model.

Contextual model is derived from a version of the CIM CDM.

Subsequent changes to CIM do not require that the contextual model be updated.

At the profile level, the participants in the profile can determine how often to update their profile.

A profile update Normally, this would not be done unless there were functional improvements needed, since an

upgrade causes the need to make software changes in participating products.

About Versioning… CIM CDM and contextual models will change.

Contextual models do not need to be updated simply because CIM CDM changes.

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How to Cope with Versions

An enterprise integration strategy based on CDM(s) is a good idea.

Multiple CDMs are likely, but keep the number small.

Extensions will be necessary when starting from core standards like CIM.

An enterprise application of CIM will typically consist of information exchanges based on more than one version of the CDM.

Critical decision: CIM CDM may be adopted just as a starting point, or the plan will be to keep current as CIM and contextual models evolve.

Use of evolving Smart Grid standards will probably demand staying with CIM.

A successful evolution strategy requires discipline in implementation to reduce the cost of subsequent updates.

There will be lots of reasons raised as to why CIM should just be used as a starting point.

This strategy chooses many projects because there isn’t enough commitment to the long term architectural goals.

To enable evolution…

Implementation must minimize direct connection between exchanged data and internal data.

i.e. Do not hardwire CIM to application internals – it makes changes too costly.

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Transformations are Key

Transform issues Clarity

Simple, low cost implementation

Maintainability

Performance!Consumer App

Instance Data

Consumer App Semantic Mdl

Exchanged CIM Standard

Data

CIM Contextual Model

Producer App

Instance Data

Producer App Semantic Mdl

TransformSpec

Trans-form

TransformSpec

Trans-form

Consumer App

Instance Data

Consumer App Semantic Mdl

CIM XData

CIM ContextMdlVersion x

Producer App

Instance Data

Producer App Semantic Mdl

TransformSpec

Trans-form

X

TransformSpec

Trans-form

Y

Version Transform

Spec

X-YTrans-form

CIM YData

CIM ContextMdlVersion y

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You may think that CIM is complex.

From the standpoint of one information exchange implementation, it is.

If you compare life cycle of 100 exchanges, each implemented in CIM, against other alternatives, CIM is much simpler.