Study On Predictive Control And Fault Tolerant Control Methods Of Hydro-turbine Governing System

The hydro-turbine governing system?HTGS?is a complex nonlinear system with multiple input,multiple output,time-varying and non-minimum phase,which is consisted of hydroelectric generating set,penstock system,excitation system and control system.The HTGS as an important intelligent equipment for hydroelectric generating units,where undertakes vital tasks such as start-up and shut-down unit,grid connection,phase modulation,sudden load increase and decrease,and weight-loaded close down.When it's running in high load,high disturbance and high random for a long time,the system's actuators,sensors and components will inevitably occur mechanical faults.The intercoupling and interaction between them can cause a great impact on the unit stable operation and the maintenance of grid frequency stability.Therefore,in this paper,intelligent predictive control algorithm and fault-tolerant control algorithm have been introduced to predict the operating state of the nonlinear HTGS.Then,based on online fault detection and diagnosis technology,the system's faults are estimated and controlled.The contacts and conclusions of this paper mainly include the following three aspects:?1?State feedback predictive control based on T-S fuzzy model.To accurately track and predict the states of the turbine governing system,this section proposes state feedback predictive control under the T-S fuzzy model.First,the six-dimensional model of hydro-turbine governing system is selected as the research object,and the discrete mathematical model of HTGS is established based on T-S fuzzy rule.Combined with Lyapunov function stability and Schur matrix complement theorem,the closed-loop control system can achieve the globally asymptotically stable state.Considering the influence of external disturbance and system parameters,the anti-interference and tracking performance of closed-loop control system is investigated.The control performance of the proposed predictive control algorithm is compared with PID control algorithm and model predictive control algorithm.The simulation test shows that the state feedback predictive control can guarantee that the system states reach the steady state within 3.5s.Compared with the model predictive control,the adjustment time is shortened by 25%.Therefore,the proposed control algorithm provides a good control quality for the closed-loop control system with short settling time and small fluctuation range.?2?Output feedback fault-tolerant control of hydro-turbine governing system.To monitor and control the mechanical faults of the turbine governing system,this section proposes an observer-based output feedback fault-tolerant control algorithm.First,considering the delay effect of servomotor in HTGS,the dynamic mathematical model of nonlinear HTGS with state delay is established.An adaptive fault diagnosis observer is proposed to diagnose and detect the mechanical faults of the nonlinear HTGS online.Moreover,a dynamic adaptive output feedback fault tolerant controller is designed.Combined with Lyapunov stability theory,the closed-loop control system can achieve the global asymptotic stability.Finally,Numerical simulation experiments verify that the observer-based output feedback fault-tolerant control algorithm can quickly stabilize the system state within 2s,and accurately track and control the system faults.?3?Sliding mode backstepping fault tolerant control of hydro-turbine governing system.To solve the failure problems of turbine governing system actuator bias-gain faults and dead zone input,this section proposes a nonlinear disturbance observer-based fault-tolerant control algorithm.Considering the influence of unknown random disturbance on HTGS,a nonlinear disturbance observer is proposed for on-line estimation and identification of external disturbance.The virtual controllers are designed and the backstepping sliding mode fault tolerant control algorithm is proposed Based on the backstepping control and sliding mode control algorithm.According to the Lyapunov function stability theorem,the global asymptotic stability of the closed-loop control system is realized.To verify the robustness and anti-interference ability of the proposed control algorithm,the time-varying bias-gain faults,the time-invariant bias-gain faults and the dead-zone input faults are considered.The control performance of the proposed control algorithm is compared with the existing fault-tolerant control algorithm.The experimental results show that the control error of the proposed fault-tolerant controller is about 10^-5,which can provide a fault-tolerant control performance with small tracking error,fast response and small fluctuation amplitude,and provide certain engineering value for the safe maintenance of the actual hydropower station.