基于模拟退火遗传算法的水电站优化调度研究

采用模拟退火遗传算法(SAGA)研究了水电站优化调度问题,与GA和经典的DP算法相比,结果表明该算法具有较强的局部搜索能力和较好的收敛能力,能以较快的速度找到全局最优解,是一种有效的搜索方法,可用于水电站优化调度中。     

基于人群搜索算法的波浪发电系统最优负载

为寻求以提高波浪发电系统的平均输出功率为目标的系统最优负载,针对遗传算法、粒子群算法等优化算法存在早熟收敛和全局搜索能力不足的问题引入人群搜索算法。该算法通过建立目标函数值与步长的关系式,根据个体当前位置的适应度值计算下一步搜索步长;采用利己、利他和预动3个方向随机加权几何平均方案,确定个体搜索方向,提高个体全局搜寻能力,使算法避免陷入局部最优解并可得到全局最优解。仿真结果表明,与传统粒子群优化算法相比,所提算法收敛速度快,可增加波浪发电系统的平均输出功率。     

基于连续蚁群算法的供水水库优化调度

针对供水水库优化调度问题,介绍了一种改进的连续蚁群算法。该算法借鉴蚁群算法的进化思想,主要包括局部搜索、全局搜索和信息素强度更新规则。在随机搜索过程中嵌入确定性搜索,以改善寻优性能,增加经验指导,从而加速收敛。将该算法与离散蚁群算法相比较,结果表明,该算法更优越,具有并行化和较强的全局寻优能力。     

基于改进参数的粒子群算法的换热网络优化

对于换热网络综合优化问题,粒子群算法能有效解决其容易陷入局部最优和无法收敛到全局最优的局限性。标准粒子群算法具有较强的随机性,可调节参数较少,不同的参数配置对算法的优化效果有显著影响。在分析粒子群算法中各参数特点的基础上,通过合理调整参数,使该算法在连续变量优化过程中具有更好的全局收敛性能。采用4股流体的小规模换热网络算例进行验证,优化结果表明,改进参数后的粒子群算法对计算换热网络综合问题有效。     

基于熵增理论的优化算法研究及其应用

针对传统机械优化算法所存在的问题提出了一种基于熵增理论的优化算法。该算法将系统的演化过程和优化问题在解空间的寻优过程相对应，将系统的构形参数与优化问题的设计变量相对应，以系统的平衡态作为优化设计问题的最优点，以系统熵最大或系统能量最小作为系统收敛的准则。在算法研究过程中，运用模拟退火算法这种可获得全局最优的抽样算法作为系统演化的机制，可以保证优化问题的全局最优性。运用该算法对数学测试函数和内燃机配气机构凸轮的轮廓曲线进行了设计，所得结果表明了该算法的有效性。     

基于全局信息融合粒子群算法的水轮发电机模型参数辨识

针对粒子群(PSO)优化算法辨识发电机模型参数时存在局部最优和后期收敛速度慢很难准确获取具有强泛化能力的模型参数的问题,提出了一种基于多粒子全局信息共享和变权重的全局信息融合PSO算法(GPSO),并通过IEEE3机9节点系统算例验证了该算法的有效性。结果表明,与常规PSO算法相比,该算法具有泛化能力强、辨识精度高和后期收敛速度快的优点。     

基于改进粒子群算法的机组负荷优化分配

针对标准粒子群算法存在容易早熟收敛的问题,在分析机组负荷优化问题的基础上,提出了一种基于解约束机制、边界反弹规则、高斯分布序列和混沌序列的改进粒子群算法。算法采用解约束机制和边界反弹规则处理优化问题的约束条件,同时在粒子移动过程中引入了高斯分布序列和混沌序列,从而克服了算法过早收敛的缺陷,提高了算法的全局优化能力。实例计算结果表明,该算法具有稳定的全局优化能力,为机组负荷优化分配问题的求解提供了新的方法。     

基于同伦法和改进的牛顿—拉夫逊法相结合的直流网络潮流分析

鉴于直流网络潮流算法的研究总体上尚处于起步阶段,特别是在收敛速度和初值选取方面仍存在缺陷,从网络分析角度出发建立直流网络方程组,在分析直流网络潮流模型的基础上进行变量分类,推演出改进的直流网络潮流算法。该算法利用同伦方法的全局收敛性获取网络的初始值,并结合改进的牛顿-拉夫逊法快速收敛到稳定解,使其同时满足计算稳定性和收敛速度的要求,适用于直流系统的在线计算和分析。算例仿真分析表明,该算法对初值要求低、收敛速度快,结果正确有效。     

基于自适应遗传算法的配电网络重构

针对目前配电网络重构基本遗传算法GA易发生早熟、非全局收敛及收敛速度慢等问题,提出了一种基于改进自适应GA配网重构方法,将最优保存策略和两两竞争相结合的方法作为新选择操作数,采用随最优个体相对保留代数自适应变化交叉和变异操作数,将最优个体最少保留代数作为算法终止条件.算例结果表明,该法全局搜索能力强、收敛速度快,为配电网络重构寻优奠定了理论基础.     

基于布谷鸟搜索算法优化BP模糊Petri网的水电机组故障诊断

针对水电机组故障诊断的复杂性和传统算法存在的缺点,提出采用布谷鸟搜索算法优化BP模糊Petri网进行故障诊断。首先利用布谷鸟搜索算法的全局搜索功能对网络参数寻优,将得出的全局最优解作为BP模糊Petri网的最优初始参数,再用选取的故障样本数据对模糊Petri网进行学习训练,建立故障特征集到故障类型集的映射关系以实现故障分类。仿真试验表明,该故障诊断方法收敛速度快、准确率高,可应用于实际水电机组故障诊断。     

A fuzzy control strategy for power smoothing and grid dynamic response enrichment of a grid‐connected wind energy conversion system

This paper concentrates on the output power smoothing and the grid dynamic response enhancement of a grid‐interactive MW‐class permanent magnet synchronous generator‐based wind energy conversion system (WECS). A simple fuzzy controller method is applied to improve the overall performance of the WECS. The proposed method can retrieve the storing kinetic energy from the inertia of a wind turbine, perfectly. As a result, it can ensure a proficient power smoothing of the variable speed WECS. On the other hand, the grid side inverter is controlled by the fuzzy controller. This approach can reduce the fluctuation of DC link voltage and can deliver a smooth power to the power grid. The proposed method is compared with two other methods such as the maximum power point tracking control method and the without fuzzy controller method. A simple shunt circuit also includes in the DC link circuit. Therefore, during the system fault condition, the WECS can perform a stable operation. Effectiveness of the proposed method is verified by numerical simulations. Copyright © 2013 John Wiley & Sons, Ltd.     

Auxiliary health diagnosis method for lead-acid battery

This paper proposes a health auxiliary diagnosis method for the lead-acid battery unit. The proposed method is based on Approximate Entropy (ApEn). Since ApEn can quantify the regularity of a data sequence and the discharging curve for a health lead-acid battery unit is smooth, the proposed method can detect the degradation of battery unit caused by the internal short, opening of internal shorted or cell undergoing reversal using the distorted discharging curve. Aging experiments for the lead-acid battery are developed to verify the proposed method. The experimental results verify that the proposed health auxiliary diagnosis method can diagnosis the degradation of battery unit caused by the internal short, opening of internal shorted or cell undergoing reversal.     

基于HHT的旋转机械故障诊断方法研究

希尔伯特黄变换(Hilbert-Huang Transformation，HHT)，是先把一列时间序列数据通过经验模态分解(Empirical Mode Decomposition，EMD)，然后经过希尔伯特变换获得频谱的信号处理新方法。详细地介绍了HHT方法的理论和算法。首先，通过仿真信号把该方法与小波变换(Wavelet Transformation，WT)方法进行了比较研究，验证了方法的优越性；然后，把该方法用于旋转机械油膜涡动故障诊断中，研究结果表明：该方法相对传统的分析方法在较低转速区能更早发现油膜涡动故障，说明把基于HHT的时频分析方法用于旋转机械故障诊断是有效的。图11参8     

一种光伏电池最大输出功率的预测方法

光伏电池输出功率受温度和光强影响,且影响程度具有非线性特征。采用建立二维表的方式来预测光伏电池最大输出功率。该方法将预测功率转化为预测温度和光强,并根据温度和光强预测结果查表得到光伏电池最大输出功率。算例表明,文中所提出的方法能够较为准确地预测光伏电池最大输出功率。     

一种考虑海上风电支撑结构非零初始条件的动力响应计算方法

提出一种能够考虑海上风电支撑结构非零初始条件的动力响应计算方法。该方法创新之处在于将波浪等环境荷载用一系列极值及留数替代,从而可在Laplace域与非零初始条件影响项进行合并。分别采用海上风电单桩式和导管架式支撑结构进行验证。结果表明:除起始短暂时刻外,所提出新方法与传统时域方法计算结果基本一致。     

海上升压站Laplace域振动响应预报方法研究

针对传统时域预报方法的准确性依赖计算时间步长、频域法只能得到稳态响应的问题,基于Laplace变换提出一种新的海上升压站动力振动响应预报方法。通过解耦得到模态坐标系振动方程,在Laplace域求解海上升压站结构振动响应的极值和留数,进而得到时域响应。该方法考虑海上升压站的初始条件,可避免时域积分引起的误差。分别采用悬臂梁模型和导管架式海上升压站模型对该方法进行验证,结果表明了其振动响应预报的准确性。     

On a direct variational method for nonlinear heat transfer

In this paper it is shown, that the partial nonlinear differential equation can be reduced to the variational problem. By means of the variational technique based on the Kantorovich method, a nonlinear boundary value problem can be reduced to the set of the ordinary differential equations. The accuracy of the method is estimated by comparing the solutions of problems solved using the variational method and the other method. In this paper the method for the construction of the trial functions is also presented. Three examples are included to illustrate the above method.     

Green’s function method hybrid with the finite element method for ballistic phonon transport at low temperatures in nanostructures of arbitrary shape

An atomistic Green’s function method hybrid with the finite element method (FEM) is presented to analyze the ballistic phonon transport in a device with arbitrary geometries. Discretized by the FEM, the continuous system is transformed into a lattice system. In this analogy, the nodes play the role of atoms, and the stiffness matrix stands for the interaction between atoms. The method can be used to calculate the phonon transmission between the terminals of device, and the local density of states in the device. The validity of the method is demonstrated by the one- and three-dimensional cases and a comparison with the transfer matrix method. The method also can be used to investigate elastic waves in the acoustic metamaterials and phononic crystals.     

一种评判燃煤锅炉结渣特性的新方法

将 Vague 集理论引入燃煤锅炉结渣的评判中,同时采用距离意义下相似度量新方法对 4台运行锅炉进行了评判.结果表明:这种新的锅炉评判方法是合理可行的,与通常模式识别方法相比,此方法所得数据结果能使现场运行人员较容易得出当前运行锅炉的结渣状况,并能较好地消除干扰因素的影响.另外,笔者开发的在线评判系统不仅能对锅炉结渣状况进行实时监视,而且还具有扩充样本锅炉数据库和对数据结果进行有效处理的功能.     

Least‐squares based coulomb counting method and its application for state‐of‐charge (SOC) estimation in electric vehicles

Coulomb counting method is a convenient and straightforward approach for estimating the state‐of‐charge (SOC) of lithium‐ion batteries. Without interrupting the power supply, the remaining capacities of them in an electric vehicle (EV) can be calculated by integrating the current leaving and entering the batteries. The main drawbacks of this method are the cumulative errors and the time‐varying coulombic efficiency, which always lead to inaccurate estimations. To deal with this problem, a least‐squares based coulomb counting method is proposed. With the proposed method, the coulombic losses can be compensated by charging/discharging coulombic efficiency η and the measurement drift can be amended with a morbid efficiency matrix. The experimental results demonstrated that the proposed method is effective and convenient. Copyright © 2016 John Wiley & Sons, Ltd.