In the 1990s, the Utility Communication Architecture (UCA) came into being as a framework for the utility enterprise’s ensemble of communication requirements. It was introduced at a time when utility managers were looking to consolidate communications among their planning, SCADA, metering, protection and control departments. The need to consolidate communications was pressing as deregulation and increasing global competition were driving utilities’ efforts worldwide to reduce costs and streamline operations through the effective use of technology. Cost-effective interoperability and intercommunication between substation devices and the substations themselves was a key component in gaining those efficiencies.
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In the early 1990s, efforts to integrate diverse communication protocols were costly. For proprietary equipment to interoperate with other devices and/or systems, an additional layer of complexity in the way of protocol translators was required. The development of UCA was a significant step in realizing the drive toward communication commonality.
UCA’s adoption as an internationally recognized standard has been more than 10 years in the making. With recent involvement on the part of the International Electrotechnical Commission (IEC), the process is finally reaching a level of consensus, helping move the utility industry toward global competitiveness.
The UCA Communications Profile
The UCA process started with the creation of a document that defined communication requirements for the various functions within a substation. This was followed by an implementation and evaluation phase that defined the “profile” of a communication structure for the substation that includes the physical, network, application and user data levels (see figure).
The goal in defining this substation profile was to open the doors to implementation of high-speed, networkable, peer-to-peer communication using as many open standard protocols as possible. In addition, the goal of user data interoperability required the definition of standard names for commonly used data objects. This standardization at all levels is especially critical in a world where speed and bandwidth capabilities are increasing at a phenomenal rate.
The UCA framework took a major step toward international standardization when the IEC selected major portions of the UCA Version 2.0 substation profile as the foundation for the next-generation substation communication protocol. Designated IEC 61850, the body of this newly proposed standard is virtually identical to that defined by UCA Version 2.0 and is now being readied for international balloting.
This drive for global recognition has been fuelled in large part by the Internet’s worldwide success. Just as the Internet has established a communication standard, revolutionizing the way businesses communicate and technology interoperates, the utility industry is striving to achieve the same ends in the interest of economy and global competitiveness. In fact, it is the utility industry, as opposed to manufacturers, that has been the major driving force behind the international convergence of regulatory and standards bodies.
The adoption of the Internet model should come as no surprise. The utility industry has consistently looked to the business world to define its own course of action. Each step along the course has met with numerous challenges, but with standardization in communications finally reaching fruition on a global scale and universal acceptance of “off-the-shelf” standards for the UCA framework established, some noteworthy developments in substation environments around the world can be expected.
The UCA framework, in fact, has already found its way into the real world. Since 1998, there has been a focus on UCA’s application in the substation environment. There are now a number of active sites or sites in development in the United States, Poland, Brazil and South Africa utilizing the UCA standard to establish peer-to-peer communications in a networked environment-with many more being implemented in the months to come.
This year also saw the first display of wireless Ethernet-based inter-manufacturer device communications at DistribuTECH 2000 in Miami Beach, Fla., and other trade shows. These working demonstrations underscored the “plug and play” interoperability that is achievable with the UCA architecture. The ability of the UCA protocol to determine the attributes of a connected device allowed users to automatically download the device definitions and selectively display information. This level of interoperability has significant implications both in terms of ease of installation and cost savings for utilities around the world.
More information about UCA’s basic framework can be found in the March and April issues of Utility Automation magazine in the two-part article titled UCA 2.0 for Dummies.
Hardware and Software Considerations
In addition to understanding the significance of UCA architecture, it is important to understand some of the related hardware and software requirements before adopting the framework.
The primary functional requirements for hardware are scalability, reliability and performance. These items became guidelines in Universal Relay platform development. Scalability was built into the communication channel’s bandwidth, and is apparent in the protection processor’s ability to process data and advanced manufacturing message specification (MMS) functions. Using a modular design, CPUs and memory can be upgraded on an as-needed basis to accommodate new developments and enhancements.
The ability to perform relay-to-relay communications with the UCA substation profile has enabled implementation of many innovative protection and control applications that use messaging over the wire. Relay-to-relay communication can be achieved through a redundant Ethernet communication architecture that automatically detects a loss of link on the primary Ethernet channel and automatically switches to the back-up Ethernet channel.
The choice of the Ethernet controller can also affect the relay’s message handling performance. In particular, hardware filtering of the link addresses can allow the processor to prioritize messages. Message handling speed is important in order to meet the UCA target of 4 milliseconds for device-to-device message processing.
As mentioned, one of UCA’s goals is to use as many “off-the-shelf” standards as possible. As a result, most software needed to perform the networking and application layer tasks is available from multiple vendors. These software components can be loaded onto the relay platform, making use of the operating system for task scheduling and interfacing with other tasks. Since the relay can serve multiple clients (users who want information), sufficient memory needs to be allocated to accommodate the requirements of each.
Reaching Global Proportions
As the UCA profile becomes more prevalent, the industry will soon begin to see tangible economic and technological benefits. The final mark of success will be the worldwide adoption of UCA as the profile of choice for next-generation substation automation. Once the IEC standard is approved, acceleration in the transition to networked communication based on MMS and object models not only in the utility but also in the industrial marketplace will definitely accelerate. The power industry-and the vendors who serve it-are ready.
Mark Adamiak is Manager of GE Power Management’s System Integration group, which is responsible for developing and implementing utility integration solutions around the world. He received his engineering degrees from Cornell University and the Polytechnic Institute of New York. For more information on substation automation, visit the GE Power Management Web site at www.GEindustrial.com/pm.
