基于自适应改进K-Means聚类算法的黑启动分区方法

针对目前黑启动分区方法中大多利用边介数法对系统进行划分并不能很好地满足系统恢复的时间性和安全性要求,在分析黑启动系统特点和分区要求的基础上,对K-Means算法进行了自适应改进,根据电网的拓扑和电气特性将系统简化为无向有权网络,利用改进后的K-Means算法对系统进行黑启动分区,并以IEEE 39节点和118节点系统为例对所提算法进行验证。结果表明,改进后的K-Means算法的分区结果更为合理,且降低了计算难度、减少了计算量。     

噪声背景下基于激光雷达点云数据的分裂导线自动提取与三维重建

提出了基于改进DPC算法的具有强抗噪性的分裂导线自动提取与三维重建方法。以噪声背景下的输电线路点云数据为分析对象,首先根据特征分析法滤除输电线路点云中的地物点和杆塔点,并采用K-MEANS聚类方法提取每根电力线点云;然后提出改进DPC算法实现分裂子导线点云的聚类和提取;最后采用最小二乘法实现各分裂子导线三维模型重建。并与K-MEANS算法的聚类结果进行了对比,证明了改进DPC算法的强抗噪性和鲁棒性。     

高效构建Delaunay三角网算法研究及应用解决方案

针对海量数据不规则三角网(TIN)的构建及现有方法存在时间复杂度高、运行速度慢等缺陷,通过对逐点内插法的改进,利用简化数据结构和使用标准模板库(STL)、改进三角形查找方法、改进外接圆检测方法等构网核心算法和技术,有效地提高了三角网构网效率,成功地解决了对海量数据的处理.     

基于改进YOLO-v3的风力机叶片表面损伤检测识别

为对风力机叶片损伤状态进行有效检测，提出一种基于改进YOLO-v3算法的风力机叶片表面损伤检测识别技术。根据风力机叶片损伤区域特点，对网络中锚框（anchor）的尺度进行调整优化；在特征提取网络后引入基于注意力机制的挤压与激励网络（squeeze and excitation networks,SENet）结构，使YOLO-v3算法更加关注与目标相关的特征通道，提升网络性能。结果表明，改进后算法的平均精度为84.42%，较原YOLO-v3算法提升了6.14%，检测时间减少了21 ms，改进后的YOLO-v3算法能较好地识别出风力机叶片表面损伤。     

基于n阶LMS自适应滤波的改进型谐波检测方法

通过分析多种谐波检测方法,提出一种FBD法和ip-iq法相结合的谐波电流检测方法 ,并对低通滤波环节进行改进。首先设计了一种在三相四线制系统中计算相对简单的谐波电流检测方法,在降低算法复杂性的同时保障了灵活性;其次使用添加了闭环回路的n阶LMS自适应滤波算法模块替代低通滤波器模块,能把测得的基波电流反馈到输入电流中,增强了滤波环节的跟踪速度和动态特性;最后通过仿真验证了改进的谐波电流检测方法的优越性和精确性。结果表明,该方法具有较高的应用价值。     

CNC系统中传统插补法的改进-弧度分割法

首先介绍了CNC系统中常用的插补算法-逐点比较插补算法的工作原理,并对其进行了速度分析。为了在此基础上进一步提高数控机床加工速度,提出了一种新的插补算法-弧度分割插补法,在对其工作原理进行了详细介绍之后,进一步进行了加工速度和加工精度分析,通过分析,证明弧度分割法无论是在加工速度和精度上都有了很大的提高。     

改进的SSOR-PCG快速求解法在高面板堆石坝求解效率和节约内存中的实践

针对大型高面板堆石坝有限元计算中常用的直接法存在存储空间大、计算时间长的问题,根据刚度矩阵稀疏性特点,采用对称逐步超松弛预处理共轭梯度法(SSOR-PCG法)的改进算法求解线性方程组,并提出了与该算法相适应的有限元刚度矩阵压缩存储的新方法,以典型面板堆石坝为例,将快速求解法和一维半带宽直接法在计算精度、内存占用、计算耗时三方面进行了比较分析。结果表明,快速求解法具有精度高、速度快、占用内存少的优点,可应用于大规模土石坝有限元分析中。     

基于改进粒子群组合算法的电网基建年度投资预测

利用SPSS软件对基建投资的主要影响因素进行了分析,并分别利用多元线性回归法、BP神经网络法、灰色系统理论法对基建投资进行了预测。为了获得更加准确的预测结果,采用了一种基于改进粒子群的组合算法,将3种方法的预测结果进行优化组合,得到最终的预测值。经过算例分析表明,该方法能够有效提高预测精度,得到较好的预测结果。     

基于IMRAN的电站锅炉效率与NO_x排放模型

电站锅炉高效低NOx燃烧优化技术越来越受到人们的重视,而锅炉燃烧效率和NOx排放模型是高效低NOx燃烧优化的基础.从提高网络的泛化能力着手,对最小资源分配网络算法的隐节点删减策略进行改进,加入惩罚策略和合并策略,并把改进的MRAN算法应用到对电站锅炉NOx排放与效率的实时建模上.仿真结果表明,改进的MRAN算法除了具有一般MRAN算法的优点外,还具有比MRAN网络更加紧凑的结构.提出的网络算法具有多输出结构,可同时预测NOx排放与效率,适于用在电站锅炉的NOx排放与效率的燃烧实时整体优化中.     

基于改进混合差分进化算法的水轮机调速系统空载PID参数优化

为优化水轮发电机组调速系统空载PID相关参数,提出一种改进混合差分进化算法(IHDE),即先根据某电站混流式水轮发电机组建立相应空载工况数学模型,其次引入IHDE对空载工况数学模型PID参数进行优化,由于DE算法易出现早熟收敛问题,对该算法缩放因子的取值进行优化;同时,为了增强差分进化算法(DE)的全局搜索性能,在DE的选择阶段加入模拟退火算法的个体更新机制进行选择操作;然后,提出一种改进的综合ITAE指标用于评价空载扰动的仿真结果,使得目标函数的评价方式更加准确且符合相关标准要求;最后,通过试验仿真与不同算法进行对比,验证了IHDE优化水轮发电机组调速系统PID参数的有效性。     

Performance simulation of heat recovery steam generators in a cogeneration system

The performance simulation of heat recovery steam generators in a cogeneration system has been investigated to see the effect of pinch and approach points on steam generation and also on temperature profiles across the heat recovery steam generator. The effects of operating conditions on steam production and also on exit gas temperature from the heat recovery steam generator are discussed. Low pinch point results in improved heat recovery steam generator performance due to reduced irreversibilites. The supplementary firing enhances the steam production. © 1998 John Wiley & Sons, Ltd.     

On-line estimation of synchronous Generator parameters using a damper current observer and a graphic user interface

This paper presents a method to identify synchronous generator parameters from on-line data measured at the terminals of the machine. An observer for estimation of synchronous generator damper currents is designed and implemented. The observer-estimator is used in a Graphic User Interface (GUI) application. Possible internal machine fault conditions can be detected and remedial action can be applied. Noise filtering and bad data detection and rejection are implemented to increase the reliability of the estimates. Saturation of the synchronous generator inductances is also considered. Secondary objectives include calculation of the error characteristics of the estimation, development of an index of confidence, study of the observability of generator parameters, and evaluation of alternative GUI features.     

Improvement to observability measures of LFO modes in power systems with DFIGs

Observation of the low-frequency oscillation (LFO) modes in power systems is important to design the damping scheme. The state equations of the power system with the doubly-fed induction generators (DFIGs) are derived to find the LFO modes related to the synchronous generator (SGs) and the DFIGs. The definition of the observability measure is improved to consider the initial output and the attenuation speed of the modes. The sensitivities of the observability measures to the control parameters are derived. The numerical results from the small and large-disturbance validate the LFO modes caused by the DFIGs, and different observability measures are compared. Adjustment of the control parameters is chosen based on the sensitivity model to improve the observability and damping ratio of the LFO mode, and the stability of the wind power system.     

Differentiation of multiple maximum power points of partially shaded photovoltaic power generators

Partial shading conditions have a major effect on the electrical characteristics of photovoltaic (PV) power generators. In this paper, the effects of partial shading on maximum power points (MPPs) of a PV power generator have been systematically studied by using Simulink simulation model of a PV power generator composed of 18 series-connected PV modules. It is shown that the local MPPs can be classified into MPPs at low and high voltages based on the MPP operating point of the PV generator. The results also show that based on the MPP current and voltage it is possible to directly know if the MPP at high voltages is a local or a global MPP. The differentiation between local and global MPPs at high voltages is based on the voltage difference between the actual MPP voltage at high voltages and the theoretical MPP voltage under corresponding uniform conditions. This differentiation method was also tested to work correctly by utilizing experimental measurements of the Tampere University of Technology Solar PV Power Station Research Plant. By using this method, it can be identified if the system is operating at a local or a global MPP. This method can further be utilized to develop global MPP tracking algorithms.     

Optimized photovoltaic generator–water electrolyser coupling through a controlled DC–DC converter

The coupling of a photovoltaic generator and an electrolyser is one of the most promising options for obtaining hydrogen from a renewable energy source. Both are well known technologies, however, since the high variability of the solar radiation, an efficient coupling still presents some challenges. Direct or through a DC–DC converter couplings are the options in isolated applications. In this work, three models, respectively, for a photovoltaic (PV) generator, a controlled DC–DC converter and a complete proton exchange membrane (PEM) electrolyser have been designed by using Matlab/Simulink. A PV-electrolyser specific algorithm to search for the optimum and safe working point for both elements is presented. Simulation results demonstrate that the use of a controlled DC–DC converter with the proposed algorithm shows better adaptability to the variable radiation conditions than the other coupling options. Therefore, it leads to a better compliance between the electrolyser and the sizing of the PV generator.     

A maximum power tracking algorithm based on Impp = f(Pmax) function for matching passive and active loads to a photovoltaic generator

In this paper, a method that forces a photovoltaic generator (PVG) to operate at its maximum power point under variable load and insolation conditions is developed. The method is based on closed loop current control, in which the reference current is determined from the fitted function of I_mpp versus P_max, points of a particular PVG. A simplified computer model of the PVG is given and computer simulations for demonstrating the effectiveness of the proposed algorithm are presented. The method has also been applied using a PC with IO interface card in the laboratory. From the results of the simulations and experimental studies, it is concluded that the proposed approach can be used as a robust and fast acting maximum power point tracker.     

Regional Observability for Semilinear Distributed Parabolic Systems

The purpose of this paper is to explore the concept of regional observability for a class of semilinear distributed parabolic systems. Then we give an approach for the reconstruction of the state on a subregion of the evolution domain. We also study the variation of the estimated state error with respect to measurements errors. At last we present an approach based on fixed point techniques leading to a numerical approach which is successfully tested through an example.     

Laboratory experiment on using non-floating body to generate electrical energy from water waves

This paper describes an innovative method of using a non-buoyant body to harness ocean waves. All the point absorbers are buoyant in nature and move up due to buoyancy and come down because of gravity. The point absorbers are designed to move along the waves to make the device efficient. These devices face excessive stress during the rough weather on account of the extreme motion of waves and cause the total device failure. The present study shows that using a non-buoyant body for conventional point absorber principle is much efficient and safer than any other device proposed till today. A small scale wave energy converter with non-buoyant body was designed, fabricated and tested in small scale wave maker. An electrical generator was coupled with the device to generate electrical energy from harnessed waves. The generator was electrically loaded and the generated power was measured. It was found from the experiments that the proposed device showed a significant improvement in electricity generation and safety during extreme conditions. In addition to the electricity generation, the characteristics of the device were also studied by using various wave and device parameters.     

Analysis and assessment of a nanoparticle seeded small scale absorption refrigeration system driven by a low‐grade waste heat source

The thermoeconomic behaviour of a nanoparticle seeded single effect LiBr‐H₂O absorption refrigeration system (ARS) is investigated for a small scale application. In the proposed method, alumina nanoparticles with volume concentrations of 3%, 5%, and 7% are dispersed into an aqua lithium bromide solution. The multiobjective heat transfer search algorithm is employed to examine the design trade‐off between the coefficient of performance (COP) and total annualized cost (TAC). To analyze the overall performance of the system, the influence of five design parameters, namely the temperatures of the generator, absorber, evaporator, condenser and heat exchanger pipe diameter, are studied. It is found that with an increase in the COP, the TAC of the system is initially raised marginally, and after that, raised rigorously with further increment. The comparative results indicate that the COP and TAC of the nanofluid based ARS system are increased by about 7% and decreased by about 3.2%, respectively, corresponding to the Pareto points of the base ARS system. A lower break‐even point of about 2.6 years is achieved for the ARS system containing nanoparticles compared to the base ARS system. Overall, the ARS system containing 5% nanoparticles is the best solution from a thermodynamic and economic point of view.     

小型风电系统MPPT模糊／PID控制仿真研究

根据最大功率点跟踪的基本原理及常用风力发电控制系统的特点,提出了一种模糊／PID双模控制。具有在线参数调整的自适应占空比扰动法,该方法同步精度高,动态响应快,能迅速调整发电机与负载之间的功率匹配,减少最大功率点的振荡,使风力机以最佳叶尖速比运行。通过仿真实验表明,采用模糊／PID控制电路,能够快速准确的跟踪风力发电系统的最大功率点,改善最大功率点的振荡,减少能量损失,提高能量转换效率。