Bruce Wollenberg, Jay Britton, Ed Dobrowolski, Robin Podmore,
Jim Resek, John Scheidt, Jerry Russell, Terry Saxton, and Chavdar Ivanov
The history behind the Common Information Model (CIM) is one of an industry searching for solutions to problems that had long been recognized by vendors and electric utility customers alike. The efforts of many groups went into the solution, and often these groups completed one stage of the solution and another group picked up the work with little continuity.
The first such group to take up the effort was the Energy Management System Architecture Task Force. This task force, under the IEEE Power Engineering Society’s (PES’s) Working Group 73-3, had as it purpose to think about and make recommendations on the energy management system (EMS) architecture of the future.
Some history of the EMS field is necessary to understand why this task force was deemed necessary. A classical EMS usually made use of computers that had the ability to respond to interrupts. These so-called “real-time” systems (also known as process control computers) would read data presented by communications systems, perform calculations, and present data on screens and map boards. There were usually two such computers so that one was instantly available if the other failed. Problems arose when these computers were called upon to perform large calculations using real-time data while still responding fast enough to the interrupts when new data or events required attention. The result was a splitting of responsibilities into more than one computer. Early efforts used mini computers to do the interrupt driven real-time tasks while large scientific mainframe computers did the large calculations.
The chief frustration with the EMS industry was expressed in an early task force report. According to John Scheidt, “The current practice of spending three to six years designing and procuring an EMS only to have it last 12–14 years has been viewed with justifiable suspicion by utility management.” Often, none of the software developed for one EMS was transferrable to the next one, even when purchased from the same vendor. Data structures changed each generation of the EMS, and this necessitated rebuilding the database from scratch. Similar issues were encountered with respect to displays and map boards. Even more frustrating was the fact that once a vendor had been selected, the customer was locked into that vendor’s solutions. No independent software could be purchased and installed, as was becoming the practice in data processing where many vendors often could supply software to run on a computer system to supply a given application.
The members of this original IEEE task force were
- John Scheidt, chair
- Robert Guberman
- Mike Ropertson
- Jerry Russell
- Howard Daniels
- Robert Green
- Paula Traynor
- James Resek
- Mark Sola Cruz
- Walter Johnson
- Bruce Wollenberg.
The EMS Architecture Task Force met at PES meetings roughly from 1982 to 1989. A final report was written, and the task force was disbanded.
The next, much larger, effort was headed by the Electric Power Research Institute (EPRI) project, the Control Center Applications Program Interface (CCAPI), which started in the early 1990s. There were engineers who had been on the EMS Architecture Task Force who worked on the EPRI CCAPI, but the EPRI CCAPI was not seen as an EMS Architecture effort. This can be seen in a news release in T&D World Magazine in 1999. Its purpose was not to invent a new EMS architecture, rather, it focused on developing an “open application environment.” In this effort, EPRI said that the “…initiative is developing ‘plug compatible’ applications in the electric power control center environment and facilitating interoperability among a broad spectrum of utility applications
and information systems.” Thus the problem of the need to only use one vendor’s software, which had been around for a while, was to be dealt with. EPRI also included a reference to a comprehensive information model, described in the T&D World Magazine news release as providing “a common definition of the electric system data, in object form, that is used by the various power system applications.”
The EPRI CCAPI project got off the ground due to efforts of Herman Amelink, then of Energy Control Consultants [later part of Kema and now part of Det Norske Veritas (Norway) and Germanischer Lloyd (Germany)], and Gerry Cauley of EPRI (now CEO of the North American Electric Reliability Corporation). Cauley was the original EPRI CCAPI project manager. Macro Corp. was the contractor to EPRI for the project with James Resek from Macro as the manager. Later David Becker took over the project at EPRI, and Terry Saxton from KEMA Consulting took over as manager. Ed Dobrowolski, then at PECO, was an advisor to EPRI. Jay Britton, Jim Resek, and Terry Saxton all worked on the project with EPRI.
The transition of the EPRI CCAPI project to the now-familiar CIM framework occurred during the years of the EPRI project itself. To allow the “plug and play” capabilities sought by both the EMS Architecture Task Force and the CCAPI project, the EPRI teams began to design an application program interface (API). Instead of concentrating on the API details that have to do with a vendor’s computers, operating system, etc., the team began the effort to develop the framework for the meaning and structure of the information exchanged between the EMS database and various applications. According to Jay Britton, “CCAPI migrated first toward semantics driven by EMS requirements and then away from an internal EMS architecture focus and toward exchange of information between control centers.”
In the beginning, it was clear that the power industry itself would have to be the source to develop the semantic model to describe the kind of data to be used in EMS applications. Jay Britton presents two questions:
Where do we to get the semantic model?
What do we do with a semantic model?
The first use of the CIM was to allow EMS operations staff to exchange network models between itself and neighboring network operations staff. But this is not an API. CIM is not an API that allows one to build a power system EMS application and “plug” it into any compliant EMS.
A parallel effort that also contributed to the CIM development was the EPRI Operator Training Simulator (OTS) project, which had the goal of developing a training simulator that could be used by any EPRI member. The simulator was built by Control Data Corporation’s EMS group in Plymouth, Minnesota, and PECO was the first EPRI member for which the simulator would be built and installed. Ed Dobrowolski provided the back story on this parallel development and how it came to influence CIM. “The requirements from EPRI were that the project be transportable to other utilities and not just usable at PECO Energy which was the host (I was project manager at PECO),” he said. “Therefore the OTS team had to develop a set of models that were not proprietary and a database for the OTS to run off of that could be reused by other utilities.”
Thus the EPRI OTS database became the first structure for the CIM. At this stage, the CIM comprised an MS Access database and entity relationship diagram that grew to cover an entire wall. The effort now was to build a semantic model. A semantic model, according to Terry Saxton, is “a vocabulary of basic terms representing real-world objects, a precise specification of what those terms mean and how they relate to each other.” The power of such a model representing the entire electric utility operations domain can scarcely be overestimated, paving the way for the CIM to become the key to achieving a model-driven interoperability solution for integrating the many disparate systems needed to operate and manage the electric grid.
The Unified Modeling Language (UML) was chosen as the language to represent the CIM semantics. The conversion of the CIM model to UML was in many ways the birth of the CIM model as we know it today—a UML model that can be directly used in electronic form by software tools to generate artifacts (like CIM-based XML message payloads and power system network models) that vendors can download and incorporate in their products.
Those who met at EPRI now realized that a much bigger effort would be required and that the end goal should be a series of international standards; consequently the group approached International Electrotechnical Commission (IEC) Technical Committee (TC) 57, Power Systems Management and Associated Information Exchange. A new working group, WG13, was appointed to start this work in primarily in the transmission operations domain, but the application of the CIM to distribution operations and market communications quickly followed with the establishment of WG14, Distribution Management Systems Interfaces, and WG16, Market Communications. Other working groups followed later that incorporated the CIM semantic model into their work as well. TC57 has expanded to include many working groups that are based on the CIM, as shown in Table 1.
Today, the CIM is composed of a series of standards comprising a single, unified UML semantic model and multiple profiles developed in these different working groups defining specific information exchanges between applications/systems/devices in support of business processes in transmission, distribution, and markets.
Another significant milestone was reached with the establishment of the CIM Users Group (CIMug) in 2005, as a subgroup of the UCA International Users Group, to provide a forum in which users, consultants, and suppliers could cooperate and leverage the International IEC CIM international standards to advance interoperability across the utility enterprise. The primary purpose of this user group is to share technology basics, best practices, and technical resources while advancing interoperability for the utility enterprise. The CIM Users Group is focused on helping its members obtain the benefits of adapting IEC TC57 modeling standards for all utility operations on a global basis.
In 2006, EPRI initiated the CIM for planning models with the objective of developing a common power system network model that both operations and planning groups can use as a basis for information exchange. David Becker, Margaret Goodrich, and Terry Saxton put significant effort to make sure the outcome of the project was considered in the IEC standards. Later in 2008, EPRI launched the CIM for dynamics models project to develop solutions to enable the exchange of dynamics models. In 2008 UCTE (Union for the Co-ordination of Transmission of Electricity) in Europe decided to use the CIM-based data exchange format and joined the international efforts of EPRI projects, CIMug, and the IEC. Chavdar Ivanov coordinated the efforts to bring the requirements of European Transmission System Operators into existing projects and develop CIM extensions to meet these requirements. With the creation of the European Network of Transmission System Operators for Electricity (ENTSO-E) in 2009, these activities expanded. ENTSO-E is now organizing interoperability tests to prove IEC standards as well as conformity testing on software applications.
In summary, the efforts went from an IEEE task force that wanted to see a new EMS architecture, to an EPRI project that wanted to design a new API, to today’s CIM semantic model and interface definitions that address the ever-growing need for interoperability between all the systems identified on the NIST Smart Grid Road Map.
|table 1. TC57 working groups.|
|7||Tele-Control Protocols Compatible with ISO and CCITT Standards||IEC 60870|
|10||Power System IED Communication and Associated Data Models||IEC 61850|
|13||Energy Management System Application Program Interface||IEC 61970|
|14||System Interfaces for Distribution Systems||IEC 61968|
|15||Data and Communication Security||IEC 62210|
|16||Framework for Deregulated Electricity Market Communications||IEC 62325|
|17||Communications Systems for Distributed Energy Resources||IEC 62350|
|18||Hydroelectric Power Plants—Communication Monitoring and Control||IEC 62344|
|19||Interoperability within TC57 in Long Term||IEC/TR 62357|
|21||Interfaces Relevant to Systems Connected to the Electrical Grid||IEC 14543
IEC 61158/IEC 61784
|Source: M. Joe Zhou, The Future of the CIM and Related Standards, 22 Sept. 2005.|