New methods for computing power system dynamic response for real-time transient stability prediction

Using new systems capable of making synchronized phasor measurements, the r eal-time stability assessment of a transient event in power systems has bec ome an important area of investigation. Using these phasor measurements as input conditions for computing a relatively good, simplified dynamic model can yield accurate and real-time transient stability prediction in a centra l location equipped with high-speed computers. In an effort to reduce the c omputing time for integrating the differential/aAlgebraic equation (DAE) mo del of postfault power system dynamics for prediction use, this paper prese nts a faster Implicitly Decoupled PQ Integration technique. Two piecewise d ynamic equivalents are also proposed, i.e., piecewise constant current load equivalent and piecewise constant transfer admittance equivalent. These eq uivalents can eliminate the algebraic equations by approximating the load f low solution piecewisely such that only internal generator buses are preser ved, while approximately retaining the characteristics of the nonlinear loa ds. The proposed techniques have been tested on two sample power systems wi th promising simulation results.