Study On The Security And Stability Analysis Of Power Systems And The Software Design

Power system security and stability analysis is necessary to the security and stability operation of power systems. With the growth and development of electrical networks, the security and stability analysis gets more and more complex and difficult. This dissertation aims to find out comprehensive and practical approaches for stability analysis and security assessment.First of all, the basic concepts of security and stability are explained. And the features of time-domain simulation and direct methods for transient stability analysis are discussed. Compared with the Chinese "Guide on security and stability for power system", the conventional analysis method is difficult to meet the requirements of comprehensiveness and effectiveness. Therefore, the new ideas and analysis approaches are proposed to solve this problem. The concept of stability margin, a factor of critical importance in security assessment, is induced into time-domain simulation method. Then extended software with the core of existing simulation program is designed, which can help analysts automatically scan predefined contingencies for the whole system, and useful information for security assessment is abstracted according to stability margins. The system security is assessed in two steps: N-1 contingency and multiple-fault contingency, whose relationship should be fully taken into account. At last, the analysis work is focused on the change of system stability with the variation of different operational parameters.According to the above ideas and approaches, the security and stability analysis software is developed. Based on a real-world power system in China, the simulations are carried out by this software and then analysis approach is demonstrated. After the system security is assessed, feasible stability control measures are investigated. It is shown that the proposed methodology is reliable, comprehensive and practical. It is significantly effective for the security and stability analysis of large-scale power systems.