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Determining contingency aware dispatch decisions by solving a security-constrained optimal power flow (SCOPF) is challenging for real-world power systems, as the high problem dimensionality often leads to impractical computational requirements. This problem becomes more severe when the SCOPF has to be solved not only for a single instance, but for multiple periods, e.g. in the context of electricity market analyses. This paper proposes an algorithm that identifies the minimal set of constraints that exactly define the space of feasible nodal injections for a given network and contingency scenarios. By internalizing the technical limits of the nodal injections and enforcing a minimal worst-case impact of contingencies to line flows, computational effort can be further improved. The case study applies and analyzes the methods on the IEEE 118 and A&M 2000 bus systems, as well as the German and European transmission systems. In all tested cases the proposed algorithm identifies at least 95% of the network and security constraints as redundant, leading to significant SCOPF solve time reductions. Scalability and practical implementation are explicitly discussed. The code and input data of the case study is published supplementary to the paper under an open-source license. [ABSTRACT FROM AUTHOR]

Assessing the performance of transit systems operating under different regulatory regimes is a topic of considerable interest in the literature. The goal of this paper is to investigate the performance characteristics and factors affecting this performance for European transit systems operating in vastly different regulatory environments. The initial results of data envelopment analysis application indicate that privately operated systems tend to be more efficient while publicly operated systems tend to be more effective; transport operators in cities where open entry form of competition has been introduced were found to perform both efficiently and effectively. Further, as the Tobit regressions focused on the effect of ownership indicate, most systems in the sample demonstrate a positive trend in both efficiency and effectiveness, a finding with important practical implications for financially strained systems. [ABSTRACT FROM AUTHOR]