针对含新能源的多区域电力系统频率稳定问题,提出一种考虑控制信号更新周期变化的采样负荷频率控制(load frequency control,LFC)方案。首先,在充分考虑系统采样特性的基础上,建立新型电力系统采样LFC模型,并将模型转化为一个采样数据...针对含新能源的多区域电力系统频率稳定问题,提出一种考虑控制信号更新周期变化的采样负荷频率控制(load frequency control,LFC)方案。首先,在充分考虑系统采样特性的基础上,建立新型电力系统采样LFC模型,并将模型转化为一个采样数据网络控制系统。然后,利用整个采样区间[t_(k),t_(k+1))信息,构建一个新的双边闭环型Lyapunov泛函。结合所提出的泛函与自由矩阵不等式,导出系统的低保守性稳定准则。基于这个准则,提出确保系统镇定的采样控制器设计方法。最后,通过实例仿真验证了所提方法的有效性与优越性。展开更多
针对不确定性传输时滞、系统参数与负荷扰动,通信带宽约束与计算负担以及风电间歇性功率,引发系统调频性能下降的问题,提出一种考虑信号采样周期与传输时滞的采样PI负荷频率控制(Sampling PI Load Frequency Control,SPI-LFC)方案,并引...针对不确定性传输时滞、系统参数与负荷扰动,通信带宽约束与计算负担以及风电间歇性功率,引发系统调频性能下降的问题,提出一种考虑信号采样周期与传输时滞的采样PI负荷频率控制(Sampling PI Load Frequency Control,SPI-LFC)方案,并引入指数收敛率来评价系统的快速性.基于通信时滞采样数据网络,建立含风电的时滞电力系统SPI-LFC模型.通过构建新的双边闭环Lyapunov泛函,并利用线性矩阵不等式技术,推导系统采样周期与通信时滞稳定裕度,以及指数收敛率相关的稳定准则与SPI控制设计方法.仿真结果表明,所提方案具有较大的采样周期和通信时滞稳定裕度与较高的指数收敛率;对不确定性系统参数、负荷扰动和风电的间歇性功率也具有较强的鲁棒性.展开更多
For a sampled-data control system with nonuniform sampling, the sampling interval sequence, which is continuously distributed in a given interval, is described as a multiple independent and identically distributed (i....For a sampled-data control system with nonuniform sampling, the sampling interval sequence, which is continuously distributed in a given interval, is described as a multiple independent and identically distributed (i.i.d.) process. With this process, the closed-loop system is transformed into an asynchronous dynamical impulsive model with input delays. Sufficient conditions for the closed-loop mean-square exponential stability are presented in terms of linear matrix inequalities (LMIs), in which the relation between the nonuniform sampling and the mean-square exponential stability of the closed-loop system is explicitly established. Based on the stability conditions, the controller design method is given, which is further formulated as a convex optimization problem with LMI constraints. Numerical examples and experiment results are given to show the effectiveness and the advantages of the theoretical results.展开更多
Software Defined Network (SDN) makes network management more flexible by separating control plane and data plane, centralized control and being programmable. Although, network measurement still remains in primary stag...Software Defined Network (SDN) makes network management more flexible by separating control plane and data plane, centralized control and being programmable. Although, network measurement still remains in primary stage in SDN, it has become an essential research field in SDN management. In this context, this paper presents a low-cost high-accuracy measurement framework to support various network measurement tasks, such as throughput, delay and packet loss rate. In this framework, we only measure per-flow edge switches (the first and the last switches). In addition, a new adaptive sampling algorithm is proposed to significantly improve measurement accuracy and decrease network overhead. Meanwhile, we consider a low-cost topology discovery approach into our framework instead of topology discovery currently implemented by SDN controller frameworks. In order to improve the accuracy of delay, we also join a time threshold value to adjust the time delay. Furthermore, we consider and analyze the balance between measurement overhead and accuracy in several aspects. Last, we utilize POX controller to implement the proposed measurement framework. The effectiveness of our solution is demonstrated through simulations in Mininet and Matlab.展开更多
文摘针对含新能源的多区域电力系统频率稳定问题,提出一种考虑控制信号更新周期变化的采样负荷频率控制(load frequency control,LFC)方案。首先,在充分考虑系统采样特性的基础上,建立新型电力系统采样LFC模型,并将模型转化为一个采样数据网络控制系统。然后,利用整个采样区间[t_(k),t_(k+1))信息,构建一个新的双边闭环型Lyapunov泛函。结合所提出的泛函与自由矩阵不等式,导出系统的低保守性稳定准则。基于这个准则,提出确保系统镇定的采样控制器设计方法。最后,通过实例仿真验证了所提方法的有效性与优越性。
文摘针对不确定性传输时滞、系统参数与负荷扰动,通信带宽约束与计算负担以及风电间歇性功率,引发系统调频性能下降的问题,提出一种考虑信号采样周期与传输时滞的采样PI负荷频率控制(Sampling PI Load Frequency Control,SPI-LFC)方案,并引入指数收敛率来评价系统的快速性.基于通信时滞采样数据网络,建立含风电的时滞电力系统SPI-LFC模型.通过构建新的双边闭环Lyapunov泛函,并利用线性矩阵不等式技术,推导系统采样周期与通信时滞稳定裕度,以及指数收敛率相关的稳定准则与SPI控制设计方法.仿真结果表明,所提方案具有较大的采样周期和通信时滞稳定裕度与较高的指数收敛率;对不确定性系统参数、负荷扰动和风电的间歇性功率也具有较强的鲁棒性.
基金supported by National Natural Science Foundation of China (Nos.61104105,U0735003 and 60974047)Natural Science Foundation of Guangdong Province of China (No.9451009001002702)
文摘For a sampled-data control system with nonuniform sampling, the sampling interval sequence, which is continuously distributed in a given interval, is described as a multiple independent and identically distributed (i.i.d.) process. With this process, the closed-loop system is transformed into an asynchronous dynamical impulsive model with input delays. Sufficient conditions for the closed-loop mean-square exponential stability are presented in terms of linear matrix inequalities (LMIs), in which the relation between the nonuniform sampling and the mean-square exponential stability of the closed-loop system is explicitly established. Based on the stability conditions, the controller design method is given, which is further formulated as a convex optimization problem with LMI constraints. Numerical examples and experiment results are given to show the effectiveness and the advantages of the theoretical results.
文摘Software Defined Network (SDN) makes network management more flexible by separating control plane and data plane, centralized control and being programmable. Although, network measurement still remains in primary stage in SDN, it has become an essential research field in SDN management. In this context, this paper presents a low-cost high-accuracy measurement framework to support various network measurement tasks, such as throughput, delay and packet loss rate. In this framework, we only measure per-flow edge switches (the first and the last switches). In addition, a new adaptive sampling algorithm is proposed to significantly improve measurement accuracy and decrease network overhead. Meanwhile, we consider a low-cost topology discovery approach into our framework instead of topology discovery currently implemented by SDN controller frameworks. In order to improve the accuracy of delay, we also join a time threshold value to adjust the time delay. Furthermore, we consider and analyze the balance between measurement overhead and accuracy in several aspects. Last, we utilize POX controller to implement the proposed measurement framework. The effectiveness of our solution is demonstrated through simulations in Mininet and Matlab.
