Research On Time-delay Stability Of Power System In Large Scale

With the rapid development of the interconnected power system in China, power system stability has been drawn more and more attention. As a matter of fact, it is the trend to control and manage power grid with the help of wide area measurement system(WAMS). However, large-scale time-delay which is caused by the signal transmission in WAMS can exert innegligible influence on power system stability. In this thesis, stability analysis on power system with time delays are deeply studied. Main work of this thesis is as following:The mathematical models of power system with time delay are discussed, and the criterion of the small-signal stability is given. Algorithm to solve the differential- algebraic equation(DAE) is given in order to simulate the power system with time delays in the time domain. To avoid the infinite recursion in Runge-Kutta method, a novel method based on interpolation process is given to obtain the past status. An efficient method based on 4-point interpolation is introduced to acquire the root trace of an dynamic system with time-delay. The odd features of the root trace such as the Archimedes helix are discovered as well.A simplified method is introduced to obtain the stability region and its boundary in laege-scale time-delay. This method tracks the eigenvalue traces of a complex matrix to obtain the system stability region and its boundary with large-scale time-delay efficiently.A typical time-delayed system and WSCC 3g9n system are employed to do some validating studies. Besides the stability region and the root trace, some non-linear features of time-delayed systems are discovered as well, for example, the oval relationship between the rotor angel and the transient voltage, and the dynamic behavior which is very similar to chaos.