Digital substations are getting a lot of attention lately. This technology is said to offer improved management, better resilience, increased flexibility, optimized grid control, and more. If done correctly, it does all of that plus the utility saves a lot of money over the traditional substation in construction, and maintenance. It can also help utilities with remote operation by lessening the need to send crews out to the substation, and that’s important in today’s COVID-19 world when resources are spread so thin.
The digital substation is not a new concept, but there has been a struggle arriving at the point of a pure digital substation. It hasn’t helped that the terms digital substation and substation automation (SA) are being used interchangeably, and that is adding to the confusion. There are purist who argue that a digital substation is only the electronics (secondary systems) found in the control building. That may have been true a few decades ago, but it is totally missing the mark with today’s digital technology. Let’s regroup and talk about these two terms.
SA typically describes a system or collection of hardware and software components. Without going too deeply, the SA concept includes the protection, control, and monitoring (PCM) elements, but with more powerful analytics and computing. The digital substation on the other hand includes the entire facility. It comprises both the primary and the secondary equipment, which has been made possible by the introduction of intelligent electronic devices (IEDs) and other digital technologies. In other words, the modern digital substation includes the complete digitalized unit and SA is an integral part of that entity.
Hardware Goes Plug & Play
IEDs added a new dimension when they were included in the hardware found in the substation yard. There were, however, a couple of problems, early IEDs and their associated platforms were propriety and did not play well with other suppliers’ components. Utilities wanted open architecture and plug-and-play functionality. Adding to those issues, there were two geographically split standards groups, IEC (International Electrotechnical Commission) and ANSI (American National Standards Institute).
Talking with Claus Vetter, Global Product Group Manager, Automation and Communication GPG at Hitachi ABB Power Grids, provided some interesting insights. Vetter said, “IEC 61850 broke this deadlock. Since its publication in 2004, it has been embraced by both the IEC and ANSI communities. The new standard was designed to provide a single protocol for a complete substation. It implements a common format to describe the substation and facilitate object modeling of data required in the substation. It defines the basic services required to transfer data using different communication protocols. And it allows for interoperability between products from different vendors.”
Vetter went to say, “The advent of IEC 61850 edition-2 in 2011 now takes the standard outside the substation. Hitachi ABB Power Grids has invested tremendous efforts in implementing this standard in its systems, tools, and products, since the company believes that IEC 61850 is the basis for a successful and modern digital grid.”
Because of the implementation of IEC 61850, the substation has been turned into a digital platform providing valuable operational and non-operational data.
Like all technological transitions, the benefits and advantages offered by digital substations outweighed staying with the old school technologies. Cost savings leads the list, and there have been some real-world examples supporting the advertising rhetoric. A study from GE focused on the cost savings at a digital substation it built at Avon on the TransGrid system in Australia. GE estimated it cost 30% less to build this digital substation with its fiber optic process bus rather than the traditional point-to-point copper cable-based substation.
GE explained that a traditional substation has a network of cable trenches and conduits connecting the control building with the yard equipment. They are filled with copper cables/copper wires for control and metering circuits. For the average substation, the total number of the wires and their terminations is staggering, and they all carry voltage when commissioned, which can be a safety issue. The fiber optic cables of the process bus eliminates all of these issues and concerns. GE estimated this resulted in a 95% reduction in copper cables and also a smaller control building at Avon.
Cost is very important to everyone, but there are other reasons for adopting the digital substation technology. Claus Vetter continued sharing his thoughts on the subject, “As a key component of smart grids, digital substations offer a host of maintenance benefits and provide greater visibility of the power network through increased data. With digital technology, utilities can digitize and gather information about the various parameters affecting the assets in the grid, thereby facilitating quick decision making under different circumstances.”
Vetter said, “For example, if there are environmental or weather conditions at play, utilities can assess and determine if or how to overload specific primary equipment in the network to allow more decision time in operating the grid. Most importantly, grid operators can use this data surge to improve business efficiencies. By gathering and harvesting mounds of data, companies become ready for future applications and long-term returns on investment by analyzing information to make better business decisions.”
Functionality has been increased in the digital substation technology by incorporating high-tech digital technologies to make some remarkable digital platforms. Interfacing advanced asset management systems (AMS) to the digital substation improved both systems with an interconnectivity boost. The equipment feeds data into the AMS and it spits out operations and maintenance recommendations.
Adding artificial intelligence (AI) to the AMS-digital substation combo has increased the total package substantially. AI analyses the big-data and defines even more useful information hidden inside it. The combination has given the digital substation situational awareness, which improves grid health and increases grid resilience, but that is just the beginning.
A Siemens white paper points out that utilities have been operating digital substations for years, but things have gotten much simpler for the user with the addition of cutting-edge technologies such as digital twin technology. Siemens has built digital intelligence into their Sensformer and Sensgear lineup at the factory. This adds a higher degree of digitalization to this type of primary equipment. It allows the utility to know what is going on inside the substation before a circuit breaker trips or a transformer overheats.
This digital twin technology brought needed user-friendless to the digital substation with a bridge between the real and virtual worlds. GE calls this “a software representation of assets and processes that are used to understand, predict, and optimize performance in order to achieve improved business outcomes.” With user-friendly technologies the digital substation is gaining in recognition and acceptance.
Off the Shelf
According to a marketing report from MarketsandMarkets, a marketing research company, “The digital substation market is projected to reach $9.1 billion USD by 2025 from $6.4 billion USD in 2020.” They said, “this can be attributed to growing infrastructure development in smart cities, increasing power demand with limited space availability, and increasing demand for replacing traditional substation infrastructure.” The technology is definitely attracting attention in the power delivery industry.
Recently, a press release from the Linux Foundation organization, LF Energy, announced its digital substation initiative. LF Energy is partnering with GE Renewable Energy, Schneider Electric, RTE, and other organizations to launch its Digital Substation Automation Systems. LF Energy said, “The goal of the group is to improve the power grid’s modularity and interoperability.”
Abu Dhabi Transmission and Dispatch Company (TRANSCO) selected Hitachi ABB to provide the first-of-its-kind ‘substation to substation’ digital solution, as part of the 400 kilovolt (kV) Al Dhafra switching station project. According to the press release, “the project includes a range of ABB products and solutions necessary to achieve a complete ‘end-to-end’ digital substation solution. It introduces new and innovative fully digital control, protection and communication features for mission-critical applications and is part of wider innovation enabling the digital transformation of the power industry.”
Today’s digitalization of the substation is a trending technology that is taking place on a global scale. The global digital market has been separated into North America, Europe, Asia Pacific, and the rest of the world. The Asia Pacific market leads the world in terms of revenue according to several studies. These studies also listed Cisco, Eaton, Emerson, General Electric, Hitachi ABB, Honeywell, Larsen & Toubro, NR Electric, Schneider Electric, and Siemens as key players.
When the smart grid was first introduced there was a lot of talk about the goals of this technology and how it would modernize the grid. Improved resilience, enhanced robustness, greater flexibility, and better adaptability lead the list. That sounds like what has been described in the benefits of the digital substation, but seriously, this technology is a major advancement in reaching the full potential of the smart grid. The digital substation is a real advantage for those taking advantage of it, and a handicap for those who do not use it!