Research On Linear Optimal Excitation System For 1000MW Hydro-generator

With expansion of power network, increasing of votagle level and operation of large capacity generators, it is especially important that how to maintain the operation of power system stable and reliable. Excitation system of synchronous generator plays an import role in preserving power system's stability and reliability, therefore, improving control performance of excitation system is considered to be the most effective and economic measures in improving stability of generator and power system.In this paper, first of all, bus-fed excitation methord is introduced, and the advantage and disadvantage of bus-fed exciation metherd applied in hydro-generator are discussed in deteal. Then main circuit of excitation system is designed and the parameters are calculated, such as line current, line votage, power on alternating current side and control angle of three phase bridge rectifier. On the basis of design and calculation, ratio and capacity of excitation transformer are calculated, the widely used de-excitation protection of excitation system is configured, and the most widely used de-excitation methord-combination of linear resistance and inverter de-excitation in hydro-generator is evaluated by de-excitation time.Sencondly, the fundamental assumption of single machine-infinite bus system is proposed, and the mathematical model of excitation power unit is established. Based on optimal control theory and linear quadratic form optimal control, according to synchronous generator's seven order Park equation, the system is simplified reasonable and the three order state equation control model of linear optimal excitatiuon controller is established, and then linear optimal excitation controller for 1000MW hydor-generator is designed.Finally, single machine-infinite bus system with linear optimal excitation controller is constructed and simulated. After debugging simulation model, the correctness of excitation system parameters and effect when excitation system maintains terminal votage stability are proved. The control effects of PID, PID+PSS and linear optimal control methords are cross compared, which proving references for the design and selection of huge hydro-generator's excitation system.