Optimal power flow (OPF) can be used in congestion management to determine the redispatch of distributed generation. Since the considered network area can be very large and consist of many nodes and lines, simplified load flow models may be necessary to calculate the redispatch in real time in 15 minutes intervals. In this research project, the suitability of different power flow models and OPF solvers for the usage in congestion management should be investigated. It should be evaluated which type of congestions (current related, voltage related) can be detected and handled with the respective models, how accurate these models are and how fast the solutions can be found using typical non-commercial solvers. Finally, it will be evaluated which models are most suitable at which voltage level.