Coordinated optimization against parallel flows in multi-infeed HVDC system

With rapid development of UHV AC and DC transmission systems, the problem of parallel flows emerges in many multi-infeed HVDC receiving-end systems in China. In this paper, an optimization method which coordinates parallel flows and stability of multi-infeed HVDC system is present. An analytical equivalent of multi-infeed short circuit ratio (MISCR) is defined based on power flow model, which considers the impact of DC system control modes. An impact factor is defined to assess the degree of the influence of the operation of opening a chosen network branch on MISCR. Considering this impact factor, an improved GN algorithm is proposed to partition the lower-voltage power network, which produces a set of partition schemes. A comprehensive evaluation factor is defined to find the optimal partition scheme which has the best partition effect and the minimum harm on stability of multi-infeed HVDC system. A case study of an actual regional power system in China validates the superiority of the method present in this paper.