Compact digital substation in Italy bring renewables to the grid. Courtesy of Hitachi Energy.

Digital Substations: Intelligence Where It’s Needed

March 21, 2024
Technology is proving to be a fountain of youth for aging power grid assets.

When it comes to trending technologies it’s pretty hard to beat what is going on with digital substations. This technology is providing modernization across the board when it comes to substations. From new substation facilities to antiquated conventional substations they’re all benefiting. It helps that the technology saves money and increases the efficiency of our substations. It also improves personnel safety and increases cybersecurity along with reducing maintenance outages while keeping the equipment healthy and many other budget friendly considerations.

For years the electrical substation has been thought of as the hub or the heart of the power grid, but there has always been something missing — intelligence. It’s been a vulnerable point. There is very little feedback on what is taking place in conventional substations, except when personnel are sent to the facility. Digital substation technology has proven to be the answer. It places intelligence exactly where it’s needed — at the hub of the power interactions. By digitalizing the substation, it’s becoming the brain of the power grid, but it’s been a slow process.

Digitalization began in the control building by replacing the old-school analog control and protection systems with digital processors. Then it moved into the yard by integrating sensors, intelligent electronic devices (IEDs), and other digital technologies directly into the substation’s outdoor equipment. It wasn’t long until manufacturers developed a digitalization strategy for the entire substation, but there was a problem, those early platforms were proprietary systems.


Proprietary devices don’t work with other manufacturer’s equipment and propriety systems have always been an issue for utilities. They want open architecture with plug-and-play practicality. It took a while, but the International Electrotechnical Commission (IEC) addressed the issue with their IEC-61850 standard.  It’s the communication standard for electrical substation automation systems, which defines interoperability between products from multiple suppliers. In a short time, IEC-61850 has matured into a series of protocols addressing areas required for advancing digital substation technologies.

This series of standards includes the primary processes along with secondary and auxiliary equipment in the substation. The  technology is still expanding, and we haven’t reached its full potential. The Business Research Company published its “Digital Substation Global Market Report” in early 2024. It estimated the digital substation market “will grow from US$ 7.3 billion in 2023 to US$ 8.03 billion in 2024 at a compound annual growth rate (CAGR) of 11.7%.” They attribute this growth “to grid decentralizing, electrification of transportation, standardization and interoperability, rapid urbanization and electrification.”  Business Research Company also project that the digital substation technology to grow to US$ 12.51 billion in 2028 at a CAGR of 11.7%.

Upgrade Aging Assets

Part of that growing market is represented by retrofitting existing conventional substations, which is an enormous market. In North America alone, it’s estimated there are over 79,000 substations in service, with an average age of these substations of around 40 years. That means the technologies in these substations can span from antique status to state-of-the-art facilities. It also means that removal and replacement of these existing substations is economically unfeasible, but retrofitting these substations with cutting-edge digital technology is a viable option.

Manufacturers offer utilities a variety of choices when it comes to retrofitting an existing substation that starts off by replacing aging analog components with digital applications. There is also the option available that includes installing a process bus out in the substation’s yard with the equipment. This retrofit enables the monitoring and control of power flow in near real-time. It also allows for faster diagnostics that can resolve potential issues before they become serious problems, but it’s getting complicated. So let’s talk with an expert in this area.

“Charging Ahead” connected with Thomas Werner, senior global product mManager at Hitachi Energy to discuss the subject of digital substation technologies. Werner began the chat saying, “There are many factors associated with designing and building a new digital substation. Topping the list are high performance and increased flexibility. There are also cost savings linked to the reduction of copper control cable, which is typically estimated at about 60-80% compared to a conventional substation. That savings is multiplied by the reduction in labor required to install the cable from the yard equipment to the control building with its marshaling cabinets and control and protection equipment racks. This is all replaced by point-to-point fiber optic cable. There are also savings associated with less equipment installed in the station, which allows for the digital substation’s smaller footprint. There is an alternative to building a new digital substation facility for those wishing to explore the available technologies. Utilities can upgrade an existing conventional substation and achieve substantial benefits while gaining experience.”

Werner continued, “Upgrading conventional substations with digital components improves reliability, allows real-time monitoring and control of the power flow, which provides better asset management. It enables component health checks, diagnostics, and automated problem solving. We have found that some utilities are high on the learning curve when it comes to retrofitting digital devices to their substations. They may elect to upgrade the entire facility. Other utilities may feel uncomfortable taking on that much at one time and decide to only implement one or two feeders. That is the advantage of utilizing a technology like Hitachi Energy’s SAM600 3.0 process interface unit. The utility is able to proceed at a pace that fits the user’s scope.”

Werner explained, “The SAM600 3.0 is designed to let the user configure it as a merging unit, a switchgear control unit, or a combination of both. It supports many different installation approaches. By combining the three units into a single device the pace of the retrofit is faster because design, installation, and testing are more efficient. The SAM600 3.0 interfaces directly with outdoor equipment like circuit breakers, disconnect switches, and other devices and it includes built-in conversion of analog-to-digital signals. It also gives users access to advanced automation and communications applications and can easily be expanded for future requirements.” 

What's Next

These conventional substations contain large amounts of digital technologies, but they’re not being used as an intelligent link. That’s where digital substation technology comes into play. It takes full advantage of informational technology and operational technology connectivity (IT/OT). It enables yard devices to share data with the control and protection schemes and other digital substations in real-time for faster response times. A network of digital substations using IT/OT shares and compares this data, which increases the efficient utilization of assets, not to mention faster response time to external events that can impact the power grid.

Installing new digital substations and/or retrofitting existing conventional substations with digital technologies will make IT/OT networking happen and that is exactly what is needed for the demands being placed on our power delivery system. Upgrading conventional substations is simpler and quicker than replacing them, which is much less costly. This type of interconnectivity can improve reaction times to extreme climate change weather related events fueled by global warming, which increases resiliency. 
Advanced asset management is moved to the next level as IT/OT enhanced digital substation networking is integrated with AI, cloud computing, and other advanced technologies. Predictive models with proscriptive analytics are only two examples of applications making digital substation technology more intelligent. It also gives digital substations a giant leap with self-monitoring, full automation, real-time data acquisition and many additional features. The total package gives a utility a dynamic view of their power system along with the tools for making faster decisions.

That is exactly what has been needed for quick reaction to our rapidly changing environment. Digital substation technologies are slowly bring accepted, but that is changing as the technology becomes more commonplace. Last year the Nepal Electric Authority awarded GE Renewable Energy’s Grid Solutions a contract to modernize 39 of their substations. The project will retrofit existing substations with digital technologies in relay panels and electrical devices to enable real-time monitoring of power transmitted through these substations.

Recently One Energy Enterprises, an industrial power solutions company, announced they had energized a fully digital, plug-and-play digital substation. The 30 megawatt (MW) substation is expandable to 150 MW and was built using Schweitzer Engineering Laboratories’ TiDL system connecting the monitoring and controls of a Hitachi Energy circuit breaker and power transformer by fiber optic cable. 
A few years ago, SP Energy Network, a United Kingdom (UK) transmission and distribution network operator, and Hitachi Energy announced their project to retrofit two bays of the existing Wishaw 275 kilovolt substation in Scotland with digital substation components. The retrofit provided valuable experience upgrading a conventional substation.

It has been hard enough keeping up with the advancements and improvements of digital technologies, and now digital substation technology has complicated it more. It gives us the ability to modernize portions or entire conventional substations. It’s the equivalent of a digital fountain of youth for these facilities, but there’s a steep learning curve to harnessing this technology!  

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