Effect of Embedded Induction Generators on Short-Circuit Detection

The application of embedded generators in distribution grids has consequences for the protection systems. A general approach is described for assessing the impact of induction generators on the detected short-circuit current in a distribution feeder. A simple system is simulated for a large number of parameter variations. The goal is to find those system configurations for which the negative impact on short-circuit detection is strongest. First, the simulated system is described and the calculation and choice of the parameters of this system are discussed. The parameters of concern are: short-circuit power of the grid, cross-sectional area of the cable conductors, location of the generator, power of the generator and minimum short-circuit current. Next, the simulation results are discussed. It is found that an induction generator does not pose a problem for detection of three-phase and double line-to-ground faults when one feeder is considered. With line-to-line faults and single line-to-ground faults, problems may occur. The significance of an additional parameter is discussed: the number of generators