Optimal DC-Segmentation for Multi-Infeed HVDC Systems Based on Stability Performance

摘要

This paper analyzes the optimal problems of dc-segmentation for multi-infeed HVDC systems based on stability performance and studies the selecting method for the optimal dc-segmentation scheme. First, three major stability problems of multi-infeed HVDC systems are pointed out, which implies the necessity of the optimization for dc-segmentation. Second, three typical evaluation indices which correspond to the above three stability problems are introduced: multi-infeed interaction factor, multi-infeed effective short-circuit ratio, and frequency bias factor. To improve evaluation effects of the typical indices, the subindices are presented. Third, in order to solve this multi-objective decision-making problem, a linear weighted sum model is built, and a comprehensive weight method is adopted to calculate the weight coefficients. Based on the stability problems, a selecting method is established to choose the optimal dc-segmentation scheme. Finally, a four-machine multi-infeed HVDC system and a practical multi-infeed HVDC system in China are taken as examples, respectively. Candidate dc-segmentation schemes of each system are evaluated by the proposed method, and the optimal one is selected. Detailed stability studies of the candidate schemes are executed. The result indicates that the stability of the optimal scheme is better than the stabilities of others, which verifies the validity of the proposed method.