Enhanced stability of EHV power networks with HVDC connections

This paper deals with the topic of power system stability in the case of expanding a conventional three-phase AC grid with HVDC connections. With respect to the requirements of modelling power system elements for stability studies a simulation model is built. A fast method for evaluating the power system stability based on modal analysis is proposed. Different scenarios of expanding or replacing overhead power lines of the original grid with HVDC connections are compared and evaluated. Three-phase faults at all buses and lines are simulated with different fault clearing times. In most cases a positive influence of the HVDC connections on the rotor angle stability is presented.