Power System Stability Simulation Study In The Power Transmission From The West To The East

With the implementation of "Power transmission from the Western China to the Eastern China and nation-wide interconnection" stratagem, a super-large-scale AC/DC hybrid power system featured with huge capacity generators, extra high voltage and long-distance transmission is coming into being in China. This brings great challenges to the power system security and stability. This thesis concentrates its attention on two problems - the stability analysis of the coordination of the relay protection and automatic devices, and the probability of self-excitation in South China Power System through time domain simulation.Digital simulation has proved to be an effective tool for the research, planning and operation of the power system. The thesis first introduces the status of power system simulation technologies and discusses the development of power system simulation software. The functions of the transient simulation software packages widely used in China are described in detail.Secondly, after the introduction of the power system stability theories, the thesis analyzes the content of the transient stability calculation and brings forward the criterion to judge the stability of the power system. The correct selection of the power system component model and parameters is the basis of the power system simulation. The thesis points out the differences of the models and the conversion of the parameters between several transient simulation software packages and introduces the method for the users to define their own models.According to "Power System Security and Stability Guide", the stability capability of Northwest China power network in the stability criterion Level 1 and 2 is verified, and the interaction between 750kV and 330kV power loop networks is investigated. Furthermore, the configuration and performance of relay protection and security automatic equipments that satisfy the demands of safe operation of Northwest 750kV power system are decided.The conditions of power system self-excitation and the influence of the automatic voltage regulator on the self-excitation are studied, and the system response characteristics of power system in the case of self-excitation are investigated. A criterion to judge the occurrence of power system self-excitation is proposed. The criterion counts on the time domain observation of the bus voltages, the rotor speed and the excitation current responses. The effectiveness of the proposed criterion is verified by the simulation results of a typical two-machine power system. Finally, the possibility of the self-excitation's potential existence in the South China Power System under two typical operation conditions in the year 2005 is tested with the proposed criterion.