The role of short circuit power for grid stability 

As the transition to renewable energy supply grows and the decommissioning of more traditional fossil-fuel based power stations increases, the need for short circuit power (SCP) has never been greater.  Here we look at the role SCP is playing in supporting grid stability and its integral part within the National Grid Stability Pathfinder Programme Phase 2.


Generated through synchronous condensers, SCP is a key component in stabilising grid power supply for renewable energy sources such as onshore and offshore wind.  SCP provides the necessary power to the high voltage system required to ensure continuity and reliability of supply to the grid that would otherwise lead to unnecessary blackouts.  Short circuit power also plays a significant role in detecting faults in the grid and is essential for the clearing those faults. Additionally, it provides the necessary power to maintain the voltage level in case of a fault.


Traditionally, SCP has been generated as a by-product of large-scale power plant operation. But with the decommissioning of traditional power stations, the rise of more renewable energy has introduced weaknesses in the grid which need to be compensated for.  This is because large fossil-based power stations produce significantly higher levels of short circuit power than the equivalent renewable generation of a similar power output. When operating a higher ratio of renewable generation, operational challenges can be faced with the potential for voltage changes causing disturbances which can trigger generation equipment to trip or, even worse, the whole system to become unstable. A back-up solution is therefore needed to avoid disruption or what could lead to a total collapse of the system.


And that solution? Short circuit power.


Ralph Morgenstern, Sales Manager at Siemens Energy explains: “If you think of the power going into the grid being a bit like water flowing through a pipe, but then a hole appears causing a leak that risks reducing supply to such a level it would cause the system to collapse. The back-up water tank, or in this case the short circuit power generated from the synchronous condenser, not only helps identify where the fault is but provides the necessary refill, or in real terms, the voltage to keep supply going.”  


Synchronous Condenser Technology


To generate SCP, synchronous condenser technology is needed. Far from being the new kid on the block, these generators were heavily used in the 1950s, 60s and 70s to manage the voltage in the grid by providing reactive power.  And in recent times they have made a bit of a worldwide renaissance for their role in providing grid stability through the creation of short-circuit power and inertia for dynamic loads.


Also helping to stabilise the network through voltage recovery during faults, Siemens Energy is one of the leading manufacturers of this technology globally supplying a broad range of generators up to a short circuit provision of more than 2,000 MVA.


Supporting the National Grid Stability Pathfinder Programme Phase 2


And it’s this technology that will play a pivotal role in the provision of short circuit power for the roll out of the National Grid Stability Pathfinder Programme Phase 2.


“We’re already working with customers on a number of projects on phase 1 of the programme, which placed a particular focus on inertia and frequency within England and Wales, this means we’re ideally positioned for phase 2 which centres around the provision of SCP to eight specific targeted ‘weak’ spots of the grid in Scotland.” said Steve Clifford, Head of Sales and Tendering, Siemens Energy.


“The location has been specifically selected for phase 2 given the higher proportion of offshore and onshore renewable energy in Scotland compared to other parts of the UK. And with expertise over the last 10 years in supplying similar short circuit power services not just at home but globally too, the team are well placed to deliver. And, we’ve put innovation into full force by optimising our transformer and synchronous condenser solution to provide the very best possible short circuit power requirements and service offering to our customers,” he adds.


Technology with a competitive advantage


As one of the largest manufacturers of high performing synchronous condensers across the globe, Siemens Energy own some of the biggest and most efficient generators available.  And it’s this expertise in building truly optimised solutions that’s providing a real competitive advantage for customers.


Ralph adds; “One of our big strengths is the flexibility and expertise to select the right technology among our wide in-house product portfolio. For Pathfinder 2, we have optimised the solution to achieve high levels of SCP with a single machine - which means our customers are able to offer the most economical and technically advantageous solution.


“Our experience in building solutions, that include some of the most efficient generators available also means we can offer the biggest cost savings to the end consumer too. So, it’s not just about great technology, but also offering customers more power for the pound! And that’s certainly a good thing I’d say.”


In addition to delivering highly optimised technology, Siemens Energy also provide customers with the option of a full service offering through long-term service agreements that span an agreed period.   Being able to provide a ‘total solution’ which covers installation and maintenance of technology including civil works and land preparation, amongst other key areas is another area which the customer can benefit from.


In the future, working on new and innovative ways of delivering sustainable power supply will continue to be a key focus at Siemens Energy. And with targets that predict a significant increase in future demand for renewable energy supply, onshore infrastructure strengthening as highlighted by the current pathfinder programmes will be an area that continues to grow and evolve.


Steve concluded “As a company with innovation and ingenuity at its core, we pride ourselves on being at the forefront of that change, offering solutions that don’t just keep the lights on today but help us move forward to a more carbon neutral tomorrow.” 


Find out more about our synchronous condensers

A proven solution to stabilize the grid