三相非对称系统对称化补偿的研究

在电网中,三相负荷随机变化,产生三相不平衡,从而给电网带来了一系列的问题.本文针对三相不平衡负荷的补偿原理和系统不平衡度进行了深入的研究,提出了全电容补偿策略.最后,根据补偿策略提出了一种新的控制算法,并对其进行的验证,表明此补偿策略是有效的.     

配电变压器负荷不平衡有源补偿技术应用研究

随着配网建设的推进和用电负荷的广泛接入,配电变压器负荷三相不平衡问题日益突出,本文研究有源三相不平衡补偿装置在配电台区的应用技术。首先指出了负荷三相不平衡带来的问题,并从理论上分析了该装置提高台区电能质量、降低配变和线路损耗的原理;然后基于贵州电科院“电网节能降损技术实验室”平台,模拟实际配变、线路及负荷情况,验证了该装置能在调节负荷不平衡的同时补偿无功,实验中还通过控制变量法得出影响装置降损效果的两个关键因数：装置接入点至变压器之间低压线路长度、装置自身效率,进而提出有源补偿装置应用于台区三相不平衡治理的技术改进方向;最后,在贵阳供电局安装了两台有源补偿装置,现场运行结果验证了理论分析和实验测试结果的正确性。     

基于链式SVG三相不平衡负荷的平衡补偿方法的仿真分析

本文对链式静止无功发生器的工作原理进行了分析,在深入研究三相不平衡负荷的平衡化补偿原理的基础上,提出了一种基于链式静止无功发生器在不平衡补偿时的分相补偿控制方法.该方法是通过对静止无功发生器各相输出电压与电网电压的相角差δ进行调节来控制各相输出电流,从而可以有效地对三相负载不平衡的系统进行平衡补偿.对所提出的补偿方法进行了仿真研究,仿真结果表明运用分相控制方法补偿三相不平衡负载,具有比较好的稳态补偿效果,补偿后电网电流三相平衡,各相电流与电压基本同相位并且幅值成相同的比例,达到了负载功率平衡和无功补偿的目的.     

智能化建筑电气低压配电负荷平衡控制方法

传统方法在进行电气低压配电负荷平衡控制时,单相负荷的换相不平稳,存在低压配电网三相负荷不平衡问题,设计智能化建筑电气低压配电负荷平衡控制方法.构建负荷平衡控制的整套流程框架,设计三相负荷平衡控制装置,通过功能单元实现单相负荷的平稳换相;采用叶节点负荷优先安排方法优化负荷分配方案,从而抑制谐波的产生,实现电流电压的稳定分配;建立不平衡补偿数学模型,使低压配电负荷平衡控制效果达到最佳,至此完成智能化建筑电气低压配电负荷平衡控制方法的研究.为验证文中方法的电气低压配电负荷平衡控制效果,设计比对实验.试验的结果表明,在建立的配电网中使用了设计的方法后,三相网侧电流波形基本能够实现正弦对称,三相不平衡度能够控制在国家标准要求的范围之内,验证了方法的有效性.     

配电变压器三相负荷不平衡对线损率的影响

三相负荷不平衡的状况,常常会在公共配电变压器负载中发生,假如三相负荷不平衡,就会加大电能在线路上面的损耗。如果三相负荷不平衡程度高出了20%,就会致使配电变压器中线的电流增大,严重着将会造成配电变压器烧毁等现象,配电变压器三相负荷不平衡的程度越大,电能的损耗就会越严重。     

矿热炉无功补偿系统仿真分析

在矿热炉系统工作过程中存在着功率因数低以及三相电流不平衡的现象,不仅消耗了大量的电能,同时也给整个供电系统带来了各种电能质量问题.可以通过对矿热炉系统的无功补偿能很好的解决上述两个问题,提出了以对称分量法为基础的无功补偿方法,并利用负荷正、负序瞬时有功、无功功率理论实现了对矿热炉系统的功率因数和三相平衡度多目标的控制.同时搭建了某矿热炉无功补偿系统的仿真模型,仿真结果表明,改进方法能有效地提高矿热炉系统的功率因数,并降低三相电流不平衡度,为矿热炉无功补偿系统的优化提供了科学的依据.     

中低压配电网不平衡无功补偿系统的设计

研究中低压配电网优化问题,针对感性负载和负载的不平衡造成电网损耗大、功率因数低等缺欠,传统的补偿装置往往只适用于三相三线制配电网或不能兼顾无功补偿和三相不平衡的校正.提出设计一种既适合三相三线制配电网又适用于三相四线制的中低压配电网不平衡无功补偿系统.运用新型无功补偿算法计算无功补偿量,再利用模糊控制器控制复合开关来实现电容投切.并通过MATLAB仿真证实设计的补偿系统既可以有效的校正三相不平衡又可以对系统无功功率进行补偿,为优化提供了参考.     

基于动态博弈的配变三相不平衡治理研究及应用

基于泛在电力物联网建设方向,结合三相负荷动态博弈分析技术,提出配变三相不平衡治理研究及应用,以信息化支撑配变三相不平衡治理,通过"户-相-变"拓扑关系自动识别和三相用户负荷动态博弈分析,提出用户相位关系调整建议,从而达到从源头治理配变三相负荷不平衡的目标.论文首先简述了配变三相不平衡治理由低压配电网拓扑关系数据采集、动态博弈分析和配变三相不平衡治理应用三部分组成,其次,介绍了采用边缘计算技术进行拓扑关系采集及校验,并通过三相用户负荷动态博弈建模,生成用户相位关系调整建议,辅助台区经理进行现场治理.最后展望系统对相关业务的支撑,旨在探讨电网企业应用配变三相不平衡治理系统的价值.     

论研究发明三相负荷不平衡测控仪原理及意义

电网改造极大的改变了低压电网的状况，但三相负荷不平衡，则可能使低压配电网的供电可靠性和运行稳定性也随之而降低，农村低压线损率上升幅度较大。本文介绍了三相负荷不平衡产生的原因及对用户生产生活带来危害，论述了研究发明三相负荷不平衡测控仪的原理及意义。     

三相负荷不平衡自动调节装置在低压配电网中的应用研究

本文通过对配电网系统中的三相负荷不平衡问题进行调查研究,分析三相四线制配电网系统中三相负荷不平衡产生的原因和危害,结合实际情况提出三相负荷不平衡智能控制系统方案,并对控制策略和工作原理进行介绍.通过选择典型台区安装试运行,计算分析结果表明设备投运后能够有效降低电能损耗,提高配电变压器台区的利用效率,保证配电网系统长期稳...     

三相四桥臂STATCOM的研究

在三相四线制电力用户中,负荷经常不平衡,零线电流大.三相四桥臂STATCOM专门用第四对桥臂对零线电流进行补偿.论文首先介绍了STATCOM的整体结构,还对无功电流检测方法和STATCOM的控制策略进行了介绍.在理论分析的基础上,利用MATLAB软件建立了系统的仿真模型,对带感性负载时稳态和不平衡情况下进行了模拟仿真,仿真结果验证了算法的可行性.     

光伏并网发电系统的DSP控制与实现

叙述了应用DSP控制光伏并网发电系统的原理和方法。DSP通过对并网系统交流侧两相电流，并网系统直流侧电压的采样和电网侧电压频率与相位的检测，运用瞬时无功功率理论，得出解藕的有功电流和无功电流分量，分别对有功电流和无功电流进行带PI调节的闭环控制，从而向电网输出有功功率和进行无功补偿。实验结果验证了用DSP控制的光伏并网发电系统是有效的和可行的。     

Economical Optimization of Grid Power Factor Using Predictive Data

We present an electrical grid optimization method for economical benefit. After simplifying an IEEE feeder diagram, we build a compact smart grid system including a photovoltaic-inverter system, a shunt capacitor, an on-load tapchanger (OLTC) and transmission lines. The system power factor (PF) regulation and reactive power dispatching are indispensable to improve power quality. Our control method uses predictive weather and load data to decide engaging or tripping the shunt capacitor, or reactive power injection by the photovoltaic-inverter system, ultimately to keep the system PF in a good range. From the perspective of economics, the economical model is considered as a decision maker in our predictive data control method. Capacitor-only control strategy is a common photovoltaic (PV) regulation method, which is treated as a baseline case. Simulations with GridLAB-D on profiled loads and residential loads have been carried out. The comparison results with baseline control strategy and our predictive data control method show the appreciable economical benefit of our method.      

Voltage stability evaluation of power system with FACTS devices using fuzzy neural network

Voltage stability has been a major concern for power system utilities because of several events of voltage collapses in the recent past. With the developments of flexible ac transmission system (FACTS) devices, power system performance has improved. This paper proposes an approach based on fuzzy neural network to calculate loadability margin of the power system with static synchronous compensator (STATCOM). A multi-input, single output fuzzy neural network is developed. Kohonen self-organizing map is employed to cluster the real and reactive loads at all the buses to reduce the input features, thus limiting the size of the network and reducing computational burden. Uncertainties of real and reactive loads, real and reactive generations, bus voltages and STATCOM parameters are taken into account by transforming them into fuzzy domains using combination of different nonlinear membership functions. A three-layered feed-forward neural network with fuzzy input variables is developed to evaluate the loadability margin. All ac limits are considered. The proposed methodology is applied to IEEE-30 bus and IEEE-118 bus systems. The proposed methodology is fast and accurate as compared to the conventional techniques. This method can also be used for online calculation of the voltage stability of the large power systems.     

永磁同步电机伺服系统功率主回路的设计

功率主回路是交流伺服系统的核心,直接驱动伺服电机工作,由三相整流电路、智能功率模块IPM组成。三相交流电流经功率主回路处理成近似对称的正弦交流电驱动永磁同步电机PMSM工作。良好性能的功率主回路是伺服系统获得好的动态性能和稳态精度的关键。     

Investigation of different load changes in wind farm by using FACTS devices

In this study, voltage, active power and reactive power variation of load bus were examined by Flexible AC Transmission Systems devices (FACTS) in grid-connected wind farm. In the system, FACTS devices, Static Synchronous Compensators (STATCOM), Static VAr Compensators (SVC), Static Synchronous Series Compensators (SSSC) and Thyristor Controlled Series Compensators (TCSC), were used. Also, dual feed induction generator (DFIG) was used as generator in the wind farm. This simulation study was done via Matlab/Simulink environment. According to different values of active and reactive loads at different times being attached to the system, shapes of load bus voltage, active power and reactive power variation were given, also the results were presented in tables. In the conclusion of this study, by means of FACTS devices that is used in the wind farm, instability was healed within a short time.     

基于DSP的PWM整流技术研究

介绍了基于TMS320LF2407控制的三相电压型PWM整流器数字系统,采用电压空间矢量脉宽调制（SVPWM）控制策略,实现了网侧输入电流的正弦化和单位功率因数运行。最后给出了实验波形。     

Psychophysical capacity of industrial workers for lifting symmetrical and asymmetrical loads symmetrically and asymmetrically for 8 h work shifts

This paper presents comprehensive maximum acceptable weight of lift (psychophysical lifting capacity) database for male and female industrial workers for lifting symmetrical and asymmetrical loads symmetrically and asymmetrically for 8h work shifts. The experimental data collected in previous studies on experienced (industrial) and inexperienced (non-industrial) materials handlers (Mital 1984a, Mital and Fard 1986) and the patterns of responses between the two populations (Mital 1985, 1987) were used to generate this database. Since previous work (Mital 1985, 1987) showed that responses of both experienced and inexperienced materials handlers to task variables are similar and also provided multipliers relating the psychophysical lifting capacities of the two populations, it was possible: (1) to convert psychophysical capacity data for asymmetrical lifting of symmetrical and asymmetrical loads, collected on inexperienced workers to reflect psychophysical lifting capacity of experienced workers for asymmetrical lifting; and (2) to take psychophysical lifting capacity data of experienced industrial workers for symmetrical lifting of symmetrical loads and generate from it their psychophysical lifting capacity for symmetrical and asymmetrical lifting of symmetrical and asymmetrical loads by using the response patterns of inexperienced workers to lifting symmetrical and asymmetrical loads symmetrically and asymmetrically. Both approaches were used and, as expected, provided almost identical values for the psychophysical lifting capacity of industrial workers for symmetrical and asymmetrical lifting of symmetrical and asymmetrical loads. Therefore, the final database tables provided in this paper used combined values generated by the two methods.     

Psychophysical capacity of industrial workers for lifting symmetrical and asymmetrical loads symmetrically and asymmetrically for 8 h work shifts.

This paper presents comprehensive maximum acceptable weight of lift (psychophysical lifting capacity) database for male and female industrial workers for lifting symmetrical and asymmetrical loads symmetrically and asymmetrically for 8 h work shifts. The experimental data collected in previous studies on experienced (industrial) and inexperienced (non-industrial) materials handlers (Mital 1984a, Mital and Fard 1986) and the patterns of responses between the two populations (Mital 1985, 1987) were used to generate this database. Since previous work (Mital 1985, 1987) showed that responses of both experienced and inexperienced materials handlers to task variables are similar and also provided multipliers relating the psychophysical lifting capacities of the two populations, it was possible: (1) to convert psychophysical capacity data for asymmetrical lifting of symmetrical and asymmetrical loads, collected on inexperienced workers to reflect psychophysical lifting capacity of experienced workers for asymmetrical lifting; and (2) to take psychophysical lifting capacity data of experienced industrial workers for symmetrical lifting of symmetrical loads and generate from it their psychophysical lifting capacity for symmetrical and asymmetrical lifting of symmetrical and asymmetrical loads by using the response patterns of inexperienced workers to lifting symmetrical and asymmetrical loads symmetrically and asymmetrically. Both approaches were used and, as expected, provided almost identical values for the psychophysical lifting capacity of industrial workers for symmetrical and asymmetrical lifting of symmetrical and asymmetrical loads. Therefore, the final database tables provided in this paper used combined values generated by the two methods.