Simulation Of Bus Fed Static Excitation System For 1000mw Hydro-generator

The power network in China is proceeding at the direction of maximization recently. Small signal stability, low-frequency oscillation, system faults as well as other problems are seriously increased due to the extensive use of large capacity generators. The problems in improving power system stability and reliability of power system are particularly prominent. Excitation system of synchronous generator plays a crucial role in improving power system stability and reliability. Improving control performance of a generator excitation system is considered to be the most effective and most economic measures in improving the generator stability.At present, bus fed static excitation mode is widely adopted in excitation system of large and middle generators. Firstly, in this paper the advantages and disadvantages of bus fed static excitation mode are discussed in detail, and the main circuit parameters of bus fed static excitation system for 1000MW hydro-generator are calculated, including calculation of excitation transformer capacity, selection of rectification circuit SCR, calculation of short circuit current when SCR fault occurs and deexcitation time.Secondly, the mathematical model of bus fed static excitation system is established. PID excitation control mode is described, and the setting methods of PID parameters are given.Thirdly, the simplified model (Heffron-Philips) of lower frequency oscillation in power system is analyzed. According to the model, the physical mechanism of negative damping is analyzed, and the simulation model of power system stabilizer is established. With inputting the deviations of speed and power, the power system stabilizers are analyzed.Finally, the simulation model of single machine infinite bus system is established with MATLAB/Simulink. By the simulation analysis of small disturbance and three phase earthing short circuit fault for the model, the selections of excitation system parameters are justified, thus the basis for the application of bus fed static excitation system in 1000MW hydro-generator is provided.