The DC voltage droop control strategy of VSC-MTDC system can ensure proper distribution according to the converter ratings.However,it does not consider the actual loading condition.In order to solve this defect,a novel scheme for appropriate power sharing taking into account the available headroom of each converter station was proposed,and possible overloading was avoided.The margin droop control strategy was introduced in the active-power controller to ensure the stability of DC voltage.Transient simulations in PSCAD/EMTDC showed that the converters which are already operating close to the limits would try to share less burden of the loss to the extent of the other converters with higher spare capacity or headroom and thus the unbalanced power would be appropriate assigned.
