Community Post: Digital Substation Pt.1 – Groundwork
This piece was contributed by Guillaume Tucker and is reprinted with permission. View the original post here.
Electricity has been a well-known commodity for over a century. When I was a student learning electronics and power applications in the early 2000s, renewable energy sources were very scarce. Generators could be found in off-grid locations and while some research was underway, not enough funding was being allocated to enable large-scale deployments. My main motivation when I entered university was to help reshape how energy is being produced in a more sustainable way, but it really was an uphill battle. So I focused more on my second passion which is open-source software.
Fast-forward twenty years or so: the temperature is still rising and the world is changing fast. In the meantime, I have acquired experience in embedded electronics, software in general and open source in particular. One of the reasons for choosing to work as freelance was to dedicate some time and effort to learning more about renewable energy as the electricity industry is now undergoing a major transformation. It was a pleasure to attend FOSDEM 2024 and spend a day at the Energy Devroom to discover so many high-profile initiatives. As this is a large open-source software conference, it’s no surprise that many in the room were also new to the energy topic which is rooted in hardware and power electronics.
First post of three
While discussing things with others at FOSDEM and then later at the LF Energy Summit, I accepted the challenge when Boris suggested to me that I write a blog post about Digital Substations and all the software that goes with it – here we are today, and thank you so much for reviewing it! In particluar, it’s really important to spread the word about this emerging sector which hasn’t yet fully matured its open-source culture. And it’s a fascinating journey for me to join the dots between my academic knowledge in electronics and my experience in software. I’m sure many others will enjoy taking part in shaping the future of energy too, the open-source way.
Then I realised it wouldn’t fit in a single blog post, so I decided to break it down into a series of three. This first one is to set the stage. The next one is going to be about how to contribute and get on board as a software developer. The last one is to go back to real-world deployments and look into modernising their equipment and workflows. The huge inertia involved with electrical grids means it can show a much higher resistance to change than pure software products. A useful parallel is how data centres have evolved using software-defined networking so we’ll touch on this topic too. Now, let’s dive in.
Traditional Substations
An electrical substation is basically a transformer with switches. Its main role is to route high-voltage electricity coming from power plants via transportation networks and distribute it to low-voltage consumer households. One of the critical missions involved is to balance the flow of electricity between producers and consumers to avoid surges or voltage drops in the grid. This isn’t a new problem and traditional substations have been dealing with it since the early days of electricity. However, things are changing radically now for two main reasons: renewable energy sources are more diverse and electricity consumption keeps increasing.
Classic substation model
Solar energy production can vary widely based on sunshine, and the same goes for wind and water turbines. Generally speaking, these sources are smaller and more distributed than traditional large-scale power plants based on oil, coal or nuclear. As such, the grid is becoming more complex and backup generators or spinning reserves which typically rely on gas are often required to ensure a continuous supply. The substations have to quickly switch generators on and off the grid accordingly.
Historically, electricity was mostly about light and industrial applications. Electrical appliances are now much more widespread within domestic households and the transition to renewable energy means more electrical vehicles need to be charged. On top of this, data centres powering the backbones of the Internet and Artificial Intelligence are growing exponentially. It’s very likely that some breakthroughs will make them a lot more efficient such as quantum computing, but it’s reasonable to assume that energy needs aren’t going to decrease over the coming years. Nuclear fusion is also probably not for this decade although it has been making a few giant leaps forward recently, and AI may help it progress further. Having small, distributed reactors is seen as a promising way forward to build a more reliable infrastructure. So in any case, electrical grids aren’t getting any simpler.
The traditional substation has now become a limiting factor to the expansion of new energy solutions. To address these growing challenges, they are gradually being replaced with their digital counterparts.
Digital Substations
While essentially based on the same electrical hardware with transformers, circuit breakers and switches, the digital substation differs greatly in how it operates and how it controls its routing. Traditional substations rely on hardware sensors and actuators connected with copper wires and have a fixed, basic control logic. In the digital world, sensors are IoT devices and communication is done over Ethernet or fibre optic. One connection carrying all the data and control commands replaces many wires with analogue voltages. Flexible algorithms and AI models replace hard-wired circuits to enable the more advanced functionality required in a modern grid.
First introduced in the early 2000s, which happens to coincide with my university years although I didn’t learn about them until recently, nearly 50% of substations world-wide are now digital. Their adoption keeps growing, especially in China and the most developed countries. It’s expected that by 2030, all newly built substations would be digital.
Standards
Ensuring interoperability is paramount to the success of digital substations and electrical grids in general. As of today, the main standard is IEC 61850 which is a very large technical document. A key section of the specifications is how services running in substations should communicate with each other. A related initiative is the Open Platform Communications foundation which is more about standard tools whereas IEC 61850 describes the protocols. From a classic open-source software point of view, one may think it would be interesting to start by looking at the Substation Configuration Language as this is a software-like description of how a substation is meant to operate. However, it’s not that simple. It’s actually pretty hard to find a full SCL example, even for illustrative purposes. The best public thing I’ve found so far is the IEC_61850_SCL_2_Nodeset repository which is 10 years old. Here’s a snippet from a file describing a protection relay:
<?xml version="1.0" encoding="utf-8"?>
<SCL xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xsi:schemaLocation="http://www.iec.ch/61850/2003/SCL SCL.xsd" xmlns="http://www.iec.ch/61850/2003/SCL">
<Header id="P145" version="1.94" revision="" toolID="AREVA IEC61850 Px40 Modelling Tool" nameStructure="IEDName">
<Text source="">IED Capability Description for P145 Feeder protection relay (based on P143 with XCPU2)</Text>
</Header>
<Communication>
<SubNetwork name="NONE" type="8-MMS">
<ConnectedAP iedName="P145_CLT" apName="AP1">
<Address>
<P type="IP">144.58.243.226</P>
<P type="IP-SUBNET">255.255.255.0</P>
<P type="IP-GATEWAY">144.58.243.1</P>
</Address>
[...]
<PhysConn type="Plug">
<P type="Type">10BaseT</P>
<P type="Plug">RJ45</P>
</PhysConn>
</ConnectedAP>
<BitRate unit="b/s" multiplier="">100</BitRate>
</SubNetwork>
[...]
Basically, these XML formats aren’t meant to be used directly by humans. That’s why there are so many tools around to manipulate them with GUIs which is also a typical part of the MS Windows corporate culture. Ergonomic tools are great, and having them based on configuration text files that humans can comprehend is even better. Being able to work on this without having to pay for a full IEC 61850 training would help open things up to the rest of the world. This is one area where the open-source community has thrived and where the electrical industry can improve. From my naive developer point of view, I would have expected a friendly YAML or even TOML intermediate format with command line tools to manipulate them and generate the XML for the machines. I guess this is something to explore further in the next blog post.
Tools
To be fair, there are actually many great open-source modern tools in the energy sector such as OCF’s Quartz Solar Forecast or Santiago’s GridCal. These typically live outside of the electrical grid infrastructure, to process solar data or simulate a grid as per the examples above. Let’s clarify the scope here and focus only on substations for now.
The Linux Foundation Energy umbrella project hosts a number of open-source tools and solutions in this area. In particular, CoMPAS is directly about IEC 61850 tooling and SEAPATH provides a real-time hypervisor for hosting virtualised digital substations. However, these haven’t generated too much interest from the wider open-source software community so far. There is a huge unresolved potential there. The XML file issue I mentioned earlier is just one small symptom of the general status quo, with MS-DOS batch scripts and proprietary tools used internally by electrical corporations.
In the day of open-source hardware boards e.g. OwnTech and CPUs with RISC-V as well as Linux servers powering the majority of data centres, wouldn’t it be great to have electrical grid workflows running on FOSS and fully open digital substation designs?
Challenges
Every digital system carries cybersecurity risks. It’s quite hard to hack into a traditional substation, in fact it can be very dangerous for a physical attacker given the high voltage hazards involved. Within a connected world, a substation then becomes a lot more vulnerable and a prized remote target for terrorists or strategic military operations.
Security is another area where it can learn from other software-oriented industries. A number of things have already been put in place such as virtualised substations and containers. This appears to be developing quickly and hopefully it will also pick up some of the momentum from other applications that rely heavily on open-source software. It appears to be an obvious way to bridge that gap and attract engineers familiar with these issues to the energy realm. Still it will probably require some amount of cultural shift from major players. It took years for Microsoft to fully embrace open source software, time will tell whether the electricity sector will be able to follow a similar trend.
Data Centres
The Open Compute Project is a typical example of a successful transition in another type of infrastructure: data centres. Coupled with software-defined networking, the hardware routers, switches and firewalls have been replaced with virtual machines decoupled from their underlying hardware which are all standard servers. This means that the network topology can change dynamically and continuously to match evolving needs and adjust when the underlying hardware is being upgraded with minimum downtime. How can we do this with substations?
Transformers are based on a very basic principle with multiple coils on a same magnetic core. As such, they would seem much less likely to go through upgrades than computer hardware. This is true to a large extent as many traditional substations have been operational for decades with a minimum amount of maintenance. The trouble is when the grid starts changing with new power sources being connected and an increasing demand in energy consumption. Expanding an existing substation or replacing parts of it to address these changes also means updating the way it operates. Being able to do it in a continuous way and with the ability to dynamically adjust the topology and energy profile to route electricity differently in real-time is what is at stake here.
Networking is about routing bits of information, which are effectively tiny amounts of energy. Here we have a similar problem at a different scale, with a lot of energy and a small but critical amount of information to orchestrate it. In fact, data centres and digital substations are closely related already. Some compute applications require their dedicated electricity generator: AI, Bitcoin mining (putting aside its unbearable carbon footprint for a moment), military deployments and large technology campuses such as Samsung Digital City.
Chaotic compute resource usage also impacts how large amounts of electricity get routed and consumed. There are many sensors in a data centre to monitor temperature, humidity, power supply voltages etc. which is also the case in a substation. In the end, new technologies require new ways of managing energy and new energy grids borrow ideas from these new technologies. In the same way that a motherboard has its own CPU voltage regulators, one might imagine how a digital substation could merge with a data centre to create an optimal architecture.
Taking part ⚡
Where shall we go next? In particular, as we’re dealing with a huge industry, how can one embark into this adventure and start contributing in a way that is both useful and fulfilling?
In the next blog post, we’ll take a closer look at software-defined networking and its related tools to compare them against digital substations and see what could be done there. We’ll also take a deeper dive into the existing tools backed by LF Energy and other open-source projects that have already gathered some community momentum. Maybe this will prove me wrong on some of the concerns I raised here if some burgeoning solutions already exist and also give us the key to improving things like SCL file handling and foster open-source adoption as a whole.
In the meantime, do feel free to reach out as always with questions, feedback and ideas by email.
