A set of novel nonlinear variable structure excitation and steam-valving controllers are proposed in this paper. On the basis of the classical dynamic equations of a generator, excitation control and steam valving con...A set of novel nonlinear variable structure excitation and steam-valving controllers are proposed in this paper. On the basis of the classical dynamic equations of a generator, excitation control and steam valving control are simultaneously considered. Design of these controllers combines the differential geometry theory with the variable structure controlling theory. The mathematical model in the form of ＂an affine nonlinear system＂ is set up for the control design of a large-scale power plant. The dynamic performance of the nonlinear variable structure controllers proposed for a single machine connected to an infinite bus power system is simulated. Simulation results show that the nonlinear variable structure excitation and steam-valving controllers give satisfactory dynamic performance and good robustness.展开更多
Considering generator rotor and valve by external disturbances for turbine regulating system, the nonlinear large disturbance attenuation controller and parameter updating law of turbine speed governor system are desi...Considering generator rotor and valve by external disturbances for turbine regulating system, the nonlinear large disturbance attenuation controller and parameter updating law of turbine speed governor system are designed using backstepping method. The controller not only considers transmission line parameter uncer-tainty, and has attenuated the influences of large external disturbances on system output. The nonlinear con-troller does not have the sensitivity to the influences of external disturbances, but also has strong robustness for system parameters variation, which is because of the transmission line uncertainty being considered in internal disturbances. The simulation results show that the control effect of the large disturbance attenuation controller more advantages by comparing with the control performance of conventional nonlinear robust controller.展开更多
In order to incorporate the decision maker＇s preference into multiobjective optimization a preference-based multiobjective artificial bee colony algorithm PMABCA is proposed.In the proposed algorithm a novel referenc...In order to incorporate the decision maker＇s preference into multiobjective optimization a preference-based multiobjective artificial bee colony algorithm PMABCA is proposed.In the proposed algorithm a novel reference point based preference expression method is addressed.The fitness assignment function is defined based on the nondominated rank and the newly defined preference distance.An archive set is introduced for saving the nondominated solutions and an improved crowding-distance operator is addressed to remove the extra solutions in the archive.The experimental results of two benchmark test functions show that a preferred set of solutions and some other non-preference solutions are achieved simultaneously.The simulation results of the proportional-integral-derivative PID parameter optimization for superheated steam temperature verify that the PMABCA is efficient in aiding to making a reasonable decision.展开更多
Based on Hamiltonian formulation, this paper proposes a design approach to nonlinear feedback excitation control of synchronous generators with steam valve control, disturbances and unknown parameters. It is shown tha...Based on Hamiltonian formulation, this paper proposes a design approach to nonlinear feedback excitation control of synchronous generators with steam valve control, disturbances and unknown parameters. It is shown that the dynamics of the synchronous generators can be expressed as a dissipative Hamiltonian system, based on which an adaptive H-infinity controller is then designed for the systems by using the structure properties of dissipative Hamiltonian systems. Simulations show that the controller obtained in this paper is very effective.展开更多
The problem of transient stability for a single machine infinite bus system with turbine main steam valve control is addressed by means of a novel adaptive backstepping method in this paper.The recursive design proced...The problem of transient stability for a single machine infinite bus system with turbine main steam valve control is addressed by means of a novel adaptive backstepping method in this paper.The recursive design procedure of the proposed controller is much simpler than that of the existing controller based on conventional adaptive backstepping method.In the system,the damping coefficient is measured inaccurately,and the reactance of transmission line also contains a few uncertainties.A nonlinear robust controller and parameter updating laws are obtained simultaneously.The system does not need to be linearized,and the closed-loop error system is guaranteed to be asymptotically stable.The design procedure and simulation results demonstrate the effectiveness of the proposed design.展开更多
A new approach for nonlinear adaptive control of turbine main steam valve is developed. In comparison with the existing controller based on ＂classical＂ adaptive backstepping, this method does not follow the classica...A new approach for nonlinear adaptive control of turbine main steam valve is developed. In comparison with the existing controller based on ＂classical＂ adaptive backstepping, this method does not follow the classical certaintyequivalence principle in the design of adaptive control law. We introduce this approach, for the first time, to power systems and present a novel parameter estimator and dynamic feedback controller for a single machine infinite bus （SMIB） system with steam valve control. This system contains unknown parameters such as reactance of transmission lines. Besides preserving useful nonlinearities and the real-time estimation of uncertain parameters, the proposed approach possesses better performances with respect to the response of the system and the speed of adaptation. The simulation results demonstrate that the proposed approach is better than the design based on ＂classical＂ adaptive backstepping in terms of properties of stability and parameter estimation, and recovers the performance of the ＂full-information＂ controller. Hence, the proposed method provides an alternative for engineers in applications.展开更多
Background： Allergic rhinitis is a nasal mucosa inflammatory disorder that is induced by exposure to an allergen which results in four major symptoms, including anterior or posterior rhinorrhea, sneezing, nasal itchi...Background： Allergic rhinitis is a nasal mucosa inflammatory disorder that is induced by exposure to an allergen which results in four major symptoms, including anterior or posterior rhinorrhea, sneezing, nasal itching and nasal congestion. Allergic rhinitis may result in sleep disturbance, fatigue, depression of mood-cognitive function and quality of life impairment. Objective： This study examined the efficacy and safety of herbal steam bath used for the reduction of allergic rhinitis symptoms, and evaluated treatment satisfaction and improvements in quality of life among participating patients with allergic rhinitis. Design, setting, participants and intervention： A single-blind randomized controlled trial was conducted at Thai Traditional and Alternative Medicine Hospital between June and December 2016, using 64 subjects, equally divided into two groups. The treatment group received herbal steam bath and the control group received steam bath without herbs for 30 rain 3 times a week for 4 consecutive weeks. Main outcome measures： Allergic rhinitis symptoms, such as itchy nose, runny nose, sneezing, nasal congestion and watery eyes, were measured using the visual analog scale at weeks 0, 1, 2, 3 and 4. Quality of life was assessed at week 0 and week 4. Results： The characteristics （sex, age, marital status, education, allergic rhinitis symptoms and frequency of symptoms） at the baseline were not statistically different （P 〉 0.05） between the two test groups. Anterior or posterior rhinorrhea symptoms, including sneezing, nasal itching and nasal congestion, were statistically reduced over the course of the treatment, but reductions were not significantly different between the control and treatment groups. The treatment group, however, was shown to be significantly more satisfied with the treatment than the control group （P 〈 0.05）. Conclusion： Both treatments appear to be able to significantly reduce the symptoms of allergic rhinitis. However, there was no difference in the effectiveness of steam bath with herbs and steam bath without herbs. Trial registration： This trial was registered in the Thai Clinical Trial Registry with the identifier TCTR20170712002.展开更多
Valve management is one of the major functions of DEH for steam turbine. It has an important practical significance for the security and economy of the steam turbine. This paper starts from the valve configuration fig...Valve management is one of the major functions of DEH for steam turbine. It has an important practical significance for the security and economy of the steam turbine. This paper starts from the valve configuration figure of the domestic-type 300 MW steam turbine, and then makes a simple comparison between the two types of valve governing modes. In order to realize the valve control, the structure of control system has been established, in which the roles of the mathematical functions are discussed. On the basis of the experiment of valve flow characteristic, this article carries out a quantitative study on the functions of the valve management and the parameter tuning method. Through a serious corrections, the sequence valve flow characteristic curve is obtained, which can provide significant guidance on the research of valve management of the similar steam turbines.展开更多
汽轮机数字电液控制系统(Digital Electro-hydraulic Control System,DEH)结构复杂,内部情况多变,很容易受到负荷扰动和气压扰动的影响,而传统的模糊PID控制方式调节精度低、抗干扰能力弱,控制效果不理想。为了更好地解决这一问题,论文...汽轮机数字电液控制系统(Digital Electro-hydraulic Control System,DEH)结构复杂,内部情况多变,很容易受到负荷扰动和气压扰动的影响,而传统的模糊PID控制方式调节精度低、抗干扰能力弱,控制效果不理想。为了更好地解决这一问题,论文提出了一种基于干扰观测器(Disturbance Observer,DOB)的控制方案,结合模糊PID控制采用前馈控制的方式提高传统模糊PID控制的动态性能。在不同工况和影响因素条件下与传统模糊PID控制方法进行仿真实验对比分析,结果表明所提出的控制方案相较于传统的模糊PID控制方式具备更快的调节速度、更强的抗干扰性能和鲁棒性能。展开更多
文摘A set of novel nonlinear variable structure excitation and steam-valving controllers are proposed in this paper. On the basis of the classical dynamic equations of a generator, excitation control and steam valving control are simultaneously considered. Design of these controllers combines the differential geometry theory with the variable structure controlling theory. The mathematical model in the form of ＂an affine nonlinear system＂ is set up for the control design of a large-scale power plant. The dynamic performance of the nonlinear variable structure controllers proposed for a single machine connected to an infinite bus power system is simulated. Simulation results show that the nonlinear variable structure excitation and steam-valving controllers give satisfactory dynamic performance and good robustness.
文摘Considering generator rotor and valve by external disturbances for turbine regulating system, the nonlinear large disturbance attenuation controller and parameter updating law of turbine speed governor system are designed using backstepping method. The controller not only considers transmission line parameter uncer-tainty, and has attenuated the influences of large external disturbances on system output. The nonlinear con-troller does not have the sensitivity to the influences of external disturbances, but also has strong robustness for system parameters variation, which is because of the transmission line uncertainty being considered in internal disturbances. The simulation results show that the control effect of the large disturbance attenuation controller more advantages by comparing with the control performance of conventional nonlinear robust controller.
基金The National Natural Science Foundation of China(No.51306082,51476027)
文摘In order to incorporate the decision maker＇s preference into multiobjective optimization a preference-based multiobjective artificial bee colony algorithm PMABCA is proposed.In the proposed algorithm a novel reference point based preference expression method is addressed.The fitness assignment function is defined based on the nondominated rank and the newly defined preference distance.An archive set is introduced for saving the nondominated solutions and an improved crowding-distance operator is addressed to remove the extra solutions in the archive.The experimental results of two benchmark test functions show that a preferred set of solutions and some other non-preference solutions are achieved simultaneously.The simulation results of the proportional-integral-derivative PID parameter optimization for superheated steam temperature verify that the PMABCA is efficient in aiding to making a reasonable decision.
基金This work was supported by the National Natural Science Foundation of China (No.G60474001) the Research Fund for Doctoral Program of Chinese Higher Education (No.G20040422059).
文摘Based on Hamiltonian formulation, this paper proposes a design approach to nonlinear feedback excitation control of synchronous generators with steam valve control, disturbances and unknown parameters. It is shown that the dynamics of the synchronous generators can be expressed as a dissipative Hamiltonian system, based on which an adaptive H-infinity controller is then designed for the systems by using the structure properties of dissipative Hamiltonian systems. Simulations show that the controller obtained in this paper is very effective.
基金supported by the National Natural Science Foundation of China(No.60874024,90816028)the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.200801450019)
文摘The problem of transient stability for a single machine infinite bus system with turbine main steam valve control is addressed by means of a novel adaptive backstepping method in this paper.The recursive design procedure of the proposed controller is much simpler than that of the existing controller based on conventional adaptive backstepping method.In the system,the damping coefficient is measured inaccurately,and the reactance of transmission line also contains a few uncertainties.A nonlinear robust controller and parameter updating laws are obtained simultaneously.The system does not need to be linearized,and the closed-loop error system is guaranteed to be asymptotically stable.The design procedure and simulation results demonstrate the effectiveness of the proposed design.
基金This work was supported by the National Natural Science Foundation of China (No. 60574013).
文摘A new approach for nonlinear adaptive control of turbine main steam valve is developed. In comparison with the existing controller based on ＂classical＂ adaptive backstepping, this method does not follow the classical certaintyequivalence principle in the design of adaptive control law. We introduce this approach, for the first time, to power systems and present a novel parameter estimator and dynamic feedback controller for a single machine infinite bus （SMIB） system with steam valve control. This system contains unknown parameters such as reactance of transmission lines. Besides preserving useful nonlinearities and the real-time estimation of uncertain parameters, the proposed approach possesses better performances with respect to the response of the system and the speed of adaptation. The simulation results demonstrate that the proposed approach is better than the design based on ＂classical＂ adaptive backstepping in terms of properties of stability and parameter estimation, and recovers the performance of the ＂full-information＂ controller. Hence, the proposed method provides an alternative for engineers in applications.
文摘Background： Allergic rhinitis is a nasal mucosa inflammatory disorder that is induced by exposure to an allergen which results in four major symptoms, including anterior or posterior rhinorrhea, sneezing, nasal itching and nasal congestion. Allergic rhinitis may result in sleep disturbance, fatigue, depression of mood-cognitive function and quality of life impairment. Objective： This study examined the efficacy and safety of herbal steam bath used for the reduction of allergic rhinitis symptoms, and evaluated treatment satisfaction and improvements in quality of life among participating patients with allergic rhinitis. Design, setting, participants and intervention： A single-blind randomized controlled trial was conducted at Thai Traditional and Alternative Medicine Hospital between June and December 2016, using 64 subjects, equally divided into two groups. The treatment group received herbal steam bath and the control group received steam bath without herbs for 30 rain 3 times a week for 4 consecutive weeks. Main outcome measures： Allergic rhinitis symptoms, such as itchy nose, runny nose, sneezing, nasal congestion and watery eyes, were measured using the visual analog scale at weeks 0, 1, 2, 3 and 4. Quality of life was assessed at week 0 and week 4. Results： The characteristics （sex, age, marital status, education, allergic rhinitis symptoms and frequency of symptoms） at the baseline were not statistically different （P 〉 0.05） between the two test groups. Anterior or posterior rhinorrhea symptoms, including sneezing, nasal itching and nasal congestion, were statistically reduced over the course of the treatment, but reductions were not significantly different between the control and treatment groups. The treatment group, however, was shown to be significantly more satisfied with the treatment than the control group （P 〈 0.05）. Conclusion： Both treatments appear to be able to significantly reduce the symptoms of allergic rhinitis. However, there was no difference in the effectiveness of steam bath with herbs and steam bath without herbs. Trial registration： This trial was registered in the Thai Clinical Trial Registry with the identifier TCTR20170712002.
文摘Valve management is one of the major functions of DEH for steam turbine. It has an important practical significance for the security and economy of the steam turbine. This paper starts from the valve configuration figure of the domestic-type 300 MW steam turbine, and then makes a simple comparison between the two types of valve governing modes. In order to realize the valve control, the structure of control system has been established, in which the roles of the mathematical functions are discussed. On the basis of the experiment of valve flow characteristic, this article carries out a quantitative study on the functions of the valve management and the parameter tuning method. Through a serious corrections, the sequence valve flow characteristic curve is obtained, which can provide significant guidance on the research of valve management of the similar steam turbines.
文摘汽轮机数字电液控制系统(Digital Electro-hydraulic Control System,DEH)结构复杂,内部情况多变,很容易受到负荷扰动和气压扰动的影响,而传统的模糊PID控制方式调节精度低、抗干扰能力弱,控制效果不理想。为了更好地解决这一问题,论文提出了一种基于干扰观测器(Disturbance Observer,DOB)的控制方案,结合模糊PID控制采用前馈控制的方式提高传统模糊PID控制的动态性能。在不同工况和影响因素条件下与传统模糊PID控制方法进行仿真实验对比分析,结果表明所提出的控制方案相较于传统的模糊PID控制方式具备更快的调节速度、更强的抗干扰性能和鲁棒性能。
