In view of three-phase unbalance of the grounding current at the sheath of submarine and land cable transition joint

a 220 kV submarine and land cable hybrid line is taken as an example to study the reason of the three-phase unbalance of grounding current at the sheath of transition joint. It is found through theoretical analysis

simulation calculation and experimental verification that the arrangement and grounding mode of the return cable are the main reasons for the three-phase unbalance of grounding current of the sheath. According to the research results

the modification scheme of the return cable arrangement and grounding mode are proposed to effectively solve the three-phase unbalance of grounding current in sheath of the transition joint and ensure safe and stable operation of the sub-marine and land cables.