School of Electrical Engineering,Northeast Electric Power University
Fault current limitation in DC power grid has become one of the important problems that must be faced and urgently solved in related fields. Most of the existing fault limitation methods adopt single component. In order to fully limit the rising rate and peak value of fault current, this paper proposes a fault limitation and optimal configuration method combining the characteristics of DC reactor and capacitive current limiter. Firstly, based on the fault equivalent circuit of modular multilevel converter, the necessity of installing fault current limiter is analyzed from two aspects of limitation principle and action sequence. Secondly, the limitation characteristics of inductance and capacitance to fault current are calculated and analyzed, and the equivalent circuit and solution method are extended to DC ring grid. The optimal configuration model is constructed with the objective of fault current and DC reactor. Finally, the optimization results are applied to PSCAD/EMTDC simulation model. Compared with the scheme using DC reactor only, the configuration results can further reduce 40% of the fault current without prolonging the fault clearance time. It is verified that the combination of DC reactor and capacitive current limiter can significantly reduce the fault current and the breaking capacity of DC circuit breaker.