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Electrical substations: In the industry they’re known as “the heart of the power supply system,” connecting parts of the grid that operate at different voltage levels. But as smart sensors, big data and the Internet of Things (IoT) continue to prove their worth with cuts in operational costs and carbon emissions, it’s only a matter of time until digital substations are the next big thing.
by Bill Hinchberger
“It all starts with the vision of a largely decarbonized energy system in a near-to-all electric world,” says Robert Klaffus, Senior Vice President for Digital Grid Systems at Siemens. “In order to achieve a significant degree of decarbonization, energy systems are going to become much more complex with decentralized and renewable energy. So, the substations of the future need to manage these multidirectional power flows while ensuring maximum reliability.”
“The technology is there,” says Marcus Stenstrand, Digitalization Manager at Fingrid, Finland’s transmission system operator, which operates and maintains over 14,000 kilometers of the country’s transmission lines and more than 100 substations. “It’s already being used in other industries, but the transmission business is conservative: After all, we need to keep the lights on.” Substations encompass what’s known as primary technology – such as switchgear and transformers – and secondary technology related to protection, control and automation systems. They come in various shapes and sizes, some operating as part of the high-voltage transmission grid and others controlling connections between the transmission and distribution grids for residential or large-scale consumers such as commercial buildings or industrial facilities.
The upcoming five years will bring more change in terms of maintenance than the previous 50 because of digitalization.
Marcus Stenstrand, Digitalization Manager at Fingrid
Substations encompass what’s known as primary technology – such as switchgear and transformers – and secondary technology related to protection, control and automation systems. They come in various shapes and sizes, some operating as part of the high-voltage transmission grid and others controlling connections between the transmission and distribution grids for residential or large-scale consumers such as commercial buildings or industrial facilities.
Traditionally, the main role of a substation is to transform high-voltage electricity from a transmission system to a lower voltage for consumption. But the traditional model of centralized generation in large power plants and distribution to consumers has been making way for a more flexible system that can integrate decentralized generation, prosumers and the latest power storage solutions. “Digitalization,” says Klaffus, “is the enabler that will help us manage these more complex, decentralized grids.”
Digitalization increases flexibility and allows utilities to prepare for the future as new technologies emerge. One example of this is the digitalization of a substation’s process level by implementing a process bus and the use of nonconventional instrument transformers (NCITs), which are a combination of low-power sensor technologies, and stand-alone merging units (MUs), transforming the analog sensor signals into digital ones. The MUs are placed close to the sensors and use fiber-optic network connections to protection devices, eliminating the need for lots of hard-wired copper connections. It also increases operational safety by isolating the primary (high-voltage switching) from the secondary process (protection, automation, digitalization).
Digitalization is made easier with standard communication protocols, notably IEC 61850. (IEC stands for International Electrotechnical Commission, a nonprofit quasi-governmental organization that oversees such things at a global level.) The protocol eases communication among intelligent electronic devices in electrical substations without the use of hard-wired connections. “The process bus based on IEC 61850-9-2,” says Klaffus, “will become the new standard for substations.”
Moreover, “the nonconventional sensors help reduce the switchgear size and weight on high-voltage level by up to 30 percent,” Klaffus adds, “which allows for smaller substations and makes it easier to extend existing ones with significantly less resources.” The reduction in size is especially helpful in urban areas where real estate can be scarce and expensive.
Digitalization is the enabler that will help us manage these more complex, decentralized grids.
Robert Klaffus, Siemens Senior Vice President for Digital Grid Systems
The six components of a digital substation as seen by Siemens are: (1) digitalization at the station level using IEC 61850; (2) digitalization at the process level, described above, using a process bus, NCITs and MUs; (3) end-to-end cybersecurity, an essential prerequisite discussed below; (4) digital asset management; (5) improved grid operation with, for example, a wide area monitoring system (WAMS) that uses new data acquisition technology to oversee transmission system conditions over large territories; and, finally, (6) integrated engineering – the seamless use of data throughout the substation’s life cycle: from simulation to design, engineering, manufacturing, testing, construction, and, ultimately, to asset management and operations.
These six components improve data collection and monitoring and allow for greater automation and efficiency. “Where Siemens really makes a difference is by enabling the substations with an installed base of Siprotec and Sicam for IoT,” Klaffus adds. The firmware on Siprotec (protection relays) and Sicam (substation automation systems) devices can be upgraded with an IoT interface based on the Open Platform Communications Unified Architecture (OPC UA). This lets substation operators access unknown amounts of data from the substation level and analyze them on their own or with the help of Siemens analytics specialists and applications that run on an IoT cloud-based platform like MindSphere. “Together, in a cocreation mode,” says Klaffus, “we then look for the ‘golden nuggets’ in each customer’s data.”
Digital protection systems also help ensure the early detection of problems, thereby serving as an “insurance policy for the grid,” Klaffus says. “It can detect faults and tell the switchgear to protect the assets – with no false tripping.” Think of a steel company that must run its furnaces constantly at high temperatures. “Imagine if the electricity goes out,” suggests Klaffus. The entire multimillion-dollar installation might be at risk.
If there is a critical problem, such as defective insulation or a tree hitting an overhead line, the alert system can help protect the transformer. “If a whole substation were to drop out, people could be without power for a considerable time,” says Klaffus. “Life-saving systems like those in hospitals can be down.” So not only do digital substations offer cost savings through investment and operating expenditure reductions, they are also better at monitoring critical systems and ensuring they operate normally through the data they provide.
In India, the state-owned electric utility Power Grid Corporation of India Limited (PGCIL) is already reaping benefits from the additional information it collects. The utility operates around 230 substations with voltage levels of 132–765 kV, aged 0–25 years: “With the help of data and various analytics,” says R.K. Chauhan, Executive Director of Engineering at Power Grid, “we can plan the maintenance of our major equipment, such as transformers, reactors, and circuit breakers. We can also continuously monitor our voltage and current transformers and find out about any deviations in the shortest possible time.”
With the help of data and various analytics we can plan the maintenance of our major equipment.
R.K. Chauhan, Executive Director of Engineering, Power Grid Corporation of India Limited
With increased digitalization, cybersecurity is becoming a more salient issue. Historically, people who might have wanted to do harm to the electrical grid had to tamper with its physical elements. With digitalization, hackers can potentially tap into sensitive systems. “Cybersecurity is at the core of digital substations,” says Klaffus. Companies such as Siemens and their customers are working on different solutions to protect sensitive data and combat potential problems such as malware and intrusion. Part of Fingrid’s cybersecurity program includes hiring so-called “white hat” hackers who try to break into their system to identify potential weaknesses. Despite the security concerns, most observers believe that digitalization will continue apace and deliver significant benefits.
The transition from conventional to digital substations may still be in “discovery mode,” as Klaffus puts it, but leading companies such as Fingrid in Finland, Statnett in Norway, National Grid in the United Kingdom, RTE in France and Power Grid in India count among those making moves. “Everyone is moving ahead with pilots,” Klaffus says. “They’re keeping their traditional systems but implementing nonconventional ones in parallel. From our point of view, that’s the right way to start.”
The normal lifespan of a substation’s primary equipment is 30–50 years, according to Klaffus. As older ones are replaced, digital will gradually take over. Many greenfield projects are expected in emerging markets such as India and parts of South America, while in more mature markets, brownfield extensions or replacements will dominate, Klaffus adds.
Fingrid began with a pilot project at a 110-kilovolt substation in the town of Kymi in southern Finland. “We put in low-cost sensors to get more information for maintenance purposes,” says Stenstrand. They plan to upgrade as many as three additional substations this year and add another five to ten next year if everything goes well. “The upcoming five years will bring more change in terms of maintenance than the previous 50 because of digitalization,” says Stenstrand.
In India, Power Grid has been moving confidently forward for quite some time now. “We introduced substation automation in a big way from 2003 onwards,” says Chauhan. “And all the substations which were ordered and commissioned after 2003 are equipped with substation automation systems based on IEC 61850.” Such rapid-fire change requires special attention to training, notes Chauhan, meaning that utilities will want to have a partnership with a reliable and knowledgeable supplier. “The handling of so many new devices was a real challenge for our field engineers,” he says. “Somehow the training couldn’t keep pace with the changes in technology, and so our dependence on our supplier increased – even for day-to-day issues.”
Klaffus believes that more and more utilities will be taking on new devices and makes the prediction: In about five years a majority of new or modified substations will be digitalized. “If we want our future generations to have a livable planet,” he says, “at least one similar to what we’ve experienced, then we need to act quickly and consistently in driving the decarbonization of the energy systems, and this will only be possible with digitalized grids.”
Bill Hinchberger is an independent journalist based in Paris, France.
Picture credits: Siemens AG, Marcus Stenstrand, Robert Klaffus
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