Simplified Short Circuit Current Calculation for DC Distribution Grids based on a Superposition Approach using Approximated Current Courses

Abstract

The use of DC distribution grids for medium and low voltage level is debated in current research. One important aspect is the short circuit current calculation, whereby for practical grid planning a simplified short circuit current calculation method is desired. Thus, this paper presents a simplified short circuit current calculation method based on a superposition approach using approximated current courses. The results demonstrate that the calculation of any desired partial short circuit current is not possible. Nevertheless, the results also highlight that a rough estimation of dimensioning relevant short circuit current characteristics for current-carrying grid equipment is possible, whereas a few restrictions are given. Therefore, we cannot guarantee a general applicability of the simplified method. Thus, further development of the promising calculation method is required. However, we recommend using transient calculations for DC distribution grids until a sufficient applicability of the simplified calculation method can be guaranteed.