Q: What are the main challenges power system operators face when it comes to the integration of renewables?

Mart: The traditional generators are coal and gas you can control and they follow the load. But the new sources like wind and solar, they are variable. And that means you don’t know always when you have the power supply. And that means that you have to find solutions for that so that the load can be supplied in a secure way. The other is, I can say, the capacity factor of equipment, for example, load, the maximum load is 18 gigawatt in the Netherlands and you have 100 terawatt-hours of energy supply. That means that for about 6000 hours, the maximum load can be supplied. But if you have solar PV, only 1200 hours of maximum load can be supplied. That means there is a big gap and that has to be filled in one way or the other. So a mix of energy is very important. And the third one is transporting energy, if you have continuous energy flow, you don’t have a certain amount of grid. For example, during 6000 hours, if you have only 1200 hours of electricity production, then you need more grid, five times more grid. And the challenge is for system operators to really avoid having huge investments five times but less.

Q:  Can we rely on integration and intelligence to integrate even more renewable energy?

Mart: Yes, you need really new solutions and say smart solutions, intelligent solutions. And that means that not only wind and solar you need but also demand-side response. How do you use the flexibility of demand or batteries? But the combination of these solutions, you have to perform a load flow, for example, and find the right mix and you have to find the right automation solutions to really make it work. So yes, it’s possible, but we have to do other things than we are used to today.

Q:  What do we need in order to enable intelligence and integration?

Mart: We need education and research. That’s the starting point, I think, as a professor.

Q:  How can laboratories help in the energy transition?

Mart: Laboratories are important if we design solutions before we can use them as an operator, the system operators, they must be sure that it’s working. So in a laboratory, you can test certain solutions in real circumstances. And in the laboratory, you not only test intelligence but also materials and new power, electronic solutions, and electrical vehicles – how to charge them in a smart way. All these mix of solutions, you can test in the laboratory just to test if it is really viable in the practice. And here we are in the control room and here everything, everything comes in at the end – all solutions, but also all not solved challenges come in the control room and they have to act all the time. And today, the operators work with many solutions in the sense of say, technologies. But in the future, with more automation, they will work with more subsystems. So from an operator to operate all details, they change over to a supervisor of intelligent solutions and test those intelligence solutions. We do that, for example, in the RTDS lab, and we will go to the RTDS lab to see more of that.

Q:  Where are we now?

Mart: We are now in the RTDS room in the RTDS lab. RTDS means Real-Time Digital Simulation. That’s all about intelligence and a very fast way of intelligence. Here we simulate the grids and especially the dynamics of the grids.

Q:  What can we simulate?

Mart: We can simulate, for example, short circuits and high voltages. And what we really simulate is the dynamic behavior of the grid, not load flow where you calculate during one year, but here you calculate during some seconds. And for example, you have a short circuit in 150 milliseconds. A circuit breaker disrupts this short circuit, and then the grid behaves in a very fast way. Transients, we call that, and that’s what we simulate. Why is this, then, real-time? You can connect real equipment to this computer system so that you can test real-time for example, control units for the HVDC converter or protection relays. So in some milliseconds, many things happen and the real voltage and the real current are on the relay and that’s – Yes, that you need to bring theory into practice.

Q:  How much renewable energy can we integrate before we reach the grid limits?

Mart: Depends on where you are, for example, in the European grid, all grids are connected to each other – one big system with one frequency. But if you take an island like UK or Ireland, there you have a limited number of production units, a limited number of loads. And the frequency can be unstable if you have too many power electronics connected – solar PV and wind, for example. Normally you have the traditional generators with a mass rotating mass and what we call inertia. But if you have more sustainable sources, you have less traditional equipment. That means they have less inertia. So you can have solar and wind connected to such an island, for example, UK 40% or 50%. We calculated that in the European project Migrate and that’s possible with the traditional grid following control. If you have advanced grid forming control, you can go further up to 70%, and if you want even more, for that research is necessary. So it depends on where you are and what kind of solutions there are available.