This paper investigates the stability of the Francis hydro-turbine governing system with complex penstocks in the grid-connected mode. Firstly, a novel fractional-order nonlinear mathematical model of a Francis hydro-...This paper investigates the stability of the Francis hydro-turbine governing system with complex penstocks in the grid-connected mode. Firstly, a novel fractional-order nonlinear mathematical model of a Francis hydro-turbine governing system with complex penstocks is built from an engineering application perspective. This model is described by state-space equations and is composed of the Francis hydro-turbine model, the fractional-order complex penstocks model, the third-order generator model, and the hydraulic speed governing system model. Based on stability theory for a fractional-order nonlinear system, this study discovers a basic law of the bifurcation points of the above system with a change in the fractional-order a. Secondly, the stable region of the governing system is investigated in detail,and nonlinear dynamical behaviors of the system are identified and studied exhaustively via bifurcation diagrams, time waveforms, phase orbits, Poincare maps, power spectrums and spectrograms. Results of these numerical experiments provide a theoretical reference for further studies of the stability of hydropower stations.展开更多
A nonlinear mathematical model for hydro turbine governing system with saturation nonlinearity in small perturbation has been proposed with all the essential components, i.e. turbine, PID t^^pe governor with saturatio...A nonlinear mathematical model for hydro turbine governing system with saturation nonlinearity in small perturbation has been proposed with all the essential components, i.e. turbine, PID t^^pe governor with saturation part and generator included in the model. Existence, stability and direction of Hopf bifurcation of an example HTGS are investigated in detail and presented in forms of bifurcation diagrams and time ＂wavefomis. The analysis show,that a supercritical Hopf bifurcation may exist in hydraulic turbine systems in some certain conditions. Moreover, the dynaiidc behavior of system with different parameters such as Tw, Tab, Ty and 尺 are studied extensively. An example with numerical simulations is presented to illustrate the theoretical results. The researches provide a reasonable explanation for the Hopf phenomenon happened in operation of hydroelectric generating unit.展开更多
A fast-slow coupled model of the hydro-turbine governing system （HTGS） is established by introducing frequency disturbance in this paper. Based on the proposed model, the performances of two time scales for bursting...A fast-slow coupled model of the hydro-turbine governing system （HTGS） is established by introducing frequency disturbance in this paper. Based on the proposed model, the performances of two time scales for bursting oscillations in the HTGS are investigated and the effect of periodic excitation of frequency disturbance is analyzed by using the bifurcation diagrams, time waveforms and phase portraits. We find that stability and operational characteristics of the HTGS change with the value of system parameter kd. Furthermore, the comparative analyses for the effect of the bursting oscillations on the system with different amplitudes of the periodic excitation a are carried out. Meanwhile, we obtain that the relative deviation of the mechanical torque mt rises with the increase of a. These methods and results of the study, combined with the performance of two time scales and the fast-slow coupled engineering model, provide some theoretical bases for investigating interesting physical phenomena of the engineering system.展开更多
机炉协调控制系统(coordinated control system,CCS)是火电机组满足电网负荷需求和保证机组本身稳定运行的重要控制措施。在分析机炉协调控制系统原理和控制方式的基础上,提出了一种适于电力系统机电暂态及中长期动态全过程仿真的机炉...机炉协调控制系统(coordinated control system,CCS)是火电机组满足电网负荷需求和保证机组本身稳定运行的重要控制措施。在分析机炉协调控制系统原理和控制方式的基础上,提出了一种适于电力系统机电暂态及中长期动态全过程仿真的机炉协调控制模型,并在电力系统全过程动态仿真程序进行编程实现。通过模型参数值的设置,该模型可以灵活模拟炉跟机、机跟炉、协调控制、直接能量平衡等火电厂机炉控制中的常见组态方式。采用两个仿真算例说明了不同CCS控制方式对机组功率的影响,以及CCS在与频率动态特性相关的电力系统动态仿真中的作用。展开更多
建立了考虑水电站引水系统水锤效应的弹性水体水轮机模型,并据此构建了水轮机调速系统模型。针对水轮机调速系统具有参数不确定性、存在干扰等特点,运用H∞鲁棒控制理论,提出了水轮机调速系统H∞双回路鲁棒控制策略,以水门开度偏差为补...建立了考虑水电站引水系统水锤效应的弹性水体水轮机模型,并据此构建了水轮机调速系统模型。针对水轮机调速系统具有参数不确定性、存在干扰等特点,运用H∞鲁棒控制理论,提出了水轮机调速系统H∞双回路鲁棒控制策略,以水门开度偏差为补偿信号构建了内环反馈回路,以发电机转速偏差为补偿信号构建了外环反馈回路。仿真结果验证了该控制策略的有效性,而且其时域性能指标明显优于传统比例–微分–积分(proportional integral derivative,PID)调节器控制效果。展开更多
基金supported by the Scientific Research Foundation of the National Natural Science Foundation-Outstanding Youth Foundation(No.51622906)National Natural Science Foundation of China (No.51479173)+4 种基金Fundamental Research Funds for the Central Universities (201304030577)Scientific Research Funds of Northwest A&F University (2013BSJJ095)the Scientific Research Foundation for Water Engineering in Shaanxi Province (2013slkj-12)the Science Fund for Excellent Young Scholars from Northwest A&F University (Z109021515)the Shaanxi Nova Program (2016KJXX-55)
文摘This paper investigates the stability of the Francis hydro-turbine governing system with complex penstocks in the grid-connected mode. Firstly, a novel fractional-order nonlinear mathematical model of a Francis hydro-turbine governing system with complex penstocks is built from an engineering application perspective. This model is described by state-space equations and is composed of the Francis hydro-turbine model, the fractional-order complex penstocks model, the third-order generator model, and the hydraulic speed governing system model. Based on stability theory for a fractional-order nonlinear system, this study discovers a basic law of the bifurcation points of the above system with a change in the fractional-order a. Secondly, the stable region of the governing system is investigated in detail,and nonlinear dynamical behaviors of the system are identified and studied exhaustively via bifurcation diagrams, time waveforms, phase orbits, Poincare maps, power spectrums and spectrograms. Results of these numerical experiments provide a theoretical reference for further studies of the stability of hydropower stations.
文摘A nonlinear mathematical model for hydro turbine governing system with saturation nonlinearity in small perturbation has been proposed with all the essential components, i.e. turbine, PID t^^pe governor with saturation part and generator included in the model. Existence, stability and direction of Hopf bifurcation of an example HTGS are investigated in detail and presented in forms of bifurcation diagrams and time ＂wavefomis. The analysis show,that a supercritical Hopf bifurcation may exist in hydraulic turbine systems in some certain conditions. Moreover, the dynaiidc behavior of system with different parameters such as Tw, Tab, Ty and 尺 are studied extensively. An example with numerical simulations is presented to illustrate the theoretical results. The researches provide a reasonable explanation for the Hopf phenomenon happened in operation of hydroelectric generating unit.
基金Project supported by the Scientific Research Foundation of the National Natural Science Foundation of China–Outstanding Youth Foundation(Grant No.51622906)the National Natural Science Foundation of China(Grant No.51479173)+3 种基金the Fundamental Research Funds for the Central Universities,China(Grant No.201304030577)the Scientific Research Funds of Northwest A&F University,China(Grant No.2013BSJJ095)the Science Fund for Excellent Young Scholars from Northwest A&F University(Grant No.Z109021515)the Shaanxi Provincial Nova Program,China(Grant No.2016KJXX-55)
文摘A fast-slow coupled model of the hydro-turbine governing system （HTGS） is established by introducing frequency disturbance in this paper. Based on the proposed model, the performances of two time scales for bursting oscillations in the HTGS are investigated and the effect of periodic excitation of frequency disturbance is analyzed by using the bifurcation diagrams, time waveforms and phase portraits. We find that stability and operational characteristics of the HTGS change with the value of system parameter kd. Furthermore, the comparative analyses for the effect of the bursting oscillations on the system with different amplitudes of the periodic excitation a are carried out. Meanwhile, we obtain that the relative deviation of the mechanical torque mt rises with the increase of a. These methods and results of the study, combined with the performance of two time scales and the fast-slow coupled engineering model, provide some theoretical bases for investigating interesting physical phenomena of the engineering system.
文摘机炉协调控制系统(coordinated control system,CCS)是火电机组满足电网负荷需求和保证机组本身稳定运行的重要控制措施。在分析机炉协调控制系统原理和控制方式的基础上,提出了一种适于电力系统机电暂态及中长期动态全过程仿真的机炉协调控制模型,并在电力系统全过程动态仿真程序进行编程实现。通过模型参数值的设置,该模型可以灵活模拟炉跟机、机跟炉、协调控制、直接能量平衡等火电厂机炉控制中的常见组态方式。采用两个仿真算例说明了不同CCS控制方式对机组功率的影响,以及CCS在与频率动态特性相关的电力系统动态仿真中的作用。
文摘建立了考虑水电站引水系统水锤效应的弹性水体水轮机模型,并据此构建了水轮机调速系统模型。针对水轮机调速系统具有参数不确定性、存在干扰等特点,运用H∞鲁棒控制理论,提出了水轮机调速系统H∞双回路鲁棒控制策略,以水门开度偏差为补偿信号构建了内环反馈回路,以发电机转速偏差为补偿信号构建了外环反馈回路。仿真结果验证了该控制策略的有效性,而且其时域性能指标明显优于传统比例–微分–积分(proportional integral derivative,PID)调节器控制效果。
