Sun, L.; Liu, H., and Bian, D., 2019. Influence factors of stability on offshore HVDC transmission systems. In: Guido-Aldana, P.A. and Mulahasan, S. (eds.), Advances in Water Resources and Exploration. Journal of Coastal Research, Special Issue No. 93, pp. 561–571. Coconut Creek (Florida), ISSN 0749-0208.

Offshore wind energy has been recognized as one of the most promising renewable energy resources available. High-voltage direct current (HVDC) appears to be the most viable option for solving the transmission of the large amount of energy over long distances of the integration of offshore wind farms. However, HVDC with large capacity is continually being commissioned, the coupling and interaction between the sending-side and receiving-side AC systems interconnected by large-scale DC links are becoming significant. Power impacts caused by DC commutation failures (CFs) may lead to power fluctuation on two-area interconnected power system. If the DC capacity is large enough, the stability of power system may be threatened. In this paper, using equal area rule, the stability limit of DC transmission capacity is analyzed. In addition, based on the power system three-stage power allocation theory after power impacts, the power fluctuation of the two-area AC/DC parallel transmission system caused by CFs was represented as the impulse response of a two-order linear system model. The key factors affecting the stability limit are furtherly discussed. Then the results are verified using advanced digital power system simulator (ADPSS) for the two-area IEEE-39 network model for AC/DC parallel transmission. Finally, the control measures for improving the stability of AC/DC parallel transmission system were put forward.