电弧炉静态无功补偿及其节能效益分析

某钢铁公司电弧炉在运行过程中谐波电流含量多,总负荷的功率因数较低,能耗较高。为改善负荷情况,提高功率因数,降低谐波,采用静态无功补偿。结果表明:电弧炉系统中应用静态无功补偿装置对提高企业生产效率和设备可靠性具有积极的作用,同时,能够节约大量电能,具有较高的经济效益。     

高塔吊的无功补偿技术改造

高塔吊的工作负荷以感性短时冲击性负荷为主,造成电压、电流畸变,系统功率因数极低.后采用动态无功功率补偿装置,补偿基波无功电流,抑制高次谐波,提高了功率因数,改善了电能质量,达到了节能降耗的目的.     

电力系统电能质量分析与谐波治理

电能质量及其各项指标对于电网的正常运行至关重要,尤其是各种非线性负荷带来的谐波污染日益增加。针对谐波治理提出了最新的技术方案,以达到提高电能质量,解决谐波污染的目的。     

电石炉无功补偿与谐波抑制

电石炉运行时,很低的功率因数使得损耗增加效率降低,产生的谐波使电网电能质量降低。讨论了电石炉无功补偿的方法,针对某厂电石炉实际运行的情况,给出了无功补偿和谐波抑制的方案,收到了节能增效的效果。     

小型风力机电能质量评价指标及影响因素研究

文章以一系列小型风力发电机为研究对象,拟采用以DH5902为主的数据采集分析系统对其电信号数据进行采集并依据IEC标准和国家标准计算其电能质量指标,研究预得到电能质量评价指标和其影响因素,为改善小型永磁风力发电机电能质量提供切实依据。研究表明:风力发电机低转速超负荷运行易引起电压波动和偏差、频率偏差和功率因数下降,然而转速过高易造成三相不平衡度增大,故在限制风机转速的同时优化负荷是提升电能质量的必要举措;再者,电能质量各指标受槽形和每极每相槽数影响较大,优化齿槽结构对提升发电机电能质量较为重要;此外,发电机绝缘老化和退磁使得气隙磁场谐波含量增大,会导致谐波畸变、电压偏差、频率偏差等多项电能质量指标恶化。     

分散式风力-太阳能混合发电系统的研制

对国内外中小型风力发电机组及太阳能发电装置进行了综合分析，采用机电一体化设计和滑模变结构控制技术研制开发实用化的分散式风力－太阳能混合发电系统，统一交流电源品质调节装置对混合发电系统的电能指标进行全局优化，即利用统一的滑膜变结构控制实现发电系统的快速电压调节，谐波抑制，功率因数补偿和非线性负荷的三相平衡，为边远地区及分散用户提供稳定的清洁能源，混合发电系统既可独立运行，也可多系统并行运行，必要时还可并网运行。     

三明电网AVC技术应用研究

保障电能质量,建设智能电网,是电网发展的必然趋势。评估电网的无功调控能力以确定关口无功功率控制范围,是电网自动电压控制的关键。采用平均功率因数限值,建立省地电网接线模型,得到功率因数与省级电网下送负荷水平的相关性曲线。并介绍分级电压控制方案,以系统网损最小为目标的最优潮流计算,并进行工程验证自动电压控制的有效性。     

分布式光伏接入用户侧对功率因数的影响

为提高电能使用效率,保证电网正常稳定运行,高压电力用户需进行功率因数考核.通过理论分析光伏并网后用户负载中有功和无功情况,发现在用户负载用电量较小时,光伏发电会向电网倒送有功,导致计量电表功率因数降低.为此提出了智能型混合滤波补偿方案,将装置安装在用户用电负荷端,可为企业对发电并网用户设备配置提供参考.     

适应负荷速变的TCT式可控电抗器控制方法

针对负荷快速变化时无功功率的补偿问题,提出一种TCT式可控电抗器优化控制方法,首先分析了晶闸管触发角与补偿后功率因数、三相不平衡、谐波畸变率之间的关系,然后利用遗传算法寻找一组最优触发角来控制无功补偿装置,使得补偿效果最佳,最后利用BP神经网络对结果进行训练,建立了负荷功率与触发角之间的映射。仿真结果表明,该方法具有较高的效率,能够快速补偿功率因数和三相不平衡,同时可有效降低线路的谐波电流含量,尤其适用于负荷快速波动的场合。     

浅析大型电动机变频技术改造

大型电动机进行变频改造的主要目的是为了节能降耗,改善经济指标,但同时使用变频装置会给电网注入谐波危害,引起电能质量的恶化。而高压变频装置采用移相变压器能够实现输入多重化,降低谐波的注入,并提高网侧的功率因数,从而可在诸多电力行业广泛应用。     

Harmonic distortion-based island detection technique for inverter-based distributed generation

A harmonic distortion-based island detection technique for inverter-based distributed generation (IBDG) is proposed. The proposed technique is classified as an active island detection technique and it is based on the voltage change at the point of common coupling (PCC) that occurs in islanding. To avoid island detection failure in case of a close matching between IBDG-generated power and load power, an active power-voltage locus is introduced to shift the reference active power for PCC voltage change, therefore breaking the IBDG-load power balance and transferring the operating point outside the non-detection zone. A new harmonic performance index, named harmonic amplification factor, is introduced to detect the island. This factor amplifies each harmonic component by its order. Besides the ability of detecting short circuit, the proposed technique can discriminate between islanding and other disturbances, as load change, grid voltage distortion and unbalance, and capacitor bank switching. The proposed technique is validated by Matlab/Simulink simulation and practically as well.     

浅谈供配电网的谐波治理

为解决工、农业飞速发展带来的供电紧张,一方面要建设许多新的电厂和输电线路,另一方面要高效利用现有的电力资源,减少电力损耗。谐波是导致电力损耗增加,供电质量下降的重要因素。本文对谐波的基本性质和测量,对配网中谐波的来源和危害进行了详细说明,并提出了治理谐波的若干方法。     

特高压直流输电系统馈入的城市电网谐波渗透特性分析

针对城市电网直流输电落点谐波从高电压等级向低电压等级渗透过程中出现的高次谐波放大现象,基于网络固有结构理论,提出一种城市电网谐波放大分析方法。注意到电缆对谐波跨电压等级渗透的影响,在谐波国标框架下按等效注入谐波电流大小评价其影响,提出等效注入感容耦合度评估其影响机理,并建立电缆分布参数模型,对其系统等值阻抗感容临界条件进行分析。利用多直流落点局部城市电网对所提方法进行分析验证,并与现场测量数据对比,结果表明所提方法能有效判别谐波敏感回路,以及分析电缆对谐波渗透的影响机理。     

基于虚拟磁通的并网逆变器直接功率控制研究

基于传统直接功率控制的策略思想,改变以L电感并人电网的拓扑结构,提出基于LCL滤波器的直接功率控制,系统分析有源阻尼,谐波抑制,虚拟磁通估计和锁相环PLL等控制算法,进而提出改进的直接功率控制策略。在MATLAB／SIMULINK的仿真平台上,分别搭建光伏并网的主电路模型。以及包含有源阻尼,谐波抑制,虚拟磁通估计和PLL模块的统一协调的控制系统,仿真结果表明改进的直接功率控制能有效改善并网逆变器的电流质量,降低总谐波畸变率,并使电网电压和注入电网电流同相,功率因数为1。     

一种功率因数校正电路在LED驱动器上的应用研究

论述了功率因数校正的原理,讨论了功率因数校正的一些方法,提出了一种应用于LED驱动器的新型功率因数校正电路.试制了一个用于100 W LED驱动电路的功率因数校正样机,实验表明,该样机的功率因数大于0.99,电流总谐波小于6％.     

Artificial intelligence based active and reactive power control method for single-phase grid connected hydrogen fuel cell systems

In grid-connected power generation systems, power factor fluctuations caused by non-linear power circuits used between the grid and source should be controlled with the help of voltage source inverters (VSI). In addition, in order to improve the quality of the electrical energy injected into the grid and to prevent possible electrical faults, the total harmonic distortion (THD) in the grid current should be controlled in accordance with IEEE-519 standards. In other respects, uncontrolled injected energy may causes losses, excessive electrical energy demand and overloading. In this study, an artificial neural network based active and reactive power control method is proposed for grid-connected single-phase Proton Exchange Membrane Hydrogen Fuel Cell (PEMFC). The aim of the proposed control structure is to have low harmonic distortion, high power factor performance as well as an easy and understandable structure. The proposed method was applied to a 6 kW prototype. Five different scenarios and nine different activation function were tried to verify the performance of the proposed control method. As a result of these processes, the power factor was measured as unity (>0.99) and the total harmonic distortion (THD) of the grid current, under all operation states, is <2%. In addition, it has been observed that the success rate of artificial neural networks is >97%.     

Speed and power factor controller for AC adjustable speed drives

The speed and power factor of an adjustable speed slip power recovery drive are controlled in order to optimize the operation. This is accomplished by means of a variable-voltage-variable-frequencies power converter. The function of the digital controller of the power converter is to provide the online speed and power factor regulation. The hardware and software are described. This scheme has an accurate voltage output with very low harmonic content, a good resolution for the phase angle regulation and the frequency control with the possibility of range extension     

Rapid transaction to load variations of active filter supplied by PV system

This paper deals with the analysis and control of a photovoltaic (PV) system connected to the main supply through a Boost converter and shunt active filter supplied by a PV system providing continuous supply of nonlinear load in variation. A robust control of a PV system connected to the grid while feeding a variable nonlinear load is developed and highlighted. This development is based on the control of the Boost converter to extract the maximum power from the PV system using the Perturb and Observe (P and O) algorithm in the presence of temperature and illumination. The proposed modeling and control strategy provide power to the variable nonlinear load and facilitates the transfer of power from solar panel to the grid while improving the quality of energy (harmonic currents compensation, power factor compensation and dc bus voltage regulation). Validation of the developed model and control strategy is conducted using power system simulator Sim-Power System Blockset Matlab/Simulink. To demonstrate the effectiveness of the shunt active filter to load changes, the method of instantaneous power (pq theory) is used to identify harmonic currents. The obtained results show an accurate extraction of harmonic currents and perfect compensation of both reactive power and harmonic currents with a lower THD and in accordance with the IEEE-519 standard.     

电容补偿与谐波对电容的影响

就用户配电系统采用电容补偿装置以提高功率因数优点以及用户母线谐波电流的产生、谐波对电容器影响等问题进行了分析探讨,并提出了使用电容器补偿装置应注意的问题     

Multilevel converters control for renewable energy integration to the power grid

The paper deals with the multilevel converters control strategy for renewable energy resources integration in distribution grids. The proposed control scheme ensures the injection of the generated power in the distribution grid with fast dynamic response, while providing an additional active power filtering capability providing the required harmonic and reactive currents to the considered non-linear loads. The proposed control scheme is applicable to a general multilevel converter and to any types of the renewable energy resources. The control scheme is validated by means of simulations with a three-level diode-clamped converter which interfaces a wind power generation system to a distribution grid supplying non-linear loads. From extensive simulation results, high performance of this control strategy in renewable energy application is demonstrated with reduced total harmonic distortion, increased power factor and compensated load’s reactive powers.