An Improved Multi-Infeed Interaction Factor Calculation Method Considering Reactive Power and Voltage Interactions

Pre-assessing the risk of simultaneous commutation failure (CF) in multi-infeed HVDC systems is of great significance for ensuring the safe operation of the power systems. The existing research methods mainly rely on simulations, and the influence of reactive power and voltage on the CF was ignored. To handle this problem, based on the multi-infeed interaction factor (MIIF), the concept of the converter bus voltage drop ratio is proposed in this paper. Firstly, the reactive power transfer mechanism between the AC and DC systems, and the coupling impedances of the two converter buses at the inverter side are analyzed. Then, an offline calculation method for MIIF that takes into account the interactions between reactive power and voltage is proposed. Furthermore, based on the criterion of the minimum extinction angle, the critical simultaneous CF factor is defined, and a comprehensive risk assessment method for simultaneous CF in multi-infeed HVDC systems is proposed. Finally, based on the PSCAD/EMTDC, the simulation results have verified the validity and correctness of the method in this paper.