Calculation of penetration level for inverter interfaced distributed generator considering protection constraints in distribution network

The existing method of calculation of penetration level for inverter interfaced distributed generator (IIDG) based on the traditional power supply model might not be applicable any more under the new code for DDG's fault ride-through capability. A method of calculation of penetration level for IIDG of low voltage ride through (LVRT) capability considering reliable action of current protection constraints is presented. The fault current characteristic of IIDG with a LVRT control strategy is studied. The accurate fault current model of IIDG is provided. Then IIDG's influence on current protection is analyzed. And the formulas of short circuit current calculation in distribution network with IIDG are deduced. The method of calculation of penetration level for IIDG considering reliable action of current protection constraints in distribution network is proposed eventually, which is verified by simulation results.