Study Of Power System CCT Based On Trajectory Sensitivity Analysis

Critical clearing time (CCT) is one of the most important stable indices in power system transient stability analysis. The existing calculation methods have some disadvantages, which can't satisfy the need of the dynamical secure control and system transient stability analysis. So, it's necessary to develop more effective CCT-calculating method, which will play an important role in improving power system stability, and provide possibility in realization of online control. Thorough study has been done to solve the problems. A fast CCT calculative method was suggested which could satisfy the precision need, the method was applied in the preventive control of the generator outputs. The main contents are given as following:Firstly, the existing sensitive analysis is analyzed in detail, and the thought of applying the trajectory sensitivity in transient stability analysis and dynamical security control is proposed. The trajectory sensitivity can overcome the shortages of the traditional sensitive methods, easily consider the discrete point appearing condition in the system trajectory, and hold high precision, which is fitful for the research of the transient stable analysis.Secondly, after analyzing the advantages & faults of time-domain simulation and the direct methods, this paper points out the key of developing the transient stable methods is the integration of both. The CCT-calculating method is presented which is based on the trajectory sensitivity and the hybrid method. And the time-domain simulation program has been programmed. The way proposed in the thesis has many advantages such as fast calculation speed, high calculation precision and promising online application. Thirdly, The contingency screening is classified as security and insecurity; only the insecure contingency needs detailed analysis and corresponding preventive control measures. After considering the localization of the traditional classified method, the paper proposes a screening method that the contingencies are sorted into three types: security, insecurity and the status between the two conditions, which is fit for preventive control. So the preventive control can be realized easily.Finally, A method that can accomplish the generation rescheduling preventive control is presented. Compared with other traditional calculative methods, the method in this thesis is simple, has fast calculation speed and can satisfy the need of on-line preventive control...