To avoid the DC circuit breaker reclosing on a permanent fault and causing a secondary impact on the system

and select different reclosing strategies for different fault types

a comprehensive reclosing strategy for DC distribution grid based on series-parallel power flow controller (SP-PFC) active signal injection is proposed. Firstly

a fault analysis model of the DC distribution grid containing SP-PFC is established

and the fault energy absorbed by SP-PFC during the fault is analyzed; Besides

to achieve the SP-PFC active signal injection

the logic block diagram and timing coordination logic of the SP-PFC power flow control

bypass control

current limiting control

blocking control and signal injection control are designed. High-frequency voltage signals are actively injected through SP-PFC

and then feature components are extracted according to the variational mode decomposition algorithm to realize fault property identification. On this basis

the identification of pole-to-ground

pole-to-dedicated-metallic- return and pole-to-pole faults based on current characteristics on both sides of the line during a fault

combined with identification of transient and permanent faults

enables DCCB comprehensive reclosing under different fault types. Finally

a simulation model of the DC distribution grid containing SP-PFC is built in MATLAB/Simulink to verify the correctness and effectiveness of the proposed strategy.