T&D World Magazine

Advanced Control of Distribution Circuits

Today, the electric industry has a full toolbox available to provide highly advanced technological solutions to the problems facing the distribution network. It also has an assortment of standards for open-system protocols that allow enterprise data collection, sharing and substation communications between vendor products.

At one time, supervisory control and data acquisition (SCADA) system was the smartest system in substations. Intelligent tools have helped SCADA evolve into an integrated network management system by combining it with the new intelligent building blocks and software. System developments such as these allow utilities to focus on gathering meter intelligence to feed into their call centers, dispatch centers and outage management systems. Intelligence gathering and intelligent operational tools are now being developed for use throughout the distribution network. Companies in the transmission and distribution industry are continually offering new and updated products to help the industry move even closer to the intelligent distribution network.

Innovations and partnerships

In 2004, Xcel Energy’s Utility Innovations Group formed the Utility Innovations partnership with industry leaders to find new ways to deliver service to electricity customers. The program proved so successful — Xcel saved more than US$2.25 million — it was continued for 2005 and 2006. Xcel’s partners include IBM, Indus, Itron, Lemar Homes, Meridium, SmartSignal and the U.S. National Renewable Energy Laboratory. The goal of the partnership is to advance automated metering to new levels of customer service.

Another innovation, developed by ABB, is the Micro-SCADA system, which offers immediate real-time information for the entire distribution network in the utility. MicroSCADA supports a wide range of protocols and industry-standard interfaces. The open architecture facilitates integration with third-party products and systems. It can also interface with business and office applications. The automated control areas will assess any situation as it develops and rapidly respond to that situation to avoid or balance the system caused by the disturbances. This is referred to as a self-healing network.

Also encouraging compatibility, the IEC 61850 communications standard was released in 2004, which is a standard for real-time substation control of equipment. Siemens and independent energy producer Aare-Tessin AG installed the first substation with complete IEC 61850-based controls in Switzerland last year. In May 2006, Siemens and the City of Naperville, Illinois, installed the first IEC 61850 substation in the United States.

The City of Naperville receives electricity through the Chicago 50 Substation. Siemens refurbished the substation using the Siemens SICAM PAS station automation system with SIPROTEC4 protective relays. Siemens also replaced the communications system with a new state-of-the-art substation information system. The positive results from this project have the City of Naperville eager to begin installation of additional substation communications projects in two of its other substations. This technology should provide increased reliability while improving network operation.

Intelligent Distribution Restoration

In 2004, TXU Electric Delivery and S&C Electric Co. began a pilot project using S&C’s IntelliTEAM automatic restoration system. It reduced customer outages by approximately 35%. TXU Electric Delivery has decided to continue the project and has increased its size to include more feeders. S&C has continued to improve the system and now offers IntelliTEAM III to automatically restore service to customers. Doug Staszesky, S&C’s director of product management, believes strong commercial and societal changes are significant drivers for improvements in technology. According to Staszesky, Georgia Power and the U.S. Department of Energy are working with S&C to start an advanced automation project, scheduled to begin in 2007, that will include 5 substations, 3 circuits and 38 devices in teams.

S&C has combined a suite of intelligent products together with a switching device called the IntelliRupter to form a consolidated automatic service restoration system. S&C uses a proven military technology for a very high-speed radio, the SpeedNet Radio, to which S&C has added some new features for the suite. This has been combined with an Automatic Protection Setup system to coordinate breakers and other protective devices. Multiple circuits are connected via the IntelliRupter and coordinated with the Advanced Adaptive Protection system. This is a major step toward the intelligent distribution network.

Monitoring, Software and Control

ABB has developed a substation monitoring system that monitors station equipment, diagnoses faults and trends the operation of station equipment. GE Energy offers substation monitoring and diagnostics systems for utilities, and AREVA T&D’s e-terra suite includes its “numerical substation” module built on IEC 61850 communication protocols.

Xcel Energy saw an increase in distribution transformer failures in 2003. The utility had monitoring systems data gathering, but needed a program to turn the data into useful information. Itron had just the program needed in its Distribution Asset Analysis (DAA) transformer load management software.

The DAA software monitored Xcel’s data from more than 460,000 transformers. It identified circuits and transformers at risk. In the first year, Itron identified 300 possible transformer failures. Xcel’s replacement program witnessed a 5% reduction in outage-related complaints. Itron has other modules available to utilities such as asset utilization to monitor SCADA data and give the operator an accurate view of systemwide loadings.

Pad- and pole-mounted distribution capacitors are widely used by utilities for voltage control and VAR management. Typically, they have been controlled by set switching points (time of day, temperature or both). The also have been known to cause undesired flicker and voltage rises with this control method. Intelligence has been added by S&C with its IntelliCAP PLUS device. Cannon Technologies has been working on its Yukon device to provide two-way communications with the distribution capacitors. These systems monitor the feeders and are able to switch the capacitors as they are needed by the system rather than having set times to operate.

In 2000, American Superconductor Corp. and GE Energy placed the first six distributed superconducting magnetic energy storage system (D-SMES) units in service in five Wisconsin Public Service substations. TVA installed D-SMES units on its system in 2001. The D-SMES uses a building-block concept to provide the distribution grid with either real or reactive power injection for grid stabilization. This is a shunt-connected flexible ac transmission system (FACTS) device that can be driven up to a substation in an 18-wheeler and parked. It is connected and supplies power as needed. The vans can supply up to 3 MW of power using state-of-the-art power electronics.

Technology Leapfrogs technology

Technology advancements are also making their way to T&D schools. The University of Texas at Austin’s power engineering program is on the move. Recently, the program was modernized and the power laboratory was expanded to give student engineers hands-on experience with power-system simulations. Current additions include expandable panel boards that can be assembled like building blocks, allowing the students to simulate three-phase distribution and transmission power systems in real time. Schweitzer Engineering Labs (SEL) donated 30 SEL-421 high-speed line-protection control systems to the department for student use. Dr. Mack Grady of the University of Texas at Austin said the commitment of companies like SEL truly helps the university to teach and the students to learn by being able to work with state-of-the-art equipment.

Ed Schweitzer, SEL founder and president, supports higher education and believes “we are growing the next generation of experts right now.” What makes the donation doubly valuable is the technology it represents. The SEL-421 is more than a relay package; it has the ability of a synchrophasor measurement unit (a device that measures the angle between voltage and current). Schweitzer points out that phasor measurement units have been around for many years, but they have been expensive and required an expensive infrastructure. Now the technology is built into the relay package and the students will be able to experiment with it.

For the University of Texas students, the donation is especially timely. SEL estimates that there are more than 10,000 of the devices in the Electric Reliability Council of Texas region alone (worldwide there are tens of thousands of SEL relays with this capacity). Upon graduation, these engineers will understand the technology and know how to use it.

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