Browsing by Author "DeMarco, Christopher L."

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    A vector energy function approach for security analysis of AC/DC systems
    (Institute of Electrical and Electronics Engineers (IEEE), 2002-08-06) DeMarco, Christopher L.; Canizares, Claudio A.
    The authors examine dynamic behavior in system models that reflect reasonably detailed third-order high-voltage DC (HVDC) dynamics along with AC system models that include reactive flows, and frequency and voltage-dependent load models. A vector Lyapunov function approach is used to define a system-wide energy function that can be used for general security analysis. They describe the derivation of individual component Lyapunov functions for simplified models of HVDC links connected to infinitely strong AC systems, along with a standard AC only system Lyapunov function. A novel method of obtaining weighting coefficients to sum these components for the overall system energy function is proposed. Use of the new energy function for transient stability and security analysis was illustrated in a test system.
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    Point of collapse methods applied to AC/DC power systems
    (Institute of Electrical and Electronics Engineers (IEEE), 2002-08-06) Canizares, Claudio A.; Alvarado, Fernando L.; DeMarco, Christopher L.; Dobson, I.an; Long, Willis F.
    The authors describe an extension of the point of collapse method developed for studies of AC systems to the determination of saddle-node bifurcations in power systems including high voltage direct current (HVDC) transmission. Bus voltage profiles are illustrated for an AC/DC test system. They significantly differ from the profiles of pure AC systems for typical system models. In particular, voltage dependent current order limits are shown to affect the voltage profiles and the loadability margin of the system. It is also shown that Hopf bifurcations, which are possible in purely AC lossless systems with second-order generator models, become plausible when the dynamics for the HVDC system are included.