Enhancing Small-Signal Stability of Intermittent Hybrid Distributed Generations

The variability of large-scale photovoltaic/wind hybrid distributed generation power integrated into the distribution system causes persistent system oscillations. The oscillations result in serious small-signal stability issues when these distributed generation units are not adequately optimised and the network dynamic variables are unconstrained as seen in the existing renewable power allocation planning works. In this paper, planning and design of optimal allocation (sizing, placement) and timing of intermittent renewable energy hybrid distributed generations such as photovoltaic and wind is being investigated with the ultimate goal of maximising the renewable power generated and absorbed into the distribution network within the required small-signal stability level at a minimum net present value of total cost. The problem is formulated as a stochastic mixed integer linear program where variables related to small-signal stability are constrained. The paper also evaluated the impact of these renewable generation output power variability on the small-signal stability of the IEEE-24 bus test system using eigenvalues analysis. The results indicate a profound improvement on the small-signal stability of the network, an increase in the quantity of renewable power absorbed and a significant reduction in the costs of emissions and electricity.