Synchronous compensators and grid Stability with Guy Nicholson (Head of Grid Integration UK @ Statkraft)

So if you think of the grid as, you know, something that takes power in and puts the power out, it needs quite a lot of management to keep that whole thing running and stable. And then there's a steady state, but then there's disturbances. You know, what happens if there's a fault, a disturbance, an event, a trip, and it's got to ride through all that and carry on doing its function. It's that it's that kind of keeping that grid stable and operational that is the the key challenge. You know, when we when we talk about grid stability, it's the last thing you want is that, you know, kind of domino effect where one thing falls over and knocks another over and the whole thing unzips or falls over.

So What is a stability path finder?

Path finders will say, well, let's try out some way of procuring it and see how it worked. And then when we've done that a couple of times, we'll then morph into a a more normal market. But we don't wanna jump into a market because we're not really ready that. So it's about sort of priming and testing and creating a market mechanism to bring on a new kind of product or service.

Hello, and welcome back to Transmission.

Grid stability becomes increasingly complex with the growing integration of renewable energy sources.

Enter technologies like synchronous compensators, advanced spinning machines that deliver the critical inertia required to balance the grid and ensure reliable power supply.

In today's episode, Guy Nicholson, head of grid integration UK at StatCraft, joins Ed Porter to explore the topics of grid stability, synchronous compensators, the stability pathfinders, and much more.

If you're enjoying the podcast, please hit subscribe so you never miss an episode, and give us a rating wherever you listen. Let's jump in.

Hello, and welcome to another episode of Transmission. Today, we are joined by Guy Nicholson. Guy, welcome.

Thank you, Ed.

And today, we are gonna be running through the world of synchronous compensators.

Yep. So I believe.

Very exciting. Okay. So we've been wanting to do this for ages, this world of sync comps, synchronous condensers, synchronous compensators.

What does it all mean? How do they all work? I'm super excited to get into it. But first, maybe let's start off with a little bit on, StackCraft.

Who are StatCraft, and what is your role within StatCraft?

Yeah. So StatCraft's, state owned by the Norwegian government. We are the largest renewable generator in Europe, thanks largely to our Norwegian hydro assets.

And we're developing wind and solar and battery and storage grid services stuff around Europe and to a degree around different places around the world. So it's kind of quite, an exciting time to be in the company in this kind of expansionist mode. Yeah.

And and your role within StackCraft?

Yeah. So my role is head of zero carbon grid solutions. That's my title.

And, I'm developing, and I've been developing what we call our greener grid parks, which are, sites where we can deliver services to the grid. So it's about decarbonizing the grid and, helping renewables run the grid. So I guess my whole career has been based on in renewables, connecting renewables to grids, and it's now nice we've got to a stage where there is so much renewables on the grid that sometimes, you know, particularly, in COVID, in lockdown when we had low demand on the grid, high renewables, the system operator had to turn off a lot of renewables, turn on a lot of gas, because we couldn't keep the grid stable without doing that. And so that was a kind of wake up call for everybody. You know, this was like leaping the clock forward ten years. And, so lots of lessons learned from that, and I think very exciting, about what's what's coming. So that was a glimpse into the future, I think.

Yeah. And to get into that role, you can do you kind of have a technical background, a commercial, or a regulatory background? How how do you find yourself there?

Yeah. So I've I've worked in in renewables all my life. I started reconnecting stuff in the early nineteen ninety. A lot of that was landfill gas, at the time.

Wind mostly distributed, and then that progressed to transmission connected to offshore wind, and then, you know, solar came along. Primarily, I I worked for developers, manufacturers, but primarily as a consultant and, primarily supporting developers to get their grid connections done. So, you know, never liked anything more than a grid company saying, no. It can't be done because then, you know, I was determined to try and find a way of of doing it.

And, yeah, built a a company called Econnect, which sadly went under, but was a great, leader at a time in this. And, yeah, was involved with the largest wind farm in Europe, P and L in Wales in the early nineties, first wind farm in Scotland at Hagshaw Hill.

I was the expert witness for the Clevehill substation for, London Array connecting into the grid there. And, yes. So lots of things along the way of all about getting renewables connected.

London Array being a large offshore Yes.

So that was where it came to shore in in Kent at Cleavehill. So, yeah, the substation is now built and, yeah, for a lot of years. But yeah.

Clevehill also the home of, I think, a very large solar and battery storage project.

Yeah. And now that's kind of, yeah, piggybacked onto that, solution. Yeah.

And we talked a little bit about their sort of a grid operator saying, oh, this can't be done. And and when they talk about that, like, what why why would they say that?

Well, it's interesting because one of the things that I did before, I started grid collections stuff was was a lot of kind of off grid standalone projects, including power systems for Mongolia nomads, lighthouse stuff, but I I spent a year on the island of Fula off Shetland putting in a a a grid system there because they didn't have any power grid and running it on wind primarily with a small amount of hydro, some diesel backup. And, so that taught me and and that was without any batteries in those days or any inverter technology. It was all fairly conventional rotating machines.

And, so that taught me a lot about how to run a grid system on a small scale. And then when I came to grid connecting renewables and and you got transmission system operators, you know, like air grid saying, oh, we can't have more than five percent economically and ten percent technically. I'm going, well, hang on a minute. If a rookie engineer like me can build and operate a system on a small island, which is quite challenging, why can't lots of clever engineers with all this grid experience do it on a big grid?

And, it it that is kind of always been a fallback, you know. Mhmm. Yes. It can be done.

It's just about up here. It's about the mindset of doing it and and finding solutions.

What are what are what are the pinch points? So as you start to kind of become a more renewables dominated grid, like, what are the parts of kind of what what are what are the grids, specifics that start to get more difficult?

One model of of the grid that people use for kind of frequency and inertia is this kind of bathtub, don't they? You have water pouring in through various taps. That's your generators, your infeeds, and you have lots of plugs and pipes going out. That's your load.

And then, you know, if you take more out, the water goes down, you put more in, whatever goes up. That's a kind of one model. But what it doesn't perhaps model very well number of things. It doesn't do very well, but it's a good analogy.

But, yeah, the so if you think of the grid as, you know, something that takes power in and puts the power out, takes power in from mute generators and in feeds, interconnectors, whatever, out to consumers to users.

It's not just like a bath. It needs quite a lot of management to keep that whole thing running and stable. And then there's the steady state, but then there's disturbances. You know? What happens if there's a fault, a disturbance, an event, a trip, and it's got to ride through all that and carry on doing its function. It's that it's that kind of keeping that grid stable and operational that is the the key challenge. And, you know, renewables are primarily inverter based.

Inverter based resources is what, you know, the the North Americans like to call it. I quite like that term. So, and also along with wind and solar, they're like that, batteries are also integrated connected and solar interconnectors. So as we move to a system where we've really dominated by wind, solar, batteries, and interconnectors as the main, you know, players on the grid pushing out the nuclear, the carbon capture, the gas, and everything else, then you don't have the old synchronous machines that you have with coal, gas, nuclear, hydro. So pushing those synchronous machines off the system.

And and what do those synchronous machines provide?

So that's when we come to, you know, favorite term like inertia, system strength. I'm gonna talk about, fault current and reactive power voltage control. So and I know you probably wanna tease into each of those. I don't wanna jump the gun, but I think, inertia is probably the easiest one to grasp.

So those spinning machines, rotating machines have got spinning mass and so on. So turning around. And, going back to my bathtub analogy, you know, if you have a a mismatch between generation and demand in feed and x feed, that mismatch comes from inertia comes from the kinetic energy in inertia. So, you know, if we have a trip on the grid, you know, and we tend we have about three large trips every fortnight, loss or of load or demand frequency step and that. So when you have that sudden disconnect, that mismatch in energy is taken from the rotating inertia in the grid. So the spinning machines slow down slightly to provide and and the energy comes out of them as they slow down and meets the gap, fills that gap.

So the thing about that inertia is when you get a trip like that, it it kinda slows the rate of change of frequency down. So if you have a a system with a lot of inertia and you have a trip, supposing, you know, IFA no. Sorry. The North SeaLink trips to Norway, so we lose one and a half gigawatts into the GB grid, then the frequency is gonna start to fall until our friends with batteries all respond and, you know, kind of pull the pull the frequency back up.

But it's that initial rate of change. So if you've got a high inertia system, it's gonna change very slowly. And then everyone's got time to react. You know?

Batteries have got time to detect it and feed power in. Control room's got time to notice it and go, oh, we might need to schedule some more power and might need to call someone up and get them to put more power into the grid. So that that inertia gives you time to react. If you have a low inertia, that frequency falls very quickly.

And the risk is before anything's got time to react, your frequency has fallen and you've got some sort of partial blackout or worse scale, full blackout.

So, yeah, that's that's the kind of thing.

And I think that's that's kind of a really important thing to talk through. So if your if your if your frequency moves too fast and hits one of the limits, what what happens to a what happens to a grid? How does that actually how like, how does that actually turn into, like, a partial blackout?

Well, let's let's take the last one, ninth of August twenty nineteen, in GB, and we had the last partial blackout. And what we had was a combination of Hornsea offshore wind farm tripping because of a transmission thing, and I can talk more about that perhaps later on.

We had, combined that with a a CCGT tripping. So you had two trips. You had disturbances on the system that then tripped to the generation. So I think we lost about, one point seven gigawatts or something like that. And so the frequency, yeah, there's a few steps, but the frequency ultimately fell to forty eight point eight forty eight point eight hertz, and that's the level where you disconnect some load. So the the load disconnection that's distributed around the grid is there to protect the grid from that complete blackout. So you hope that, you know, the frequency comes down, you trip some load, and it bounces back again.

So that's the the defense mechanism, but the result is some consumers do get interrupted.

And, particularly, that that event happened on Friday night during rush hour. Because the frequency dropped below forty nine hertz, some of the trains that were from Germany had some software in them that said, if the frequency is below forty nine hertz, something disastrous has gone wrong because the the European grid never goes that low. So, lockout, call for a technician. So all these trains all locked out and the drivers couldn't restart them and that. So people were stuck on trains.

I was stuck on one of those trains.

Yeah. Yeah.

I was stuck on one of the I can confirm this happened.

Yeah. Okay. No. Brilliant. I think that really helps people to kinda picture, both the move to more inverter based resources, the spinning systems we have, and then also what kinda happens when it goes wrong.

I think just just for people who may be not so familiar with the energy space, one thing that might come up is someone will say, well, look, you're after spinning things. I've seen a wind turbine. They spin. Why doesn't that help?

Excellent. Yes. Great question. So, and and wind turbines, you know, did used to be directly coupled to the grid with usually with induction generators.

Now they've been decoupled with inverters. So the spinning part of this the wind turbine, the rotor, the generator, the gearbox are not linked to the grid frequency. So unlike one of our synchronous compensators or unlike a gas or coal station where the the grid frequency and the machine are locked together, through through, yeah, that synchronous coupling. That's not the case with even with wind with spinning.

And interestingly, you know, there was a there was a, a kind of fad at one stage for wind inertia or synthetic inertia from wind, which wasn't really inertia. It was frequency response. You know? So the idea was we've got these spinning rotors.

If we're kind of need power in the grid, what we could do is use our inverters to slow those rotors down, pull out the energy, and feed it into the grid. You think that was a great idea, but, you know, if you imagine you've got a grid with, say, thirty gigawatts of wind going and you lose the interconnector one and a half gigawatts to Norway, then you take your wind and go, right. Okay. We've lost one and a half gigawatts.

Let's slow down our wind turbines, pull out instead of thirty gigawatts, let's pull out thirty one and a half extra energy.

You solve that problem for a short time. But what you've done then is you've slowed all those wind turbine rotors down, and you disturb the optimum level of their, wind capture. So now your thirty gigawatt wind farm fleet turns into a twenty five gigawatt wind farm fleet. So you've solved a one and a half gigawatt hole for thirty seconds, and you've created a five gigawatt hole a minute or thirty seconds later. So unless you were relying on lots of OCGs to start up or fast diesels or something, it hasn't solved any problems.

OCGs, open cycle gas turbines.

Thank you. And you would be into accidental acronyms, so well spotted. Thank you.

Okay. And and maybe just like last one and just to kind of defining what's going on here. So we we talk we talked a little bit about frequency response. So things like batteries, sensing that frequency's moved and then responding to it.

Yeah. And we've talked about inertia. Yeah. What is the different what what is the time period we're looking at here between the the the kind of the gap between the real kind of live system and then the the first response from, say, a battery?

So the the great thing about the synchronous machine where it's a synchronous compensator or generator or motor and and and the inertial responses, it's built into the physics. It's locked in. So that machine is rotating with the grid. If that's fifty hertz, it's rotating round up, you know, maybe fifteen hundred RPM.

And if the grid slows down, it it's dragging that machine. That machine can't unless it pole slips in the in, you know, in a stability issue. But in a frequency response, that's not gonna happen. So so, you know, it's it's locked together with the with the grid, and and that's, so if it if the grid frequency slows, it's pulling energy out of the Mhmm.

That that drive train, that machine, that in spinning mass. If the frequency increases, it's having to push energy into it to speed it up. Mhmm. So it's it's built into the physics.

So that's the inertial response, and that's so really important for that kind of when you have a an instant loss of of a large infeed like a a big interconnector or a big generator, that's so important to say to rate change of frequency. The batteries and and, you know, batteries have done a fantastic job in terms of frequency response. So, you know, when enhanced frequency response came in, you know, I remember I was involved with element power at the time, sitting around the board table going, what price are we gonna put in? And the price was mooted.

I don't know. No. It's worth three times more of that. We can't bid that low.

You know? Because it it really did cut the price of frequency response in about a third. And and since then, as you know, the whole frequency response cost has even come down. So, you know, batteries have really massively reduced cost of frequent response on the on GB grid by probably down ten percent of what it was five, ten years ago.

That's more or less the right number, which is just this this this kind of crazy win for for consumers. Right? In that instead of paying large gas turbines to be running for frequency response, we're getting the same thing, but at low carbon and also for, like, a tenth of the price. Like, it's a huge win Yeah. Of transitioning your system. So, okay. Well, let's let's then go from kind of what is, grid stability, why is it important.

Let's go into the stability pathfinders. Yeah.

So what is a stability pathfinder?

So the pathfinders was, something that the grid brought out in terms and they've used it for a number of things. Stability as opposed notable to say, well, we want to explore how to create a market for this. And, you know, hands up for ESO, the NESO, and the history do have had a, a track record of going out and procuring stuff, rather than just mandating it, and that is to be applauded.

So the staff finders will say, well, let's try out some way of procuring it and see how it works. And then when we've done that a couple of times, we'll then morph into a, a more normal market. But we don't wanna jump into a market because we're not really ready that. So it's about sort of priming and testing and creating a market mechanism to bring on a new kind of product or service. Yeah.

And so what does that what does that look like in terms of the projects that you're working on?

So interestingly so go back to stability pathfinder phase one. That was announced on the fifth of November twenty nineteen, coincidentally, not long after the ninth of August event. So there's some linkage there of oops. We might have a short of inertia and stuff.

And, was a very fast turnaround. You know, we bid in January. So November to January was designed really for existing generators who could operate in sync comp mode. So, you know, maybe put a clutch in between the generator and the, and the prime mover or close down the power station and just run with the the generator as a synchronous compensate or synchronous machine.

What was it buying?

It was buying inertia, but not totally actually. Because when you look at when you analyze the bid prices and you can it's there in the public domain. You can see that, StarCraft's products were the the highest paid for just inertia, if you like. Some products with a higher price than us didn't win a contract, but there were a couple of projects, Crufen and, Rasal that won contracts at much higher prices.

So if they were just contracting inertia, they wouldn't have been in merit order. So they were contracting inertia and, what else, short circuit current system strength, voltage control, reactive power. But it wasn't explicit, so it was a bit opaque. But given the timescales, that'd be fair dues.

And and that's maybe just going back to that frequency response example, it's kind of a good demonstration of run a pathfinder, see who can respond, get yourself the right terms of the market, and then run it into a kind of, an auction type process going forward. And if we take the example of the frequency response we've just been talking about Yeah. If you'd sign those gas units up to a ten year contract from ten years ago, we'd all be locked into some really expensive contracts. And the hope is that as we build a market, better solutions will come along.

Okay. So one of the interesting things about this is that not everyone's doing this. Right? Mhmm. So why are these markets attractive to StatCraft?

Well, I think we, again, going back to pre pre StackCraft element power, because Stack bought element power, we were, we had a synchronous machine running on a a wind farm in Ireland for various reasons, to to kind of explore this concept of how do you make wind and the grid work better together.

And, so then we realized that, yeah, what we need is what we're gonna need is a lot of inertia on the grid. When we got a lot of wind on, we're gonna push off the gas. There's gonna be no inertia. Gonna need inertia at least on the grid.

So we were exploring high inertia, synchronous machines, synchronous compensate as to to do that. And we thought it was gonna happen in Ireland first, and, yeah, National Grid ESO or NESO, jumped the gun on on AirGrid by quite a way. Actually, AirGrid have eventually caught up and, and done their low carbon inertia service tender. But, yeah.

So, we we were there. We were actually the the reason we were able to do our our new build projects at Keith and Lister, which won contracts instability round one, was that we were already working with GE, on their rotating stabilizer for some of the projects.

And, so we're well down the road with procurement design and everything. And when, the the SPP stability pathfinder phase one tender came out, we were right. We've got all the ingredients here. We've got the machines. We had a couple of sites that we were developing for other reasons. We put all that work together and we're able to bid in and because the timescales were very aggressive to actually get delivered for for a new build. We could just do it.

Let let's let's do that. So from day one of the stability pathfinder being awarded, how long does it take you to turn that into a project?

Yeah. You know, you're talking three years kind of timescale or more depending on it's primarily your grid connection. And and since, you know, since then, we've had the Ukraine war. We had the impacts of COVID, the whole supply chain thing.

Yeah. So now it's about lead time for transformers, switchgear, the machines themselves, everything. It's it's all primarily driven by by lead times and and getting a good connection with the whole the hiatus of the connection queue at the moment as well is just another spanner in the works of things. Yeah.

And the grid operators want, a sync comp on their site. Is that something that they that they they want that on the network, or is it kind of a a trouble for them?

No. It's great. I mean, if if you if we look at this you know, it's quite interesting to look at stability pathfinder phase ones, not just our projects, but everybody's.

And, you know, they were contracted primarily for inertia.

But we we need for inertia, you know, maybe, I don't know, thirty percent of the time, something like that or or less. But we're actually run. They run us pretty well all the time. And, even when we're not needed for inertia, and that's because, you know, of the system strength capabilities that the Syncros machine brings, the fault current, the ability to deal with voltage fluctuations, supply reactive power where we soak up harmonic currents through our machine windings. So there's all sorts of other benefits that the machine brings. Yeah.

So we're not just put on the bars when there's low inertia. We run pretty well all the time because of that insurance policy. You know? It's costing grid a little bit of money to supply for stability pathfinder phase one that pay for the energy that the machines use. So, you know, you're talking about what about two megawatts for one gigawatt second of inertia. So if you had to, you know the the grid needs, let's say, a hundred gigawatt seconds of extra inertia.

So, that that's gonna be about two hundred megawatts of power to run all those synchronous machines to to provide all the inertia you need on the grid and a lot more besides the that whole system strength of those machines running.

Can we can we stop there? Because that that is so that's that's really interesting. Right? So so two hundred megawatts of power will get us all of the inertia we need for the GB system. Yeah.

Because when we talk about the transition, like, one of the things that's really or kind of always comes up is kind of the lack of inertia on the system. And when you phrase it like that, it feels so doable.

It's it's very it's very doable. Yeah. Very doable.

You know, so interestingly so I say, you know, at the moment, the frequency risk control report, FRCR acronym, you know, is we're on about a hundred and twenty gigawatt seconds of inertia, and they're talking about bringing that down to a hundred.

I think it that's that's a risk, and I would caution against rushing into it without some some extra contracts, frequency response inertia. But, the I've lost my thread now.

But let let me let me pick that up. So, one one thing we are seeing, so that inertia that's being required from the grid is dropping from, like, a hundred and twenty to around a hundred.

A hundred and forty. The previous FCR dropped to a hundred and twenty earlier this year. They're talking about dropping again to a hundred this year. It's quite a steep fall without and it's a bit yeah. It's not not not properly thought through in my Okay. Mind.

But is is part of the logic there that the that the growth of battery storage and the success of the frequency response from it, even though the inertia's falling, even if it does fall, you'll still have the batteries there to bring it back to fifty hertz.

You've got that fast frequency response. Yeah. So there there's a bit of a a combination, you know, as I say, the inertia determines what this kind of rate of change of frequency is. So if you've got a faster response that batteries can give Mhmm.

Yeah. We're talking about, you know, fast response in low three hundred milliseconds or Yeah. That kind of time scale compared to the old, you know, gas turbines and pump storage, which needed ten seconds to or one second to do anything and ten seconds to get there. You know, it's much faster.

So you can have higher rate of change of frequency. And and we we've moved to that now from, you know, point one two five hertz per second to one hertz per second. So Yeah. They've already moved that.

But it's it's yeah. It is risky to to make all these changes given what's going on the grid.

We have to talk about that. So, what what what are the risks? What why would you caution that grid moves slower on the drop in inertia?

There's a lot a lot to unpack in that.

You know, the the the FRCR report, this thing is is really came in for, when we move from this point one two five hertz per second limit, which was driven by rock off protection relays on distributed generation. So what we used to have, you know, go back to the old faults like ninth of August. Again, you have a a fast rate of change of frequency that gets picked up by protection relays on lots of distributed small stuff, and that all goes, oh, we think there's a local grid fault, so let's trip off. And, so you start with a a a largish problem with a big trip on the grid, but you that creates a disturbance on the grid, which then cascades that problem.

You know, it's that domino effect. You know, when we when we talk about grid stability, it's the last thing you want is that, you know, kinda domino effect where one thing falls over and knocks another over and the whole thing unzips or falls over. So trying to decouple things so that they're robust against something else going wrong is is key about maintaining a stable grid.

You're you're so you're worried about the kind of systemic element, but I suppose the other side of it is also true that you wouldn't want, say, the UK to be procuring double the amount of inertia it currently is because, historically, we've got that from gas.

And Yeah.

That can be quite expensive, but also carbon emitting.

Yes. So, you know, it's it's about getting the balance. And, you know, it should be a a cost benefit analysis. What's the risk of of something going wrong?

What's the cost of it going wrong? What's the cost of sorting it? And the cost of sorting it is going down rapidly. The cost of it going wrong is going up rapidly because we're all so much reliant on electricity and, and will be more so.

And the and the risk in my mind is the backlash against, you know, the whole decarbonization of the grid and the whole net zero mission. You know? If we have something that goes wrong and, you know, we have a partial blackout or something like that, then critics will jump in and go, you're going too fast. You need to go back to fossil fuels.

This is all a disaster. You know? We've had that before, people blaming renewables for for grid incidents and grid trips.

Whereas as as you're saying, this kind of two hundred megawatts of of power can get us all of the inertia we need. Yeah. Okay. And last question on the stability pathfinders. So they end. What happens when they end?

So, yeah, we've had stability phase one, stability phase two, which is in Scotland, stability phase three. So they've good twelve and a half gigawatt seconds of inertia in one, seven gigawatt seconds in phase two, and, seventeen gigawatt seconds in phase three.

Those phase two and phase three are still in construction and coming on the bars. All the phase ones are operating.

So, that's yeah.

National Grid has now moved to a stability market, and we've just had the results of the first, what's called, midterm round one auction, or or tender last week. So, you know, that's showing that there's some new entrants in there. There's couple of projects from stability phase one that have gone into that. Our projects will go into that annual market next year along with a lot of others. So we're starting to see that annual market, so that contracts a year.

And it's really for existing assets, but some it's got some new build assets that are multifunctional in there.

And and there's also, alongside that, gonna be a day ahead market. So let's say I bid into the year ahead with an existing asset, don't win a contract, then I'll drop into the day ahead market. That's still to be Okay. Put in price. And, theoretically, I could bid into the balancing mechanism, but would I actually get would I get skipped?

I don't know.

And then, theoretically, there's a what they call a y minus four or long term. So if if the if they need a lot more inertia than is kind of available with these year ahead contracts, then they can kinda do another stability pathfinder phase four, but it won't be called that.

Okay.

But it'll be basically the similar model, really, if you like.

Oh, so hopefully, people are getting a picture there as kind of a a really kind of robust process for bringing in new projects, but then also taking them through the course of their life into kind of serving the the grid for the twenty, thirty, forty year lifetime of these of these assets.

Yeah. Great. And it's great for us because yeah. When we when we got our board approval for our building our stability phase one, it was like a, yeah, a six year contract, and we were gonna miss the first year of it. And we missed a bit more with COVID. So, you know, with no prospect of what the market was at the end. So the fact that the ESO has, you know, delivered on that market, has put it in place, that really creates a good, you know, good vibes for investment in in these kind of, services and products.

So so I I I feel like we so moving on from stability pathfinders, people are gonna be at home kind of going, oh, like, we've we've we've talked about synchronous condensers, synchronous compensators.

I could there are so many terms what seems to be the same thing. Like, what's the right term, maybe first question, and then we'll come on to what it is, second question. So, like, what what's the right term for synchronous compensators?

Well, I'm gonna turn your question the other way around just to be awkward.

So, yeah, it's a synchronous machine. And a synchronous machine can be a motor, can be a generator, or it can be a synchronous compensator. So if you take a synchronous machine and put a hydro plant on the end of it, spin it around, then it becomes a synchronous generator. If I put a pump on the end of it, becomes a synchronous motor.

If I don't put anything on the end of it and just connect it up to the grid, it's a synchronous compensator or condenser or rotating stabilizer depending on what you want to call it. So they're all the same thing. They're all a synchronous machine depending on what they're doing. You can call them different things.

And when they're a synchronous compensator or condenser or rotating stabilizer, it's just a different term for the same thing. I'm sorry for all the, words suit there. But yeah. Yeah.

No. I think it will help people because I've heard them referred to as many different things. Yeah. And it's not always particularly clear what people actually mean by them.

So Yeah. It's useful clarity. But then, actually, what actually is that thing? Is it just like a giant spinning top?

No. So it's a it's an electrical machine. You know? So, obviously, they were built primarily as generators and motors in the first place.

And then, you know, the the these have been used traditionally.

I saw one at, tail and bend in in Australia, so in Adelaide and and Melbourne where it's just doing voltage control. So it's it's a synchronous compensator, but just managing voltage. And then those sort of machines were replaced with power electronics, SATCOMS, SVCs, switch caps and reactors. So those those voltage control kind of, uses kinda went away. And now we brought back synchronous machines for stability, inertia, and and you you can have machines so like our g machines at Keith, they've got high inertia built into the electrical machines. It's like a a a flywheel with an electrical machine wrapped around it, if you like.

And then, like, our listed drive site, which has got ABB machines, they've got a a standard electrical, synchronous machine connected to a flywheel, and that gives it the extra inertia. And that's kind of a model that's common with many suppliers. So Yeah.

And let's let's come back to the voltage control and stat comms in a second because I thought we kind of just just nudge that into the conversation, but it's kind of opening another can of worms. But I think just just onto the the synchronous condensers, just a a sense of scale for people at home. Is it is it kind of is it like the size of a bus?

How how big is this thing? Is it in a shed? Would you notice if you drove past it?

Probably not. So, you know, if I take our our listed drive site in Liverpool, it's kind of tucked in between the cash and carry and substation and a road, and, it's a one acre site. On there, we've got a two seven five kV transformer down to LV. We've got our medium voltage switch gear.

We've got our cooling systems. We've got two sheds with the Synchronoss machines in.

The sheds are, well, in double decker bus terms, probably about, you know, four double decker buses or something of that order. I haven't actually tried to squeeze one in, but that that kind of size.

Okay. And then and then within that shed, as you were saying, we kind of initially planned to run, say, maybe thirty percent of the time, but now more often running nearly all of the time. And so within there, there's essentially something that is spinning. Did you say a hundred and fifty RPM?

So, depends on the number of poles on the machine. So fifteen hundred RPM is kind of probably the fastest. You might get three thousand RPM for a two pole machine.

So I think I'm right. Listed drives fifteen hundred, Keith's five hundred. So it's a twelve pole machine going slower. So depends on the electrical machine. But, yeah, those kind of stuff.

Something in there spinning all of the time and Yeah. Power going in to keep it spinning to Yes. Pay for the frictional losses of the system?

Yeah. The windage, the friction, the bit of heating.

Does it generate does it generate a lot of heat?

So well, let's say, you know, we're talking about for the our machines round about a megawatt each.

That will vary depending on the reactive power and whether it's doing voltage control or not. So it might be less, might be more than that. And that that appears that energy goes into heat, so then that gets dissipated through the cooling systems. Yeah.

Okay. And and how do they so how do you how do you so do they break, and how do you maintain them?

Yeah. So, you know, when you've got something high inertia like this, if you just disconnect it from grid, you might have to wait best part of a day for it to slow down and stop unless you've got a break. Or, you know, nowadays, well, we can slow them down. So you have to start them up.

Yeah. So you generally have some sort of variable speed drive, and that might be direct onto the machine or it might be through a pony motor that spins it up, and and drives it up to synchronous machine, synchronous speed. Sorry. Mhmm.

And then we synchronize it with the grid, close the breakers.

Okay. So you get it to fifteen hundred RPM, close the breakers.

Get it in the right voltage, right phase Yeah. Right orientation, close-up, and then you synchronize the grid. And then you you disconnect your drive starter, and it's then brings in power from the grid Okay. To keep it spinning.

And so in terms of, like, the I I I'm still stuck on this idea that someone's turned it off, and then they've had to wait a day for the for it to slow down.

Well, we we yeah. That was a scenario. It's not the case.

Not anymore. Okay.

You need to pull the power out to slow it down somehow.

Yeah. And and so what do you have to do to like, how do you keep that working? Do you kind of is it what what what does the maintenance program look like?

Pretty low maintenance. You've gotta maintain the bearings. You've gotta maintain the cooling system. I mean, the machine itself is there's really nothing to maintain a wrong clean filters, these kind of things. So it's it's pretty low maintenance and man sites, yeah, and pretty very reliable stuff. Okay. Touch wood.

Yeah. Touch wood. Okay. And then, so sort of last question on this, who who actually makes these? Because they feel like such a unique thing. You mentioned GE and ABB. Right?

Yeah.

All the all the usual suspects who make anyone who makes an electrical machine, you know, synchronous machine, large synchronous machine. So anyone who makes a generator for a power station will make a a an electrical machine which can be used as a synchronous compensate. Yeah. So you it pays your money. It takes your choice.

Yeah. All sorts of varieties of flavors of size, speed, cost, inertia, fault level, reactive capabilities.

So there's a lot of flexibility in this in terms of what you can actually procure? Yeah. Okay. And and then are we is is GB sort of ahead of the curve on this, or are we kind of miles behind others?

No. We are really world leading in this, definitely.

You know, you think so synchronous compensate has been procured by you know, in the Europe, there's still a bit of the despite the European directive that says these services should be let out to the market, there's still a bit of a TSO. Well, these are our assets. We build these kind of things. So there's quite a bit a few synchronous machines going in in the Baltics because of, you know, disconnecting from the the Russian grid, the Soviet grid.

There's any in Denmark have have got a couple of synchronous compensators sitting around some of their HVDC links.

So, not necessarily with high inertia. It might just be synchronous compensators delivering the Uh-huh. A bit of inertia and the system strength for what you control things. So, yeah, there's there's there's a bit of it about that GB has led, particularly with the open procurement and competition.

You know, that's driven down prices. It's been a it's a highly competitive market. You know? Talking about stability path, and as you know, it's kinda like waiting for the results.

You know? The worst thing is you haven't won anything. The next worst thing is you won everything because you've obviously bid too low and copped up. So it's, so, you know, trying to make sure you win, you know The right amount.

The right amount is is, Yeah. Is is key in this, really.

Definitely. And that's the fact that's the value of the pathfinders. Right? You can start to put a like, you start to get an idea of what the value is for the service, which means it's easier to procure going forward.

Exactly. And, you know, you you start to discover the market price. You can look at everybody's bids. Yeah. The the date is out there.

So, you know, you can kinda see how how this all stacks up and Mhmm.

Yeah. And works out.

Okay. And and we kind of put been in a question earlier about statcoms and voltage control.

Let's go back to that. Why is a statcom different to a synchronous compensator?

So statcom is like power electronics. So it's a bit like your inverter with a instead of a battery, you might have a capacitor on the end of it. So you've got some energy storage, but not not that much. So it's able to, you know, particularly take in real power, and move reactive power around.

So that's the So it's not a big spinning, mass.

Kinetic mass. It's all done on power electronics.

Kinda the same as an inverter. You know, we wouldn't prefer a battery system that's kind of can operate that in a similar manner.

Okay.

I'm not a power electronics expert. So some people on the Yeah. Podcast are gonna go, no.

He's, you know, he's he's off Okay.

Off the mark on that. So apologies to the power electronics, gurus out there.

Yes. Yeah. Yeah.

A call for the for our experts to come on and explain voltage control and follow-up with them.

Yes, please. Yeah. I would be very happy to host them. Okay. So so moving on to our sort of final two questions. So first question is, is there anything you'd like to plug?

Yes. System strength. So I've and I've used this term a bit liberally in this discussion.

But and and it wasn't really a a term used much until a couple of years ago.

It's starting to be used. It's not really defined. People wouldn't know what is system strength.

And, you know, I think that the challenge as we move to inverter based resources is we've got all of these inverters with their interconnectors, batteries, turbine, wind turbines, solar.

They've all got software and programs and stuff behind them. And those control systems can interact with each other in bizarre ways, and and it's impossible to predict whether that might happen. You try people try to create models. They try to analyze it.

They try to, you know, train them, test them, things like that. But you can never be absolutely certain. So the risk is we've got, you know, these inverter based resources becoming unstable in some way or some of them or one of them. You know?

It doesn't take much. So and that's a new kind of challenge on the system. And, you know, I think we've started to see that in some of the data we're collecting from some of our sites. So, system strength is kind of the ability to resist those disturbances.

And the traditional disturbances are what we've talked about, big infeed losses, so like losing the North Sea link or losing the French interconnector.

Traditional faults like a four hundred kV transmission line going to Earth and the voltage collapses till the fault protection clears it. You know, these are the kind of traditional faults that we've been worried about. And, I think that we've gotta worry about new kind of faults, and the system strength resists those kind of faults. And I think the synchronous machines bring that system strength.

You can't reprogram a synchronous machine without a big hammer. You know? Yeah. Whereas all the other control systems, you can reprogram.

Okay. And then, final question.

Do you have a contrarian view, something that you believe that the majority of the market doesn't?

So most of what I do is a contrarian, I think. You go nuclear, biomass, wherever you wanna go, connection skew. But I think given we're talking about stability today, then I thought about this. I thought that I'd like to talk about reaction to to faults and what codes and system operators seem to want plant to do.

So in the old days, when you connect to the grid, as soon as there's a fault was, like, trip off because we don't want you on. We'll sort the grid out, and then we'll bring you back on. That was alright when he had a little bit of distributed generation. I remember going doing a project some projects in Crete and going into the control room and saying, what settings do you want us to trip off on?

And they went, no. If there's some problem on the grid, you need to stay on. You know? We're relying on you wind turbines to to keep going.

So that was like the first, oh, that's a completely different attitude. And then we had, oh, fault ride through. You need to be able to ride through faults. We don't want you to trip off.

So okay. That was it. And then we want you to provide fault current. So we want you to contribute fault current into the fault.

And that's kind of again, get ramped up on and we're now on fault current on steroids.

You know? So when I talk about ninth of August twenty nineteen and Hornsea disconnected from the grid, it was trying to push reactive power from an offshore wind farm through a long AC power system to shore through the grid to respond to a a transmission fault quite remote. So transmission fault happens. There's a small voltage dip that appears on the system. By the time it gets out to, Hornsea, it's relatively small. It reacts, pushes out a lot of reactive power into the grid to prop up the voltage.

The fault clears. Suddenly, all this reactive current's flowing and the fault's gone and the volts goes up. So the wind farm goes up. The volts gone up quick. Reverse all the reactive power. So it's trying to do this in a remote offshore wind farm.

Don't make it do that. Just let it produce megawatts.

Get your synchronous compensators, maybe batteries, other stuff that's located close to the fault to do that fault Mhmm. Ride through stuff. Don't try and make everything look like an old synchronous machine, which did all this stuff. You know, let's divvy up the services into stuff that does it best. Batteries doing frequency response, synchronous compensated giving system strength, offshore wind farms delivering megawatts. You know, let's try not to make everybody do everything because that will result in a massive cock up at some stage.

Agreed. Agreed. Guy, thank you very much for coming on, transmission. It's been a superb episode. We've covered so much ground. We'll definitely put some links into the show notes in terms of synchronous compensators, statcoms, etcetera, etcetera, so people can kind of swap up on that should they choose to. Thank you very much for coming on.

Thank you, Ed. It's been really interesting. Great and great interview, Techni. Thank you.

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