Will the power grids buckle under the pressure?
25. November 2021
To pull the plug on any rumours right at the start of this article, the answer is a definitive “no”! Of course, there are significantly more complex answers to this question, otherwise the current political, economic, social and technical discussions on this topic would be superfluous. With all the experience gained with renewable energies, and with customers now having become “prosumers” (that is, both producers and consumers of electricity), electric mobility is now of a different order. But where does the actual problem lie?
Kevin Kotthaus in the smart grid laboratory of the Chair of Electrical Power Supply Technology © Berenika Oblonczyk
Will the power grids buckle under the pressure?
While most cables to household connections can provide the electrical charging capacity of an 11-kW or 22-kW wallbox, the strain on supply cables in the street or on the local mains transformer can represent a problem. If, as is often raised in discussions these days, all the residents of a street were to charge their electric cars at the same time after arriving home from work at 5:30 p.m. in future, the cumulative peak load, that is the electricity demand at that moment, in most energy grids will exceed the capacity of the network. It is certainly possible for grid bottlenecks of this kind to occur, but even with growing numbers of electrically powered vehicles and charging stations, they will be the exception rather than the rule.
The reason for this is what’s known as diversity factors. In network planning processes, these predict the consumption patterns of end customers based on statistical probability. User behaviour varies widely among car owners – so not everyone will be charging their vehicles at 5:30 p.m. When it comes to charging electric cars, influencing factors such as the distance travelled each day and different working hours lead to diversity factors that must be taken into consideration when planning. But what happens when the demand for power to charge vehicles is significantly higher than usual?
It would be technically feasible to introduce suitable solutions such as intelligent network components and charging management systems that implement optimised charging strategies depending on the current network load by temporarily reducing the charging capacity available, and postponing the charging process for a while without inconveniencing the end customer. However, the current regulatory framework conditions and unresolved issues relating to billing, data communication and how to handle the costs incurred at the distribution network operator through innovative measures, are impeding the introduction of such systems, which must come sooner rather than later according to experts.
While the latest Verteilnetzstudie NRW (NRW Distribution Grid Survey) by the Ministry of Economic Affairs, Innovation, Digitalization and Energy of the State of North Rhine-Westphalia (MWIDE) estimates that North Rhine-Westphalia alone requires around Euro 15.4 billion of investment to expand the grid between now and 2040, the sheer costs are not even the biggest challenge. The magnitude of the work required to expand the grid will be virtually impossible to manage – simply because of the planning and scheduling necessary at the network operator level, and in particular because of the civil engineering work involved. In contrast, the use of intelligent controls on charging, which can be implemented far more flexibly than conventional expansion measures, can make it possible to defer expansion work and, according to experts, reduce the investment needed by around Euro 6 billion. To sum up: electric mobility is coming and, yes, the power grid is facing challenges – but it won’t buckle under the pressure.
About the authors of this guest article
Professor Markus Zdrallek
Professor Markus Zdrallek studied Electrical Engineering at the Technical University of Darmstadt and completed his doctorate at the University of Siegen. From 2000 to 2010, Professor Zdrallek held various senior positions at the energy supplier RWE in Siegen, Brauweiler, Neuss and Warsaw (Poland) – most recently as Authorised Representative at RWE Rhein-Ruhr Netzservice GmbH. He was appointed Professor at the University of Wuppertal (BUW) and Director of the Chair of Electrical Energy Supply Technology in April 2010. Professor Zdrallek is also Scientific Director of Neue Effizienz – Bergische Gesellschaft für Ressourceneffizienz mbH.
Kevin Kotthaus has been a Senior Engineer at the Chair of Electrical Energy Supply Technology since March 2021. Until the beginning of the year he oversaw the “Energy Markets and Flexibility Management” research group. Kotthaus gained his Bachelor of Science in Industrial Engineering: Electrical Engineering at the University of Wuppertal in 2015, and obtained his Master of Science in Industrial Engineering: Energy Management at the same university two years later.
About the research activities of the Chair
A team of 50 scientists led by Professor Markus Zdrallek at the Chair of Electrical Energy Supply Technology at the University of Wuppertal (BUW) are researching innovative planning methods and charging management systems, looking for intelligent and economically viable ways of integrating electric mobility into the grid. A dedicated smart-grid laboratory and a test grid are also used here to evaluate technically innovative solutions in an environment that closely reflects real-world conditions. The department’s main research areas include the condition evaluation of equipment, modelling and optimising networks and grid operations, and intelligent grids for the energy transformation. Working with partners from the fields of power supply, industry and energy service providers, the Chair for Electrical Energy Supply Technology is designing the future structure of energy supply. Project partners include the German federal government, the state government of North Rhine-Westphalia, European authorities, major energy suppliers, public utility companies and associations. The department has won numerous scientific awards for its research.