变压器式可控电抗器(controllable reactor of transformer type,CRT)目前的调节模式仅限于单绕组调节模式,此时CRT的谐波电流含量无法满足要求更高的应用场合。为进一步改善CRT的谐波性能,提出了多绕组调节模式的基本概念;采用分段线...变压器式可控电抗器(controllable reactor of transformer type,CRT)目前的调节模式仅限于单绕组调节模式,此时CRT的谐波电流含量无法满足要求更高的应用场合。为进一步改善CRT的谐波性能,提出了多绕组调节模式的基本概念;采用分段线性化的方法,推出CRT工作绕组瞬时电流的计算通式;利用傅里叶级数分析方法求得工作绕组电流基波及各次谐波分量有效值与各触发角之间的函数关系式。将CRT整个容量范围进行离散,依次以各离散容量点为等式约束,以CRT向电网注入的谐波电流含量为目标函数,建立非线性优化模型,并调用Matlab中的求解非线性约束最小化问题的函数(Fmincon)逐点求解,从而实现了CRT的谐波优化调节模式。算例分析显示谐波优化调节模式的谐波性能明显优于目前公认的谐波性能最好的固定单支路调节模式。最后借助CRT等值电路仿真模型指出文中提出的谐波优化方法的本质是基于谐波对消原理,在相控方式下,"对消"原理比已有的"稀释"原理能够更显著地减小CRT注入电网的谐波含量。展开更多
间歇采样转发式干扰与雷达发射信号相参,可以获得部分脉压增益,具有极强的干扰效果,亟需有效的干扰先验知识对抗。针对该问题,本文根据间歇采样转发干扰脉冲压缩后的结果,构造出含有加窗向量的非线性整数优化模型,将参数估计问题转化为...间歇采样转发式干扰与雷达发射信号相参,可以获得部分脉压增益,具有极强的干扰效果,亟需有效的干扰先验知识对抗。针对该问题,本文根据间歇采样转发干扰脉冲压缩后的结果,构造出含有加窗向量的非线性整数优化模型,将参数估计问题转化为向量估计问题,然后利用交替方向乘子法(Alternating Direction Method of Multipliers,ADMM)将非线性整数优化模型分解为整数归整模型和连续模型,求解出加窗向量,实现切片宽度和数量的估计。最后计算机仿真验证了该方法的有效性。展开更多
Small signal instability may cause severe accidents for power system if it can not be dear correctly and timely. How to maintain power system stable under small signal disturbance is a big challenge for power system o...Small signal instability may cause severe accidents for power system if it can not be dear correctly and timely. How to maintain power system stable under small signal disturbance is a big challenge for power system operators and dispatchers. Time delay existing in signal transmission process makes the problem more complex. Conventional eigenvalue analysis method neglects time delay influence and can not precisely describe power system dynamic behaviors. In this work, a modified small signal stability model considering time varying delay influence was constructed and a new time delay controller was proposed to stabilize power system under disturbance. By Lyapunov-Krasovskii function, the control law in the form of nonlinear matrix inequality （NLMI） was derived. Considering synthesis method limitation for time delay controller at present, both parameter adjustment method by using linear matrix inequality （LMI） solver and iteration searching method by solving nonlinear minimization problem were suggested to design the controller. Simulation tests were carried out on synchronous-machine infinite-bus power system. Satisfactory test results verify the correctness of the proposed model and the feasibility of the stabilization approach.展开更多
A design and optimization approach of dynamic and control performance for a two-DOF planar manipulator was proposed.After the kinematic and dynamic analysis,several advantages of the mechanism were illustrated,which m...A design and optimization approach of dynamic and control performance for a two-DOF planar manipulator was proposed.After the kinematic and dynamic analysis,several advantages of the mechanism were illustrated,which made it possible to obtain good dynamic and control performances just through mechanism optimization.Based on the idea of design for control(DFC),a novel kind of multi-objective optimization model was proposed.There were three optimization objectives:the index of inertia,the index describing the dynamic coupling effects and the global condition number.Other indexes to characterize the designing requirements such as the velocity of end-effector,the workspace size,and the first mode natural frequency were regarded as the constraints.The cross-section area and length of the linkages were chosen as the design variables.NSGA-II algorithm was introduced to solve this complex multi-objective optimization problem.Additional criteria from engineering experience were incorporated into the selecting of final parameters among the obtained Pareto solution sets.Finally,experiments were performed to validate the linear dynamic structure and control performances of the optimized mechanisms.A new expression for measuring the dynamic coupling degree with clear physical meaning was proposed.The results show that the optimized mechanism has an approximate decoupled dynamics structure,and each active joint can be regarded as a linear SISO system.The control performances of the linear and nonlinear controllers were also compared.It can be concluded that the optimized mechanism can achieve good control performance only using a linear controller.展开更多
文摘变压器式可控电抗器(controllable reactor of transformer type,CRT)目前的调节模式仅限于单绕组调节模式,此时CRT的谐波电流含量无法满足要求更高的应用场合。为进一步改善CRT的谐波性能,提出了多绕组调节模式的基本概念;采用分段线性化的方法,推出CRT工作绕组瞬时电流的计算通式;利用傅里叶级数分析方法求得工作绕组电流基波及各次谐波分量有效值与各触发角之间的函数关系式。将CRT整个容量范围进行离散,依次以各离散容量点为等式约束,以CRT向电网注入的谐波电流含量为目标函数,建立非线性优化模型,并调用Matlab中的求解非线性约束最小化问题的函数(Fmincon)逐点求解,从而实现了CRT的谐波优化调节模式。算例分析显示谐波优化调节模式的谐波性能明显优于目前公认的谐波性能最好的固定单支路调节模式。最后借助CRT等值电路仿真模型指出文中提出的谐波优化方法的本质是基于谐波对消原理,在相控方式下,"对消"原理比已有的"稀释"原理能够更显著地减小CRT注入电网的谐波含量。
文摘半挂车辆的非稳定运动学特性为其泊车过程中自主运动规划带来严峻挑战。针对半挂车在多障碍物的静态场景中泊车运动规划算法效率低、结果平滑性差等问题,本文提出了序列式运动规划方法(sequential motion planning algorithm,SMPA)。首先,提出了基于二次规划策略和改进双向快速扩展随机树(bidirectional rapidly-exploring random tree algorithm,Bi-RRT)的初始路径生成方法。然后,结合车辆非完整微分约束下的路径节点可行性判别方法研究,提出基于概率的目标偏向采样策略,提高了采样效率。最后,构建了面向车辆系统控制变量连续性的非线性最优化控制模型,解决泊车换向点的对接问题,提高了泊车轨迹平滑性。仿真结果表明,该方法在多障碍物场景中,规划时间相比Hybrid A*和Bi-RRT分别降低了86.71%和21.44%,轨迹质量也更具优越性。
文摘间歇采样转发式干扰与雷达发射信号相参,可以获得部分脉压增益,具有极强的干扰效果,亟需有效的干扰先验知识对抗。针对该问题,本文根据间歇采样转发干扰脉冲压缩后的结果,构造出含有加窗向量的非线性整数优化模型,将参数估计问题转化为向量估计问题,然后利用交替方向乘子法(Alternating Direction Method of Multipliers,ADMM)将非线性整数优化模型分解为整数归整模型和连续模型,求解出加窗向量,实现切片宽度和数量的估计。最后计算机仿真验证了该方法的有效性。
基金Project(51007042)supported by the National Natural Science Foundation of China
文摘Small signal instability may cause severe accidents for power system if it can not be dear correctly and timely. How to maintain power system stable under small signal disturbance is a big challenge for power system operators and dispatchers. Time delay existing in signal transmission process makes the problem more complex. Conventional eigenvalue analysis method neglects time delay influence and can not precisely describe power system dynamic behaviors. In this work, a modified small signal stability model considering time varying delay influence was constructed and a new time delay controller was proposed to stabilize power system under disturbance. By Lyapunov-Krasovskii function, the control law in the form of nonlinear matrix inequality （NLMI） was derived. Considering synthesis method limitation for time delay controller at present, both parameter adjustment method by using linear matrix inequality （LMI） solver and iteration searching method by solving nonlinear minimization problem were suggested to design the controller. Simulation tests were carried out on synchronous-machine infinite-bus power system. Satisfactory test results verify the correctness of the proposed model and the feasibility of the stabilization approach.
基金Project(2009AA04Z216) supported in part by the National High Technology Research and Development Program of ChinaProject(2009ZX04013-011) supported by the National Science and Technology Major Program of ChinaProject(20092302120068) supported by the Doctoral Program of Higher Education of China
文摘A design and optimization approach of dynamic and control performance for a two-DOF planar manipulator was proposed.After the kinematic and dynamic analysis,several advantages of the mechanism were illustrated,which made it possible to obtain good dynamic and control performances just through mechanism optimization.Based on the idea of design for control(DFC),a novel kind of multi-objective optimization model was proposed.There were three optimization objectives:the index of inertia,the index describing the dynamic coupling effects and the global condition number.Other indexes to characterize the designing requirements such as the velocity of end-effector,the workspace size,and the first mode natural frequency were regarded as the constraints.The cross-section area and length of the linkages were chosen as the design variables.NSGA-II algorithm was introduced to solve this complex multi-objective optimization problem.Additional criteria from engineering experience were incorporated into the selecting of final parameters among the obtained Pareto solution sets.Finally,experiments were performed to validate the linear dynamic structure and control performances of the optimized mechanisms.A new expression for measuring the dynamic coupling degree with clear physical meaning was proposed.The results show that the optimized mechanism has an approximate decoupled dynamics structure,and each active joint can be regarded as a linear SISO system.The control performances of the linear and nonlinear controllers were also compared.It can be concluded that the optimized mechanism can achieve good control performance only using a linear controller.
