共查询到20条相似文献，搜索用时 125 毫秒
1.
Modeling of D-STATCOM in distribution systems load flow 总被引：1，自引：0，他引：1
HOSSEINI Mehdi SHAYANFAR Heidar Ali FOTUHI-FIRUZABAD Mahmud 《浙江大学学报(A卷英文版)》2007,8(10):1532-1542
This paper presents modeling of Distribution STATCOM (D-STATCOM) in load flow calculations for the steady- state voltage compensation. An accurate model for D-STATCOM is derived to use in load flow calculations. The rating of this device as well as the direction of required reactive power injection for voltage compensation in the desired value (1 p.u.) is de- rived and discussed analytically and mathematically by the phasor diagram method. Furthermore, an efficient method for node and line identification used in load flow calculations is presented. The validity of the proposed model is examined by using two standard distribution systems consisting of 33 and 69 nodes, respectively. The best location of D-STATCOM for under voltage problem mitigation approach in the distribution networks is determined. The results validate the proposed model for D- STATCOM in large distribution systems. 相似文献
2.
This paper presents a novel approach to find optimum locations and capacity of flexible alternating current transmission system （FACTS） devices in a power system using a multi-objective optimization function. Thyristor controlled series compensators （TCSCs） and static var compensators （SVCs） are the utilized FACTS devices. Our objectives are active power loss reduction, newly introduced FACTS devices cost reduction, voltage deviation reduction, and increase on the robustness of the security margin against voltage collapse. The operational and controlling constraints, as well as load constraints, were considered in the optimum allocation. A goal attainment method based on the genetic algorithm （GA） was used to approach the global optimum. The estimated annual load profile was utilized in a sequential quadratic programming （SQP） optimization sub-problem to the optimum siting and sizing of FACTS devices. Fars Regional Electric Network was selected as a practical system to validate the performance and effectiveness of the proposed method. The entire investment of the FACTS devices was paid offand an additional 2.4% savings was made. The cost reduction of peak point power generation implies that power plant expansion can be postponed. 相似文献
3.
引入开关函数的概念,考虑了统一潮流控制器(UPFC)各相桥臂电力电子器件具体的开关状态以及三相电网电压的不平衡因素,建立了可反映UPFC装置内部开关特性和运行机理的UPFC暂态数学模型.该模型能够反映UPFC最终的输入控制量及输出量,并合理地设计了应用于该模型的电压空间矢量脉宽调制(SVPWM)控制方案. 相似文献
4.
传统的机电暂态仿真对电力电子装置例如HVDC和FACTS采用准稳态模型,因而不能仿真动态过程中电压、电流的变化.而电磁暂态仿真程序（例如EMTP,EMTDC）受计算规模的限制,一般要对研究对象的外部电力系统进行等值化简,因此,不能反映系统机电暂态过程对电磁暂态过程的影响.该文中的混合仿真算法为弥补上述两种方法的不足,对电力网络采用准稳态模型,而对待研究的电力电子装置使用电磁暂态模型,EMTP仿真中考虑了频率偏移对电磁暂态仿真的影响.混合仿真算法为研究各种FACTS电力电子装置及其控制系统的动态性能提供了一种实用的工具. 相似文献
5.
随着大系统的互联,出现了区域间振荡现象．为抑制这种振荡,本文提出了一种新的ＦＡＣＴＳ装置,并根据输电线模型和纵向机电模型的相似性,推导了该ＦＡＣＴＳ装置的最佳参数和最佳安装位置的确定方法．用一４２０ｋＶ 纵向系统和一个复杂电力系统为例进行了仿真计算．结果显示该装置可有效地抑制区域间振荡． 相似文献
6.
Based on elastoplastic model, 2D and 3D finite element method (FEM) are used to calculate the stress and displacement distribution in the soft clay slope under gravity and uniform load at the slope top. Stability analyses indicate that 3D boundary effect varies with the stress level of the slope. When the slope is stable, end effect of 3D space is not remarkable. When the stability decreases, end effect occurs; when the slope is at limit state, end effect reaches maximum. The energy causing slope failure spreads preferentially along y-z section, and when the failure resistance capability reaches the limit state, the energy can extend along x-axis direction. The 3D effect of the slope under uniform load on the top is related to the ratio of load influence width to slope height, and the effect is remarkable with the decrease of the ratio. 相似文献
7.
为了满足工程上广泛应用的PI控制器的性能要求，又能克服一般PI控制器参数整定和调整的困难，基于dqo同步旋转坐标系下的UPFC串联侧的数学模型。采用BP神经网络PI控制器分别对有功和无功进行控制，使PI控制器的参数可以自动整定，省去了繁琐的人工整定过程，并能随系统的变化在线调节，使有功和无功达到较好的控制性能。 相似文献
8.
Vector shift (VS) is one of the typical methods used for islanding detection in distributed generations. This paper investigates the impact of both the active power imbalance and load variation on VS method. The investigation was conducted via simulation test in the power system dynamic simulation laboratory of Shandong University. The results show that it will take longer time for the VS relay to detect islanding state with the decrease of active power imbalance. In some cases, the vector shift angle is smaller than the setting and VS method would not be able to detect islanding state. In addition, the performance of VS method is impacted by the load variation in normal operation in which the distributed generator is operated in parallel with the main grid. The simulation results show that VS method would cause nuisance tripping if the load changes sharply. It can be summarized that VS method would be unable to reliably discriminate islanding state and normal system disturbances in some cases. 相似文献
9.
为了达到最佳的负载均衡效果，将负载分给多个服务器分担，负载控制器需要根据网络流量状态和服务器资源来分配负载，这就需要应用优化的负载分配策略，达到平均分配负载的目的，本文讨论了特定流量条件下网关数目的计算模型，分布式路由策略实现负载分配的策略的方法，并研究了基于网络地址转换在Free BSD unix环境下实现负载均衡网关的方法。 相似文献
10.
以3艘典型海洋运输主力船型(13500TEU集装箱船、46000 t成品油轮和47500DWT散货船)为研究对象,分别讨论其在结构吃水、设计吃水、空载吃水3种装载工况下纵倾调整对航行所需主机功率的影响。采用试验的方法获取缩比模型阻力并换算至实船主机功率,比较同一载重不同纵倾下主机功率相对平浮增减值。结果表明:三大主流船型纵倾姿态调整对主机功率影响显著,不同载重工况下将船舶调整至最佳纵倾工况主机功率有3%~4%的降低空间。基于最小航行阻力原则在实际运营时可将船舶调整至对应纵倾姿态。 相似文献
11.
黄靖 《福建工程学院学报》2012,10(6):588-591
针对目前中频发电机在满载时,采用开环控制运行下,系统抗干扰能力较差的问题,提出了一种基于自抗扰控制器（ADRC）的逆变器控制方法。自抗扰控制器完全独立于被控对象的具体数学模型,把系统所有不确定因素与外部扰动归结于系统总扰动,通过扩张状态观测器（ESO）对扰动进行观测,然后利用非线性状态误差反馈律（NLSEF）进行补偿。仿真和实验结果表明,所设计的自抗扰控制器能有效抑制负载及永磁发电机的干扰,具有良好的动态特性及较强的鲁棒性。 相似文献
12.
基于结构健康监测的润扬悬索桥有限元模型修正与验证 总被引：5，自引：0，他引：5
采用大型有限元分析软件ANSYS建立了润扬悬索桥的三维有限元模型并对其进行了自振特性分析,同时计算了各种工况下大桥的应力及位移响应.基于灵敏度的物理意义以及罚函数的思想,提出了一种结构有限元模型修正的新方法.该方法仍以自振特性为目标函数,以结构设计参数为待修正参数,但设计参数的上下限根据测试所得静力响应值和理论值的对比以及工程经验来确定,因此静力响应可用于验证修正后的有限元模型.采用结构健康监测系统数据及提出的方法对大桥有限元模型进行了修正与验证,得到了能够较好地反映大桥整体动静力性能的有限元基准模型,为润扬悬索桥的健康监测和损伤预警提供了研究基础. 相似文献
13.
WANG Wei JIN Ruo-jun JIANG Jing-ping 《浙江大学学报(A卷英文版)》2007,8(12):1889-1893
This paper develops a unified methodology for a real-time speed control of brushless direct-current motor drive systems in the presence of measurement noise and load torque disturbance. First, the mathematical model and hardware structure of system is established. Next, an optimal state feed back controller using the Kalman filter state estimation technique is derived. This is followed by an adaptive control algorithm to compensate for the effects of noise and disturbance. Those two algorithms working together can provide a very-high-speed regulation and dynamic response over a wide range of operating conditions. Simulated responses are presented to highlight the effectiveness of the proposed control strategy. 相似文献
14.
针对网络控制系统(NCS)存在时延的情况下如何设计控制器问题,提出了一种新的网络闭环控制系统建模方法-离散模糊T-S模型,并在此模型的基础上应用平行分布补偿原理设计了NCS模糊控制器;应用Lyapunov理论和LMI方法,研究了系统的模糊稳定控制问题,给出了基于线性矩阵不等式的不依赖时滞的状态反馈模糊控制器的设计方法,并获得了NCS模糊控制的稳定充分条件为求解一组线性矩阵不等式;通过仿真验证了该控制方法的有效性。 相似文献
15.
温控负荷是电力系统最为重要的负荷类型之一,它对电力系统的小干扰稳定具有重要的影响。针对这类以恒温控制器控制的负荷（温控负荷）展开研究,通过对恒温控制器动态加热方程的分析,建立用于小干扰稳定分析的温控负荷的数学模型。以3机9节点系统为算例在MATLAB的电力系统分析工具箱（PSAT）中对温控负荷接入电力系统后对系统小干扰稳定影响进行仿真分析。最后以简单的单机无穷大系统为例,进一步分析其负荷参数变化对系统小干扰稳定的影响。仿真分析结果表明:相对于传统的静态负荷温控负荷不利于系统小干扰电压稳定;温控负荷比例控制增益,环境温度,参考温度,对系统的小干扰稳定影响较大;积分控制器增益,积分控制器时间常数,负荷时间常数对系统小干扰稳定性影响较小。 相似文献
16.
为了解决基三分层互连网络(THIN)系统中的负载平衡问题,提出一种采用多播树技术提高节点间交换负载信息效率的动态负载平衡(DLB)算法--THINDLBA.设计了一套完整的DLB消息和各节点处的信息维护机制以辅助算法实现.重载节点的负载迁移请求消息沿着一棵以该节点为根的多播树传播,被该树覆盖的轻载节点均成为负载迁移的候选目标节点,可以沿着该树和重载节点交互负载信息,从而使重载节点能够在算法的一次执行中外迁最多的过载进程,尽快改善自身负载状态.算法设计中约束了多播树的构造过程,以避免因树间覆盖造成的消息误传或冗余.通过实验对比了4种DLB算法的性能,结果证明THINDLBA能更有效地缩减THIN系统处理计算密集型任务的时间. 相似文献
17.
A method was presented to implement the detecting and tracking of moving targets through omnidirectional vision.The method combined optical flow with particle filter arithmetic.in which optical flow field was used to detect and locate moving targets and particle filter was used to track the detected moving objects.According to the circular image character of omnidirectionaI vision.the calculation equation of optical flow field and the tracking arithmetic of particle filter were improved based on the polar coordinates at the omnidirectional center.The edge of a randomly moving object could be detected by optical flow field and was surrounded by a reference region in the particle filter.A dynamic motion model was established to predict particle state.Histograms were used as the features in the reference region and candidate regions.The mutual information(MI)and Gaussian function were combined to calculate particle weights.Finally,the state of tracked object was computed by the total particle states with weights.Experiment results show that the proposed method could detect and track moving objects with better realtime performance and accuracy. 相似文献
18.
Thebubblecolumnreactor (BCR) ,withbatchfeedandcontinuousgasaerated ,hasobtainedwideapplica tionsinbiochemicalengineering ,chemicalengineeringandwastewatertreatment ,etc .OneimportantfeatureofBCRisthattheconversionandtheyieldofthereactioncanbehighlyincreasedundertheunsteady stateopera tion .Sincethemassandtheheattransferpropertiesinaprocessmainlydependontheflowbehavior ,itisstronglydesirabletoinvestigatetheunsteady stateflowstructurebeforethedesignandscale upofBCRwithhighreactiveconversionsa… 相似文献
19.
徐戊矫 《重庆大学学报(英文版)》2003,2(2)
1. Introduction The double-envelop hourglass worm gearing is characterized by multi-tooth line contact and good lubrication condition. It has high load-carrying capacity and is often built in heavy-duty machines. Like other line-contact gear drive, it is sensitive to manufacturing errors, misalignment errors and load-dependent deformations, which cause the tooth end contact and large transmission errors [1]. The classic theory for meshing analysis of a gear drive overlooks diverse errors and l… 相似文献