Comparative stability analysis of LCC, MMC and dualinfeed HVDC operating with weak AC network

This paper comparatively analyses small signal stability of the LCC, MMC and the dual-infeed HVDC system considering north French AC grid. It investigates the minimum AC grid strength at which each of the three topologies can provide stable operation and have well damped dynamic performance. This is investigated by observing root locus of the dominant eigenvalues for different HVDC loading. The obtained results show that the MMC HVDC can operate at the lowest SCC (Short Circuit Capacity). The LCC HVDC can operate with weaker AC systems if the nearby MMC is operating as STATCOM. Further study with the dual-infeed system conclude that MMC controlling AC voltage is more beneficial compared to reactive power control. The results are obtained using eigenvalue study on analytical small signal models, and they are confirmed on detailed EMTP models.