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Arenko's chief technology officer, Roger Hollies. Image: Arenko.
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Current± Chats: Arenko’s Roger Hollies on Dynamic Containment and the growth of batteries

Arenko's chief technology officer, Roger Hollies. Image: Arenko.

Following an interconnector trip, Arenko became one of the first companies to take part in National Grid ESO’s new Dynamic Containment service, helping to keep the lights on in a post fault scenario.

With the growth of renewables, the operator is increasingly looking to develop balancing services to secure supply. One key way of doing this is through a series of three new dynamic services, the first of which – Dynamic Containment – was launched at the beginning of October.

Current± caught up with Arenko chief technology officer Roger Hollies about how the service works, the growth of batteries in the UK and searching for the next big thing.

Could you tell me a little about the introduction of Dynamic Containment?

With the evolution of the grid, we are moving away from big, slow fossil fuel generators - gas, coal, oil - and we’re moving towards more distributed renewable energy, so the characteristics of the system are changing. Therefore, the requirements to maintain 50Hz change because low carbon technologies have less weight, less inertia.

So National Grid is moving as quickly as they can to design new services to maintain the power on the grid in the face of these changes. There's three of them, Dynamic Containment, the post fault service, Dynamic Moderation for adjusting for large but gradual changes in frequency and then there's Dynamic Regulation for minor adjustments around 50Hz .

They started with Dynamic Containment, which is the post fault service. Essentially it's when you lose a huge part of the network either through losing demand, or - as is more often the case - you lose a huge amount of generation and the frequency jumps accordingly. In terms of grid stability one of National Grid's main problems is the concept of a single loss of load.

The biggest loss of load the system can lose at one time is the big generators or the big interconnectors. They've developed this Dynamic Containment service to provide power at that stage. So, there's a huge drop in generation, then the frequency slows down rapidly, and you quickly have to inject the power into the into the network to support and to get that system back up to 50Hz.

So, you respond with a little bit of power in normal conditions, when the frequency is within 0.2Hz. Outside of that, you have a real steep response curve. You're measuring frequency and as that frequency changes, you change your power output. This is why batteries are very, very good at this service because they are power electronics and can change their power in the sub second speed that's required.

How often do faults like the trip in the interconnector recently occur?

Big faults seem to be becoming more commonplace. We have had 3 since the service began in October that we responded to, and we obviously had the August 2018 blackout which was caused by two systems arguably tripping each other off and a huge loss of generation onto the system. This actually pushed the frequency so far out that you actually had to isolate sections of the grid, with the ultimate consequence of allowing the frequency deviation being a blackout.

I think we are seeing an increasing frequency of events causing issues because of the low demand at times on the system. A single loss of load, so a 1GW interconnector say, that drops off at peak demand time, if you've got 40GW on the system it’s not going to have a big impact. If you lose 1GW when you've only got 13GW of demand on the system, you're losing nearly 10%. And that could cause a huge frequency fluctuation.

So with changing from the big inertia-driven, traditional power stations towards low carbon systems, which do have less inertia, these instances could become more commonplace. I think the recognition, and why they are bringing these services in, is that these loss of load faults are going to be more impactful. So, you need these services to be in place in order to have a stable grid moving forward.

Ultimately you need them for an in a low carbon system, which is the big driver that we've got in the UK.

Is the battery industry growing fast enough to help meet the demand?

I think yes, and I think this is largely down to companies like Arenko and the work that we have done with National Grid on opening up these new services and these new revenue streams. It's actually making the case for the investment.

I think we are going to see a massive, massive investment in batteries and other reserve and balancing technologies to provide the services that National Grid need over the next two years.

It's going to be an extremely exciting time for energy storage and for the low carbon agenda because the UK needs this. We have a very interesting islanded grid, although we have interconnectors, and our mix of renewables in what is quite a small islanded grid is very, very high. So we are leading the world in how to operate a low carbon, quite dynamic grid system; I think we are developing the techniques which are going to be globally relevant.

It's a very exciting time for us to be involved in this because I think the services – and particularly the software – that we're developing works independently of the market or the market that it's in, all it knows is how to control power and power quality to a highly accurate level over time. You can take that concept and adapt it to any global market. Most of the markets work along similar methods of local frequency control, balancing services to keep supply and demand even. And then the wholesale markets behind that.

I think UK has a real opportunity to lead the way in low carbon and network operation. Really, really exciting.

Do you think with these pathways, that's now enough of an economic incentive for battery storage?

The one thing that I think we don't want is government incentives, because government incentives can be pulled away - we saw it with feed-in tariffs - we've seen it across the board with nearly any examples of heavy government intervention.

Could you tell me about the dashboard you’re developing to work with Dynamic Containment?

It’s become a key module in our platform for sure and we've been developing the capability for Dynamic Containment since 2015, since our first frequency response contract. Looking ahead we're now developing the next stages of what you can do alongside or on top of Dynamic Containment.

There is the ability to stack the service with other markets, for example the Balancing Mechanism; we already have the technical capability to do that. It's these services that Arenko will be looking to launch over the next six months to our customers. As soon as National Grid figure out from their end how to make these things possible, we're ready to go.

It's important that we can stack more services from one asset while still providing the quality of services required; quality of delivery is fundamental for this post fault type of service that essentially keep the lights on.


Molly Lempriere Editor, Current±

Molly Lempriere is UK editor at Solar Media, responsible for its publications Solar Power Portal and Current±.


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