This article investigates virtual reality (VR)-based teleoperation with robustness against modeling errors. VR technology is an effective way to overcome the large time delay during space robot teleoperation. However,...This article investigates virtual reality (VR)-based teleoperation with robustness against modeling errors. VR technology is an effective way to overcome the large time delay during space robot teleoperation. However, it depends highly on the accuracy of model. Model errors between the virtual and real environment exist inevitably. The existing way to deal with the problem is by means of either model matching or robot compliance control. As distinct from the existing methods, this article tries to combine m...展开更多
In recent years, power generation using renewable energy sources has been developed as a solution to the global warming problem. Among these power generation methods, wind power generation is increasing. However, as t...In recent years, power generation using renewable energy sources has been developed as a solution to the global warming problem. Among these power generation methods, wind power generation is increasing. However, as the penetration level of wind power generation increases, the low inertia and lack of synchronous power characteristics of the penetrated power system can have a significant impact on the transient stability of the grid. The virtual synchronous generator provides the ability of virtual inertia and synchronous power to interconnected inverters. The interconnected inverter with the virtual synchronous generator ability uses, in general, PI control based current controller. This paper proposes a new current-control method and compares it with conventional methods. The proposed current control is a method that follows virtual synchronous generator model that changes every moment by solving the discrete-time linear quadratic optimal control problem for each sampling time interval. The new method follows the conventional method, and therefore the reactive power fluctuation can be suppressed and the interconnected inverter will be downsized.展开更多
In recent years, power generation using renewable energy sources has been increasing as a solution to the global warning problem. Wind power generation can generate electricity day and night, and it is relatively more...In recent years, power generation using renewable energy sources has been increasing as a solution to the global warning problem. Wind power generation can generate electricity day and night, and it is relatively more efficient among the renewable energy sources. The penetration level of variable-speed wind turbines continues to increase. The interconnected wind turbines, however, have no inertia and no synchronous power. Such devices can have a serious impact on the transient stability of the power grid system. One solution to stabilize such grid with renewable energy sources is to provide emulated inertia and synchronizing power. We have proposed an optimal design method of current control for virtual synchronous generators. This paper proposes an optimal control method that can follow the virtual generator model under constrains. As a result, it is shown that the proposed system can suppress the peak of the output of semiconductor device under instantaneous output voltage drop.展开更多
自然风速的随机性与波动性,风电机组输出功率易出现剧烈波动,不仅降低风能利用效率,还会对电网频率稳定性造成显著冲击,给电力系统安全带来极大隐患。针对这一问题,提出一种考虑风速变化的频率综合控制策略。该策略首先采用模型预测控制...自然风速的随机性与波动性,风电机组输出功率易出现剧烈波动,不仅降低风能利用效率,还会对电网频率稳定性造成显著冲击,给电力系统安全带来极大隐患。针对这一问题,提出一种考虑风速变化的频率综合控制策略。该策略首先采用模型预测控制(model predictive control,MPC)对阵风信号进行优化处理,精准提取有效风速,据此生成最优转速参考值,有效提升最大功率点跟踪(maximum power point tracking,MPPT)的风能捕获效率与稳定性;进而将提取的有效风速作为模糊控制的关键输入,构建自适应虚拟惯性控制模块,通过动态调整控制参数,增强风电机组对电网频率变化的响应速度与调节能力,提升一次调频性能。在MATLAB/Simulink仿真平台搭建仿真模型,模拟不稳定风速工况进行测试,验证所提策略的有效性。仿真结果表明,该综合控制策略能够有效平抑风电机组输出功率的波动,显著抑制电网系统频率的快速变化,为不稳定风速下风电并网系统的安全稳定运行提供可靠保障。展开更多
We present a method for designing free gaits for a structurally symmetrical quadruped robot capable of performing statically stable, omnidirectional walking on irregular terrain. The robot＇s virtual model is construc...We present a method for designing free gaits for a structurally symmetrical quadruped robot capable of performing statically stable, omnidirectional walking on irregular terrain. The robot＇s virtual model is constructed and a control algorithm is proposed by applying virtual components at some strategic locations. The deliberative-based controller can generate flexible sequences of leg transferences while maintaining walking speed, and choose optimum foothold for moving leg based on integration data of exteroceptive terrain profile. Simulation results are presented to show the gait＇s efficiency and system＇s stability in adapting to an uncertain terrain.展开更多
基金National Natural Science Foundation of China (60675054)National High-Tech Research and Development Program (2006AA04Z228)"111" Project (B07018)
文摘This article investigates virtual reality (VR)-based teleoperation with robustness against modeling errors. VR technology is an effective way to overcome the large time delay during space robot teleoperation. However, it depends highly on the accuracy of model. Model errors between the virtual and real environment exist inevitably. The existing way to deal with the problem is by means of either model matching or robot compliance control. As distinct from the existing methods, this article tries to combine m...
文摘In recent years, power generation using renewable energy sources has been developed as a solution to the global warming problem. Among these power generation methods, wind power generation is increasing. However, as the penetration level of wind power generation increases, the low inertia and lack of synchronous power characteristics of the penetrated power system can have a significant impact on the transient stability of the grid. The virtual synchronous generator provides the ability of virtual inertia and synchronous power to interconnected inverters. The interconnected inverter with the virtual synchronous generator ability uses, in general, PI control based current controller. This paper proposes a new current-control method and compares it with conventional methods. The proposed current control is a method that follows virtual synchronous generator model that changes every moment by solving the discrete-time linear quadratic optimal control problem for each sampling time interval. The new method follows the conventional method, and therefore the reactive power fluctuation can be suppressed and the interconnected inverter will be downsized.
文摘In recent years, power generation using renewable energy sources has been increasing as a solution to the global warning problem. Wind power generation can generate electricity day and night, and it is relatively more efficient among the renewable energy sources. The penetration level of variable-speed wind turbines continues to increase. The interconnected wind turbines, however, have no inertia and no synchronous power. Such devices can have a serious impact on the transient stability of the power grid system. One solution to stabilize such grid with renewable energy sources is to provide emulated inertia and synchronizing power. We have proposed an optimal design method of current control for virtual synchronous generators. This paper proposes an optimal control method that can follow the virtual generator model under constrains. As a result, it is shown that the proposed system can suppress the peak of the output of semiconductor device under instantaneous output voltage drop.
文摘光伏等新能源及储能系统基于电力电子接口融入微电网,其低惯量问题显著,面临严峻的频率稳定风险。为了改善微电网频率动态特性,利用模型预测控制(model predictive control,MPC)协同优化外环与内环,提出了一种基于级联模型预测(cascaded model predictive control,CMPC)的虚拟同步机(virtual synchronous generator,VSG)控制策略。在外环,利用MPC的滚动优化,对输入VSG的有功功率参考值进行实时修正。在内环,优化通过两个阶段寻找最优电压矢量(voltage vector,VV)的离散空间矢量模型预测控制(discrete space vector model predictive control,DSVM-MPC)方法,减少跟踪外环输出误差,使频率控制更为精确。仿真结果表明,所提策略能够提升频率响应和限流效果,避免频率过冲。
文摘自然风速的随机性与波动性,风电机组输出功率易出现剧烈波动,不仅降低风能利用效率,还会对电网频率稳定性造成显著冲击,给电力系统安全带来极大隐患。针对这一问题,提出一种考虑风速变化的频率综合控制策略。该策略首先采用模型预测控制(model predictive control,MPC)对阵风信号进行优化处理,精准提取有效风速,据此生成最优转速参考值,有效提升最大功率点跟踪(maximum power point tracking,MPPT)的风能捕获效率与稳定性;进而将提取的有效风速作为模糊控制的关键输入,构建自适应虚拟惯性控制模块,通过动态调整控制参数,增强风电机组对电网频率变化的响应速度与调节能力,提升一次调频性能。在MATLAB/Simulink仿真平台搭建仿真模型,模拟不稳定风速工况进行测试,验证所提策略的有效性。仿真结果表明,该综合控制策略能够有效平抑风电机组输出功率的波动,显著抑制电网系统频率的快速变化,为不稳定风速下风电并网系统的安全稳定运行提供可靠保障。
基金supported by the Science and Technology Innovation Fund for the Doctor
文摘We present a method for designing free gaits for a structurally symmetrical quadruped robot capable of performing statically stable, omnidirectional walking on irregular terrain. The robot＇s virtual model is constructed and a control algorithm is proposed by applying virtual components at some strategic locations. The deliberative-based controller can generate flexible sequences of leg transferences while maintaining walking speed, and choose optimum foothold for moving leg based on integration data of exteroceptive terrain profile. Simulation results are presented to show the gait＇s efficiency and system＇s stability in adapting to an uncertain terrain.
