Optimized regulation of dispersed generation units for minimization of reactive power consumption

Because of the increasing share of renewable energies violations of the statuary voltage limits occur more and more often in the German distribution grids. Therefore, distribution system operators take advantage of reactive power support by dispersed generation units for voltage regulation. Commonly, only one standard cosφ(P)-profile is implemented as a control-method for all units to decrease voltage rises. This profile is independent of network characteristics and the point of common coupling. However, additional reactive power consumption causes additional reactive power unbalances in the networks which have to be compensated by the overlaid transmission grid. This becomes more difficult in times of a decreasing number of large conventional power plants. In order to reduce the additional reactive power demand caused by the improvement of statuary voltage stability this paper describes two methods to calculate optimized cosφ(P)-profiles for reactive power support. Beside the reduction of reactive power demand the optimized control-methods have also the positive effect of lower power losses in the distribution grids.