Trajectory Sensitivity Based Power System Dynamic Security Assessment

Contemporary methods for dynamic security assessment (DSA) mainly rely on time domain simulations to explore the influence of large disturbances in a power system. These methods are computationally intensive especially when the system operating point changes continually. The trajectory sensitivity method, when implemented and utilized as a complement to the existing DSA time domain simulation routine, can provide valuable insights into the system variation in response to system parameter changes.;The implementation of the trajectory sensitivity analysis is based on an open source power system analysis toolbox called PSAT. Eight categories of sensitivity elements have been implemented and tested. The accuracy assessment of the implementation demonstrates the validity of both the theory and the implementation.;The computational burden introduced by the additional sensitivity equations is relieved by two innovative methods: one is by employing a cluster to perform the sensitivity calculations in parallel; the other one is by developing a modified very dishonest Newton method in conjunction with the latest sparse matrix processing technology.;The relation between the linear approximation accuracy and the perturbation size is also studied numerically. It is found that there is a fixed connection between the linear approximation accuracy and the perturbation size. Therefore this finding can serve as a general application guide to evaluate the accuracy of the linear approximation.;The applicability of the trajectory sensitivity approach to a large realistic network has been demonstrated in detail. This research work applies the trajectory sensitivity analysis method to the Western Electricity Coordinating Council (WECC) system. Several typical power system dynamic security problems, including the transient angle stability problem, the voltage stability problem considering load modeling uncertainty and the transient stability constrained interface real power flow limit calculation, have been addressed. Besides, a method based on the trajectory sensitivity approach and the model predictive control has been developed for determination of under frequency load shedding strategy for real time stability assessment. These applications have shown the great efficacy and accuracy of the trajectory sensitivity method in handling these traditional power system stability problems.