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The number and locations of transmission lines that are likely to get simultaneously congested are useful information for analysis of power market. In this paper, we present a study that demonstrates the number of simultaneously congested transmission lines is very limited, as well as an algorithm for identifying a small set of transmission lines that may become simultaneously congested based on the current states of the system and market. To this end, we first investigate the maximum number of simultaneously congested lines. Then, a novel algorithm is developed to identify a smaller set using two scientific criteria – one is concerned with the absolute impact of generation dispatch decisions, and the other, the relative sensitivities of line flows with respect to the changes of generation outputs. The effectiveness of the proposed algorithm is demonstrated through two simulation studies, one based on IEEE 39-bus for illustration of concepts, and the other based on a large-scale, real-world power system for showing the practical application and significance of results. [ABSTRACT FROM AUTHOR]

In this paper, we introduce an approach for a fast assessment of the dynamic characteristics of system frequency during the period of cold load pickup following a large-scale blackout. The approach is developed based on a load model and a model of generation control system: the load model considers the unique time-dependent characteristic of inrush power surges during the period of cold load pickup, while the model of generation control system mimics the characteristics of various governors that are crucial to the determination of the key variables including initial rate of frequency change, frequency nadir and settling frequency. With the proposed linearization and estimation methods, the model of generation control system can be quickly constructed to offer a great amount of flexibility and simplicity for the study of the impact of cold load on frequency response. The proposed approach allows system operators to quickly evaluate many different options for system restoration. The application of the proposed approach is demonstrated in a case study based on the IEEE 39-bus system. The differences between the results obtained using the proposed approach and those obtained from complete PSS/E simulation are very small, which suggests that the linearized model of generation control system is fast, and accurate enough to address the major concerns of cold load pickup in system restoration. [ABSTRACT FROM PUBLISHER]

Many important issues of power system dynamics are often studied by looking at the dynamic responses of generators connected through the power grid, taking their interactions into consideration. In this paper, we present a specific study on the significant impact of grid structure on the power system dynamics with quantitative evidence. Specifically, it is found that the impact of grid structure heavily depends on two types of grid-structure-related variables: 1) electrical distances among the generator internal buses, and 2) electrical distances between the generator internal buses and the faulted bus. Furthermore, with the examples of coherency identification problem, the significance of grid structure is demonstrated by the strong agreement of identification results between using a set of criteria that only takes into account the grid-structure-related variables and dynamic simulations. [ABSTRACT FROM PUBLISHER]