By John Cooper, Grid Net
During any week this year, you could find a smart grid conference, and you wouldn’t have to look hard. There is no shortage of discussion on smart grid whether it’s online, at a conference or in the office. But for all the talk about fixing the grid, upgrading the grid and adding to the grid, when the discussion begins with the applications or tools that will define the solution (such as an AMI project), as it often does, that discussion jumps ahead of itself. A smart grid project must start with decisions on the network design or face the risk of the application decisions’ limiting the network options needed to meet future needs, plus raising the complexity, cost and overall risk of the smart grid project.
Traditionally, electric utilities have been organized in functional silos: generation, transmission, distribution and retail. Vendors sell solutions to those silos, and when it comes to applications and hardware, managers have purchased solutions bundled with a supporting network. Building a smart grid this way shortchanges the network decision, as the single application drives network parameters. A just-good-enough network becomes suboptimal when subsequent applications are concerned. And with each application’s bringing a new network, the number of projects multiplies and the costs of system integration rise with the complexity of the system. Compatibility and interoperability issues arise to stress the original plans, and expensive work-around projects are not uncommon. There is a better way.
Vision of the Smart Grid Future
When we describe a vision of the smart grid, we are talking about more than adding new applications to solve old problems. We are talking about a long-term vision that involves a fundamental redesign of the grid to harness the digital revolution and engage new thinking about network architecture based on lessons learned from the Internet. If we were to start from scratch to build a power grid with all we know now that we didn’t know 100 years ago, we would build an energy Internet capable of routing power and information in much the way the Internet routes bits and bytes today. By necessity, the project plan for the smart grid will be incremental and affordable and might take years to implement, but the plan must be informed by such a long-term vision that accommodates a dramatically different set of needs. The need to bring consumers into the picture through demand response and the need to accommodate distributed energy resources integration begs the question of how the system will be kept in harmony with millions of devices integrated into the grid from all points.
How will tens of thousands of home energy management systems cycling hundreds of thousands of appliances on and off be enabled in a grid blind to activities that lie beyond the distribution substation? How will the grid add electric vehicle charging stations that appear in a neighborhood over a few months (especially when the transformer located at the end of a distribution feeder was designed decades ago to manage a static load limit based on the number of houses it served)? How will the system accommodate energy storage units when technology matures this decade and makes energy storage an economical solution? As grid parity approaches, how will bedroom communities with multiple rooftop solar installations feed their excess power back onto the grid while residents are at work during the day, when the grid is designed for one-way power flow? How will grid managers address grid stability when large amounts of intermittent energy from wind and solar farms are added? We can’t add ever more generation-based solutions to balance services needed to accommodate intermittency.
Each question requires a more advanced smart grid that must address new problems of increasing complexity. Each question carries the discussion beyond transitioning from analog to smart meters to address current problems as the need for interval data to support time-of-use rates and the need to improve visibility of grid conditions during outages.
The answer is an energy Internet designed to be resilient and robust, sufficient to support the demands described in the preceding paragraph, and future needs. The challenge grid owners and managers face is nothing less than going back to design an infrastructure capable of meeting 21st–century needs. Once that design is in place, a project plan is needed to transition from the current state to the future state while maintaining reliability.
The network architecture for a robust future must support and integrate current and emerging domains and unidentified future domains. Current domains start with centralized generation and its automated generation control systems that support reliable dispatch. The second domain involves generation market operations, and the third concerns the system operations of the utility. Systems in the third domain support transmission (energy management systems and supervisory control and data acquisition) and distribution systems (geographic information systems, outage management systems and emerging distribution management systems).
The next critical domain is metering, where the popular system is advanced metering infrastructure (AMI), which consists of a smart meter end device, a wireless communication network, data backhaul network and meter data management system back-office function to provide interval consumption data collection and processing for use in revenue metering and bill production. AMI also provides such ancillary functionality as outage management and remote turn on and turn off.
The next two domains involve emerging functionality of premise-based systems. Demand response systems consist of a remote control unit connected to a wireless network used to automate load curtailment as an alternative to dispatching additional supply resources. Distributed energy resources (DER)—premise-based systems in this analysis—include distributed generation, electric vehicles and energy storage. Each of these DER elements includes some combination of metering and submetering, customer portals, in-home devices, building management systems and home energy management systems to support functionality at the ends of distribution feeders.
The Ultimate Smart Grid
The ultimate advanced smart grid design must start with a supporting broadband communication network and a network management system. The foundation of the project will be an information technology back office designed to support access to a common database from applications and process more data than has been managed within any information technology back office. A service-oriented architecture approach provides the necessary functionality and smoothest path to the prescribed objective.
Telecom networks depend on a network operations center (NOC) to provide the centralized monitoring and control to let operators manage the devices and growing system complexity. Connected to an integrated broadband network consisting of a fiber backbone and a 4G wireless broadband network, the NOC becomes the interface between the back office and the smart devices and field operations of the advanced smart grid.
Network design decisions must address the build-or-buy question as well: Should the utility own its own network or buy services from a carrier?
A hybrid blend of the two approaches is needed to provide the universal coverage for utility operations and redundancy for mission-critical activities. For the build portion, a thin wireless network design with larger cell sizes and lower costs best meets the needs of the smart grid’s machine-to-machine communications. Utilities may substitute carrier network services for a utility-owned network, or they may limit their use of carrier services to providing coverage for the less dense, rural service territories and to gap-filling in their own network coverage.
Starting with the end in mind—a robust network—helps a utility avoid risks and costs from redundant networks and unnecessary project management and system integration. The network-first approach enables the addition of applications and solutions in a plug-and-play manner, similar to today’s Internet. Lessons learned from projects around the globe highlight the benefits of the advanced smart grid approach outlined in this article—namely, lower total cost of ownership and increased functionality with less risk. The steps outlined are meant to inspire utility managers to recognize the need for a distributed network architecture that can withstand any potential threat and can grow with the utility in new directions as new technologies come into the picture.
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