Digital substations are a catalyst to achieving net zero

The energy transition is driving transmission and distribution network operators to adopt new methods that facilitate multidirectional power flows. As part of our Countdown to COP series, Prash Desai of Burns & McDonnell discusses the role digital substations will play in that process.

The prime minister’s radical new climate change commitments will set the UK on course to cut carbon emissions by 78 per cent by 2035. Hitting the target and achieving the government’s overall aim of net zero emissions by 2050 will require more electric cars, low-carbon heating, and renewable electricity. Digital substations will be a key feature in ensuring the electricity grid can cope.

With the UK driving ever faster towards its target of achieving net zero carbon emissions by 2050, it is expected that current electricity demand will rise from 59GW to 96GW over the same period, almost doubling current requirements. To deliver the increasing demand, the electricity grid will include a higher number of distributed energy resources such as solar photovoltaics, batteries, windfarms, tidal sources and microgrids. This will significantly change the demography of the electricity grid and the way it operates, increasing complexity and driving transmission and distribution operators to adopt a different operating model which facilitates multidirectional power flows.

As the electricity grid becomes more distributed, demanding, localised and dynamic, grid operators will need to transform their systems using digital solutions. They will rely upon the availability of dynamic data, demand patterns and greater intervention at a distribution level to run a reliable, efficient and safe grid.

Substations are a key part of the grid that connects the various conventional and renewable sources of generation to the consumers. Building and operating traditional substations requires often large areas of land and thousands of point-to-point costly copper signalling wires to connect primary systems with secondary systems. It demands labour intensive construction, outage planning and a complex commissioning schedule. Traditional approaches result in costly periodic testing and maintenance during the substation lifecycle. The solutions do not generate dynamic information such as demand patterns or consumer behaviour, which also hinders the utility company’s ability to carry out predictive maintenance.

To address the inefficiencies associated with traditional design, almost all UK T&D operators have developed strategies to transform existing analogue substation systems to digital. The next decade will see a phenomenal growth in asset replacement, investment in new capacities, innovative techniques, and data management.

The adoption of digital substation solutions will replace thousands of copper control cables with fibre optic communication alternatives. It will also supersede conventional copper wound measuring equipment such as current transformers and voltage transformers with optical sensors and congested junction boxes/marshalling kiosks with slim merging units and faster ethernet switches.

Since being released in 2003, the IEC 61850 standard has been directing the approach to digital transformation and has become a key reference point for digital substations, covering all aspects of substation design. Nearly all major utility companies in the world have either embraced it or are in the process of adopting it. The standard provides interoperability between various manufacturers, the human equivalent being to suddenly be able to understand the dialect of every language and efficiently communicate, collaborate and undertake complex tasks.

The standard also sets out a roadmap to digital transformation, enhances security, and has evolved to become a “way of life” for utility automation.  There are many benefits offered by digital substations based on IEC 61850 compared to the traditional analogue alternatives. These include:

• Reduced cabelling: Up to 70 per cent reduction in copper protection and control cables. On an average substation, that would result in more than 20 tons of reduction in materials. This will significantly reduce capital and transportation costs, as well as manufacturing efforts, both contributing to reduce the carbon footprint.
• Compact construction: The digital solution eradicates the requirement for conventional relays and protection equipment, resulting in a reduction of up to 50 per cent in the number of control panels. Further space saving can also be achieved through optimised engineering design using the digital assets. The net result is the ability to offer a more compact substation control building, reducing the overall footprint of substation, limiting civil construction activities and generating further cost savings.
• Enhanced Cyber Security: Initially utility companies were hesitant to implement digital substation solutions based on IEC 61850 due to potential security vulnerability. IEC 61850 was primarily created to provide interoperability and seamless connectivity between various devices inside the substation. It was not developed to provide enhanced security as a mainstream function. As a result, solutions could be compliant with IEC 61850 but still be vulnerable to malicious communication messages generated by hackers, and known as “fake GOOSE”, to cause wide-spready blackouts across the electricity grid. To address this, communication messages have been combined with IEC 61351 protocol to protect such attacks. IEC 61351 standard enables the “check for villains” approach for compromised messages and truly provides extremely crucial hack proof architecture.
• Asset management: One of the biggest benefits of digital substations is the ability to provide data in real time to utilities operating companies. Collecting asset data is now a less rigorous exercise than previously. Flexibility of IEC 61850 protocol to work with third party devices has greatly reduced time and cost to make data available to inform decision making. This results in an enhanced lifecycle, increased system availability and more reliable operations. It can be used to optimise strategies for planned investment and operational and maintenance expenditures (CAPEX/OPEX).
• Reduced commissioning time: As a result of standardisation and the ability to carry out design and commissioning remotely on substation design, digital substations require reduced on-site commissioning time. This reduces outage time to improve the system and improves system reliability.
• Increased Personal Safety: A significant advantage of digital substations is the reduced risk of contact with live infrastructure due to the replacement of copper cables with fibre optic cables. Digital CTs and VTs are significantly lighter and smaller compared to traditional builds. As a result, personal safety in handling and installation is also improved. Equipment blast risk due to open circuit during commissioning and substation maintenance is now effectively eliminated.

Over the years, the IEC 61850 standard has received criticism. The standard is complex, large, and demanding. However, since release, the standard has evolved to address various bugs, and security issues. Manufacturers have adopted it into their designs which has created communication issues related to forward and backward compatibilities. The benefits clearly outweigh perceived disadvantages.

The path to achieve net zero passes through the digital transformation of the network. No matter what shape the energy market takes, a decarbonised economy and digital technology are two significant contributors. The integration of various technologies and finding solutions to propel the UK towards a truly net zero economy strongly supports the digitalisation of energy networks, providing utility companies with valuable network data which enables them to adopt changes, respond to challenges and invest in the right direction.