Wireless applications in power: No wires, no limits

In the generation sector of the electric power industry, John Blaney is likely the most passionate supporter of wireless communications networks. The controls expert got CTOTF’s Gen-EI&C (generators/high-voltage electrical/I&C) Roundtable moving on a high note with an entertaining but serious technical backgrounder on wireless communications and an overview of the technology’s future. Blaney, who has more than three decades of experience designing, installing, and troubleshooting powerplant control systems, is Emerson Process Management’s point person on PlantWeb® applications for the company’s Ovation® platform.                           

Field networks. Blaney’s mission was to get the group to kick back and think of the benefits associated with extending the reach of the plant network using wireless technology. Wireless networks, he said, can be characterized as either field or plant networks. Each serves different applications and has specific requirements for bandwith, power, and standards. Field networks, formed by wireless field devices and gateways, are configured for process applications, process control, and diagnostics. Typical applications include monitoring of (1) stacks and vents to avoid fines for exceeding permitted limits of pollutants and (2) valve position to ensure equipment is properly aligned.

He told the group that wireless technology has matured from the point-to-point field networks that some attendees recalled as having limited reliability to self-organizing networks, commonly referred to as “meshes,” available as a process industry standard through the HART Communication Foundation. Self-organizing networks are the only industry standard available today, Blaney continued, because they are the only ones capable of providing the reliability of data transmission required for power and process applications.

The ability of self-organizing networks to automatically reroute data to an open frequency/channel, and to the most efficient device for communications, enables data transfer reliabilities of more than 99% regardless of process environment or application, he said—adding that the WirelessHART network automatically adjusts to satisfy plant requirements as your environment and network changes. The wireless champion pointed out that while it may seem counterintuitive, self-organizing networks become stronger with each device added because the number of communication paths increases. You use wireless, he said, but you don’t have to fully understand it to use it. The WirelessHART experience base currently spans 2500 sites worldwide with more than 300 million hours of operating time in real applications.

Security probably was on the mind of virtually every owner/operator in the room given NERC’s (North American Electric Reliability Corp) emphasis on that subject today. Blaney reported that WirelessHART integrates best-in-class security to protect wireless networks from outside threats. Also, that Emerson’s security approach has been validated and tested by customers and wireless experts. Here are the key elements of the WirelessHART approach to security:

    • Data encryption to protect valuable information.

    • Ability to authenticate sender and receiver to ensure that only devices within the network communicate with each other.

    • Ability to verify that the data have not been changed during transmission.

    • Anti-jamming technology, specifically channel-hopping, to avoid interference and improve reliability.

    • Automatic key rotation (password management) to protect your network from unauthorized access.

The gateway interface between the wireless field network and the wired network world employs all components of the security solution described above and is responsible for managing security as well. Because the wireless field devices do not use TCP/IP messaging, if an intruder tries to compromise that side of the network, the attempts will be ignored. However, because communication from the gateway to the control system does uses TCP/IP messaging, Emerson relies on industry standard techniques—such as VPN and HTTPS—to assure what the company believes is the most robust wireless security in the industry.

Plant networks. Whereas field networks are used to communicate critical process control information, wireless plant networks serve applications not necessarily central to the basic power-generation process. These include data connectivity, video/perimeter security, voice communication, and people and asset tracking. Plant wireless, Blaney said, relies on commercial off-the-shelf (CTOS) technologies—such as Wi-Fi, which is defined by IEEE 802.11, an accepted industry standard.

Because plant networks use open IT standards, security measures must be added to address evolving concerns. Blaney said this means it’s in your best interest to choose a plant network supplier with the capabilities to address the full range of security concerns to the satisfaction of the IT community. Emerson has done many implementations combining field WirelessHART and plant Wi-Fi networks, he added. Customized solutions are developed to accommodate a specific problem or area of the world.

To dig deeper, access Blaney’s “Benefit by installing reliable, secure wireless communications networks at your plant,” which appeared in the CCJ’s 2009 Outage Handbook.


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