电力系统谐波问题分析及改进

非线性配电设备和用电设备都会引起工频正弦波电压和电流畸变,产生谐波。谐波电压和谐波电流对公用电网会造成污染,使得用电设备所处的环境恶化,也对周围的通信系统和公用电网以外的设备带来危害。本文针对重庆卷烟厂4#变压器补偿电容器炸毁的事故,对谐波测试数据进行了理论分析,结论是由于纯电容补偿造成5次谐波放大,最终导致电容损坏。通过在补偿电容器回路中串联6%电抗器,使该变压器母线上的谐波得到了有效抑制。     

供电系统中谐波产生的原因危害及防治

1概述 在理想干净的电力系统中，电流和电压都是标准的正弦波。但实际供电电压的波形会由于某些原因发生偏离，即产生谐波。产生谐波的根本原因是由于具有非线性阻抗特性的电气设备用电的结果。这些非线性负荷在工作时向电源反馈高次谐波，导致供电系统的电压、电流波形畸变，使电力质量变坏。     

浅谈电网谐波危害与消除措施

随着科学技术的发展,工业生产水平和人民生活水平的提高,非线性用电设备在电网中大量投运,造成了电网的谐波分量占的比重越来越大。供电系统中谐波干扰增大,造成电网电压、电流波形严重畸变,成为影响供电质量的新的突出问题,并严重危及电力系统及用电设备的安全经济运行。本文对电网谐波危害和抑制消除措施进行分析归纳。     

配电网谐波的产生与防治浅析

近年来,由于冶金、化工、矿山、电气化铁道等部门大量采用硅整流设备和换流技术,以及其他非线性用电设备的投运,电力系统中非线性、冲击性负荷急剧增加,尤其是电弧炼钢炉容量增大,注入电网的高次谐波日益增多,造成电压、电流正弦波形畸变,使电能质量下降,对电网安全经济运行和广大用户安全用电构成极大威胁。为了确保电力用户和电力系统的安全及电能质量,必须对各种非线性、冲击性用电设备所引起的电网谐波加强管理和限制。本文分析了谐波基本性质,对配电网中谐波的来源和危害进行了详细说明,总结和提出了治理谐波的若干方法。     

谐波对电能计量影响的研究

一、引言随着电力电子技术在各工业部门和用电设备上的广泛应用,现代工业生产设备使用的整流设备、交直流换流设备、电子电压调整设备、电弧炉、感应炉、非线性负荷以及家用电器和照明设备等数量越来越多,容量越来越大,由于这些因素产生的大量谐波电流注入电网,使电力系统电压、电流发生了严重的畸变。电力系统谐波的存在,使得工业和日常生活中常用的感应式电能表的电能计量失准,给国家造成了严重的经济损失。在电气化铁道,由于受电力机车整流负荷的影响,27．5kV电网上的谐波电压、电流大大超过部颁标准规定的允许值,引起了电能计…     

10KV变电站无功补偿熔断器群爆原因及解决方案

随着高科技产业的发展,电力用户对供电质量和可靠性越来越敏感,电器设备的正常运行甚至使用寿命都与之息息相关。电能质量问题又可分为电压质量和电流质量两个大的方面。电压质量问题指会影响用户设备正常运行的不理想的系统电压,包括电压的闪变（flick）、瞬时过电压（swell）、谐波畸变（harmonics）、各相电压不平衡（unbalance）等情况;电流质量问题指电力电子设备等非线性负荷给电网带来的电流畸变,包括流入电网的谐波电流,以及无功、不平衡负荷电流、低频负荷变化造成的闪烁等。面对电网的电能质量被干扰或污染,面对日益恶化的电力品质问题,就得有针对性地对电网进行电能质量改善。国家电力公司明文规定：因电网或用户用电原因引起的电能质量不符合国家标准时,按“谁干扰,谁污染,谁治理”的原则及时处理,并贯穿于电网及用电设施设计、建设和生产的全过程。     

纯电动公交充电站谐波分析的模型方法

通过建立纯电动汽车高频充电机的一般等效模型的方法,研究了大功率高频充电机产生的电流谐波的构成以及影响电流谐波含量的主要因素,在此基础上建立了分析纯电动公交充电站谐波电流污染供电网和用电设备问题的仿真模型,并用此模型进行了基于纯电动公交运行特点和纯电动汽车蓄电池参数的充电站谐波电流仿真分析.仿真分析的结果可用于纯电动公交充电站谐波污染情况的预测分析,并作为选择谐波抑制设备的依据.     

基于电力系统中谐波的分析与消除的应用

本文简要介绍了电力系统中谐波的产生原理以及非线性电器设备导致电流发生畸变产生的危害,一般在实际工业生产中消除谐波对电力系统污染是在大容量静止滤波源（如大型晶闸管整流器）与电网连接处装设分流滤波器。     

谐波电流分析和测量方法探讨

随着科学技术的发展,工业生产水平和人民生活水平的提高,非线性用电设备在电网中大量投运,造成了电网的谐波分量占的比重越来越大。这不仅增加了电网的供电损耗,而且干扰电网的保护装置与自动化装置的正常运行。为了电网的安全运行,必须对谐波进行治理。治理谐波的前提即要对谐波进行准确可靠的分析和测量,本文从理论基础到实际运用,简要探讨了谐波电流的分析和测量方法。     

有关K-factor变压器的浅析和探讨

在过去几十年中,随着我国电力电子技术的迅速发展,大量可控硅的整流设备,制钢用电弧炉,电网用变压器群,饱和电抗器,敏感电子器件,UPS系统等具有非线性阻抗特性的电气设备投入到基础工业部门。这些设备在电力系统中产生大量的谐波,导致系统波形畸变严重,对输配电网络,通信线路,电气设备等造成巨大影响,尤其对配电变压器损害更大。K-factor变压器就是可应用于这些非线性负载(non-liner loads)条件下的变压器。     

Design of reactive power compensators for distribution systems with harmonic distortion

Abstract

The objective of this paper is to derive a systematic algorithm to decide the optimal location and size of shunt capacitors and filters for distribution systems with harmonic distortion. In this paper, the problem of reactive power compensation is first formulated as a nonlinear programming of minimization of real power loss and capacitor cost under voltage constraint to decide the optimal locations and sizes of shunt capacitors. The harmonic load flow is then applied to solve the total voltage harmonic distortion factor (HDF). Finally, the tuning frequency of the single‐tuned filter and the capacity and voltage ratings of the corresponding reactor and capacitor are determined so that both the harmonic distortion and the reactive power compensation can be solved simultaneously. To demonstrate the performance and effectiveness of the proposed methodology, a practical distribution feeder with nine large industrial customers is selected for computer simulation. It is concluded that proper design of harmonic filters should be undertaken to solve the harmonic resonance problem, as well as the reactive power compensation for distribution systems with nonlinear loads.     

Resource‐Efficient Low‐Temperature Synthesis of Microcrystalline Pb2B5O9X (X = Cl,Br) for Surfaces Studies by Optical Second Harmonic Generation

Optically nonlinear Pb₂B₅O₉X (X = Cl, Br) borate halides are an important group of materials for second harmonic generation (SHG). Additionally, they also possess excellent photocatalytic activity and stability in the process of dechlorination of chlorophenols, which are typical persistent organic pollutants. It would be of great interest to conduct in situ (photo‐) catalysis investigations during the whole photocatalytic process by SHG when considering them as photocatalytic materials. In order to get superior photocatalytic efficiency and maximum surface information, small particles are highly desired. Here, a low‐cost and fast synthesis route that allows growing microcrystalline optically nonlinear Pb₂B₅O₉X borate halides at large quantities is introduced. When applying the ionothermal growth process at temperatures between 130 and 170 °C, microcrystallites with an average size of about 1 µm precipitate with an orthorhombic hilgardite‐like borate halide structure. Thorough examinations using powder X‐ray diffraction and scanning electron microscopy, the Pb₂B₅O₉X microcrystals are indicated to be chemically pure and single‐phased. Besides, the Pb₂B₅O₉X borate halides' SHG efficiencies are confirmed using confocal SHG microscopy. The low‐temperature synthesis route thus makes these borate halides a highly desirable material for surface studies such as monitoring chemical reactions with picosecond time resolution and in situ (photo‐) catalysis investigations.     

Numerical simulation of cascaded third harmonic generation for both phase matched and mismatched schemes

Numerical solutions to the nonlinear coupling-wave equations of second harmonic (SH) and third harmonic (TH) generators are investigated for both phase matched and phase mismatched configurations. For phase mismatched TH generation, several kinds of schemes (the phase mismatch either in second harmonic generation (SHG) or sum-frequency generation (SFG) process) are considered and analyzed. The physical nature corresponding to the different ratios of the coupling coefficients is discussed.     

电源谐波与空调器噪声振动关系

在空调器的实际使用中，经常会出现令人烦恼的异常振动和噪声。主要原因是由于电力系统中非线性的负荷增大，电网的电流谐波成了严重的干扰。通过空调外挂压缩机及管路系统实例的分析，探索了在一些谐波下形成振动和噪声的机理，从而提出了解决空调机抗谐波干扰问题的渠道，对于工程实践具有参考意义。     

变摩擦TMD特性和简谐激励控制效果的研究

提出一种变正压力式变摩擦装置,通过改变摩擦面正压力实现摩擦力随系统位移增大而增大。将其用于TMD能有效克服常摩擦TMD摩擦力不可变的缺点。采用一阶谐波平衡法推导了变摩擦系统的等效阻尼比和等效频率,分析了系统各参数对其等效阻尼比和等效频率的影响,通过与经典阻尼单自由度系统的比较探讨了单自由度变摩擦系统的频率响应特性。从理论和试验两个方面研究了简谐激励下变摩擦TMD对单自由度主结构振动控制的特点。分析结果表明,变摩擦TMD的频率响应特性与经典阻尼TMD类似,二者都能有效减小主结构频率响应曲线的峰值,试验结果验证了变摩擦TMD在简谐激励下的有效性     

纵横向耦合梁的谐波响应分析

本文用谐波增量平衡法分析纵横向耦合梁的谐波响应。梁的动力方程由伽辽金法转化成含有二次和三次非线性项的常微分方程，求得了简谐载荷作用下梁的横向基谐波、超谐波响应和纵向基谐波、倍频基谐波及倍频超谐波响应，并发现了谐波响应的倒峰值现象。本文为求解含有二次和三次非线性振动系统的谐波响应提供了一套理论分析方法。     

The effect of harmonic torque to torsional vibration of induction machines

Abstract

An increasing number of industrial control applications and home appliances employ power electronic devices which cause large concomitant harmonic currents. These harmonic currents distort the waveform of the voltage source and, in doing so, the distorted voltage can induce harmonic pulsating torque in the air gap and rotor harmonic torque of an induction machine. This harmonic pulsating torque generally causes torsional vibration. In addition, when the natural frequency of the mechanical system is in the proximity to the frequency of the rotor harmonic torque, the magnitude of the vibration becomes amplified and deteriorates rapidly; the torsional resonance occurs as well. In this investigation, we analyze the phenomena of torsional resonance caused by rotor harmonic torque and torsional vibration caused by harmonic pulsating torque.     

噪声和振动信号的谐波小波时频表示

谐波小波变换的时频表示方法应用于持续时间、带宽和采样率差别很大的多种目标的噪声和振动信号处理当中,将其结果与基于STFT方法的结果进行了比对,并给出了其在不同应用场合的参数。结果表明,谐波小波方法用于信号的时频表示,具有很好的灵活性和突出的性能优点,有较好的应用前景。     

Harmonic generation in laser-produced plasmas containing atoms,ions and clusters: a review

A review of studies of the high-order harmonic generation of laser radiation in laser-produced plasma revealed recent developments in this field. These include new approaches in application of two-colour pumps, generation of extremely broadened harmonics, further developments in harmonic generation in clusters (fullerenes, carbon nanotubes), destructive interference of harmonics from different emitters, new approaches in resonance-induced enhancement of harmonics, applications of high pulse repetition rate lasers for the enhancement of average power of generating harmonics and observation of quantum path signatures, etc. We show that this method of frequency conversion of laser radiation towards the extreme ultraviolet range became mature during multiple sets of studies carried out in many laboratories worldwide and demonstrated new approaches in the generation of strong coherent short-wavelength radiation for various applications.