共查询到20条相似文献,搜索用时 62 毫秒
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我局对一台80MVA/220kV电力变压器进行了原铝绕组更换成铜绕组并加强匝间绝缘的改造。该变压器的电压为220±2×2.5%/66/11kV,匝数为880±2×22%/457/44匝,联结组为YNd11y12,变压器一次绕组为中部出线,绕组由上下两... 相似文献
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本文提出了基于几何模型的快速视觉检测方法。该方法采用几何模型驱动的图像处理策略,利用产品的几何模型,根据用户的检测要求,制定检测索引表,用检测索引表导计算机进行数据处理,以提高机器视觉的智能程度和数据处理速度。实验表明,采用该方法的激光机器视觉检测系统,在速度和精度上都可达到在线检测的要求。 相似文献
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本文主要对电力变压器的故障原因进行了分析,然后针对每一种故障提出一些实质性的解决办法,如果能够正确合理地排除变压器的故障的话对于变压器的正常运行以及电力系统的正常供应能够起到很好的效果。 相似文献
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针对某35kV变电站主变差动保护动作情况,利用气相色谱法、超高频法、超声波法判断故障性质,最后通过对该变压器进行停电吊芯检查确定故障点。 相似文献
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为及时发现电子式电流互感器误差状态的稳定性问题,保证电能贸易结算的公平性,有必要对电子式电流互感器的误差状态进行预测。建立了电子式电流互感器误差模型,将其误差表征为单输出变量和多输入变量的理论模型,确定了模型输入变量和输出变量。针对模型输入变量和输出变量之间无明确函数关系的问题,提出了基于聚类RBF神经网络的误差状态预测方法,针对变量单位和数量级不同的问题,采用Z-score标准化法对数据进行预处理,为了简化神经网络,采用K-Means聚类算法对输入变量进行聚类分析。算例分析结果表明比差预测误差的绝对值小于0.05%,角差预测误差的绝对值小于10’。该预测方法可提供电子式电流互感器误差状态的变化信息,防范电能贸易结算的风险。 相似文献
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端子作为线束生产的重要组件,利用视觉成像检测其姿态是汽车智能制造领域的研究课题之一。线束端子旋转角度自动检测设备通常利用机器视觉获取端子的姿态,提出一种线束端子角度姿态的视觉检测方法,利用电机将端子匀速旋转90°,并在旋转过程中连续采集图像,获得端子的旋转图像序列;根据端子旋转过程的成像特点,找到金属面正对的图像帧,并提取ROI图像;以该ROI图像为对象,利用端子模板库进行匹配,判断得到该金属面所属类别,从而计算出端子需要旋转的角度传输给电机。大量实验结果表明,所提出的方法可以有效地识别端子的角度姿态,并且快速准确地计算旋转角度,可以达到工业智能制造的要求。 相似文献
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Ángel L. Trigo José L. MartínezJesús Riquelme Esther Romero 《Electric Power Systems Research》2011,81(2):553-560
This paper presents an operational tool designed to help the system operator to control the reactive power flow in transmission-subtransmission boundary transformers. The main objective is to determine the minimum number of control actions necessary to ensure that reactive power flows in transmission/subtransmission transformers remain within limits. The proposed iterative procedure combines the use of a linear programming problem and a load flow tool. The linear programming assumes a linear behaviour between dependent and control variables around an operating point, modelled with sensitivities. Experimental results regarding IEEE systems are provided comparing the performance of the proposed approach with that of a conventional optimal power flow. 相似文献
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This paper presents a new method for calculating winding temperature gradient in large power transformers. A general formulation of the problem is made using the electrical analogy. An expression for the thermal resistance of the solid insulation is found using analytical methods. Expressions for the thermal resistance of the oil boundary layer for natural and directed oil flow are then found through correlation of test results from actual transformers. A comparison of the results of the new method and previous methods is presented. The new method is found to be a significant improvement. 相似文献
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The transfer function concept is well known as an additional method of evaluating the impulse test of power transformers in the test laboratory, Another application for this method is monitoring of power transformers in service. According to the method of how to measure transient signals for the calculation of transfer functions, two kinds of monitoring can be distinguished: off-line and on-line monitoring. Both kinds of monitoring as well as their influencing factors are discussed with on-site measurements on power transformers in service 相似文献
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实际中不同变压器故障类型的误分引发的危害程度往往不同,仅追求正确率并不一定会带来符合实际意义的分类结果。针对此,提出了代价敏感相关向量机(CS-RVM)。CS-RVM以误分代价最小为目标,按贝叶斯风险理论预测新样本类别。在用典型算例验证了CS-RVM具有代价敏感性的基础上,尝试将其应用于变压器故障诊断。基于溶解气体分析(DGA)数据的变压器故障诊断实例分析表明,CS-RVM全局诊断正确率略高于BP神经网络和支持向量机,略低于多分类相关向量机(M-RVM),但CS-RVM趋于提高误诊代价高的故障类型的诊断正确率,具有代价敏感性;CS-RVM的诊断速度足以满足变压器故障诊断的工程要求。 相似文献
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针对电力变压器状态评价过程中存在的不确定性,提出一种基于云相似度和证据融合的电力变压器状态评价方法。首先,考虑到各指标在状态等级边界处的随机性与模糊性问题,采用云模型来建立状态评价的基本框架。其次,为兼顾状态等级划分的严明性和模糊性,采用改进的云熵优化算法确定云模型的熵值。然后,考虑到指标数据本身的不确定性,利用正向云发生器和云合成算法生成各试验项目待识别云和标尺云,并采用模糊贴近度计算二者间的相似度作为证据源的基本概率分配。最后,采用考虑证据可信度和不确定度的冲突证据修正方法修正证据源,并融合不同证据以判断电力变压器的最终状态。经实例验证,相较于传统方法,所提方法能够有效处理状态评价过程中的不确定性,评价结果符合电力变压器的真实情况,对电力设备状态评价有一定参考价值。 相似文献
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《Electric Power Systems Research》2001,60(2):107-113
Recent studies by various authors have shown as the IEEE Transformer Loading Guide model and the more recent modified equations, proposed by the Working Group K3 of the IEEE ‘Power System Relaying Committee’, are lacking in accuracy in predicting the winding hottest-spot temperature of a power transformer in presence of overload conditions. This is mainly due to the deviation of the parameters of the thermal model of the power transformer in the presence of overload conditions. In the paper, a novel technique to identify the thermal parameters to be used for the estimation of the hot-spot temperature is presented. The proposed method is based on a genetic algorithm (GA) which, working on the load current and on the measured hot-spot temperature pattern, permits to identify a corrected set of parameters for the thermal model of the power transformer. Thanks to data obtained from the experimental tests, the GA based method is tested to evaluate the performance of the proposed method in terms of accuracy. 相似文献
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Jie Wang Jun Liu Lingling Sun Mingzhu Zhou 《International Journal of Numerical Modelling》2016,29(2):255-264
An accurate compact model for stacked transformers is proposed. The parasitics between the primary metal coils and the substrate are taken into consideration. The model parameters can be analytically extracted from open‐loaded S‐parameters measured from two‐port test structures. The modeling methodology renders excellent agreement with the data from both simulation and measurement over the frequency range of 0.1–20 GHz for a monolithic stacked transformer manufactured in 0.18‐µm Radio frequency Complementary Metal Oxide Semiconductor (RF CMOS) technology. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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针对电力变压器状态评估中存在多特征指标和多故障类型问题,提出一种基于模糊综合评估模型和皮尔逊相关系数的改进D-S证据理论的变压器状态评估方法。建立了变压器状态评估体系,引入层次分析方法和改进的三角梯形隶属函数确定特征指标的基本概率。基于皮尔逊相关系数的改进D-S证据理论融合不同特征指标以评判变压器综合状态评估。经过实例分析,该方法的评价结果与变压器实际运行状态一致,其准确率达到95.83%,验证了该方法的合理性和可行性。该方法对变压器状态评估具有一定的参考价值。 相似文献