Understanding Today`s Protocol Standardization Efforts
By John D. McDonald and Terrence L. Saxton, KEMA Consulting
The use of international protocol standards is now recognized throughout the electric utility industry as a key to successful integration of the various parts of the electric utility enterprise. KEMA Consulting, an independent consulting firm, is deeply involved both in the development of standards through participation in standards development efforts and in advising utilities in the application of these standards on many utility integration and automation projects. This article reports on progress and status in two critical areas. The first area deals with the exchange of real-time power system operations data between utilities, control centers, power plants and substations using the Inter-Control Center Communications Protocol (ICCP). The second area addresses substation integration and automation protocol standardization efforts. Both of these efforts have taken place within the framework provided by the Electric Power Research Institute`s (EPRI) Utility Communication Architecture (UCA).
EPRI Utility Communications Architecture
The UCA is a standards-based approach to utility data communications which provides for wide-scale integration from the utility enterprise level (as well as between utilities) down to the customer interface, including distribution, transmission, power plant, control center and corporate information systems. The UCA Version 1.0 specification was issued in December 1991 as part of EPRI Project RP2949, Integration of Utility Communication Systems. While this specification supplied a great deal of functionality, industry adoption was limited, due in part to a lack of detailed specifications about how the specified protocols would actually be used by applications. For example, the Manufacturing Messaging Specification (MMS) ISO/IEC 9506 protocol was specified for real-time data exchange at many levels within a utility, but specific mappings to MMS for exchanging power system data and schedules or for communicating directly with substation or distribution feeder devices was lacking, resulting in continuing interoperability problems.
The UCA (MMS) Forum was started in May 1992 to address these UCA application issues. Six working groups were established to consider issues of MMS application in power plants, control centers, customer interface, substation automation, distribution feeder automation and profile issues. Since then MMS Forum has served as a mechanism for utilities and suppliers to build the technical agreements necessary to achieve a wide range of interoperability using UCA/MMS. Out of these efforts came the notion of defining standard power system objects and mapping them onto the services and data types supported by MMS and the other underlying standard protocols. This heavily influenced the definition of the UCA Version 2.0 specification issued in late 1996, which now endorses 10 different protocol profiles including TCP/IP and ICCP as well as a new set of common application service models for real-time device access.
Inter-utility real-time data exchange has become critical to the operation of inter-connected systems within the electric power utility industry. The ability to exchange power system data with boundary control areas and beyond provides visibility for disturbance detection and reconstruction, improved modeling capability and enhanced operation. A key example in this area is the implementation and interconnection of security nodes throughout the United States to create the National Energy Regulatory Commission (NERC)-mandated Intra-regional Security Network (ISN). Another is the establishment of independent system operators (ISO) to provide reliable operations for member utilities.
Historically, utilities have relied on in-house or proprietary, non-ISO standard protocols, such as WSCC, IDEC, and ELCOM, to exchange real-time data. ICCP began as an effort by these data exchange protocol support groups, power utilities, consultants and a number of SCADA/EMS vendors to develop a comprehensive, international standard for real-time data exchange within the electric power utilities industry. To accomplish this goal, the Utility Communications Specification (UCS) Working Group with sponsorship and funding support from EPRI was formed in September 1991. EPRI Research Project 3830-01, managed by KEMA Consulting, was initiated to:
develop the protocol specification,
develop a prototype implementation to test specification,
submit the specification for standardization and
perform inter-operability tests among ICCP vendors.
ICCP Standardization in the IEC
Once a stable specification was achieved as a result of the above efforts, the UCS submitted ICCP to the International Electrotechnical Commission (IEC), which has agreements with the International Standards Organization (ISO) to development joint ISO/IEC standards for the electric utility industry, for standardization. Successful early implementations of ICCP between SCADA/EMS control centers led to further expansion to enable communications between control centers and power plants and to large scale transmission substations where host computers have been installed as part of a substation integration/automation upgrade project.
At the present time, ICCP is a Draft International Standard maintained by the Power System Control and Communications Technical Committee 57 Working Group 7. ICCP, known as the Telecontrol Application Service Element 2 within the IEC, is defined in the IEC 870-6-503, -702 and -802 series of specifications. The UCS Working Group is now incorporated into the UCA Forum Control Center Working Group, where KEMA Consulting continues in a supporting role as editor for the ICCP specifications and other new standards developments within the UCA Forum.
ICCP Vendor Support and Project Implementations
ICCP has considerable international vendor support, with eight ICCP vendors successfully participating in the latest interoperability tests held in Fort Collins, Colo., in February 1997. The vendors participating in this testing were ABB Systems Control, Cycle Software Inc., Cegelec ESCA, GE-Harris Energy Control Systems, Landis & Gyr, Siemens Power Systems Control, SISCO and Valmet. Other vendors with announced products include Bailey Network Management Systems, CAE and QEI. This second round of interoperability testing included the following conformance blocks (as defined in the ICCP specifications):
Block 1: Periodic power system data.
Block 2: Extended data set condition monitoring, including report-by-exception.
Block 4: Information messages.
Block 5: Device control and tagging.
Block 8: Transfer account/scheduling and device outage object transfer.
ICCP is currently either deployed or is being deployed in a large number of utilities, power pools and countries worldwide, with the latest count of individual utilities expected to be using ICCP by the end of 1997 at well over 100. ICCP has been chosen for inter-utility communications by ISOs and power pools in almost every NERC region. In addition, the NERC ISN has mandated the use of ICCP for intra-regional real-time power system data exchange to begin in late 1997. While ICCP is not the solution for all data exchange requirements, it has achieved its intended purpose of providing a single international standard for real-time power system data exchange in its application domain.
Substation Automation Protocol Standardization Efforts
The integration of intelligent electronic devices (IED) in the substation presents many challenges to electric utilities. For example, each IED can provide massive amounts of data, both instantaneous and historical, with limited filtering capabilities in the IED or in the IED protocol. The proprietary IED protocols have required interface modules, at additional cost, for protocol conversion and for functionality not supported by present IEDs. In addition, there is no standard LAN protocol for the substation. Finding a network protocol to handle data acquisition as well as high-speed protection requirements has been an ongoing industry activity. The various industry efforts attempting to solve the standardization problems within the substation and their status are discussed below.
The Data Acquisition, Processing and Control Systems Subcommittee of the Institute of Electrical and Electronic Engineers (IEEE) recognized the need for a standard IED protocol in the late 1980s and formed a task force to examine existing protocols and determine, based on two sets of screening criteria, the two best candidates. IEEE Standard 1379, Trial Use Recommended Practice for Data Communications Between Intelligent Electronic Devices and Remote Terminal Units in a Substation, is scheduled to be published later this year. This document does not establish a communication standard. To quickly achieve industry acceptance and use, it instead provides a specific implementation of two existing communication protocols in the public domain. The first is DNP 3.0, the Level 2-subset implementation as published by the DNP Users Group. The second is IEC 870-5-101, developed by IEC Technical Committee 57 Working Group 03, including the T101 companion standard (profile). The task force decided to use the IEEE “trial use recommended practice” designation for this work, with a limited lifetime, that these recommendations would fill a void on an interim basis until a longer term, more permanent solution (such as EPRI UCA) was ready to be implemented.
EPRI-Sponsored Utility Substations Initiative
The EPRI UCA/Substation Automation Project began over three years ago, to produce industry consensus regarding substation integrated control, protection and data acquisition, and to allow interoperability of substation devices from different manufacturers. An open process has been followed on this project, to review each major project document and milestone in the open forum of standards-related organizations. There have been over 600 participants in this review process worldwide. The Substation Protocol Reference Specification recommended three of the 10 UCA 2.0 profiles for use in substation automation. Future efforts in this project are integrated with the efforts in the Utility Substations Initiative described below.
In mid-1996 American Electric Power hosted the first Utility Substations Initiative meeting, as a continuation of the EPRI UCA/Substation Automation Project. After eight meetings in less than one year, approximately 25 utilities and 15 vendors are participating, having formed vendor/utility teams to define the vendor IED functionality, and to implement a standard IED protocol (UCA 2.0 profile) and LAN protocol (Ethernet). Prototype protocols and topologies are based on sound technology and have been staged and benchmarked to verify the recommended approaches.
Generic Object Models For Substation and Feeder Field Devices (GOMSFE) are being developed to facilitate suppliers in implementing the UCA/Substation Automation Project substation and feeder elements of the Power System Object Model. The GOMSFE work merges the UCA Forum Substation and Feeder Automation work with that of UCA 2.0 in order to produce common generic object models for implementation of UCA 2.0 compliant field devices in electric utilities.
New IED products with this functionality are scheduled to be commercially available in mid-1998. The utilities will provide demonstration sites for the implementation of the new IED products, to occur in the last half of 1998, to demonstrate interoperability between IED equipment from different vendors and to evaluate and recommend a suitable UCA-compliant substation LAN.
John D. McDonald is senior principal consultant and manager, Substation Automation Consulting Services for KEMA Consulting. He manages all substation automation consulting services work, including the EPRI UCA/Utility Substation Automation project. John McDonald received a master`s of science degree in electric power engineering from Purdue University and a master`s degree in business administration from the University of California-Berkeley.
Terrence L. Saxton is a senior principal consultant with KEMA Consulting. He received a master`s of science degree in electrical engineering from the Massachusetts Institute of Technology in 1966 and has more than 25 years experience in the analysis, design, development and implementation of a wide range of distributed computing systems and computer communications networks for EMS/SCADA systems and other applications. Saxton is the project manager to EPRI for development of the ICCP Specification.
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