Simplified hybrid reliability simulation approach of a VSC DC grid with integration of an improved DC current flow controller

Abstract

In this paper, different reliability simulation approaches of an improved DC current flow controller (CFC) integrated voltage-sourced converter (VSC) based DC grids are investigated with the following contributions: (1) In order to achieve bidirectional power flow control and fault current blocking capability, an improved DC CFC topology with a set of reversed switches is analysed to enhance the controllable path and control margins; (2) Two different reliability simulation approaches of the improved DC CFC integrated meshed multi-terminal DC (M2TDC) grid are analysed. In Approach 1, the VSCs and their AC sides are modelled without simplification. In Approach 2, the VSCs and their AC sides are represented by ideal DC voltage/current sources to simplify the system modelling; (3) Synthesizing the merits of both approaches while avoiding the deficiencies, a hybrid reliability simulation approach is proposed with high efficiency of simulation while maintaining the accuracy; (4) In order to further enhance the simulation efficiency, a different reliability simulation approach of the ideal DC current source, namely improved ideal DC current source, is proposed. Simulation systems are established in PSCAD/EMTDC for verification.