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
Terminal sliding mode controller method is introduced to enhance the regulation performance of the hydraulic turbine governing system(HTGS).For the purpose of describing the characteristics of controlled system and de...Terminal sliding mode controller method is introduced to enhance the regulation performance of the hydraulic turbine governing system(HTGS).For the purpose of describing the characteristics of controlled system and deducing the control rule,a nonlinear mathematic model of hydraulic turbine governing system with bifurcated penstocks(HTGSBF)under control input saturation is established,and the input/output state linearization feedback approach is used to obtain the relationship between turbine speed and controller output.To address the control input saturation problem,an adaptive assistant system is designed to compensate for controller truncation.Numerical simulations have been conducted under fixed point stabilization and periodic orbit tracking conditions to compare the dynamic performances of proposed terminal sliding mode controllers and conventional sliding mode controller.The results indicate that the proposed terminal sliding mode controllers not only have a faster response and accurate tracking results,but also own a stronger robustness to the system parameter variations.Moreover,the comparisons between the proposed terminal sliding mode controllers and current most often used proportional-integral-differential(PID)controller,as well its variant NPID controller,are discussed at the end of this paper,where the superiority of the terminal sliding mode controllers also have been verified.展开更多
As a key backbone project in developing and harnessing the Yangtze, the Three Gorges Project (TGP) is a largest water conservancy and hydropower project in China and all the world as well. With a huge comprehensive be...As a key backbone project in developing and harnessing the Yangtze, the Three Gorges Project (TGP) is a largest water conservancy and hydropower project in China and all the world as well. With a huge comprehensive benefit from flood control, power generation and navigation improvement, TGP, when completed, will exert a significant influence on the socio economic development across the Yangtze Basin and all China. Decisions on key technical issues concerning the construction of TGP were made on a huge number of scientific tests and verifications. The structural pattern selection of the penstock and the spiral case in the TGP power station is not only an important technical and economic issue, but also relating to the long term operation of the power station itself.展开更多
针对地震作用下地面明钢管滑动支座容易产生较大横向滑移的问题,采用有限元方法,研究了支座限位装置对明钢管地震响应的影响。计算结果显示:当支座不设置限位装置时,地震作用下管段中部支座滑移量较大,钢管横向弯曲,对结构稳定不利;当...针对地震作用下地面明钢管滑动支座容易产生较大横向滑移的问题,采用有限元方法,研究了支座限位装置对明钢管地震响应的影响。计算结果显示:当支座不设置限位装置时,地震作用下管段中部支座滑移量较大,钢管横向弯曲,对结构稳定不利;当支座设置限位装置后,明钢管的横向位移减小,但在地震中支座滑板与限位装置会产生碰撞,瞬时加速度可超100 m/s 2,支承环的应力大幅增加,支座横向力可达静力状态下的几十甚至上百倍;支座限位值越小,地震中结构受力越大;支座限位挡块和支座滑板接触面上设置一层弹性模量3 MPa的薄垫层后,能缓冲地震中支座受到的冲击,有效减小结构加速度和受力,支座横向力和竖向力的比值可基本控制在摩擦系数以内。因此,支座限位对强震区的明钢管结构是有必要的,在确定限位值时,应同时考虑结构位移和应力2个方面的要求,为减小地震中支座滑板和限位装置碰撞产生的不利影响,可在限位挡块上设置缓冲材料薄层。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.
基金supported by Open Fund of Hubei Provincial Key Laboratory for Operation and Control of Cascaded Hydropower Station in China Three Gorges University(No.2019KJX02).
文摘Terminal sliding mode controller method is introduced to enhance the regulation performance of the hydraulic turbine governing system(HTGS).For the purpose of describing the characteristics of controlled system and deducing the control rule,a nonlinear mathematic model of hydraulic turbine governing system with bifurcated penstocks(HTGSBF)under control input saturation is established,and the input/output state linearization feedback approach is used to obtain the relationship between turbine speed and controller output.To address the control input saturation problem,an adaptive assistant system is designed to compensate for controller truncation.Numerical simulations have been conducted under fixed point stabilization and periodic orbit tracking conditions to compare the dynamic performances of proposed terminal sliding mode controllers and conventional sliding mode controller.The results indicate that the proposed terminal sliding mode controllers not only have a faster response and accurate tracking results,but also own a stronger robustness to the system parameter variations.Moreover,the comparisons between the proposed terminal sliding mode controllers and current most often used proportional-integral-differential(PID)controller,as well its variant NPID controller,are discussed at the end of this paper,where the superiority of the terminal sliding mode controllers also have been verified.
文摘As a key backbone project in developing and harnessing the Yangtze, the Three Gorges Project (TGP) is a largest water conservancy and hydropower project in China and all the world as well. With a huge comprehensive benefit from flood control, power generation and navigation improvement, TGP, when completed, will exert a significant influence on the socio economic development across the Yangtze Basin and all China. Decisions on key technical issues concerning the construction of TGP were made on a huge number of scientific tests and verifications. The structural pattern selection of the penstock and the spiral case in the TGP power station is not only an important technical and economic issue, but also relating to the long term operation of the power station itself.
文摘针对地震作用下地面明钢管滑动支座容易产生较大横向滑移的问题,采用有限元方法,研究了支座限位装置对明钢管地震响应的影响。计算结果显示:当支座不设置限位装置时,地震作用下管段中部支座滑移量较大,钢管横向弯曲,对结构稳定不利;当支座设置限位装置后,明钢管的横向位移减小,但在地震中支座滑板与限位装置会产生碰撞,瞬时加速度可超100 m/s 2,支承环的应力大幅增加,支座横向力可达静力状态下的几十甚至上百倍;支座限位值越小,地震中结构受力越大;支座限位挡块和支座滑板接触面上设置一层弹性模量3 MPa的薄垫层后,能缓冲地震中支座受到的冲击,有效减小结构加速度和受力,支座横向力和竖向力的比值可基本控制在摩擦系数以内。因此,支座限位对强震区的明钢管结构是有必要的,在确定限位值时,应同时考虑结构位移和应力2个方面的要求,为减小地震中支座滑板和限位装置碰撞产生的不利影响,可在限位挡块上设置缓冲材料薄层。
