Stability analysis and stabilization for discrete-time singular delay systems are addressed,respectively.Firstly,a sufficient condition for regularity,causality and stability for discrete-time singular delay systems i...Stability analysis and stabilization for discrete-time singular delay systems are addressed,respectively.Firstly,a sufficient condition for regularity,causality and stability for discrete-time singular delay systems is derived.Then,by applying the skill of matrix theory,the state feedback controller is designed to guarantee the closed-loop discrete-time singular delay systems to be regular,casual and stable.Finally,numerical examples are given to demonstrate the effectiveness of the proposed method.展开更多
The robust reliable H∞ control problem for discrete-time Markovian jump systems with actuator failures is studied. A more practical model of actuator failures than outage is considered. Based on the state feedback me...The robust reliable H∞ control problem for discrete-time Markovian jump systems with actuator failures is studied. A more practical model of actuator failures than outage is considered. Based on the state feedback method, the resulting closed-loop systems are reliable in that they remain robust stochastically stable and satisfy a certain level of H∞ disturbance attenuation not only when all actuators are operational, but also in case of some actuator failures, The solvability condition of controllers can be equivalent to a feasibility problem of coupled linear matrix inequalities （LMIs）. A numerical example is also given to illustrate the design procedures and their effectiveness.展开更多
An indirect adaptive fuzzy control scheme is developed for a class of nonlinear discrete-time systems. In this method, two fuzzy logic systems are used to approximate the unknown functions, and the parameters of membe...An indirect adaptive fuzzy control scheme is developed for a class of nonlinear discrete-time systems. In this method, two fuzzy logic systems are used to approximate the unknown functions, and the parameters of membership functions in fuzzy logic systems are adjusted according to adaptive laws for the purpose of controlling the plant to track a reference trajectory. It is proved that the scheme can not only guarantee the boundedness of the input and output of the closed-loop system, but also make the tracking error converge to a small neighborhood of the origin. Simulation results indicate the effectiveness of this scheme.展开更多
The memory state feedback control problem for a class of discrete-time systems with input delay and unknown state delay is addressed based on LMIs and Lyapunov-Krasovskii functional method. Under the action of our des...The memory state feedback control problem for a class of discrete-time systems with input delay and unknown state delay is addressed based on LMIs and Lyapunov-Krasovskii functional method. Under the action of our designed adaptive control law, the unknown time-delay parameter is included in memory state feedback controller. Using LMI technique, delay-dependent sufficient conditions for the existence of the feedback controller are obtained. Finally, the effectiveness of the proposed design method is demonstrated by a numerical example.展开更多
This article deals with the robust stability analysis and passivity of uncertain discrete-time Takagi- Sugeno （T-S） fuzzy systems with time delays. The T-S fuzzy model with parametric uncertainties can approximate n...This article deals with the robust stability analysis and passivity of uncertain discrete-time Takagi- Sugeno （T-S） fuzzy systems with time delays. The T-S fuzzy model with parametric uncertainties can approximate nonlinear uncertain systems at any precision. A sufficient condition on the existence of robust passive controller is established based on the Lyapunov stability theory. With the help of linear matrix inequality （LMI） method, robust passive controllers are designed so that the closed-loop system is robust stable and strictly passive. Furthermore, a convex optimization problem with LMI constraints is formulated to design robust passive controllers with the maximum dissipation rate. A numerical example illustrates the validity of the proposed method.展开更多
The mixed l1/H2 optimization problem for MIMO (multiple input-multiple output) discrete-time systems is considered. This problem is formulated as minimizing the l1-norm of a closed-loop transfer matrix while maintaini...The mixed l1/H2 optimization problem for MIMO (multiple input-multiple output) discrete-time systems is considered. This problem is formulated as minimizing the l1-norm of a closed-loop transfer matrix while maintaining the H2-norm of another closed-loop transfer matrix at prescribed level. The continuity property of the optimal value in respect to changes in the H2-norm constraint is studied. The existence of the optimal solutions of mixed l1/H2 problem is proved. Because the solution of the mixed l1/H2 problem is based on the scaled-Q method, it avoids the zero interpolation difficulties. The convergent upper and lower bounds can be obtained by solving a sequence of finite dimensional nonlinear programming for which many efficient numerical optimization algorithms exist.展开更多
A multivariable regression(MVR) approach is proposed to identify the real power transfer between generators and loads.Based on solved load flow results,it first uses modified nodal equation method(MNE) to determine re...A multivariable regression(MVR) approach is proposed to identify the real power transfer between generators and loads.Based on solved load flow results,it first uses modified nodal equation method(MNE) to determine real power contribution from each generator to loads.Then,the results of MNE method and load flow information are utilized to determine suitable regression coefficients using MVR model to estimate the power transfer.The 25-bus equivalent system of south Malaysia is utilized as a test system to illustrate the effectiveness of the MVR output compared to that of the MNE method.The error of the estimate of MVR method ranges from 0.001 4 to 0.007 9.Furthermore,when compared to MNE method,MVR method computes generator contribution to loads within 26.40 ms whereas the MNE method takes 360 ms for the calculation of same real power transfer allocation.Therefore,MVR method is more suitable for real time power transfer allocation.展开更多
To avoid unstable learning, a stable adaptive learning algorithm was proposed for discrete-time recurrent neural networks. Unlike the dynamic gradient methods, such as the backpropagation through time and the real tim...To avoid unstable learning, a stable adaptive learning algorithm was proposed for discrete-time recurrent neural networks. Unlike the dynamic gradient methods, such as the backpropagation through time and the real time recurrent learning, the weights of the recurrent neural networks were updated online in terms of Lyapunov stability theory in the proposed learning algorithm, so the learning stability was guaranteed. With the inversion of the activation function of the recurrent neural networks, the proposed learning algorithm can be easily implemented for solving varying nonlinear adaptive learning problems and fast convergence of the adaptive learning process can be achieved. Simulation experiments in pattern recognition show that only 5 iterations are needed for the storage of a 15×15 binary image pattern and only 9 iterations are needed for the perfect realization of an analog vector by an equilibrium state with the proposed learning algorithm.展开更多
目前,现有研究缺乏对综合能源系统为上级电力系统提供灵活性支持潜力的评估,且未充分考虑综合能源系统内部多元负荷不确定性对上述潜力的影响,提出一种基于保守度自适应优化的综合能源系统鲁棒灵活性评估方法。首先,从上级电力系统视角...目前,现有研究缺乏对综合能源系统为上级电力系统提供灵活性支持潜力的评估,且未充分考虑综合能源系统内部多元负荷不确定性对上述潜力的影响,提出一种基于保守度自适应优化的综合能源系统鲁棒灵活性评估方法。首先,从上级电力系统视角出发,以综合能源系统的外部电力需求为量化指标,建立综合能源系统灵活性的确定性评估模型;其次,考虑多元负荷的不确定性,改进传统鲁棒优化模型的保守度约束条件,提出保守度参数自适应优化方法,在此基础上对外部电力需求区间上、下界分别建立max-min-max和min-max-min二阶段鲁棒优化模型;再次,利用KKT(Karush-Kuhn-Tucker)条件、McCormick松弛对子问题中存在的双层结构进行对偶和线性化处理,采用列与约束生成(column and constraint generation,C&CG)算法将二阶段鲁棒优化模型分解为主问题与子问题循环求解。最后,结合算例验证了本评估模型和求解方法的有效性。展开更多
为解决综合能源系统(integrated energy system,IES)多元负荷序列间耦合特性紧密复杂、准确预测难度较大的问题,提出一种基于模态分解与多任务学习模型的IES多元负荷短期预测方法。首先,为处理原始负荷序列的强随机性特征,采用多元变分...为解决综合能源系统(integrated energy system,IES)多元负荷序列间耦合特性紧密复杂、准确预测难度较大的问题,提出一种基于模态分解与多任务学习模型的IES多元负荷短期预测方法。首先,为处理原始负荷序列的强随机性特征,采用多元变分模态和样本熵将多元负荷序列同步分解重构出高、中、低3种频段的模态分量;其次,构建基于多头注意力机制的多任务学习混合预测模型动态分配耦合特征,对于复杂度较高的中高频序列,采用单编码器-多解码器结构的多任务Transformer模型充分挖掘负荷波动信息,对于低频序列,基于双向门控循环单元网络提取平稳分量特征。最后,将各分量预测结果叠加得到多元负荷最终预测结果。基于美国亚利桑那州立大学Tempe校区的多元负荷数据进行测试,结果表明:所提方法电、冷、热负荷平均绝对百分比误差分别为0.61%、0.80%及0.83%,相比其他模型具有更高的求解精度和计算效率。展开更多
基金supported by the National Natural Science Foundation of China (6090400960974004)
文摘Stability analysis and stabilization for discrete-time singular delay systems are addressed,respectively.Firstly,a sufficient condition for regularity,causality and stability for discrete-time singular delay systems is derived.Then,by applying the skill of matrix theory,the state feedback controller is designed to guarantee the closed-loop discrete-time singular delay systems to be regular,casual and stable.Finally,numerical examples are given to demonstrate the effectiveness of the proposed method.
基金the National Natural Science Foundation of China (60574001)Program for New Century Excellent Talents in University (05-0485)Program for Innovative Research Team of Jiangnan University
文摘The robust reliable H∞ control problem for discrete-time Markovian jump systems with actuator failures is studied. A more practical model of actuator failures than outage is considered. Based on the state feedback method, the resulting closed-loop systems are reliable in that they remain robust stochastically stable and satisfy a certain level of H∞ disturbance attenuation not only when all actuators are operational, but also in case of some actuator failures, The solvability condition of controllers can be equivalent to a feasibility problem of coupled linear matrix inequalities （LMIs）. A numerical example is also given to illustrate the design procedures and their effectiveness.
基金surported by Tianjin Science and Technology Development for Higher Education(20051206).
文摘An indirect adaptive fuzzy control scheme is developed for a class of nonlinear discrete-time systems. In this method, two fuzzy logic systems are used to approximate the unknown functions, and the parameters of membership functions in fuzzy logic systems are adjusted according to adaptive laws for the purpose of controlling the plant to track a reference trajectory. It is proved that the scheme can not only guarantee the boundedness of the input and output of the closed-loop system, but also make the tracking error converge to a small neighborhood of the origin. Simulation results indicate the effectiveness of this scheme.
基金supported by the National Natural Science Foundation of China (60574006 60804017+2 种基金 608350017)the Foundation of Doctor(20060286039)the Jiangsu Provincal Sustentation Fund of Recruiting Post Doctor(1660631171)
文摘The memory state feedback control problem for a class of discrete-time systems with input delay and unknown state delay is addressed based on LMIs and Lyapunov-Krasovskii functional method. Under the action of our designed adaptive control law, the unknown time-delay parameter is included in memory state feedback controller. Using LMI technique, delay-dependent sufficient conditions for the existence of the feedback controller are obtained. Finally, the effectiveness of the proposed design method is demonstrated by a numerical example.
基金supported by the National Natural Science Foundation of China(60710002)Self-Planned Task of State Key Laboratory of Robotics and System(SKLRS200801A03).
文摘This article deals with the robust stability analysis and passivity of uncertain discrete-time Takagi- Sugeno （T-S） fuzzy systems with time delays. The T-S fuzzy model with parametric uncertainties can approximate nonlinear uncertain systems at any precision. A sufficient condition on the existence of robust passive controller is established based on the Lyapunov stability theory. With the help of linear matrix inequality （LMI） method, robust passive controllers are designed so that the closed-loop system is robust stable and strictly passive. Furthermore, a convex optimization problem with LMI constraints is formulated to design robust passive controllers with the maximum dissipation rate. A numerical example illustrates the validity of the proposed method.
基金This project was supported by the National Nature Science Foundation of China (60374009)Nature Science Foundation of Guangdong Province of China (990795).
文摘The mixed l1/H2 optimization problem for MIMO (multiple input-multiple output) discrete-time systems is considered. This problem is formulated as minimizing the l1-norm of a closed-loop transfer matrix while maintaining the H2-norm of another closed-loop transfer matrix at prescribed level. The continuity property of the optimal value in respect to changes in the H2-norm constraint is studied. The existence of the optimal solutions of mixed l1/H2 problem is proved. Because the solution of the mixed l1/H2 problem is based on the scaled-Q method, it avoids the zero interpolation difficulties. The convergent upper and lower bounds can be obtained by solving a sequence of finite dimensional nonlinear programming for which many efficient numerical optimization algorithms exist.
文摘A multivariable regression(MVR) approach is proposed to identify the real power transfer between generators and loads.Based on solved load flow results,it first uses modified nodal equation method(MNE) to determine real power contribution from each generator to loads.Then,the results of MNE method and load flow information are utilized to determine suitable regression coefficients using MVR model to estimate the power transfer.The 25-bus equivalent system of south Malaysia is utilized as a test system to illustrate the effectiveness of the MVR output compared to that of the MNE method.The error of the estimate of MVR method ranges from 0.001 4 to 0.007 9.Furthermore,when compared to MNE method,MVR method computes generator contribution to loads within 26.40 ms whereas the MNE method takes 360 ms for the calculation of same real power transfer allocation.Therefore,MVR method is more suitable for real time power transfer allocation.
基金Project(50276005) supported by the National Natural Science Foundation of China Projects (2006CB705400, 2003CB716206) supported by National Basic Research Program of China
文摘To avoid unstable learning, a stable adaptive learning algorithm was proposed for discrete-time recurrent neural networks. Unlike the dynamic gradient methods, such as the backpropagation through time and the real time recurrent learning, the weights of the recurrent neural networks were updated online in terms of Lyapunov stability theory in the proposed learning algorithm, so the learning stability was guaranteed. With the inversion of the activation function of the recurrent neural networks, the proposed learning algorithm can be easily implemented for solving varying nonlinear adaptive learning problems and fast convergence of the adaptive learning process can be achieved. Simulation experiments in pattern recognition show that only 5 iterations are needed for the storage of a 15×15 binary image pattern and only 9 iterations are needed for the perfect realization of an analog vector by an equilibrium state with the proposed learning algorithm.
文摘目前,现有研究缺乏对综合能源系统为上级电力系统提供灵活性支持潜力的评估,且未充分考虑综合能源系统内部多元负荷不确定性对上述潜力的影响,提出一种基于保守度自适应优化的综合能源系统鲁棒灵活性评估方法。首先,从上级电力系统视角出发,以综合能源系统的外部电力需求为量化指标,建立综合能源系统灵活性的确定性评估模型;其次,考虑多元负荷的不确定性,改进传统鲁棒优化模型的保守度约束条件,提出保守度参数自适应优化方法,在此基础上对外部电力需求区间上、下界分别建立max-min-max和min-max-min二阶段鲁棒优化模型;再次,利用KKT(Karush-Kuhn-Tucker)条件、McCormick松弛对子问题中存在的双层结构进行对偶和线性化处理,采用列与约束生成(column and constraint generation,C&CG)算法将二阶段鲁棒优化模型分解为主问题与子问题循环求解。最后,结合算例验证了本评估模型和求解方法的有效性。
文摘为解决综合能源系统(integrated energy system,IES)多元负荷序列间耦合特性紧密复杂、准确预测难度较大的问题,提出一种基于模态分解与多任务学习模型的IES多元负荷短期预测方法。首先,为处理原始负荷序列的强随机性特征,采用多元变分模态和样本熵将多元负荷序列同步分解重构出高、中、低3种频段的模态分量;其次,构建基于多头注意力机制的多任务学习混合预测模型动态分配耦合特征,对于复杂度较高的中高频序列,采用单编码器-多解码器结构的多任务Transformer模型充分挖掘负荷波动信息,对于低频序列,基于双向门控循环单元网络提取平稳分量特征。最后,将各分量预测结果叠加得到多元负荷最终预测结果。基于美国亚利桑那州立大学Tempe校区的多元负荷数据进行测试,结果表明:所提方法电、冷、热负荷平均绝对百分比误差分别为0.61%、0.80%及0.83%,相比其他模型具有更高的求解精度和计算效率。
