Episode Transcript

Cortney Piper: Welcome to Energizing Tennessee, powered by the Tennessee Advanced Energy Business Council. We’re your number one podcast for news about Tennessee’s advanced energy sector. I’m your host, Cortney Piper. If you have ever wanted to learn about the nittygritty of microgrid work. This episode is for you.

We’re big fans of Schneider Electric at the Tennessee Advanced Energy Business Council. Not only have they been a valued TAEBC member since the beginning, but they have also graciously hosted our annual meeting at their Nashville headquarters for years. On this episode, we’re speaking with two representatives from Schneider Electric about a microgrid project for Middle Tennessee Electric.

Early adopters of microgrids included hospitals and data centers, places where reliability and resiliency are essential. But today, organizations of all kinds are turning to microgrids and distributed energy resources for financial benefits and to gain control over energy costs, advance sustainability efforts, and increase resiliency. Keep listening to learn more.

And as always, if you enjoyed today’s episode, please subscribe and leave a rating or review. It helps us spread the word and support the fantastic work in the advanced energy sector.

Today, I’m speaking with two representatives from Schneider Electric, a valued TAEBC member. Ryan Egly is a senior microgrid solutions and project development engineer, and Daniel Gyampo is a microgrid quality and support engineer.

Ryan and Daniel, thank you for coming on the show.

Ryan Egly: Great to be here.

Daniel Gyampo: Thank you for having me.

Cortney Piper: All right, we are big fans of Schneider Electric here at TEABC. You all have served on our board and are fantastic contributors to Tennessee’s advanced energy sector, and I’m looking forward to talking with you all about a microgrid project in middle Tennessee. But before we start talking about this project, I want you all to share with our listeners: What is a microgrid?

Because you ask 10 engineers how to define a microgrid, and I swear you will get 10 different answers. So, for the purposes of leveling out our listenership, Ryan or Daniel, what is a microgrid?

Ryan Egly: Yeah. I’ll take that one. So there’s a Department of Energy definition where you create a defined electrical boundary.

You can imagine if you have a site plan, you have a building, you have some energy assets, just draw a circle around those. And then, that one definition is that you can control those as a single entity. And then there’s an in front of the meter, behind the meter concept that’s important. And we might get into that.

Behind the meter is really what the name implies. You have a customer utility meter. Anything behind that is generally a fair game. The customer owns the equipment. There’s a lot you can do. When you’re on the utility side, you still can have the concept of microgrids, but there are very few in the country that will let you work on that side of the meter.

So, usually, when we talk about microgrids, it’s a defined electrical boundary that is on the customer side of the utility meter.

Cortney Piper: Great. So now we’ve got a foundation, we’ve got a basis. Let’s talk about your microgrid project with Middle Tennessee Electric. We love Middle Tennessee Electric at the Tennessee Advanced Energy Business Council.

They’re always doing some really great, innovative things to meet their customers’ demands and needs. So, let’s talk about this microgrid project. Give me an overview of the microgrid project and how it came about.

Ryan Egly: Oh, yeah. So I’ll take how it came about. It was one of the first projects I started working on in 2018.

Daniel, if you want to take on the renovation project and how that worked.

So, it came about because Middle Tennessee Electric is fairly advanced in their thinking in terms of new energy, the new energy landscape, and new energy technologies. I did want to highlight two amazing project sponsors with Middle Tennessee who weren’t able to make the podcast but have been fantastic partners throughout this process.

Avery Ashby and Adam Miller. It’s been a great group to work with.

The short version of how it came about is that they started with ground mount solar PV, 60 kilowatts DC, and then they started looking at storage. So, they’d already put battery storage at some of their substations. And they wanted to create sort of a test microgrid at their operations center in Lebanon, both to learn and then also to host demos for their commercial customers.

Cortney Piper: Oh, nice.

Ryan Egly: That’s the high-level why, where it came about.

Cortney Piper: Okay. And Daniel, give us an overview of the project itself. What are we looking at here in terms of their particular microgrid?

Daniel Gyampo: Yeah. So this project actually started as an engineer to model microgrid projects, but we had some difficulties with this solution, and so we had to pivot to what we call the configure to auto approach. And what this basically entails is it leverages a preconfigured microgrid solution. So, you have an energy system that is already designed with standardized components that are ready to deploy on the go. And all this takes is going in and picking your DERs, Distributed Engine Resources, and setting the use cases for the site that you’re ready to go and deploy the solution on site.

This is done on one of our solutions that we have called the EcoStruxure Microgrid Build on the Schneider Electric sites. Unlike your fully custom-built microgrids, which usually require an extensive design and engineering from scratch, this solution comes with proven configurations.

It also makes it easier and faster to deploy and more cost-effective. In addition to that, we had all the sequence of operations. So this is when you’re going from your great to best, best to great, all tested, validated, and documented. And I guess I might as well also add into the fact that we had three main DERs, which were our battery, our generator, and the PVs.

So, being able to transition from the main anchor resources, which are the best and the genset, was very important for this project. So how we went about implementing this was that we, for this site specifically, took that preconfigured solution. We made modifications based on what was already existing on the site setup with support from our line of business and were able to adjust some examples that we had was adjusting the IO blocks, which send hardwired signals to your generator, your breakers for your shunt tripping. We’re able to make those adjustments and successfully integrate into the updated system. To have it as a future-ready microgrid project.

Cortney Piper: Okay, Daniel, I’m going to get back to you a little bit more on the nuts and bolts and the components of the project. But, Ryan, you mentioned that this was a learning project for Middle Tennessee Electric. Can you tell us more about why Middle Tennessee Electric decided on this particular microgrid solution?

Ryan Egly: Yeah, it kind of dovetails into what Daniel described. So in any electric building, you have what’s called a switchboard. So if you go into the electrical room, you see all the breakers. We have a very specialized piece of microgrid equipment that we launched about five years ago called the Energy Control Center.

And so this product combines operable breakers with motor operators and metering, close coupled, which means you put the controls and mix it, and you deliver it as one piece of equipment. And we pre-wire, pre-test all that in the factory. So, that was kind of the cornerstone of the building blocks for this project.

Daniel described that this project started long enough ago that the control side was very custom. It was a custom PLC, very customized. But then, since this project was delivered, we developed this new platform that aims towards standardization. Our companies focus big time on standardization for cost benefits, but also just long term performance.

Cortney Piper: Okay, now let’s go into more of the details itself because what I’m hearing from you all is, there was this initial site, and then you had to do some modernization, or there was some old electrical equipment that you had to modernize as part of this process.

So, give me more of the details about all of that.

Ryan Egly: Yeah, they had 25-year-old fused equipment, which is just an older style of electrical equipment that you can’t operate. It’s just an electric fuse, and you can’t really do much with it. We started in one model with the project, and then we learned of a separate renovation project that they were pursuing.

And so we were able to co benefits between the projects, we changed the design approach to not augment their existing equipment, but to replace the old equipment. And one other detail I think we should mention here, Daniel, a really important design criteria in microgrids is the transition time from the grid.

So if you have a utility outage, the time it takes to transfer, that’s one of the initial questions you get into. That’s one of the first things we started with here. Middle Tennessee, in terms of the learning project, an extremely fast transition time. So, 10 seconds is a code requirement for a standard backup generator.

So the whole site goes dark, generator comes back up. With batteries, you can get a lot faster. The fastest is called Voltage Ride Through, where you don’t really see a blip. You might see the lights flicker, but the entire building transfers to the battery, but you never really see the site go dark.

A lot of the design of this project was built around trying to achieve that.

Cortney Piper: Okay, and you all touched on the asset mix of this particular microgrid. There was the ground mount solar PV. You had battery storage, generation interaction. But go through each one of those components.

Ryan Egly: So we have 60 kilowatts DC of solar, and in solar systems, you have a DC rating, which is the total of the panels and then the inverter, which is 80 to 90 percent of that, 80 to 85 percent of that on the AC side.

So, you have a 60-kilowatt DC system and a 230-kilowatt diesel generator, like Daniel described, that was existing. And that’s a big part of these projects is figuring out how, if you even can, integrate with existing assets. And whether or not you need to modify the controls approach or if you can use what’s there.

And then, we had a 250-kilowatt battery system. I think we’ll talk a little later about battery sizing. And then there’s a Schneider Electric UPS at this project.

Daniel, it’d be a good one for you to talk about the difference between a UPS and the IT loads and their battery, like a stationary battery. It’s always a really big topic in these projects.

Cortney Piper: Yeah.

Daniel Gyampo: Yeah. So for this project specifically, the main function of the UPS that we had in the Schneider Control Center is basically to power those control devices. So in your switchboard, you have your MT51, which I see that as the brains of operations in the whole control system, which is taking care of all your transitions when you move from your utility to the BESS, when you move from the BESS to the genset, this control PLC is what sort of taking care of those transitions.

So we have the UPS, which is actually powering these devices when we have those power slips. When we lose power for a brief amount of time, it’s able to power these little devices and allow them to make the transitions. Now, the BESS, which is separate from the UPS, that’s what’s actually going to take charge of the power and power the whole site.

So, I think the main difference is what each of these devices is powering. With the UPS, we’re using them to power those small controllable devices in the switchboard, and the BESS takes over to power the whole site when we make those final transitions.

Cortney Piper: Okay, let’s talk a little bit more about the challenges and the benefits.

Ryan, you talked about outage transfers. What else would you like to cover in terms of the challenges and benefits of this particular system?

Ryan Egly: Okay, so benefits, and on the UPS topic, there’s also a larger UPS for the customer’s IT loads. And that’s really common in these projects where if they have a, they’re running a mini data center.

Cortney Piper: Yes.

Ryan Egly: This question comes up weekly. Stationary battery storage is not equivalent to a UPS for it loads and you can’t use it to replace a UPS, and you’re still, in most cases, during a power outage, you’re gonna have a blip that would trip your IT loads offline and that’s usually UPSs are pretty expensive, so you don’t, you size those to the IT infrastructure.

And the technology’s not at a place to reliably get rid of UPSs. But in terms of what this project was delivering, there are two fundamental modes of operation that we look at in microgrid design. There’s grid-tide, so all of your equipment is referencing the utility voltage, and you’re trying to save money.

So there’s a couple of ways you do that. There’s direct offset, the solar’s producing energy. I mentioned earlier it’s 60 kilowatts. The reason for that is this had to be a nonexporting site. So, Middle Tennessee Electric cannot export to TVA just in terms of their agreement for this site. And so what we did, the first step, is you look at what’s called their interval data.

You look at the load profile, and some projects, we export a lot because they want to overproduce for net-zero targets. At this site, the solar is specifically sized not to export. That’s one money saving. The other is called demand charge reduction. Probably your listeners, if they’re listening to this podcast, have heard about demand charges.

They can either be on a monthly basis or a demand ratchet could be on a rolling 11-month basis for larger customers. But, what the battery can do when you’re grid-tied is reduce your demand peaks, for demand savings. Grid-tied and then islanding- those are the two modes of operation in terms of what we’re targeting in these projects, and each has its own design criteria and constraints.

Daniel Gyampo: Just to add to what Ryan mentioned about demand charters. So, we’ve actually seen examples of this happening in the site as recently as January. So we had that cold front, and we had these demand spikes on the AFAC systems in the site. The battery was able to come in and offset the power coming from the utility to save the site money of exceeding these demand charges.

That was one of the great examples we’ve seen of this microgrid in action, saving the site some money.

Cortney Piper: Okay.

Daniel Gyampo: Yeah.

Cortney Piper: What did you all learn from this project?

Ryan Egly: I’ll be really short here because Daniel’s the one supporting it every day. I would say the benefit of a standard architecture and validated controls approach.

Going back to what Daniel already said, we started out in a custom PLC coded environment, and then we transitioned this project to the more standard platform because five years ago, every microgrid project was highly customized, and we’ve just seen a lot of benefits and put a lot of R&D into standardization.

Daniel Gyampo: From my perspective, I think a lot of things that we’ve learned was the value of having remote access to this site. I think this is one of the key lessons that we’ve learned: Being able to access the site from a service perspective in order to troubleshoot issues and deal with whatever happens.

It also helps us be proactive and take care of some issues that arise on-site before they become fatal. Another very important lesson, and I think we can talk about this much more was alarming, being able to set triggers on various factors in the site, like the state of charge, the battery’s frequency, and being able to catch those changes whenever these triggers are passed, and being able to catch them and respond to them on time.

So I think these are valuable lessons that we’ve learned, and it’s helped us improve our microgrid solution going forward into the future.

Cortney Piper: From your customer’s standpoint, if you can put your Middle Tennessee Electric hat on. What benefits did they see? You mentioned some cost savings, but from their perspective or from that local power company’s perspective, what were the benefits to them?

Ryan Egly: Yeah, project learning, grid-type cost savings, avoided generator use. And we see this a lot, especially in California, but really any customer investing in this type of equipment. They mostly want to prefer to transition to the battery first and we didn’t talk about this, but, sizing of batteries, a big part of what we do is looking at, like, you can size the battery for full backup and a really important detail is that batteries as inverter based resources have a more limited ability to handle spikes and load.

And so the generator is 230-kilowatts. A rule of thumb is 5 to 7x the nominal rating of the generator. The generator, with its rotational inertia, can take those load spikes. So you still have to consider it when you’re sizing a generator. When you look at the spec sheet for a battery, you’re going to see 1.2 to 1.5x. So, if you have a 100-kilowatt battery, that means a maximum of 150-kilowatts. Anything above that, the battery is going to self protect and trip offline. So a big part of these projects is characterizing the load and sizing the battery. Then, one other thing you made me think of, we have a specific engineering study around battery stability. We’ve developed it through, frankly, stubbing our toes a bit on some of these topics. And we’ve got that to a pretty good place. The resting charge, the resting state of charge of the battery. A lot of engineers of record who are designing these systems treat the batteries kind of equivalent to a generator, and in some ways, it is.

But on that power stability inrush of spikiness of the load topic, that’s important. Then, the second parameter of the battery. You’ve got the kilowatt – that’s the power rating. Kilowatt hours is how they’re sized. So this is a 250-kilowatt battery. A 224 kilowatt hour. And those, those two metrics are how you size the battery.

Where you set the resting state of charge determines how long that battery could support the site during an outage. These are all things you develop in terms of design intent, and then people like Daniel go in and optimize it. They look at how it’s performing, they might tweak it and raise it, might lower it, and there’s all sorts of implications.

You might think, well why not just hold it at 100%? Well, just like your cell phone and degradation, if you hold batteries at a high state of charge constantly, over 10 years, that has a huge impact on degradation. So there’s all these things you gotta look at for an optimized system.

Cortney Piper: Daniel, do you have any parting thoughts or final words for us?

Daniel Gyampo: Thinking about some of the things that we have learned from this project. One thing I’d like to add is also the fact of this site being used as a demo site. It’s been really great showing that microgrid solution to folks interested in the whole microgrid solution. So you don’t get to only just talk about microgrids, but you actually get to show the benefits live in person. So that has been very valuable to us. In addition to that, I think this being one of the first microgrid projects that we worked on, I think a lot of what we’ve learned from it has gone towards our new solutions and how we actually go about executing and implementing our different microgrid solutions.

All in all, for the customer and for Schneider Electric, this product has been very beneficial.

Cortney Piper: Great. Before I let you all go. Where can people go to learn more about you, your work, and Schneider Electric?

Daniel Gyampo: I’ll say the best place to go is on our Schneider Electric microgrid solutions website.

We have a direct website for the global microgrids and the USA specific websites, which do a great job explaining what the microgrids are and also showing the offers that we have. Additionally, I would recommend following the Schneider Electric LinkedIn page, where we post a lot of updates on our projects, innovations, and industry insights.

For folks who are interested, this is a great way to stay in touch and follow our work.

Cortney Piper: All right. Daniel Gyampo and Ryan Egly, thank you for joining us on Energizing Tennessee.

Daniel Gyampo: Thank you for having us.

Ryan Egly: Thanks so much.

Cortney Piper: And that’s our show. Thanks for tuning into Energizing Tennessee, powered by the Tennessee Advanced Energy Business Council, your number one podcast for news about Tennessee’s advanced energy sector. Subscribe on Apple Podcasts, Spotify, or wherever you get your podcasts. And if you like what you heard, please share it with others or leave a rating and review.

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