Stability control of multi-parameter adaptive wireless communication systems based on multi-Lyapunov function

With the occurrence of burst interference,bit error rate( BER) stability of the wireless communication system( WCS) always degrades significantly. To cope with it,a stability control algorithm is proposed,utilizing the stability theory of switched systems,which is specifically applicable for multi-parameter adaptive WCS with spectrum sensing ability,and it is capable of stabilizing BER within a reasonable range. Firstly,WCS is modeled as a switched system. Then,based on the multi-Lyapunov function,controlling rules are presented to enable the switched system to satisfy stable condition asymptotically. Finally,analysis and numerical simulation results demonstrate that the switched WCS with the proposed controlling rules is superior to conventional power-controlled WCS with or without state feedback control in terms of stability performance.

Global Practical Stabilization of Discrete-Time Switched Affine Systems via a General Quadratic Lyapunov Function and a Decentralized Ellipsoid

This paper addresses the problem of global practical stabilization of discrete-time switched affine systems via statedependent switching rules.Several attempts have been made to solve this problem via different types of a common quadratic Lyapunov function and an ellipsoid.These classical results require either the quadratic Lyapunov function or the employed ellipsoid to be of the centralized type.In some cases,the ellipsoids are defined dependently as the level sets of a decentralized Lyapunov function.In this paper,we extend the existing results by the simultaneous use of a general decentralized Lyapunov function and a decentralized ellipsoid parameterized independently.The proposed conditions provide less conservative results than existing works in the sense of the ultimate invariant set of attraction size.Two different approaches are proposed to extract the ultimate invariant set of attraction with a minimum size,i.e.,a purely numerical method and a numerical-analytical one.In the former,both invariant and attractiveness conditions are imposed to extract the final set of matrix inequalities.The latter is established on a principle that the attractiveness of a set implies its invariance.Thus,the stability conditions are derived based on only the attractiveness property as a set of matrix inequalities with a smaller dimension.Illustrative examples are presented to prove the satisfactory operation of the proposed stabilization methods.

一种新的Lure型Lyapunov函数及其在电力系统稳定性分析中的应用

本文构造了一类多变量非线性控制系统新的李雅普诺夫函数,并将它用于电力系统稳定性分析,得到了单机无穷大系统、多机系统的改进型李雅普诺夫函数。计算例题表明:该类型李雅鲁诺夫函数和传统的Lure型李雅普诺夫函数相比,能更准确地给出电力系统暂态稳定域。

Finite-time Stability of Heating Furnace Temperature Control System

A finite-time stabilization controller for the heating furnace temperature control system is proposed.Based on the extended Lyapunov finite-time stability theory and power integral method,a finite-time stable condition of the heating furnace temperature control system is given.The temperature of the heating furnace is directed by the finite-time stabilization controller to make it stable in finite time.And the quality and quantity of slabs is improved.The simulation example is presented to illustrate the applicability of the developed results.

Stability of Motion ＂In the Large＂ of Some Class of Phase Systems

This article focuses on the study of stability of motion of the phase systems described by differential equations whose right-hand sides are periodic in the angular coordinate. The article deals with the mathematical model which has been investigated for stability ＂in the large＂ using the second Lyapunov method. Based on the theoretical results obtained in the work,the computational experiments on concrete examples of electric power systems, which showedthe sufficient efficacy of the proposed method for the studied phase system, were conducted.

事件触发改进一致性算法的孤岛混合微电网并联互联变流器分布式协调控制策略

在交直流混合微电网中,并联互联变流器(parallel bidirectional power converters,BPCs)可以实现大容量的功率传输,以满足新型电力系统在空间上的供需匹配。如何在占用更少资源的同时协调控制BPCs实现功率的比例共享,是交直流混合微电网中BPCs控制的研究难点。因此,该文设计了一种针对BPCs的事件触发改进一致性协调控制策略。以归一化下垂控制为基础,提出了改进的比例功率一致性算法,实现BPCs间高精度比例功率共享。在此之上,基于BPCs比例功率误差建立事件触发改进一致性算法,并预设触发函数的预判阈值,从而降低系统在稳定状态下的通信次数。最后进行仿真对比分析,结果表明该文提出的方法相比基本一致性算法通信量减少98.35%;同时,与现有控制策略相比,该文提出的方法有着更好的控制性能。

基于鲁里叶型Lyapunov函数的电力系统次同步谐振稳定运行域的分析

将汽轮发电机六段轴系模型转化成标准鲁里叶控制系统,应用鲁里叶型Lyaponov函数对该非线性系统在平衡位置的稳定性进行详细的分析,确定轴系的稳定运行域,为电力系统SSR稳定运行域的可视化描述提供了新的思路。由于该方法是直接针对非线性系统的,故对小干扰和大扰动下的轴系扭振的分析均能适用。对IEEE第一基准模型(两段和六段轴系)的仿真结果表明了该方法的有效性。

基于权值评估的Lyapunov时滞稳定判据改进方法

在含有时滞环节的电力系统稳定性分析中,基于Lyapunov稳定理论和线性矩阵不等式(LMI)技术的时滞稳定判据被广泛采用。然而,这类判据往往存在计算量大、计算效率低的问题,尤其在高维系统中计算效率迅速降低,亟需寻求科学手段来提高判据计算效率。对此,文中借助数值计算方法,分析了Lyapunov函数各构成项随时间的变化规律及各项占函数的权值,进而提出一种通过权值计算来甄别Lyapunov函数冗余项的有效方法。通过剔除冗余项,减少了判据的待求变量数,在不影响判据保守性前提下,有效提高了计算效率。最后,通过典型二阶时滞系统和3机9节点时滞系统分别对两种Lyapunov时滞稳定判据进行简化改进,验证了文中方法的有效性。

基于自由矩阵积分不等式方法的电力系统时滞相关稳定性分析

研究了电力系统时滞相关鲁棒稳定性问题。首先,建立了考虑系统时滞的电力系统模型;然后,通过构造时滞乘积增广型Lyapunov-Krasovskii泛函,并应用自由矩阵积分不等式方法,对泛函导数进行界定,得到了低保守性的稳定新判据;最后,通过单机无穷大系统、4机11节点系统和典型二阶系统验证了所提方法的有效性。

Transient Stability Analysis of Large-scale Power Systems:A Survey

Transient stability analysis is a key problem in power system operation and planning.This paper aims at giving a comprehensive review on the modeling ideas and analysis methods for transient stability of large-scale power systems.For model construction,the general modeling of traditional power systems and special modeling for renewable generations and high-voltage direct-current transmissions are introduced.For transient stability analysis,Lyapunov based methods and non-Lyapunov based methods are thoroughly reviewed.In Lya-punov based methods,we focus on the energy function method,the sum-of-squares based method and decentralized stability analysis methods.Meanwhile,in non-Lyapunov based methods,the time-domain simulation,extended equal-area criterion and data-driven based methods are considered.The basic working principles,features and recent research progresses of all the above-mentioned methods are described in detail.In particular,their performances on several aspects,such as computational speed,conservativeness of stability region estimation or stability margin calculation,and adaptability to various types of system models,are mentioned.Finally,a brief discussion of potential directions for future research on transient stability analysis of large-scale power systems is included.Index Terms-connective stability,large-scale system analysis,Lyapunov functions,power systems,transient stability analysis.

融合储能的光伏发电系统并网逆变器建模与稳定性分析

以新能源为主体的新型电力系统中,大量电力电子器件接入系统,导致其暂态行为改变且拓扑结构状态变量阶数变高。针对上述问题,基于下垂控制方法建立了融合储能的光伏发电系统并网逆变器模型,采用奇异摄动降阶理论与变量梯度法构建了其李雅普诺夫函数。然后,将构建的李雅普诺夫函数与等面积法则相结合,分析了储能系统的接入对新能源系统功角稳定的影响,同时验证了储能系统对光伏系统出力支撑以及出力波动的抑制能力。最后,基于Matlab仿真结果对融合储能的新能源系统特性进行了分析和验证。

时变时滞多区域互联电力系统滑模负荷频率控制方法

开放式通信网络在互联电力系统中的普遍使用,使原来专用通道的恒定时滞变成了时变时滞。时变时滞恶化了负荷频率控制(LFC)的动态性能,导致系统频率不稳定,因此提出了一种用于时变时滞多区域互联电力系统的滑模LFC方法,并基于Lyapunov泛函进行了稳定性分析。首先,Caputo型分数阶Lyapunov泛函被引入到稳定性分析,通过调整函数积分的上限,减少了稳定性分析的保守性;然后,结合Lyapunov理论和积分不等式,得到线性矩阵不等式描述的时变时滞电力系统的稳定性条件;最后,通过仿真,验证了所提出的控制策略对LFC动态性能的影响,及对负载扰动和风机功率波动的鲁棒性。

基于Lyapunov函数的MMC-RPC非线性控制策略

为综合治理牵引供电系统中的电能质量问题,以功率补偿向量图为基础,分析V/v牵引变压器左右两侧供电区间的功率关系,选取模块化多电平的铁路功率调节器(MMC-RPC)为研究对象,通过有功功率平衡、无功功率补偿和谐波功率反向注入等方式综合治理牵引供电系统中的负序、谐波等电能质量问题。在整个MMC-RPC控制系统中,为提高系统正常工作时内外部扰动下的鲁棒性,通过Lyapunov函数的非线性控制方法对MMC-RPC进行控制,外环采用定功率和定电压的控制策略,内环则采用基于Lyapunov函数的非线性控制策略;内环从稳定性角度出发,选取最优控制参数,保证供电臂上的线路参数在发生摄动或者负载切换时,系统仍能稳定可靠运行。在MATLAB/Simulink中搭建MMC-RPC仿真系统,模拟牵引网负载突变和线路参数摄动时,控制系统的动态调节和抗扰动能力,与传统双闭环PI控制策略效果相比,展现了该控制策略的可行性和有效性。

基于新积分不等式的时滞负荷频率控制系统稳定性分析

该文研究了具有时变时滞和负荷扰动的负荷频率控制系统的稳定性问题。首先,构造新的增广向量和具有多重积分项的Lyapunov-Krasovskii泛函,建立不同变量间的耦合关系;其次,为了与所构造的泛函紧密配合,提出基于时滞相关矩阵和自由矩阵的积分不等式及基于时滞相关矩阵的反凸组合不等式,对泛函导数进行更精确的估计,从而得到具有较小保守性的负荷频率控制系统的稳定性判据;最后,通过对典型二阶时滞系统和单区域时滞负荷频率控制系统进行仿真分析,验证了所得的稳定性判据具有较小保守性,并分析了负荷扰动和控制器参数对系统时滞上界的影响。

基于一种改进型事件触发传输机制的网络欺骗性攻击下的电力系统负荷频率控制

研究了网络攻击下的电力系统事件触发负荷频率控制问题.为了减少网络中的非必要资源浪费,提出了一种新的事件触发传输机制.与一般的事件触发机制相比,这种事件触发传输机制利用了历史信号数据信息.结合电力系统网络环境中所存在的网络攻击,建立了一种广义的电力系统状态空间系统模型.运用李雅普诺夫稳定性定理,通过构造一种依赖于系统状态的分段李雅普诺夫泛函,并结合积分不等式,推导出能够保证网络攻击下的电力系统均方渐近稳定性定理,该定理既能获得负荷频率控制器增益,又能得出事件触发参数.最后,在仿真分析部分,通过考虑电力系统网络中有无攻击的两种情况去说明了文中所提出的方法的有效性与优越性.

基于瞬态能量函数法的电力系统暂态稳定性分析

随着“双碳”目标的提出并持续推进,电力系统向清洁型方向转变的需求更加强烈,更多的新能源出力将代替常规发电机组出力,导致系统的稳定性发生改变。基于瞬态能量函数法对常规机组被新能源机组取代后的电力系统的暂态稳定性进行分析,探讨新能源比例不断提高对电力系统造成的影响,并提出改善策略。

Stability Analysis of Sampled-data Control System and Its Application to Electric Power Market

The stability of sampled-data systems is investigated using a new type of Lyapunov functional.The interval from the sampling point t_(k) to t_(k+1) is assumed to be a sampling interval.By fully utilizing the characteristic information on the whole sampling interval,a new two-sided closed-loop Lyapunov functional is proposed,which utilizes the information on both the intervals from the sampling point t to k_(t) and from t to t_(k+1).Based on the two-sided closed-loop Lyapunov functional and modified free-matrix-based inequality,a less conservative stability criterion is derived for a sampled-data control system,and three numerical examples are provided to verify the effectiveness and reduced conservativeness of the proposed method.Furthermore,the proposed method is applied to solve the stability problem of electric power markets,and the practical significance of reducing the conservativeness is discussed.

一个基于上界函数的暂态稳定域估计方法

基于多机系统均匀阻尼模型,借助拉格朗日中值定理和拉萨尔不变性原理提出了一个构建暂态稳定域的闭合子集的解析方法:一阶上界函数法。介绍了构建此稳定域方法的解析表达式和计算步骤,并针对 3 个不同的算例系统进行了系列仿真,结果表明该方法结果尽管保守,但严格可靠,该方法的显著特点是简单可靠,而且还避免了计算不稳定平衡点这个传统能量函数法存在的困难。

有源电力滤波器预测电流控制及稳定性分析

为补偿有源电力滤波器的控制延时,提出了一种基于横向滤波器的参考电流预测算法。该算法采用基于Widrow-Hoff学习算法的横向滤波器预测下一控制周期参考电流,结合空间矢量脉宽调制方法,实现APF预测电流控制。本文建立了预测电流控制的APF系统等效结构,将稳定性分析分解为电流预测算法稳定性和SVPWM稳定性两部分。通过Lyapunov函数分析参考电流预测算法的稳定性,根据SVPWM调制的APF闭环传递函数分析SVPWM部分的稳定性。APF的长期稳定运行结果证明了预测电流控制的有效性及APF稳定性分析的正确性。

基于李亚普诺夫方法的有源电力滤波器电流稳定控制

为确保负载和系统参数变化时有源电力滤波器的稳定运行,提出一种基于李亚普诺夫理论的控制方法。以补偿电流和直流侧电压的跟踪误差作为状态向量和输出向量,逆变器开关通断的占空比为输入向量来建立状态方程。用状态向量构建李亚普诺夫函数,根据稳定条件确定输入向量,保证控制过程的收敛性。考虑到时变负载会引起直流侧电压较大的波动,用直流侧电压的平均值来建立状态向量。分析系统参数与性能之间的关系,得到参数的取值范围。通过Matlab/Simulink进行整流负载和直流调速负载仿真实验,在负载时变和系统参数变化的情况下,有源电力滤波器运行稳定,证明该方法的有效性。