谐波对电网阻抗的影响及抑制方法

高次谐波对电网质量的影响及如何抑制谐波是目前急需解决的重要课题。从理论上分析了谐波对变压器阻抗，输电线路阻抗，负荷阻抗的影响，同时提出了几种抑制谐波的方法。     

高次谐波电流对电网的影响及其抑制

本文简述了大型变频调速装置的高次谐波电流对电网的影响及其抑制方法,并介绍了谐波滤波器抑制高次谐波电流的实例及其抑制效果。     

关于大型钢铁企业电网谐波的分析与计算

论述了电力系统中高次谐波的产生及其对电网所造成的危害,介绍了一些计算谐波电流、谐波电压的实用方法及实例,对鞍钢目前电网中高次谐波的状况进行了分析,并提出了切实可行的改进意见。具有一定的理论性和应用价值。     

大型变频调速装置的高次谐波电流对电网的影响及其抑制

本文简述了大型变频调速装置的高次谐波电流对电网的影响及其抑制方法，并介绍了采用谐波滤波器抑制高次谐波电流的实例及其抑制效果。     

来冶三期锌电解整流的谐波计算方法及计算公式探析

以来冶锌电解整流的谐波计算为例，全面系统地分析和探讨各种谐波计算方法的特征及其实用性。对谐波的计算作了较为完整的介绍，也是对来冶三期工程锌电解整流谐波计算正确性的论证。     

消谐装置误动作原因分析

介绍了谐波产生的原因及谐波危害,阐述采用降低谐波源的谐波含量、加装静止无功补偿装置等措施来减少谐波产生。     

热轧电网中谐波的危害及治理

分析了冶金企业电网中谐地企业生产及日常生活造成的危害,同时针对不同谐波源提出了相应的治理方法。总结了热轧电网中谐波的治理及效果。     

大功率可控硅整流装置运行过程中的谐波探讨

对山铝电解铝厂大功率可控硅整流装置运行过程中的谐波进行测试,发现系统存在着较严重的非特征谐波,分析了非特征谐波产生的主要原因,并相应地采取了抑制措施。     

迁钢2250热轧生产线低压谐波治理研究与实践

阐述了低压谐波的危害,针对钢铁企业热轧生产线,通过实际检测,确定低压谐波产生的主要设备来源,并提出谐波治理的具体方案.最后给出了EP谐波吸收装置投入后的应用效果.     

配电网络高次谐波的产生和防止

供电网络中电力器件及其装置的使用和非线性负荷在电网中的投运 ,伴生了大量的高次谐波 ,引起电网正弦波形严重畸变。这将干扰通讯设备运行 ,影响计量仪表精度 ,甚至造成电气设备烧毁。本文分析了配电网络高谐产生的因素 ,指出了它的主要危害 ,并提出了防止和抑制高次谐波的措施     

有色企业供电系统谐波抑制和治理探讨

介绍了有色企业供电系统的谐波状况和造成的主要危害,分析了系统谐波的产生原因,在对目前企业供电系统中进行谐波抑制常用的措施进行综述的基础上,针对有色金属企业供电系统的谐波现状、治理中面临的问题,提出了进行谐波抑制与治理的思路.     

电解铝厂滤波方案的分析比较

电解铝厂为了选择最佳的滤波系统方案,必需对滤波装置的接入位置、各种滤波器的接线方案以及能耗进行分析比较。本文从这几个方面分析了电解铝厂可以选择的滤波方案,归纳出各自的特点,可为电解铝厂选择适合的滤波方案提供依据。     

电力谐波对电能计量的影响分析

主要讨论谐波功率对计量的影响，说明民用电中零序性质的谐波问题，提出了抑制谐波对电能计量影响的合理措施，从而提高供用电质量。     

Native tissue harmonic imaging improves endocardial border definition and visualization of cardiac structures

BACKGROUND: The purpose of this study was to examine the impact of native tissue harmonic imaging on endocardial border definition, wall motion scoring, and visualization of intracardiac structures. METHODS AND RESULTS: For wall motion analysis, 60 consecutive patients underwent standard transthoracic echocardiograms in both harmonic and fundamental modes. Three experienced echocardiographers reviewed each echocardiogram. Endocardial border definition for each wall segment was graded from 1 to 4 (1 = excellent endocardial definition). Wall motion was scored by using a standard 16-segment model and 1 to 5 scale. For visualization of cardiac structures, 50 consecutive patients were studied. Two experienced interpreters reviewed each echocardiogram for both normal and abnormal structures by using the following scoring scale: (1) harmonic is much better than fundamental, (2) harmonic is slightly better than fundamental, (3) harmonic and fundamental are equivalent, (4) fundamental is slightly better than harmonic, and (5) fundamental is much better than harmonic. Visualization of 64% (95% confidence interval [CI] 0.61 to 0.66) of all segments improved in harmonic mode, with 26% (95% CI 0.24 to 0.29) improving from poor/not seen to good/excellent. Of 444 segments deemed poor/not seen, visualization of 312 (70%) (95% CI 0.66 to 0.75) improved to good/excellent with harmonic mode. Of these 312 segments, 55% comprised the lateral and anterior walls on apical views. Interobserver agreement on endocardial border definition was 82% to 86%. Scoring of wall motion was altered in 171 of 1075 (16%) of segments by harmonic mode. This was significantly greater than the interobserver disagreement, which was only 10% (p<0.002). Mitral valve chordae and papillary muscles were visualized slightly/much better with harmonic mode in 40 of 50 echocardiograms. Left atrial boundaries were seen slightly/much better in harmonic mode in 29 of 50 studies. Abnormal structures were seen slightly/much better in harmonic mode in 12 of 14 cases. CONCLUSIONS: Native tissue harmonic imaging has significant impact on endocardial border definition and wall motion scoring and improves the visualization of both normal and abnormal cardiac structures.     

铜电解整流器谐波的抑制

电解整流器等非线性电力设备接在企业配电系统和电网上运行时,将向配电系统及电网注入谐波电流,并产生不良影响及危害。从自身运行的安全和对电网限制谐波要求两方面考虑,都必须对整流设备及其它非线性用电负荷设备产生的过量谐波进行有效的抑制。     

Strategies for harmonic structure discrimination by zebra finches

We trained zebra finches on a go/no-go operant conditioning procedure to discriminate between two harmonic structures that differed only by the presence or absence of the second harmonic. Test sessions revealed that the birds responded to probe stimuli based on the presence or absence of the second harmonic regardless of the other frequency components. Some of the birds also tended to use the fundamental frequency as a discriminative cue when the number of harmonics was few. These results indicate that birds use multiple strategies for this type of harmonic structure discrimination.     

Tissue harmonic imaging: why does it work?

The recent utilization of harmonic frequencies in the imaging of both tissue and contrast agents has dramatically improved echocardiographic image quality. In contrast harmonics, the harmonic frequency energy is generated on reflection from the microbubble contrast agent. In tissue harmonics, the harmonic frequency energy is generated gradually as the ultrasonic wave propagates through the tissue. Critical to the utility of tissue-generated harmonic frequencies is their origin beyond the chest wall and their nonlinear relation to the fundamental frequency energy strength. These two characteristics of tissue-generated harmonics ensure that the echoes most likely to produce artifact are least likely to produce harmonic waves. Armed with an understanding of how these images are produced and with data emerging as to their clinical utility, we anticipate that harmonic imaging will become the standard for assessing regional and global left ventricular function in technically difficult studies.     

铜冶炼行业电力谐波的产生、危害与治理

简要介绍铜冶炼行业电力系统中谐波产生的原因,列举谐波的影响及造成的危害,分析电容器放大谐波的原理及其解决方法,提出在铜冶炼行业采用谐波抑制和滤波的办法消除谐波影响和危害的实施对策。     

交流电弧炉炼钢过程谐波状况的实测研究

由于电弧电阻具有非线性特性,不管电弧炉的容量和功率水平如何,都是电网的非线性负荷。即使电网电压本来是理想的正弦波,电极电流却会出现波形畸变,即除基波电流外,还包含有各高次谐波。特别是在电弧炉炼钢的熔化初期,由于产生大量的高次谐波注入电网,能引起电网电压的剧烈波动。根据南京钢铁集团有限公司70／100t高阻抗电弧炉实测谐波参数,结合电弧炉炼钢的工艺特点,研究大型交流电弧炉炼钢过程中的谐波问题,并讨论了谐波与操作电抗的关系。