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通过对三西甲、丙、丁三条平行线路零序互阻抗现场实测分析,得出三条平行线路测试方法,由于平行线路条数及地线条数增加对线路零序自阻抗产生的影响,故当平行线路数增加时,其零序自阻抗及零序互阻抗亦必须重测。 相似文献
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500 kV输电线路零序阻抗受线路结构、运行方式、干扰电压、地质情况等因素的影响,其测量结果会产生误差,具体分析了零序阻抗原理、不同运行方式下零序阻抗实测的方法和理论分析,并结合实际研究了几条500 kV输电线路零序参数,提出了在实测和计算中注意的问题,提高实测数值的准确性。 相似文献
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500 kV输电线路零序阻抗的测量及研究 总被引:1,自引:0,他引:1
500 kV输电线路零序阻抗受线路结构、运行方式、干扰电压、地质情况等因素的影响,其测量结果会产生误差,具体分析了零序阻抗原理、不同运行方式下零序阻抗实测的方法和理论分析,并结合实际研究了几条500 kV输电线路零序参数,提出了在实测和计算中注意的问题,提高实测数值的准确性. 相似文献
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强工频干扰环境下传统异频法在测量输电线路零序阻抗时存在严重的测量原理错误。针对这一错误,提出了一种测量输电线路零序阻抗的新型异频测量方法。该方法基于GPS技术,同时采集异频电流注入后所有有电磁耦合的输电线路两端的电压和电流信号,在滤除工频干扰信号后,用最小二乘法求解阻抗方程组,得到线路异频下的零序阻抗,再换算到工频下的线路零序阻抗。采用PSCAD软件建立互感线路模型,并用两种异频测量方法进行了仿真测试与比较。给出了采用两种异频法测量某电网220 kV同塔双回线路零序阻抗参数的实例。理论分析、仿真测试和实测结果均表明,所提出的新型异频测量方法,测量原理正确,测量精度可满足工程测量的需要。 相似文献
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介绍了某110 kV线路覆冰条件下及融冰过程中发生单相接地故障时,在非故障相中出现较大感应电流的现象,指出互感应电流的产生与故障点所在位置及微气象环境条件的相关性,依据附加测量阻抗计算了故障点的零序互感阻抗值,简要分析了零序互感电流对接地距离和零序电流保护的影响。并指出110 kV线路因运行电压较超高压、特高压等级低,互电感耦合问题并不很突出和普遍,在无实测参数条件下,还可以从加强保护配置方面去消除零序互感的潜在不利影响。 相似文献
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介绍了某110 kV线路覆冰条件下及融冰过程中发生单相接地故障时,在非故障相中出现较大感应电流的现象,指出互感应电流的产生与故障点所在位置及微气象环境条件的相关性,依据附加测量阻抗计算了故障点的零序互感阻抗值,简要分析了零序互感电流对接地距离和零序电流保护的影响.并指出110 kV线路因运行电压较超高压、特高压等级低,互电感耦合问题并不很突出和普遍,在无实测参数条件下,还可以从加强保护配置方面去消除零序互感的潜在不利影响. 相似文献
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输电线路正序阻抗测量方法对比研究 总被引:1,自引:0,他引:1
输电线路参数是电力系统相关计算的基础,意义重大。传统的测量方法存在诸多弊端,无法准确测量线路参数,特别是零序自阻抗和互阻抗。叙述了常规的输电线路参数测量的方法对正序阻抗的测量,通过建立数学模型,详细推导了基于长线方程的双端信息算法。最后,通过PSCAD仿真得到了单端算法和双端算法各自适用范围。 相似文献
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《电气》2011,(2):14-18
With the incessant development of power market reform,the existing cross-subsidy in electricity tariffs has become a critical problem in China’s power industry development.On the basis of the theories of cross-subsidy and electricity universal service,the authors take foreign countries’ experience as reference to design several solutions to cross-subsidies in electricity tariffs in different phases of China’s power industry development.Furthermore,the application and implementation of these solutions are analyzed in this paper. 相似文献
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The author suggests that the confidence which many biologists have in problem-solving methods is unwarranted and that there are very important limitations in almost all current methods for solving biological problems. The standard problem solving approach that computer scientists use is outlined. An example of an error in an evolutionary tree problem-the case of the African Eve-is discussed 相似文献
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无色透明材料形成的单层薄膜,其颜色由干涉色决定。以白光照射其表面,随薄膜厚度的增加,将出现一系列色彩,这是由薄膜干涉所致。我们可以根据薄膜颜色,估计薄膜厚度。显然,当厚度增大到后界面的影响可以忽略不计的程度(相当于只有一个界面的半无限大情形,本文简称“厚膜”),则“厚膜”颜色恢复为无色透明。半透明材料在基底上形成的薄膜系统,以白光照射所呈现的颜色,由于基底及吸收的影响,则不能简单地以薄膜干涉来分析。对于半透明薄膜系统,首先测量它的光强反射率谱和透射率谱,运用传递矩阵[1]方法计算出薄膜的介质光学常数,再以光学常数计算单层薄膜与“厚膜”的光强透射率谱与反射率谱及它们的色坐标。以菲涅耳公式计算出的反射率谱为半无限大介质反射率谱,这时的色坐标可视为“厚膜”的色坐标。 相似文献
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A survey is provided of Japanese research on ceramic materials for substrates, microwave dielectric ceramics, piezoelectric ceramics, semiconducting ceramics, and superconducting ceramics. Novel processing technologies are described, covering the use of amorphous materials, superfine powders, lamination, multilayer thin films, porous ceramics, and superlattices 相似文献
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Recent progress in inverse problems in electrocardiology 总被引:5,自引:0,他引:5
The considerable progress achieved in the inverse problem of electrocardiography over the last decade has provided grounds for optimism about the possibility of approaching significant clinically relevant applications in the next decade. However, there are a number of basic questions that still remain. In addressing these questions, the authors feel it is important to seek solutions that emphasize physiological rather than mathematical significance. This approach leads to twin requirements for useful inverse solutions: accuracy, defined in a physiologically meaningful (and not just averaged and mathematical) sense, and reliability, not only to measurement noise but also to geometric modeling errors and other uncertainties that are inescapable in practical application. Studies using analytically tractable models may still be relevant, but it seems more important to find solutions to practical inverse problems, which will move the field toward wider acceptance and credibility 相似文献
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