针对持续扰动下的分布式状态耦合非线性系统,提出一种新的多耦合分布式经济模型预测控制(Economic model predictive control,EMPC)策略.由于耦合非线性系统的经济性能函数的非凸性和非正定性,首先引入关于经济最优平衡点的正定辅助函...针对持续扰动下的分布式状态耦合非线性系统,提出一种新的多耦合分布式经济模型预测控制(Economic model predictive control,EMPC)策略.由于耦合非线性系统的经济性能函数的非凸性和非正定性,首先引入关于经济最优平衡点的正定辅助函数和相应的辅助优化问题.接着,利用辅助函数的最优值函数构造原始分布式EMPC的一类隐式收缩约束.然后,建立状态耦合分布式EMPC的递推可行性和闭环系统关于最优经济平衡点的输入到状态稳定性(Input-to-state stability,ISS).最后,以耦合的四个连续搅拌釜反应器(Continuous stirred tank reactors,CSTRs)为例,验证本文所提策略的有效性.展开更多
文章提出基于贝叶斯推理的结构非线性概率模型参数估计方法,结合非线性参数的后验概率分布估计结果,实现结构在动力荷载作用下的失效概率预测。利用结构实测加速度响应作为输入,构建贝叶斯推理的似然函数,采用过渡马尔可夫蒙特卡洛(tran...文章提出基于贝叶斯推理的结构非线性概率模型参数估计方法,结合非线性参数的后验概率分布估计结果,实现结构在动力荷载作用下的失效概率预测。利用结构实测加速度响应作为输入,构建贝叶斯推理的似然函数,采用过渡马尔可夫蒙特卡洛(transitional Markov chain Monte Carlo,TMCMC)算法估计非线性概率模型参数的后验概率分布。当模型参数的后验概率分布被计算之后,利用更新后的参数后验概率分布作为输入,通过随机抽样算法预测结构在动力荷载作用下的失效概率。为验证方法的可行性,对地震荷载作用下的5层钢框架结构进行数值模拟,通过钢框架结构的缩尺振动台试验进一步验证该方法的有效性。研究结果表明:该方法能够准确实现非线性模型参数的后验概率密度计算,能够对结构在地震荷载下的失效概率进行有效预测。展开更多
馈线区段故障的快速准确辨识对于提升配电网可靠性与自愈性有重要作用。针对基于逻辑关系的间接故障定位方法在数值稳定性和决策效率上的不足,该文基于代数关系描述和互补约束理论构建了配电网故障区段定位的互补约束新模型,其优势在于...馈线区段故障的快速准确辨识对于提升配电网可靠性与自愈性有重要作用。针对基于逻辑关系的间接故障定位方法在数值稳定性和决策效率上的不足,该文基于代数关系描述和互补约束理论构建了配电网故障区段定位的互补约束新模型,其优势在于:1)避免了对群体智能算法的过分依赖,可采用数值稳定性好的梯度算法优化求解;2)利用互补约束条件将离散变量松弛为连续变量,降低了故障定位问题决策时的复杂性。在此基础上,提出基于扰动因子的故障定位模型光滑化求解算法。仿真表明,新模型和决策算法不仅能够实现馈线故障区段的准确高容错性辨识,且进行优化决策时具有数值稳定性好、优化效率高的优点,在大规模配电网故障定位中有良好的应用前景。Fast and exact feeder fault location method plays an important role in enhancing reliability and self-healing of distribution network.Logic relationship based conventional indirect fault location model and method has the drawbacks of excessive reliance on swarm intelligence algorithm in optimization computation,numerical optimization instability and low decision-making efficiency.In order to overcome the above shortcomings,on basis of algebra relationship description and complementary theory,a novel complementarity constraints fault location model is proposed as follows:1min()()1,0[(1),(2),,()],[(1),(2),,()],0,,i N S i N N f KB x x x NκκκN=?=???+=⊥=?==?≥∈∈?X∑X X X X X XκκκκRκR(1)Because the feasible points of the above complementarity constraints model can not satisfy the nonlinear programming constraint specification,the optimal solution can not be obtained by using the nonlinear programming to satisfy the Karush-Kuhn-Tucker(KKT)condition.In order to solve the novel fault location model effectively used by nonlinear programming directly,the Fischer-Burmeister auxiliary function with the perturbation factor is used to transform the complementarity constraints fault location model into a continuous smoothing model,which can satisfy the B-stability point.The smoothing model for fault location with complementarity constraints can be expressed as:212 2 2min(,,)()()()()11 2 0()()0[(1),(2),,()][(1),(2),,()][(1),(2),,()],0,N i N N F f i f x x x N N Nφφεφκκκεεε=?=+??=??+=??-++=??=?=?=??=?≥??∈∈?∑X X X XεX XκεX XκεεεκκεκRεR(2)In this model,the feasible point satisfies the nonlinear constraint specification,which can be solved by nonlinear programming directly.When the value of the perturbation factor tends to zero and the KKT extremum condition is established,the optimal decision vector of the fault location model can be obtained,so that the feeder fault section can be found.The correctness and effectiveness of the fault location model with complementarity constraints are verified by(sequence quadratic program)SQP in Matlab2010 a simulation platform.The simulation study shows that:1)The novel model of distribution network fault location based on the theory of complementarity constraints can effectively reflect the correlation characteristics between the causal devices,which can accurately locate the fault section of the feeder fault,and has high fault tolerance.2)The model is proposed based on relational algebra description modeling,so in optimization decision process can avoid the fault identification model excessive reliance on swarm intelligence algorithm in optimization computation,in which the gradient algorithm with good numerical stability can be used,which has the advantage in numerical stability.3)By through the feeder fault status information complementarity constraints conditions,the fault identification model can be transformed from discrete optimization space to continuous optimization space,which can effectively reduce the complexity of fault location model in optimization decision.4)The smoothing method based on the perturbation factor auxiliary penalty function can improve the non-smoothing characteristics of the complementarity constraints model,which can lead the optimal value to converge to the stable point,so as to accurately locate the feeder fault section.5)The novel fault location model and decision method proposed in this paper can be applied to the feeder fault location problem in large scale distribution network.展开更多
文摘针对持续扰动下的分布式状态耦合非线性系统,提出一种新的多耦合分布式经济模型预测控制(Economic model predictive control,EMPC)策略.由于耦合非线性系统的经济性能函数的非凸性和非正定性,首先引入关于经济最优平衡点的正定辅助函数和相应的辅助优化问题.接着,利用辅助函数的最优值函数构造原始分布式EMPC的一类隐式收缩约束.然后,建立状态耦合分布式EMPC的递推可行性和闭环系统关于最优经济平衡点的输入到状态稳定性(Input-to-state stability,ISS).最后,以耦合的四个连续搅拌釜反应器(Continuous stirred tank reactors,CSTRs)为例,验证本文所提策略的有效性.
文摘大量研究表明,粗粒材料的强度和变形特性受初始颗粒级配(grain size distribution,简称GSD)影响显著。然而,当前关于考虑颗粒初始GSD影响的粗粒材料本构模型的研究尚不多见。通过引入能够反映颗粒破碎难易程度的初始级配指标?,将材料初始GSD和终极GSD相联系,系统地探究并阐明了?对粗粒材料峰值抗剪强度qp和峰值应变εap以及e-p平面临界状态线(critical state line,简称CSL)位置的影响机制。针对?对qp和εap影响的研究表明,随着?增加,qp降低;而εap则随着?的增加而增加。结合上述结论,以沈珠江提出的驼峰型二次曲线模型为基础,建立了考虑初始级配和围压影响的切线杨氏模量;针对?对CSL位置影响的研究显示,随着?减小,CSL向下移动的同时还会沿逆时针方向旋转。基于此结论,以临界状态土力学为框架,通过引入状态参数,建立了考虑初始级配和围压影响与状态相关的切线泊松比。对一种粗粒材料而言,该模型只用一套模型参数,且模型预测结果与试验结果较为吻合。
基金Supported by National Natural Science Foundation of China （61164013, U1334211, 51174091）, the Key Program of China Ministry of Railway （2011Z002-D）, and Natural Science Foundation of Jiangxi Province （20122BAB201021）
文摘文章提出基于贝叶斯推理的结构非线性概率模型参数估计方法,结合非线性参数的后验概率分布估计结果,实现结构在动力荷载作用下的失效概率预测。利用结构实测加速度响应作为输入,构建贝叶斯推理的似然函数,采用过渡马尔可夫蒙特卡洛(transitional Markov chain Monte Carlo,TMCMC)算法估计非线性概率模型参数的后验概率分布。当模型参数的后验概率分布被计算之后,利用更新后的参数后验概率分布作为输入,通过随机抽样算法预测结构在动力荷载作用下的失效概率。为验证方法的可行性,对地震荷载作用下的5层钢框架结构进行数值模拟,通过钢框架结构的缩尺振动台试验进一步验证该方法的有效性。研究结果表明:该方法能够准确实现非线性模型参数的后验概率密度计算,能够对结构在地震荷载下的失效概率进行有效预测。
文摘馈线区段故障的快速准确辨识对于提升配电网可靠性与自愈性有重要作用。针对基于逻辑关系的间接故障定位方法在数值稳定性和决策效率上的不足,该文基于代数关系描述和互补约束理论构建了配电网故障区段定位的互补约束新模型,其优势在于:1)避免了对群体智能算法的过分依赖,可采用数值稳定性好的梯度算法优化求解;2)利用互补约束条件将离散变量松弛为连续变量,降低了故障定位问题决策时的复杂性。在此基础上,提出基于扰动因子的故障定位模型光滑化求解算法。仿真表明,新模型和决策算法不仅能够实现馈线故障区段的准确高容错性辨识,且进行优化决策时具有数值稳定性好、优化效率高的优点,在大规模配电网故障定位中有良好的应用前景。Fast and exact feeder fault location method plays an important role in enhancing reliability and self-healing of distribution network.Logic relationship based conventional indirect fault location model and method has the drawbacks of excessive reliance on swarm intelligence algorithm in optimization computation,numerical optimization instability and low decision-making efficiency.In order to overcome the above shortcomings,on basis of algebra relationship description and complementary theory,a novel complementarity constraints fault location model is proposed as follows:1min()()1,0[(1),(2),,()],[(1),(2),,()],0,,i N S i N N f KB x x x NκκκN=?=???+=⊥=?==?≥∈∈?X∑X X X X X XκκκκRκR(1)Because the feasible points of the above complementarity constraints model can not satisfy the nonlinear programming constraint specification,the optimal solution can not be obtained by using the nonlinear programming to satisfy the Karush-Kuhn-Tucker(KKT)condition.In order to solve the novel fault location model effectively used by nonlinear programming directly,the Fischer-Burmeister auxiliary function with the perturbation factor is used to transform the complementarity constraints fault location model into a continuous smoothing model,which can satisfy the B-stability point.The smoothing model for fault location with complementarity constraints can be expressed as:212 2 2min(,,)()()()()11 2 0()()0[(1),(2),,()][(1),(2),,()][(1),(2),,()],0,N i N N F f i f x x x N N Nφφεφκκκεεε=?=+??=??+=??-++=??=?=?=??=?≥??∈∈?∑X X X XεX XκεX XκεεεκκεκRεR(2)In this model,the feasible point satisfies the nonlinear constraint specification,which can be solved by nonlinear programming directly.When the value of the perturbation factor tends to zero and the KKT extremum condition is established,the optimal decision vector of the fault location model can be obtained,so that the feeder fault section can be found.The correctness and effectiveness of the fault location model with complementarity constraints are verified by(sequence quadratic program)SQP in Matlab2010 a simulation platform.The simulation study shows that:1)The novel model of distribution network fault location based on the theory of complementarity constraints can effectively reflect the correlation characteristics between the causal devices,which can accurately locate the fault section of the feeder fault,and has high fault tolerance.2)The model is proposed based on relational algebra description modeling,so in optimization decision process can avoid the fault identification model excessive reliance on swarm intelligence algorithm in optimization computation,in which the gradient algorithm with good numerical stability can be used,which has the advantage in numerical stability.3)By through the feeder fault status information complementarity constraints conditions,the fault identification model can be transformed from discrete optimization space to continuous optimization space,which can effectively reduce the complexity of fault location model in optimization decision.4)The smoothing method based on the perturbation factor auxiliary penalty function can improve the non-smoothing characteristics of the complementarity constraints model,which can lead the optimal value to converge to the stable point,so as to accurately locate the feeder fault section.5)The novel fault location model and decision method proposed in this paper can be applied to the feeder fault location problem in large scale distribution network.
