Dynamic simulation of renewable energy sources and requirements on fault ride through behavior

Currently, power generation from renewable energy sources is of global significance and will continue to grow during the coming years. The grid integration of intermitting renewable energy sources is not only an issue of distribution networks, but effects the transmission grids as well. The largest amount of new installations are connected to the transmission grid, especially into 110-kV. Further, large wind farms with some 100 MW have already been connected to the 400-kV-system. The renewable energy sources are connected to the power network via power electronic converters, and this type of connection schema can change the short circuit conditions in the network. Today, usually a tripping command is generated within the first period, but in the future contributions to the short circuit current by renewable sources are necessary to fulfil the selective clearing of faults. To investigate the new requirements some novel simulation models are necessary, and described in the paper, for: converter connected DC sources (fuel cell, PV plants), doubly fed induction generator, DFIG, converter connected synchronous generator. Using these models the simulation allows for investigating the behavior for various control design. Requested is the delivery of rated current up to voltage dips of 100% for the whole duration of the fault. The results of some simulations and discussion of them have led to new rules for grid access. These rules are implemented into the grid code