September 11, 2012
For years, some have assumed that the interval or “smart” meter would be the interface between an industrial customer and the utility. In other words, that communications data, curtailment requests, generation requests, and price signals would all occur through an advanced metering infrastructure (AMI) system.
Based on an assessment of the systems themselves and the needs of industrial customers, however, the AMI approach may not be the only, or even the most desired, interface. And those two factors should be high priorities for the consulting specifying engineer designing industrial control systems and their utility interface.
This issue has big implications for industrial customers because the design and features and functions of their industrial control system is going to depend on which direction they take.
Let me explain. First, the bidirectional communications that a smarter grid will require can be handled independently of the interval meter AMI. Second, meters and AMI are largely proprietary systems, potentially leading an industrial customer to vendor lock-in. Third, it’s early in the AMI industry and technical alternatives exist. Consequently, there will be winners and losers; if a utility’s AMI vendor goes belly-up or migrates to different technology, that could mean stranded assets for the customer.
A different approach would use the meter solely to record usage and employ a separate appliance or gateway for bidirectional communications.
This approach has several advantages, besides avoiding dreaded vendor lock-in and stranded assets. One advantage is that the gateway could use a high-speed Internet connection rather than be hobbled by the communication limitations of the AMI. Or the gateway could use dedicated communication lines to the electric utility, providing greater bandwidth for greater functionality. The appliance-as-portal option also gives the industrial user more flexibility for interconnections with other systems and, therefore, the data for greater insight into its operations.
Today, AMI protocols are vendor specific. If you purchase a meter from vendor X, you must also purchase the data collection and protocol system from vendor X. In contrast, the gateway approach allows the utility and the industrial customer to immediately employ industry standard protocols such as IEEE Standard 1815 (aka DNP3), which provides the means for robust security.
What remains uncertain at this point is whether both options will be available from the utility. Consulting specifying engineers and their industrial customers should discuss this issue with the utility. If both options are available, then compare the two options’ costs, design challenges, features, and functions, taking into account the projected future needs of the industrial customer.
It’s important to understand that the cost-benefit ratio for AMI remains unproven; it’s still being evaluated. Much of the current deployment of AMI has been subsidized by 50% by the U.S. Dept. of Energy’s Smart Grid Initiative Grants in the US. Without those incentives, it is unclear whether the deployments will continue to spread, or be profitable. Some state regulators remain unconvinced that AMI is a cost-effective expenditure of rate payers' money.
Finally, because smart meters and AMI are a programmable system, greater potential exists for hackers accessing the system, a threat that has already been observed as noted in my previous blog.
Perceived, widespread AMI adoption alone is not a good basis for an engineer to make an assessment of whether that's an appropriate technology choice. He or she needs to make a professional judgment about the systems themselves, and their technical capabilities, and not be swayed by the apparent spread of AMI systems. Talk to the utility to which you are designing your customer’s interconnection. You may find that other, more “future-proof” alternatives are available.
Sam Sciacca is an active senior member in the IEEE and the International Electrotechnical Commission (IEC) in the area of utility automation. He has more than 25 years of experience in the domestic and international electrical utility industries. Sciacca serves as the chair of two IEEE working groups that focus on cyber security for electric utilities: the Substations Working Group C1 (P1686) and the Power System Relay Committee Working Group H13 (PC37.240). Sciacca also is president of SCS Consulting.