Impact of high penetration of renewable resources on power system transient stability

Environmental concerns and technology development are driving power systems to a new stage where the increased penetration of renewable energy resources (RES) is replacing the conventional fossil fuel-based power plants. This transition brings the sustainable and ecological credentials but at the same time involves the major challenge of low-inertia systems, unfamiliar dynamics of electronics-interfaced generations as well as their regulation and interaction with the rest of the system. In this paper, by virtue of graph theory, cutset properties are explored and applied to transient stability analysis in high RES penetrated power systems. First, the relationship of transient stability and the critical cutsets are studied and explained theoretically. Second, two indexes, i.e., Cutset index (CI) and Improved cutset index (ICI), are investigated and compared for identifying the vulnerable cutset as well as estimating the critical energy for determining stability region. Different RES penetration levels are explored from 0 to 100% with different network size, topology and dynamics. Numerical studies are conducted on large-scale IEEE test systems as well as nine open-source synthetic transmission systems. Simulation results show that the increased penetration of RES can affect system stability and the specific influence depends on the penetration levels, system structures and the RES replacement.