Quick-Switch Adaptive Droop Control of MMC-MTDC for Large-Scale Renewable Energy Integration

According to the high curtailment rate of wind and solar power in northwest of China and the low efficiency of power delivery line, a quick-switch adaptive droop control strategy was proposed for large-scale renewable energy integration by MMC-MTDC (Modular Multi-level Converter based Multi-terminal HVDC). By means of constructing a unified control mode of MMC, the control mode of MMC can be switched quickly and seamlessly. Then, improved adaptive droop control was proposed by using the factor of power margin to optimize the performance of DC system in different conditions. Finally, the simulation of five terminal MTDC with wind and solar power was processed with PSCAD/EMTDC. The simulation results showed that the proposed control strategy is suitable for the condition that power flow changes frequently and is conducive to integration and consumption of renewable energy.