By Curt Goldman
A well-planned data communications network offers a clear picture of the operating status and overall health of a smart grid in real-time. With the best-fit communication technology in place, a utility operator can monitor critical data and seamlessly automate transmission and distribution processes within their service area. For the past several years, a top focus for utilities and their smart grid operators has been enabling the demand side management aspect of its grid, e.g. the advanced metering infrastructure (AMI). Having said this, the distribution layer of the smart grid is increasingly a main focus for electric utilities, municipalities and cooperatives. Newer mandates and government regulations require increased grid efficiency and new investment is needed to improve the distribution of power to the end user. Distribution automation serves many critical functions within a smart grid, even if its benefits remain misunderstood or unknown to decision-makers. To stay competitive, utilities need to upgrade their existing infrastructure and improve the distribution layer to stay profitable in the years ahead. Distribution automation, unlike conventional means, allows remote monitoring, operations, isolation and implementation of fault recovery response in a fraction of the time previously experienced. Costs ultimately are reduced and revenue integrity is ensured at a greater level than previously thought possible.
There are a variety of critical distribution automation functions within the smart grid where reliable data communication solutions will benefit the entire system. Some of the more recent functions/devices within the distribution layer being automated and remotely monitored are reclosers, feeder switches, capacitor banks, fault circuit indicators and voltage regulators. Reclosers, automated feeder switches and fault circuit indicators provide critical functionality within the distribution automation scheme because electric power can be instantaneously re-routed around a fault, improving power delivery and limiting any issues with end-users. Capacitor banks and voltage regulators play an integral role in grid optimization by increasing stored energy and improving system power quality.
To improve distribution automation and leverage the power of the devices previously mentioned, utilities also must choose the ideal data communication technology. In other words, distribution automation practices are only as successful as the communication network technology that binds them together. It is important, therefore, for a utility operator to understand the needs of these applications within the individual system, as well as look to what has worked for other utilities.
Case Study Example:
The key to successful smart grid operations is reliable, secure communications. Wireless data communication systems provide real-time visibility to system performance through an owned, self-operated network. This is unlike public infrastructure communications-such as cellular or satellite systems-that have recurring fees and limited accountability for outage resolution.
Dairyland Power, an electric power cooperative based in La Crosse, Wis., is an example of a utility organization that has leveraged robust, long-range wireless data communication networking for its distribution automation layer and, as a result, improved grid efficiency and business operations across the board.
Dairyland was looking for a communication system that could monitor data in the distribution of electric power. Dairyland serves more than 600,000 customers in a service area of 45,000 square miles. The cooperative specifically serves rural communities and provides wholesale electricity to 25 member distribution cooperatives and 16 municipal utilities in four states (Wisconsin, Minnesota, Iowa and Illinois).
Dairyland's earliest distribution substations did not have real-time data acquisition. Instead, metering data was recorded on magnetic tapes, which was translated monthly by having a field technician drive to the substation and manually gather data. The company recognized the need to streamline its power delivery by deploying a more advanced monitoring system. At the time, wireless communication technology for data transmission in utilities was a new concept. While it had come a long way from its manual beginning, Dairyland's existing infrastructure was complicated, limiting in nature and was increasingly expensive.
When Dairyland first implemented wireless data radios, it deployed a small installation base of frequency hopping spread spectrum wireless data radios. The power cooperative, however, also wanted to test the other available options. After conducting a distribution automation study comparing various types of communication technologies that faced harsh weather conditions and line-of-sight challenges from hilly terrain, the robust and reliable data transmission provided by a leading spread spectrum wireless data radio manufacturer helped convince Dairyland to continue using wireless data communications exclusively in its distribution network. After deployment, the product performed up to expectations and the wireless data radios eventually replaced the majority of Dairyland's pre-existing technology-lead circuits, analog cell phones, etc.-enabling real-time data collection across the distribution system. In some of the network's areas there was no prior technology, so wireless data radios were deployed, creating a fully integrated solution across Dairyland's entire communication network.
These same wireless data radios are now used for a variety of distribution automation applications within the Dairyland data communication network, including AMI backhaul, transmission capacitor bank control, transmission line sectionalizing, and fault detection and isolation. The cooperative also uses industrial 900 MHz wireless Ethernet radios for applications that require more effective throughput. The radio network features a single-system design that is easily maintained. Much of the maintenance is credited to the technology vendor's diagnostic software and 24/7 technical support-another important consideration for selecting a communication technology and owning/operating the network. Overall, Dairyland has achieved single system integration, link performance and reliability by implementing a wireless data communications network.
With the proper technology, automation of distribution applications in the power grid can streamline operations, improve grid efficiency and ultimately benefit the end user. By choosing a spread spectrum wireless provider, for example, Dairyland Power was able to create single system integration for a variety of applications. In addition, with wireless automation, there is continuous data available for monitoring and control that can be managed from the utility operator's desktop. Some technology can offer security and reliability, all while transmitting data from remote locations. As more utilities adapt a wireless communications system, reputable technology providers are working hard to continue meeting the communication needs within the industry.
About the author: Curt Goldman is the utilities market manager at FreeWave Technologies, a radio frequency design and manufacturing organization. Before FreeWave, Goldman was the regional accounts manager for Two Technologies Inc. He has a Bachelor of Science from Shippensburg University and a Master of Business Administration from La Salle University in Philadelphia. Goldman can be reached at firstname.lastname@example.org.
Acknowledgements: A special thank you goes to Ken Graves, director of Telecom and Control at Dairyland Power for his assistance in developing the ideas presented in this article.