Protection Scheme of Flexible DC Distribution Line Based on Voltage Variation Weighted Summation

Fast and reliable identification of line faults is a key factor restricting the application and development of flexible DC distribution system. A protection scheme using single terminal voltage and current to identify fault is proposed for medium voltage flexible DC distribution system. Firstly, the expressions of fault current and voltage of flexible DC distribution line are deduced. Based on the analysis of the difference between fault voltage and out of area fault in the case of metal fault and short circuit through transition resistance, a voltage variation weighted accumulation algorithm is proposed. The protection scheme is highly sensitive in the case of high resistance fault Finally, built a simulation model on PSCAD/EMTDC platform to verify the correctness and feasibility of the proposed protection scheme.