Research on Electromechanical Transient Equivalent Modeling of MMC-HVDC Connected to Passive Network

In this paper, electromechanical transient models of MMC-HVDC connected to passive network are analyzed. Comparisons between voltage and current source equivalent models are carried out. First, the complex dynamic process inside converter is ignored and converter control loops are retained, establishing the voltage source equivalent model. Afterwards, the dynamic process of inner loop controller is simplified, establishing the current source equivalent model. Compared with the MMC-HVDC electromagnetic transient model under different operating conditions, the validity of electromechanical transient models under different disturbance are verified. For small disturbance analysis, both voltage source model and current source model are applicable. For large disturbance analysis, simulation results of voltage source model are more consistent with those of electromagnetic transient model.