Research On Stray Current Corrosion Of Jacket Caused By HVDC-flexible

HVDC-flexible doesn't depend on line to commutate and doesn't need reactive power compensation, so it can supply passive system and needs less space. It is fit for supplying passive system on the jacket where space is valuable. However, when voltage source converter fault, cable disconnection fault, cable grounding fault, or transmitting electricity after cable insulation breakdown occurs, there will be stray current in seawater which causes stray current corrosion of jacket. In order to research on stray current's effect on jacket as well as its cathodic protection system, stray current path is analyzed, then research conditions are obtained. For jacket without cathodic protection, protected by impressed current, or protected by sacrificial anodes, experiments are done in the conditions that jacket discharges stray current, stray current flows into jacket, jacket lies in the path of stray current and jacket lies out of the path of stray current in the sea. For steel plate protected by sacrificial anode, laboratory experiments are done in the conditions that steel plate discharges constant and pulse stray current.According to experiment results, stray current's effect on jacket without protection, protected by impressed current or sacrificial anodes, as well as sacrificial anodes is obtained, current density index which is used to determine whether stray current corrosion exists is proposed, stray current's effect on jacket in different conditions is compared. When impressed current is uniform on the jacket, impressed current can be adjusted to be against stray current corrosion.