If the lights in your home have ever flickered briefly during a storm—and didn’t then stay out—a lot of Smart Grid technology kicked in between the time the lights blinked out and the few hundred milliseconds later when they came back on again.
During that brief time an operation control center detected the loss of power to your area and redirected power from another substation to compensate, perhaps diverting power from a third source to compensate for the additional load on the second substation. When the break was repaired, the transformer replaced, or the breaker in your local substation automatically reset after a lightning strike, the control center automatically brought your substation back online and rebalanced the loads between all substations. In that way the Smart Grid is said to be self-healing, though humans will always have to repair line breaks and blown transformers.
Figure 1: Electrical power distribution and transmission.
There are two types of substations: primary and distribution (Figure 1). Primary substations work on the supply side, taking power from a variety of primary sources—hydroelectric, solar, wind, geothermal, and nuclear—and putting it out on the grid. This involves synchronizing highly variable inputs such as solar—which is clearly only available during the day—with wind power, which peaks at night. The substations must also regulate the loads on the power sources, which may vary considerably in capacity.
For each primary substation there may be dozens of distribution substations, which work on the demand side, ensuring load sharing between residential, industrial, and transportation end users. When a substation starts nearing its peak capacity it signals the control center to bring other sources online to get it through peak demand, avoiding the ‘rolling blackouts’ that preceded the Smart Grid.
The Smart Grid works because substations can all communicate with each of the elements under their control, sending that information back to a master control center that controls all the substations. IEC 61850 is the IEC standard for substation automation, replacing a myriad of proprietary protocols whose lack of interoperability delayed the advent of the Smart Grid.
On the Level
There are three different levels in Smart Substation architecture: the Station Level, the Bay Level, and the Process Level. Advantech provides numerous Intel-based IEC 61850 certified Smart Substation solutions in each of these areas. Its UNO-4600 series Substation Automation Computers can operate as HMI/SCADA, Terminal (serial-port) Servers, Protocol or Communication Gateways, Cyber Security Servers (UTM), and Substation/Networking Recorders.
At the Station Level the Advantech UNO-4683 provides the communication gateway between the remote control center and all the environmental monitoring and control devices at the substation; it also provides cyber security for the substation. The UNO-4683 Automation Computer is based on an Intel® Core™ i7 running at 2.0 GHz with 4 GB of DDR3 SDRAM. It provides two RS-232/422/485 isolated serial ports with automatic flow control; 2 x 10/100/1000Base-T and 4 x 10/100Base-T Ethernet ports; and six USB 2.0 ports with three domain I/O expansions.
At the Bay Level (Figure 2) the Advantech UNO-4673A protocol server provides a data gateway between intelligent devices and the station-level controller. The UNO-4673A is based on a 1.66 GHz dual-core Intel Atom processor with 2 GB of DDR2 SDRAM. Sitting on the Ethernet backbone the Advantech UNO-4672 acts as a network recorder and analyzer, passing device data back up to the station level. The UNO-4672 is powered by either an Intel® Pentium® M running at 1.4 GHz or an Intel® Celeron® M at 1.0 GHz, each with 1 GB of on-board DDR DRAM.
Figure 2: Substation automation at the Bay Level.
Finally, at the Process Level either the Advantech UNO-4671A (Intel® Atom™ D510 @ 1.66 GHz) or UNO-4673A (dual-core Intel® Atom™D510 @ 1.66 GHz) acts as an Intelligent Electronic Device (IED) that continuously monitors the status of transformers, circuit breakers, and switch gears, warning of excessive temperature, vibration, leakage or other issues that could cause device failure.
When the lights go out they don’t just blink for everyone—sometimes they go out for hours. The basic design of the electrical power grid is over 100 years old, and it’s only gradually being computerized. Most utilities have begun to automate the restoration process by installing supervisory control and data acquisition (SCADA) systems that monitor and control line reclosers and switches, but the system is still a long way from being completely automated. Smaller cities and other customers are usually connected to their local substation by a single radial feeder. Outages to these feeders are called in by a customer to the control center, which then dispatches a person to the area to manually restore power to customers.
Implementation of automated devices such as SCADA-enabled switches and line reclosers would cut outages. Distribution circuits could also be sectionalized with SCADA-operated devices between each section. Open points that connect to other circuits could be replaced with SCADA-enabled switches. Then in the event of a failure the system could automatically isolate the problem, opening adjacent switches and rerouting power to unaffected sections by closing connections to adjacent circuits.
The Smart Grid is getting smarter, and substation automation is the key element to its success. Advantech already has a wide range of Intel-based products that can provide a complete, automated solution. It’s just a matter of time before the Smart Grid all comes together and your lineman will need to find another line of work.
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Roving Reporter (Intel® contractor), Intel® Intelligent Systems Alliance
Editor/Publisher, Low-Power Design
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