多端直流输电工程大地-金属回线转换策略OA

In view of the problem that the metallic return transfer break(MRTB)protection acts in the process of ground-metallic return conversion at different power levels in the first conventional multi-terminal high voltage DC transmission system in China,which leads to switch rejection and ground-metallic return conversion failure,this paper analyzes the current loop in the process of ground-metallic return conversion.The mathematical expressions of each converter station current are deduced when earth and metal loop coexist.On the basis of these expressions,the reason of MRTB operation failure is obtained and the improvement strategies and operation suggestions are proposed to provide a reference for engineering design and operation maintenance.Finally,the correctness of the analysis conclusion is verified by the simulation,which shows that the proposed strategies has the engineering application promotion value.