Testing tech: putting power systems through their paces

9 January 2019 (Last Updated January 10th, 2019 09:41)

From transistors to batteries, every aspect of a power system needs to be put through its paces to ensure safety and durability. But just how do you go about testing power technologies? Molly Lempriere speaks to Andrew Burstein and Theo Bosma from DNV GL about the changing demands of technologies.

Testing tech: putting power systems through their paces
In Arnhem, the Netherlands, the company has a series of laboratories in which it can test everything from turbine blades to transistors. Credit: Courtesy of DNVGL

Before any power technology begins operations, it must undergo rigorous testing to ensure that it is not only safe, but also efficient and effective. Global quality assurance and risk management company DNV GL has been involved in testing energy technologies for over 80 years.

In Arnhem, the Netherlands, the company has a series of laboratories in which it can test everything from turbine blades to transistors. One laboratory that has seen a particular increase in testing activity in recent years is the Flex Power Grid Laboratory, which is specially designed for testing smart grid components at real distribution voltages and power levels.

As the energy landscape changes, and with the smart grid market estimated to be worth as much as €3.5bn, the tests that power technologies undergo are becoming increasingly important and complex. DNV GL Group Technology and Research, Power and Renewables researcher Andrew Burstein and program director Theo Bosma offer their insights.

Molly Lempriere: Could you tell me a little about the establishment of the Flex Power Grid Laboratory?

Theo Bosma (TB): Well the lab has been around since 2008, when we established this laboratory together with Dutch universities TU Delft, Eindhoven University of Technology and ECN, so three technical universities, and at that time, a company called KEMA. We jointly started this lab to do testing, but also development in the area of power electronic dominated grids.

Since 2016, DNV GL took over the lab, and we’ve actually changed it a little bit. Originally it was focused on physical devices mainly, for example solar inverters, battery systems and wind energy systems, but since 2016 we’ve added the cyber part of it.

The Flex Power Grid Lab is now partly simulating an environment and partly physically making the real power. We now have the capabilities to do what we call power hardware in the loop.

ML: What led you to adding this cyber capability?

Andrew Burstein (AB): It’s becoming a much more dominant part of networks I think, a lot of what you see has to do with smart grid technologies and a lot of communication and controls of power electronic devices.

So now we’re testing a lot more on a large-scale basis, looking at smart grid operations, looking at control of smart grids and island networks, and in order to do this we really need to dive into the controls and emulation of these types of networks.

ML: With smart grids becoming increasingly common, have you seen an increase in the number of tests you run?

TB: Yes, the requests that we actually get to run tests are increasing, but also, maybe more importantly, the complexity is increasing. Just to give you an example, one of the reasons we actually started to add more control and more power hardware in the loop, is that you can actually do testing in the field. So you could take a windfarm controller, and bring it into the field, connected to your windfarm and start testing whether this device works or not. But preferably you want to know before you place it in the field whether your windfarm controller is working in the proper way.

So then people ask us, ok can you perform the tests of a windfarm controller in your lab? But obviously we don’t have a windfarm in the lab, and it’s not connected to a windfarm. So what we have to do is simulate a windfarm, and connect the controller as if it is connected to a real windfarm.

Questions about whether you can you connect hardware devices to the lab are obviously increasing, but I would also argue that the complexity of the question is increasing. And this lab is specially tailored to handle those complex questions. And as I said in the beginning, the lab is positioned a little bit in between a standard lab where you can do grid compliance, safety testing, and a development lab, where we can also build the strange and odd things.

ML: You mentioned that the tests are getting more complex; what are the scale of the tests?

AB: It really depends on the test, so what’s really nice when we do controller in the loop testing, so the complex system with windfarm or other renewable integration, then we can really be talking about huge systems of tens of megawatts. Then in that case, what we’re testing is the stability of controllers and the interaction of the controllers. So all of the real power is stimulated.

In our lab itself, we can have real power flowing up to 1MVA; typically when we’re testing real equipment in the lab, we’re talking about low voltage equipment (230V), generally in the tens to hundreds of kilowatts range. But we can go up to 24kV.

ML: What exactly are you looking for in most of the tests?

AB: We do quite a lot of performance testing, so we’re testing all these systems for stability, reliability and robustness. For a lot of these power electronics we want to see their capabilities, so full performance of active and reactive power. We test these systems that are grid connected against different grid phenomena, so we’re tested against certain voltage jumps or faults on the network. We can also test for how it responds with the background harmonics, and things of this nature.

TB: That’s correct, and we see the importance of power quality increasing. The lab is perfectly tailored to do this entire power quality standard testing, and go a little bit beyond it.

AB: Now we’re also doing quite a few tests for island operation. Not only are we testing these devices for when they’re connected to the grid, but also when they’re forming the grid. Then we have to change it a bit, so not looking at how it’s responding to the grid but how it responds to different loads, so we can test for a difference in balance loads as well as non-linear and active loads.

ML: Have you ever had any weird requests for testing technologies?

Both: Yes!

TB: Absolutely yes, and this is the fun part of the work we do. There are a lot of people that come with new technology and we always take it seriously. With the lab facilities we can help to develop ideas further and partly materialise it with the free programmable equipment we have.