A bipolar DC power transmission scheme comprises: DC poles, each including a respective power transmission medium extending between two ends; a plurality of converters, wherein each end of the power transmission medium of the first pole is respectively operatively connected to a converter, and each end of the power transmission medium of the second pole is respectively operatively connected to a converters; a controller programmed to block one or more of the converters in response to a fault occurring on either of the first and second poles; and a monitoring device configured to identify the faulty poles on which the fault has occurred, wherein the controller is further programmed to deblock the or each blocked converter connected to the other of the poles after the monitoring device has identified the faulty one of the poles on which the fault has occurred.