Appropriate transmission grid representation for European resource adequacy assessments

To manage power shortages, system operators must rely on involuntarily demand curtailment to keep the grid operational. Curtailment causes damages to consumers, the cost of which should be balanced against investments in a more reliable power system. To understand the behavior of the system and the expected character of shortages, we rely on resource adequacy studies. These studies provide a probabilistic quantitative framework by emulating system operation over many future years. However, the methods to emulate the power system must balance computational efficiency with accuracy and rely on different simplifications and approximations of the power system and its behavior. Here we show that the transmission model choice particularly impacts the results of these studies, especially for large systems where scarcity risk is shared through markets with significant inter-regional transmission capacities. Our results demonstrate that the most commonly used simple transmission grid models highly distort key adequacy metrics and are likely to cause the misinterpretation of system needs.