This study considers a superconducting electrodynamic maglev train of MLX01 type.The characteristics of the electromagnetic spring coefficient of a single bogie under different magnetomotive force(MF) of the supercond...This study considers a superconducting electrodynamic maglev train of MLX01 type.The characteristics of the electromagnetic spring coefficient of a single bogie under different magnetomotive force(MF) of the superconducting coil and standard air gap(Sag) were explored.In view of the small electromagnetic damping,a passive damping control strategy and an active damping control strategy were designed to increase the electromagnetic damping force between the superconducting coil and ground coil.Combined with the coupling numerical model of a single bogie,the vibration characteristics of the bogie in different directions with different damping control strategies were studied when the Sag and MF were fixed.The results can provide important theoretical support for stable operation control of maglev trains.展开更多
A semi-active strategy for model predictive control （MPC）, in which magneto-rheological dampers are used as an actuator, is presented for use in reducing the nonlinear seismic response of high-rise buildings. A mult...A semi-active strategy for model predictive control （MPC）, in which magneto-rheological dampers are used as an actuator, is presented for use in reducing the nonlinear seismic response of high-rise buildings. A multi-step predictive model is developed to estimate the seismic performance of high-rise buildings, taking into account of the effects of nonlinearity, time-variability, model mismatching, and disturbances and uncertainty of controlled system parameters by the predicted error feedback in the multi-step predictive model. Based on the predictive model, a Kalman-Bucy observer suitable for semi-active strategy is proposed to estimate the state vector from the acceleration and semi-active control force feedback. The main advantage of the proposed strategy is its inherent stability, simplicity, on-line real-time operation, and the ability to handle nonlinearity, uncertainty, and time-variability properties of structures. Numerical simulation of the nonlinear seismic responses of a controlled 20-story benchmark building is carried out, and the simulation results are compared to those of other control systems. The results show that the developed semi-active strategy can efficiently reduce the nonlinear seismic response of high-rise buildings.展开更多
As the existing coordinated control strategies between grid and unit have limitations in isolated power system, this paper introduces new coordinated control strategies which can improve the stability of isolated syst...As the existing coordinated control strategies between grid and unit have limitations in isolated power system, this paper introduces new coordinated control strategies which can improve the stability of isolated system operation. This paper analyzes the power grid side and unit side influence factors on the isolated power system. The dynamic models which are suitable for islanding operation are applied to simulate and analyze the stability and dynamic characteristics of the isolated power system under the conditions of different load disturbances and governor parameters. With considering the differences of frequency characteristics between the interconnected and isolated power system, the adjusting and optimization methods of under frequency load shedding are proposed to meet the frequency stability requirements simultaneously in the two cases. Not only proper control strategies of the power plant but the settings of their parameters are suggested to improve the operation stability of the isolated power system. To confirm the correctness and effectiveness of the method mentioned above, the isolated system operation test was conducted under the real power system condition, and the results show that the proposed coordinated control strategies can greatly improve stability of the isolated power system.展开更多
Real-time hybrid simulation is an attractive method to evaluate the response of structures under earthquake loads. The method is a variation of the pseudodynamic testing technique in which the experiment is executed i...Real-time hybrid simulation is an attractive method to evaluate the response of structures under earthquake loads. The method is a variation of the pseudodynamic testing technique in which the experiment is executed in real time, thus allowing investigation of structural systems with rate-dependent components. Real-time hybrid simulation is challenging because it requires performance of all calculations, application of displacements, and acquisition of measured forces, within a very small increment of time. Furthermore, unless appropriate compensation for actuator dynamics is implemented, stability problems are likely to occur during the experiment. This paper presents an approach for real-time hybrid simulation in which compensation for actuator dynamics is implemented using a model-based feedforward compensator. The method is used to evaluate the response of a semi-active control of a structure employing an MR damper. Experimental results show good agreement with the predicted responses, demonstrating the effectiveness of the method for structural control performance assessment.展开更多
受特高压直流送电容量大、多直流密集落点以及负荷高密度分布等因素影响,受端电压稳定问题已成为威胁电网安全稳定运行和制约负荷接纳能力的重要因素之一。通过逆变器准稳态模型,解析其无功消耗与送电有功间的强关联特征;通过时域仿真,...受特高压直流送电容量大、多直流密集落点以及负荷高密度分布等因素影响,受端电压稳定问题已成为威胁电网安全稳定运行和制约负荷接纳能力的重要因素之一。通过逆变器准稳态模型,解析其无功消耗与送电有功间的强关联特征;通过时域仿真,明晰逆变器无功消耗与容性补偿器无功出力动态差异,明确该差异可使逆变站成为动态无功源,即直流有功回降后逆变站可向交流电网注入动态无功。在此基础上,提出改善受端电网电压稳定性的直流紧急控制启动判据和撤销判据,以及具备在线应用前景的基于逆变站换流母线电压受扰轨迹的直流紧急控制策略。呼盟—豫西?800 k V/8 000 MW特高压直流受端电网大扰动时域仿真结果,证实了所提控制策略是提升受端电网电压稳定性和规避切负荷的经济有效措施。展开更多
提出一种"直流卸荷电路+定子动态变阻值撬棒保护(stator dynamic series resistor crowbar,SDSRC)+静止无功补偿器+网侧无功控制"的综合控制策略,并从电压跌落程度、功率损耗角度出发,考虑SDSRC适用范围,将控制策略分为两种模...提出一种"直流卸荷电路+定子动态变阻值撬棒保护(stator dynamic series resistor crowbar,SDSRC)+静止无功补偿器+网侧无功控制"的综合控制策略,并从电压跌落程度、功率损耗角度出发,考虑SDSRC适用范围,将控制策略分为两种模式,其中SDSRC取值为动态变阻值,以能更好地适应电压跌落水平的变化,起到提升机组低电压穿越能力和稳定运行能力的作用。在PSCAD平台下构建基于综合控制策略的双馈风电机组模型,通过仿真验证了不同电压跌落下的双馈风电机组低电压穿越能力,以及两种模式的综合控制策略的可行性。研究结果表明,所提方法不仅能有效保护机组直流侧电容和转子变流器,增强机组低电压穿越能力,而且增强了故障穿越后机组和系统运行的稳定性,克服了传统crowbar技术的弊端。展开更多
文摘This study considers a superconducting electrodynamic maglev train of MLX01 type.The characteristics of the electromagnetic spring coefficient of a single bogie under different magnetomotive force(MF) of the superconducting coil and standard air gap(Sag) were explored.In view of the small electromagnetic damping,a passive damping control strategy and an active damping control strategy were designed to increase the electromagnetic damping force between the superconducting coil and ground coil.Combined with the coupling numerical model of a single bogie,the vibration characteristics of the bogie in different directions with different damping control strategies were studied when the Sag and MF were fixed.The results can provide important theoretical support for stable operation control of maglev trains.
基金Fujian Province Youth Foundation for InnovativResearch Under Grant No. 2006F3008Fujian ProvincEducational Special Foundation Under Grant No. JA06027
文摘A semi-active strategy for model predictive control （MPC）, in which magneto-rheological dampers are used as an actuator, is presented for use in reducing the nonlinear seismic response of high-rise buildings. A multi-step predictive model is developed to estimate the seismic performance of high-rise buildings, taking into account of the effects of nonlinearity, time-variability, model mismatching, and disturbances and uncertainty of controlled system parameters by the predicted error feedback in the multi-step predictive model. Based on the predictive model, a Kalman-Bucy observer suitable for semi-active strategy is proposed to estimate the state vector from the acceleration and semi-active control force feedback. The main advantage of the proposed strategy is its inherent stability, simplicity, on-line real-time operation, and the ability to handle nonlinearity, uncertainty, and time-variability properties of structures. Numerical simulation of the nonlinear seismic responses of a controlled 20-story benchmark building is carried out, and the simulation results are compared to those of other control systems. The results show that the developed semi-active strategy can efficiently reduce the nonlinear seismic response of high-rise buildings.
文摘As the existing coordinated control strategies between grid and unit have limitations in isolated power system, this paper introduces new coordinated control strategies which can improve the stability of isolated system operation. This paper analyzes the power grid side and unit side influence factors on the isolated power system. The dynamic models which are suitable for islanding operation are applied to simulate and analyze the stability and dynamic characteristics of the isolated power system under the conditions of different load disturbances and governor parameters. With considering the differences of frequency characteristics between the interconnected and isolated power system, the adjusting and optimization methods of under frequency load shedding are proposed to meet the frequency stability requirements simultaneously in the two cases. Not only proper control strategies of the power plant but the settings of their parameters are suggested to improve the operation stability of the isolated power system. To confirm the correctness and effectiveness of the method mentioned above, the isolated system operation test was conducted under the real power system condition, and the results show that the proposed coordinated control strategies can greatly improve stability of the isolated power system.
基金National Science Foundation Graduate Research Fellowship
文摘Real-time hybrid simulation is an attractive method to evaluate the response of structures under earthquake loads. The method is a variation of the pseudodynamic testing technique in which the experiment is executed in real time, thus allowing investigation of structural systems with rate-dependent components. Real-time hybrid simulation is challenging because it requires performance of all calculations, application of displacements, and acquisition of measured forces, within a very small increment of time. Furthermore, unless appropriate compensation for actuator dynamics is implemented, stability problems are likely to occur during the experiment. This paper presents an approach for real-time hybrid simulation in which compensation for actuator dynamics is implemented using a model-based feedforward compensator. The method is used to evaluate the response of a semi-active control of a structure employing an MR damper. Experimental results show good agreement with the predicted responses, demonstrating the effectiveness of the method for structural control performance assessment.
文摘受特高压直流送电容量大、多直流密集落点以及负荷高密度分布等因素影响,受端电压稳定问题已成为威胁电网安全稳定运行和制约负荷接纳能力的重要因素之一。通过逆变器准稳态模型,解析其无功消耗与送电有功间的强关联特征;通过时域仿真,明晰逆变器无功消耗与容性补偿器无功出力动态差异,明确该差异可使逆变站成为动态无功源,即直流有功回降后逆变站可向交流电网注入动态无功。在此基础上,提出改善受端电网电压稳定性的直流紧急控制启动判据和撤销判据,以及具备在线应用前景的基于逆变站换流母线电压受扰轨迹的直流紧急控制策略。呼盟—豫西?800 k V/8 000 MW特高压直流受端电网大扰动时域仿真结果,证实了所提控制策略是提升受端电网电压稳定性和规避切负荷的经济有效措施。
文摘提出一种"直流卸荷电路+定子动态变阻值撬棒保护(stator dynamic series resistor crowbar,SDSRC)+静止无功补偿器+网侧无功控制"的综合控制策略,并从电压跌落程度、功率损耗角度出发,考虑SDSRC适用范围,将控制策略分为两种模式,其中SDSRC取值为动态变阻值,以能更好地适应电压跌落水平的变化,起到提升机组低电压穿越能力和稳定运行能力的作用。在PSCAD平台下构建基于综合控制策略的双馈风电机组模型,通过仿真验证了不同电压跌落下的双馈风电机组低电压穿越能力,以及两种模式的综合控制策略的可行性。研究结果表明,所提方法不仅能有效保护机组直流侧电容和转子变流器,增强机组低电压穿越能力,而且增强了故障穿越后机组和系统运行的稳定性,克服了传统crowbar技术的弊端。
文摘针对基于集成发电机/起动机(ISAD)技术混合动力各部件的特性,在实现柴油机、ISG(Integrated Starter Generator)电机、蓄电池和传动系统最佳匹配的前提下,设计了混合动力系统动态转矩协调控制策略.以转矩为控制变量,通过转矩总需求和柴油机万有特性脉谱图,确定了状态切换的条件及柴油机和ISG电机的目标转矩.采用Matlab/Simulink平台进行了CYC_ECE_EUDC工况的动力性仿真.仿真结果表明:文中提出的控制策略能够满足ISAD迅速起动、低速补偿转矩、加速提供辅助动力、充电功率恒定等要求;瞬态工况时,通过ISG电机助力,缩短了工况过渡时间;稳态工况时,通过电机转矩补偿,实现了无转矩波动的状态切换,改善了状态切换过程中动力传递的平顺性;柴油机和ISG电机工作点集中在高效率区域,SOC(Stat of Charge)维持在最佳工作区域;整车实现起步-助力-发电一体化的功能,并为开发控制软件平台提供了理论依据.
