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With the ever-increasing share of renewable energy sources in future energy production, the complexity of our power grid is also increasing. It requires management and monitoring to a different extent than we are used to today.
In parallel with the developments in electricity production and the power grid, there are also developments in the available computing power. In particular, there are high expectations for what the quantum computers of the future will be able to solve.
The two parallel developments have led Brynjar Sævarsson, PhD student at DTU (Danish Tech University) Wind, to ask the question: What role can the quantum computer play in ensuring the stability of the power grid of the future?
“There is a lot of potential in quantum computers if they are big enough. In that case, it seems that they can be used as a tool in the power system,” Brynjar Sævarsson says.
The intersection between power grid calculations and the use of quantum computers to solve the calculations is a relatively unchallenged field.
As Brynjar Sævarsson and his colleagues describe in a scientific article, which has been accepted for presentation at a conference this autumn, only a few researchers around the world have tried to make power grid calculations on a quantum computer—and only on simulated quantum computers.
Thus, as far as is known, the researchers from DTU are the first to actually carry out calculations on current quantum computers. They ran five calculations on IBM’s publicly available 5- and 7-qubit computers in collaboration with IBM.
Brynjar Sævarsson and his colleagues have solved the so-called load flow problem, which is a tool for analysing the flow in a power system to ensure that there is not too much current in individual lines and that all voltages are within the correct range, the PhD student explains.
“We have found that we can use the quantum computers to do calculations on a small test system. We are really happy about the results, even though the quantum computers are still very limited in relation to what we can do with them,” Brynjar Sævarsson says.
Brynjar Sævarsson and his colleagues from DTU have great confidence in the role of quantum computers in power grid calculations of the future due to the possibility of having qubits in superposition and not just assuming the values 0 and 1 separately as with classic computers.
The quantum states make it possible to solve several functions with several variables at the same time, which in the context of a power grid can help increase security of supply.
The overview shows the many power supply routes from the energy islands in the North Sea to the power grid on the continent.
“Quantum computers are suitable for making calculations for many different scenarios at the same time and parallel processes. This fits very well with a power grid with renewable energy, where fluctuations and uncertainties give rise to having to count on many parallel scenarios,” Brynjar Sævarsson says.
He mentions forecasts for energy production from wind turbines as an example of a situation in which quantum computers may become important.
Claus Leth Bak, professor at Aalborg University Energy, is not part of the DTU research project, but works with power grid computer calculations in the form of complicated simulation models.
He explains how the green transition, including the huge energy island projects, means that there is a need for more and more detailed and accurate simulation models of the entire power grid. Not only in Denmark, but also for the countries the energy projects are expected to be connected to. Something we have also described several times here at Ingeniøren.
Claus Leth Bak believes that there is potential if, in the future, computing power of normal computers can be supplemented with quantum computers for use in simulations of the power grids.
“As we add more renewable energy to the power grid, the management of the grid becomes much more complex. Therefore, there is a need for online real-time management methods with sufficient computing power. Quantum computers could play a role in this,” Claus Leth Bak says.
According to Claus Leth Bak, real-time solutions in particular call for great computing power, which the quantum computers of the future can hopefully provide.
“Behind the power grid calculations are models which, in step with increasing complexity and uncertainties in the power grid, must also become increasingly complex. Today, the models often try to simplify in order to compensate for the lack of computing power,” the AAU professor says.
“The more computing power we have available, the more accurate, global models we can create. And as the power grid will in the future be more vulnerable to fluctuations than we've been used to for the past 20–30 years, it’s important to have more accurate models for real-time calculations that can keep the power grids stable. Modern society is very much dependent on the reliability of our power supply not deteriorating as a result of the green transition.”
But before we get there, there are a lot of things we still need to work on.
“There is still a lot of noise in the current quantum computers, which also has a lot of limitations,” Brynjar Sævarsson says.
He explains that it has also been a challenge to build algorithms for the calculations with an appropriate scalability. The algorithms have proved insufficient if the systems are larger than the test case. And then there is the whole question of the size of the quantum computer, which today does not make it favourable in relation to current supercomputers.
“Theoretically, methods should be exponentially faster on a quantum computer than on classic computers. The result of our research is that we can run the calculations on a current machine—we are still not faster than a classic computer,” Brynjar Sævarsson says.
So is it at all realistic to assume that we will have the desired quantum computer computing power available when the green transition really takes hold? For example, with a quadrupling of the production of solar and wind energy on land alone with the current government plans.
“It’s difficult to say how quantum computers will develop. We see very positive results from IBM and others in building ever larger machines,” Brynjar Sævarsson says.
His hope is therefore that research like his own can contribute to the development of the necessary algorithms, so that there is a method ready when we are suddenly faced with a power grid based on up to 100 percent renewable energy.
And then the quantum computer should hardly stand alone, the DTU researcher says. Rather, it should be seen as complementary to the classic computers.
“The quantum computer can do something special, but it’s not better for everything. Therefore, we will probably see some tasks solved on classic computers, while some will be solved on quantum computers,” Brynjar Sævarsson says.
