Investigation on Probabilistic Small-Signal Stability of Power Systems as Affected by Offshore Wind Generation

This paper investigates the impact of the complementarity, connection technology and network control strategy of offshore wind generation on the probabilistic small-signal stability of power systems. The cumulant-based theory is firstly applied to assess the variances of both the complementarity of combined wind power and the probabilistic small-signal stability of power systems. These variances are later employed as two indices to explain how the different complementarity levels, connection topologies and DC network control schemes of offshore wind generation affects the probabilistic distribution of critical eigenvalue and thus the probabilistic small-signal stability. In the paper, an example of 16-machine 5-area power system with three grid-connected offshore wind farms is presented. The index of probabilistic small-signal stability is computed and then compared under two complementarity conditions, two typical HVDC transmission systems through which the offshore wind farms are connected, and two DC grid control schemes, respectively. It is demonstrated that complementarity can effectively enhance probabilistic stability and multi-terminal HVDC may have either beneficial or detrimental impact on small-signal stability depending on the control pattern and setting when compared with point-to-point topology.