DC short-circuit analysis for systems with static sources

When calculating available sustained fault currents for DC systems with static converters as sources, the internal resistance of the source must be adjusted based upon the terminal voltage of the source. If the system has a single source, an iterative technique is normally used. However, this becomes cumbersome when solving systems with multiple sources and multiple fault locations. Previous methods have adjusted the resistance of all static sources by a fixed percentage. Methods for providing multiplying factors to adjust the fault contributions of static sources which differentiate between local and remote sources are discussed. Individual multiplying factors for each source may be calculated by means of a formula, or an approximate multiplying factor for all sources may be found by iteration. The multiplying factors are then applied to the results of a single-step matrix solution for the short-circuit currents. This facilitates the use of computer spreadsheet programs for the solution of the problem. It is concluded that the use of a fixed multiplying factor may offer the most conservative solution method.