A Novel Approach for the Calculation of Steady States in Transmission Systems Using Simplified Time-Domain Simulation

With the constant development of renewable energies, power electronic devices and special protection schemes, the transmission system’s dynamics are greatly evolving. This not only has an influence on the dynamic behavior of the system, which is of prime interest for stability studies, but also on its steady state after one or several events. Power flow tools, that are used today to calculate the system’s steady state, are not adapted to such changes, as they are mainly based on heuristics and external loops supposed to mimic the controllers actions. Such an approach cannot capture all the complexity and interactions between the different controls, especially when new and more complex ones are added to the system. To cope with that, a new approach based on a simplified time-domain simulation is proposed. This method enables to calculate the correct steady state point of a system with special protection schemes and power electronic devices while classical approaches fail, as shown on some illustrative test cases. A first implementation of this approach, already available and open-source, provides promising results both in robustness and quality for larger test cases like the French transmission system.