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基于泄漏电流基波阻性分量的绝缘子污秽度表示方法的研究 总被引:3,自引:2,他引:1
绝缘子污秽状态判断对电网安全工作意义重大。基于污秽绝缘子串等效电路的理论分析,建立了绝缘子串泄漏电流试验回路,对洁净及不同污秽情况下的绝缘子串泄漏电流进行了测量,并利用FFT变换分析绝缘子泄漏电流频谱,提取了泄漏电流基波阻性分量,研究了泄漏电流基波阻性分量同污秽度及相对湿度间的关系。结果表明,污秽干燥情况下,绝缘子泄漏电流较小且主要为容性电流;与洁净时相比,绝缘子串染污时总的泄漏电流及其基波分量的变化并不明显,而泄漏电流基波阻性分量同污秽盐密及相对湿度呈非线性关系,低湿度情况下变化更显著,可以通过泄漏电流基波阻性分量来表示绝缘子的污秽程度,这比利用总泄漏电流进行判断更有效;高湿度情况下泄漏电流基波阻性分量法已不适合判断绝缘子污秽度。且该方法无需对绝缘子串安装集流环,保证了系统安全性。 相似文献
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分析了表征污秽绝缘子运行状态的特征量,比较了各特征量的特点及其适用场所,总结了影响泄漏电流的特征量,在人工污秽试验的基础上,讨论了泄漏电流在闪络过程中的特征,得出了泄漏电流与其基本特征量之间的关系,通过希尔伯特变换的方法提取了泄漏电流包络线,分析了电弧延伸在污闪发展过程中对泄漏电流的影响。 相似文献
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绝缘子污秽度检测与污闪预警研究综述 总被引:2,自引:0,他引:2
概述了现今绝缘子污秽度检测方法的优缺点,提出泄漏电流是污闪预测中最为重要和科学的参量.分析了泄漏电流特征量提取的时域和频域的各种有效方法,及各方法的优点和局限性.结合绝缘子的污秽特点,指出了今后绝缘子污秽检测方法的研究方向和重点是应建立基于泄漏电流的多参量的综合预警模型. 相似文献
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基于PSO-SVM的高压绝缘子污秽等级评定 总被引:3,自引:1,他引:2
污秽等级评定是绝缘子泄漏电流在线监测系统的重要内容,评定的难点在于泄漏电流的各种电气特征量、环境因素与绝缘子表面污秽状况之间存在着复杂的非线性关系。笔者在实验室模拟试验和现场实测数据基础上,采用粒子群算法优化支持向量机的参数,建立了污秽等级评定的支持向量机模型。该方法利用支持向量机结构风险最小化原则和粒子群快速全局优化特点,通过对样本数据的学习,可以快速建立泄漏电流有效值、泄漏电流峰值、泄漏电流脉冲频度、环境湿度、温度与污秽等级之间的映射关系。实验结果表明,该方法是有效的。 相似文献
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ABSTRACT In this paper, the triac is used to control the welding transformer leakage reactances and thus the welding currents. This new method keeps the input and output currents and voltages in sinusoidal wave forms. The triac is connected across the terminals of a coil wound on a fixed limb magnetic shunt. A simple triggering circuit is used to control the current of the triac and thus the current of magnetic shunt coil. This leads to variation of welding transformer leakage flux, leakage reactances and thus a variation of welding current. The distortion due to the triac is only affecting the leakage flux of the welding transformer. The leakage flux is very small (compared with main flux) and most of it passes in the transformer window. Then, no harmonic pollution in the bus–bar or in the welding transformer. Thus, high operating efficiency is obtained. This new method can be used with single or three phase are welding transformer. In this work, a three phase multi–operator welding transformer is experimentally checked with the new system. The recorded wave forms support the system advantages. Performance characteristics are experimentally measured and give adequate results. 相似文献
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本文给出了变电站线路绝缘子泄漏电流在线监测的方法,对其测量所涉及的干扰,测量精度以及整机电路的性能作了研究和分析,提出了相应的解决措施,给出了实验数据,初步实现了对变电站线路绝缘子泄漏电流的在线监测。 相似文献
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电力变压器绕组轴向振动稳定性分析 总被引:11,自引:1,他引:11
研究了变压器绕组的机电耦合振动稳定性问题,建立了变压器绕组轴向机电耦合的动力学模型。将变压器绕组的漏磁场简化成二维磁场,得到其解析解,采用机电耦合系统的Lagrange方程,分析得到变压器绕组机电耦合的非线性振动方程,以及简化的耦合振动方程。应用动力学理论分析载流的变压器绕组轴向振动的稳定性,得到了模型变压器绕组主要设计参数的稳定域和不稳定域,分析大电流引起变压器绕组失稳的机理。 相似文献
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Each time switching occurs, a PWM inverter produces high‐frequency leakage currents flowing through stray capacitors. Since the inverter for a trash conveyance crane is installed far away from the motor, the shield power cables between them become long, and leakage currents pass through the stray capacitances of the shielded cables and flow to the ground. This paper proposes a model circuit for analyzing leakage currents which flow into the shields of the cables. The effectiveness of the proposed model circuit is verified by comparison of simulated leakage currents using the proposed method and measured leakage currents. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(2): 65–72, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.2002 相似文献
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用镜像法计算大型电力变压器漏磁场的研究 总被引:3,自引:1,他引:2
大型电力变压器漏电抗及电磁力的计算实际上就是变压器漏磁场的计算,采用镜像电流法对变压器铁心窗中的漏磁场进行了计算,给出了场点处磁感应强度与最高镜像电流次数奇偶性的关系,用最高镜像次数相邻的镜像电流及实际电流算得的场点处磁感应强度的平均值近似场点处磁场感应强度的实际值。用此方法计算变压器的漏磁场,在编程及计算工作量相对较小的情况下,可获得具有很高精度的磁感应强度。 相似文献
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A new current-measuring device called the Dynamic Current Transducer (DCT) is described [1]. Its performance is demonstrated using measurements of symmetrical and asymmetrical fault currents, fast, high-level oscillating currents, and post-arc currents. Practical applications as the main part of a control and protection system in power distribution and as the principal diagnostic tool in circuit breaker testing are discussed. Its key features are a simple, rugged construction, small size, low cost; large bandwidth; high level of immunity to magnetic saturation, over-heating and electromagnetic interference; and the possibility of achieving high BIL values with a self-contained fiber-optic signal link. 相似文献
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波形对称原理的变压器差动保护 总被引:53,自引:28,他引:53
提出利用差电流导数的前半波与后半波作对称比较以区别励磁涌流和故障电流。用此方 法实现的变压器差动保护,经试验证明动作可靠,抗干扰能力强。 相似文献
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Charge trapping is responsible for long transient leakage currents observed in parallel plate thin film BST capacitors. The presence of such time dependence complicates the measurement of leakage current as a function of an applied voltage, with the voltage sweep introducing hysteresis in the absence of ferroelectricity. The effect of long transients on current-voltage sweeps is discussed, as well as a method of obtaining current-voltage characteristics in the presence of transient leakage currents. 相似文献