Study On Simulation And Controller Of Extra-Low Frequency Oscillation Of Turbine Governor

With the continuous development of water turbine governing system,the impact of speed regulation system on low frequency oscillation of power grid has attracted more and more attention.Through theoretical analysis,control system will not only affect the damping characteristic of low frequency oscillation in power grid,but also to the grid injection ratio of ultra low frequency oscillation modes of low frequency oscillation frequency is lower,it often appears in the control system of the action,a serious threat to the safe and stable operation of power grid.Turbine speed control parameters in the actual system,usually through the step response,impulse response and other experimental methods,and combined with the curve fitting method,the model parameters often have some errors,so the parameter uncertainty.On the other hand,the hydraulic turbine speed regulating system is a typical non minimum phase system,and the design principle of the damping controller can not use the conventional methods such as lead lag compensation.In this paper,the simulation analysis and controller design of ultra-low frequency oscillation of hydraulic turbine governing system are mainly studied.In this paper,the small signal stability analysis theory is briefly introduced,mainly introduces the theory and method of small signal stability analysis and steps are performed on a single machine infinite bus system and multi machine system is analyzed,the mathematical model is built and the power system is mainly composed of sub modules.The 7 type hydraulic turbine speed control system as an example,through the torque analysis theory,the influence of hydraulic turbine governing system in the low frequency oscillation of power system damping is analyzed in detail,and in Matlab/Simulink software,respectively to verify the 7 type turbine speed control system,6 type turbine speed control system and PID hydraulic turbine governing system,and the simulation results are analyzed and compared.Through the analysis of the simulation results also demonstrate the power system low frequency oscillation is due to the governor parameters multi units(change),unreasonable and the interaction between them,which makes the system damping ratio caused by a serious decline,but only one machine governor parameters change does not make the system of ultra low frequency oscillation.Describes the theoretical basis and related lemmas of linear matrix inequalities,for the typical design of robust non minimum phase system of water turbine governing system controller,increase the damping ratio of the system and make the system stable performance can be improved,and the system has good dynamic performance and robust performance.