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

Using new systems capable of making synchronized phasor measurements, the real-time stability assessment of a transient event in power systems has become 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 central location equipped with high-speed computers. In an effort to reduce the computing time for integrating the differential/algebraic equation (DAE) model of postfault power system dynamics for prediction use, this paper presents a faster implicitly decoupled PQ integration technique. Two piecewise dynamic equivalents are also proposed, i.e., piecewise constant current load equivalent and piecewise constant transfer admittance equivalent. These equivalents can eliminate the algebraic equations by approximating the load flow solution piecewisely such that only internal generator buses are preserved, while approximately retaining the characteristics of the nonlinear loads. The proposed techniques have been tested on two sample power systems with promising simulation results.