Algebraic Modelling of Converters without DC Fault Ride-Through Capability for Short Circuit Current Calculation of DC Distribution Grids

This paper presents an novel algebraic model to approximate the DC short circuit current contribution of converters without DC fault ride-through capability. The model is used for an algebraic short circuit current calculation method of DC distribution grids. In a first step, this paper analyses the behavior of different converter topologies in case of a DC side short circuit. Afterwards, a general algebraic model for converter without DC fault ride-through capability is derived by calculating short circuit current characteristics and approximating the current course. Finally, the model is evaluated by comparing the results of the model with the results of detailed transient simulations. Thereby, the model is verified for different parameter variations. Furthermore, the presented model is compared to an existing model which is provided by standard IEC 61660. The comparison proves that the novel model is advantageous.