Starting method for inter-site polar line circuit breaker of multi-terminal flexible direct-current power grid in forbidding

The invention discloses a method for starting an inter-site polar line circuit breaker of a multi-terminal flexible direct-current power grid in a forbidden state. Comprising the following steps: sequentially converting grounding devices of all network sites, metal return lines of the network sites and corresponding new energy island stations, polar line-4 disconnecting links, positive and negative electrode lines of the network sites and the corresponding new energy island stations, and positive and negative electrodes of the network sites except special electrodes into operation states; starting the positive and negative current converters of each networking station and the corresponding positive and negative current converters of the new energy island station according to a sequence, converting the inter-networking-station metal return line into a running state, and stopping redundant in-station grounding devices; starting a current converter according to a sequence of a special pole of the special web sit