Voltage balancing strategy of series-connected valve groups in the process of single valve group online entrying in hybrid multi-terminal UHVDC transmission system
Combined with the process of single valve online entrying in LCC-MMC hybrid multi-terminal transmission system, the mechanism of voltage imbalance among series valve groups is analyzed, and then a voltage balance strategy based on correcting the voltage deviation is proposed. This strategy corrects the voltage deviation of the high and low valves by introducing a function whose decreasing rate is the same as that of the boost rate of the input valve group .Based on the PSCAD/EMTDC simulation platform, a model of the UHV three-terminal hybrid DC transmission system was built, and the effectiveness of the strategy was verified by comparing the impact of the removal/input strategy on the dynamic characteristics of the system.