Decision-Making Support Method for Control Strategies of Hybrid Cascaded MTDC System

For large scale renewable energy integration, the appliance of hybrid cascaded HVDC transmission technology has become a development trend in the future DC power grid, which combines the advantages of LCC-HVDC such as high capacity and low cost, as well as the advantages of VSC-HVDC such as flexible power control and passive power supply. At present, hybrid cascaded HVDC transmission technology has been adopted in the Baihetan and Wudongde DC transmission projects, with advantages verified. However, for the simultaneous application of different converter station technologies in the system, the control mechanism of the system becomes complex, and there will be an exponential growth trend in the number of control strategy combinations for multiple converter stations. In the actual power system operation control, it is difficult for dispatchers to analyze the operation mechanism and select the feasible ones from many control strategy combinations according to the demand, which brings decision difficulties to dispatchers. Therefore, this paper presents a decision-making support method for control strategies of hybrid cascaded MTDC system, which analyses the system operation status based on scheduling requirements and provides reasonable control modes and corresponding command values for different converter stations. Simulation results based on PSCAD/EMTDC verify the effectiveness of the proposed method.