Linear Models of the VSC-MTDC Systems with the Droop Controls for Power Flow Analysis

The DC droop control would introduce nonlinearities to the power flow analysis of hybrid AC and DC systems, making the calculation and optimization of such complex hybrid systems more intractable. To tackle this issue, we propose a technique to linearize the voltage source converter based multi-terminal DC (VSC-MTDC) system model with different droop controls (e.g., voltage-power and voltage-current droop controls). The novel linear DC system models could be easily embedded into the unified power flow analysis of the hybrid AC and DC systems. Based on this, we furthermore describe a linear power flow model for the hybrid AC and DC systems with droop control, which is much easier to be solved due to the linear nature. Finally, the accuracy of the proposed linear power flow model is verified on several hybrid AC and DC systems with different sizes.