Wireless Radio Communications for Distribution Automation in Smart Grid

by Colin Lippincott, FreeWave Technologies Inc.

People worldwide are consuming more energy every year. Electricity use in 2009 was about 13 times greater than electricity use in 1950, according to the U.S. Department of Energy (DOE). Everything from new gadgets to electric vehicles and urban infrastructure developments adds to the increasing, annual energy-consumption rate. Energy consumption is outpacing generation.

A few ways exist to help alleviate this problem. One way is to add electrical generation more quickly. For years, emphasis has been placed on alternative energy resources, but the sun’s not always shining and the wind’s not always blowing. Electricity is a real-time commodity. For utilities, the necessary capacity of electric power is important because there must always be enough electricity to continuously meet peak demand. The alternative is to make the electric grid more efficient by optimizing or eliminating transportation and distribution inefficiencies. Enter smart grid, routing electric power from where it’s generated to where and when it needs to be consumed in the most efficient way.

Because of growing demand and the need for more efficiency, electric utility operators are thinking about how to make their electric grid smarter. Automation is the primary driver. Automation enables utilities to improve distribution automation and make it more cost-effective, safer and more resilient. For years, many electric utilities have implemented supervisory control and data acquisition systems for better control. As reliability and load requirements continue to increase, so does the need to minimize costs. Therefore, the extension of intelligent control over electrical power grid functions to the distribution layer and beyond via distribution automation is a key enabler for smart grid success.

Data communications are critical to supporting time-sensitive distribution automation applications. At the distribution automation layer, many critical functions and actions are automated, such as the monitoring of critical feeders, fault detection, isolation and restoration to reduce outage duration and impact. These systems also support shifting loads between sources to help avoid or alleviate overload conditions, controlling capacitor banks and more. Many smart grid utility operators are finding the need for more secure, reliable, efficient forms of communication to deploy distribution automation effectively. No single technology satisfies all requirements and priorities of system managers, especially communication requirements as complex as smart grid’s. Think of the communications link as an enabler or catalyst of grid continuity. It resembles the highway system: It doesn’t do anything itself, but connects everything together.

Critical success factors to the communications component in the smart grid distribution automation layer are:

  • Reliability,
  • Security,
  • Throughput,
  • Flexibility,
  • Ease of installation, and
  • Cost.

Communications options for the distribution layer include:

  • Private radio spectrum, unlicensed,
  • Private radio spectrum, licensed,
  • Cellular,
  • Satellite, and
  • Wired, copper or fiber.

Data communication technologies are viable options for several applications within the electric power industry. Every technology has advantages and disadvantages. Some systems can send data very far while technologies are purely for very short-range applications.

 

Frequency-hopping Spread Spectrum (Unlicensed Private Radios)

A longtime staple to distribution automation, private radio tools remain important to the smart grid success. They allow real-time, accurate monitoring of distribution automation and offer reliable data that can be sent over long distances. Some types of data radio offerings aren’t reliably robust, sufficiently secure and field-proven. Some others are not as well-qualified. Wireless data communication equipment providers have taken a leap forward for customers who need industrial-grade serial and Ethernet radios that operate in harsh, challenging and congested radio frequency (RF) environments. They work well over long and short distances. Some wireless data communication equipment providers offer frequency-hopping spread-spectrum (FHSS) radio technology for private radio network solutions in unlicensed spectrums for reliable, secure data transmission with low latencies, attractive range and throughput rates.

FHSS technology has been trusted since World War II, when Hedy Lamarr, an Austrian-born actress, together with George Antheil co-patented a secret communication system that allowed radio control of torpedoes that could not be easily discovered, deciphered or jammed. The secret was frequency hopping–coordinated, rapid changes in radio frequencies that hop in the radio spectrum to evade detection and the potential of interference. The frequency hopping capability prevents sent critical data from being intercepted or jammed. This technology has been implemented for years in many industries, including military, oil and gas, water and wastewater, security and electric power. Providing the lowest cost of ownership, combined with ease of installation, quick deployment and supportive network management tools, wireless data radio communications are growing in attractiveness for smart grid applications. Organizations that count on data communications for operational success–where failure and downtime are not an option–are realizing the value of this technology.

FHSS radios have real and perceived limitations. They require an infrastructure that is line-of-sight in nature. They are more susceptible to interference in heavily wooded areas than other technologies. Some people are concerned about frequency saturation in areas where many unlicensed radios operate. Others are concerned that these radios operate in an a shared spectrum (e.g., 902-928 megahertz).

FHSS radios also have many advantages. They provide for much higher throughput than licensed systems. They do not require a license and attendant administrative costs and headaches. They are very flexible in many ways, including that by using repeaters, the achievable range is unlimited.

Fixed Frequency (Licensed Private Radios)

These radios can be deployed in various frequencies nearly anywhere in the world. The radios can be very tolerant of Mother Nature’s and humans’ link challenges, especially in the lower frequencies. At 400 megahertz or 200 megahertz, for example, the radios will penetrate wooded areas better than 900 megahertz FHSS.

The theory behind using a fixed-frequency radio is that the user owns that frequency in the geography where the license is held with the Federal Communications Commission (FCC) in the U.S., for example. They assume that because they own the frequency, they will not face interference from another user in the same area.

Disadvantages of the licensed radios include low bandwidth. In some frequencies, the channel spacing can be as limited as 6.25 kilohertz and no more than 25 kilohertz. Even at 25 kilohertz, most radios will deliver only 19.2 kilobits per second. When Ethernet is layered into the equation, the throughput takes an overhead hit. These radios require a license from the FCC. In some frequencies and geography combinations, the licenses for a required throughput are not available. In other cases, there might be plenty of spectrums available, though it might be prohibitively expensive.

Satellite Systems

Satellite systems have broadband capabilities and tend to be reliable and ideal for long-range backhaul applications. Nevertheless, satellite systems are very costly to deploy and have monthly recurring costs. These costs add burdens to operating budgets.

Satellite systems can be deployed almost anywhere. They are, however, a nonprivate system with shared bandwidth. Plus, system maintenance–repairs in the event of an outage–are not in the control of the user. Only the system provider has access to rectify outage events, perform maintenance or add to system throughput with more infrastructures.

Satellite systems are not deployed commonly for distribution automation applications. They are too expensive to justify when other less expensive, low latency, reliable, secure systems such as unlicensed and licensed systems can be deployed. In the event that data is required from a local system to be accessed from far away and there is not local Internet access, satellite systems are very useful.

Cellular

Cellular systems function similarly to satellite systems. They use an existing public network of communication infrastructure and devices that have monthly charges. Using a cellular network for distribution automation has several advantages. There is no need for the user to craft a tower infrastructure plan. For the most part, a technician turns on the cell modem and a link is created. The network design is far simpler than unlicensed or licensed radio systems.

Disadvantages, in comparison, include the monthly charges and that this is a public network with shared spectrum. The utility has no real control over the system use and especially not during an outage in the cell network. Also, cell coverage can be inconsistent to nonexistent. Many nonurban areas have low or no coverage. Even in urban areas, service commitments notwithstanding, there can be coverage problems. One more disadvantage to cell networks for some utilities is the way the systems manage Internet Protocol (IP) addresses. In radio systems, the IP addresses are fixed to a device by the information technology team at the utility. In cell networks, the IP addresses are assigned randomly when a connection is made with the modem.

Latency in cell systems often is discussed as a potential problem for distribution automation networks. With utilities’ and agencies’ recommending the latency for any one-way communication be equal to or less than 50 milliseconds, the utility must be confident that the communication technology selected will perform reliably to this level.

Copper or Fiber

Distribution automation applications between distribution automation devices and substations and network operations centers can be far apart. Copper or fiber solutions can provide much more throughput, but these long distances often make either technology impractical because of cost and other issues such as right-of-way. If cost and right-of-way are not issues for the utility, these options, especially fiber, are compelling choices. No other technology discussed will provide speeds and reliability of fiber. It is not maintenance-free, but that is another variable in the total cost-of-ownership equation. Some utilities will make fiber their choice for some of the critical infrastructure links they will not trust to wireless of any kind.

Copper theft has become a big business nearly everywhere. If the communications system is using copper wiring and theft is a significant risk, the system is at risk. The price of copper has grown significantly during the past 10 years from less than $1 a pound in March 2001 to nearly $5 a pound in March 2011. So did copper theft, which has proven very lucrative for criminals across the world. The economic impact of copper theft has totaled more than $1 billion a year, according to the DOE, and there are no signs of its slowing. The recent increase in copper theft, often impacting data communication lines, make cost-effective, quick and easy-to-deploy wireless data communication solutions an attractive alternative to copper and fiber.

Case Study: Wireless Data Radios for Distribution Automation

A major energy company that serves hundreds of thousands of U.S. retail customers wanted to improve the distribution automation component of its comprehensive smart grid network. Upon considering all communication options, the energy provider decided to build a private wireless communication network for the distribution automation layer. Decision drivers included cost savings combined with the advantages of making the grid more resilient and efficient in one installation. The wireless solution chosen could provide the reliability required with the security suite desired.

The energy company evaluated several wireless data communication providers. Each provider has products proven in the field for automation applications. One company was selected based upon the driving factors discussed, reliability and security. The system security uses a layered approach to protect the utility’s network. AES 128, Radius authentication and many other layers combine to defend the system from outside penetration and denial of service attacks. Another factor that surfaced during the evaluation was the provider’s service model and commitment. That model was confirmed by reference companies that are also utilities.

The data radio provider is involved heavily in the network design and installation. It provided the energy company with extensive path study information and network design options and is aiding in the full deployment of the data radios. In addition, the provider supplied the utility with a software platform for managing radio configurations and network application needs from a single interface. In using the software, the energy company and solutions provider built templates for the network design and easily commissioned the radios with the proper configuration to deploy them in the field.

The utility and provider are working together in the deployment phase of the data radio solutions into hundreds of distribution automation devices. These new smart grid communication capabilities will enable the utility to continue enhancing energy distribution services to customers by having less frequent outages, as well as reducing the duration of outages that might occur.

Electricity usage is continuing to increase in the U.S. and throughout the world. Smart grid utility operators are meeting these demands by developing smarter and more comprehensive network systems to help automate the processes and make electric power delivery as efficient as possible. The distribution smart grid automation layer is a key to the long-term success of the energy distribution system. There are many data communication technology options to consider for communications in distribution automation. Each option has advantages and disadvantages. The key to selecting the right provider and technology starts with establishing system objectives. The variables are reliability, security, throughput options and more.

Technology is challenging to evaluate and select, and the provider’s service model should be in the selection criteria. There are many data communication technology options to consider, but deploying reliable wireless data radio technologies for distribution automation can save time, money and increase the efficiency of system management while meeting a best-fit requirement to the objectives of the organization.

Successful deployment of a smart grid system depends on the right technology from the beginning.

Author
Colin Lippincott is the general manager of energy markets at FreeWave Technologies Inc. He has served in senior management positions at FreeWave since joining the company in January 2003. He graduated in 1983 with an MBA from the University of Colorado.

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