CHANGE OF CURRENT RETURN PATH IN A BIPOLE POWER TRANSMISSION SYSTEM

摘要

An arrangement for changing current return path in a bipole direct current power transmission system includes a converter station having an active and a passive converter connected in series between an active and a passive pole line via a first neutral bus, a metallic return transfer switch in an electrode line, a ground return transfer switch in a current redirecting path between the passive pole line and the neutral bus and a control unit which in case of change to the passive pole line for providing a return current path is configured to, upon control of power related to the active converter from steady-state to zero, close the ground return transfer switch and thereafter open the metallic return transfer switch, whereupon power related to the active converter may be controlled back to steady state.