【作者】 田野；

【导师】 程养春；

【作者基本信息】 华北电力大学 ， 高电压与绝缘技术， 2014， 硕士

【摘要】 变压器是电力系统最重要的设备之一,其可靠性直接影响电网的安全运行。对其绝缘性能进行局部放电在线检测,能够连续、实时的反映出变压器内部的绝缘劣化状况,是掌握变压器绝缘状况的重要手段之一。宽频带脉冲电流法检测法与常规脉冲电流法相比具有测量频带宽、灵敏度高、包含的局部放电信息量大等优点,可以更加真实地反映局部放电的原始脉冲电流特征,为采用脉冲电流波形分析的方法进行信号与噪声分离提供了可能,因此本文对其进行了研究。本文研制了一套能在变电站环境下使用的宽频带局部放电在线检测系统,包括宽频带电流传感器、工频相位发生器、宽频带信号放大器、滤波器、数字示波器和计算机。在3台三相双绕组真实变压器和1台三相三绕组模型上研究了宽频带局部放电脉冲在实际变压器中的传播规律和耦合机理,可为变压器局部放电在线监测和定位提供指导。本文利用所设计的宽频带局部放电在线检测系统采集了某地多个变电站内变压器铁芯接地线上的局部放电信号,并将每个变电站的信号进行了频谱分析,从频域内研究宽频带局部放电的规律；然后进行了基于相位分布的统计分析,并将有疑似放电的数据进行了基于等效时频法的放电类型的识别。更多还原

【Abstract】 Transformer is one of the most important equipment in power system, its reliability directly affects the safe operation of power grid. The on-line monitoring of partial discharge for its insulating properties in real-time can reflect the condition of transformers’internal insulation degradation continuously, is one of the important means to master the insulation condition of transformer. Compared with the conventional pulse current method, the wideband pulse detection current method has the advantages of wider measurement bandwidth, higher sensitivity and contains more information of partial discharge that can reflect the original pulse current characteristics of partial discharge pulse more accurately, it makes the use of pulse current waveform analysis method to separate the signal and noise possible, therefore be studied in this paper.This paper developed a wideband partial discharge on-line monitoring system that can be used in the substation environment, including wideband current sensors,50Hz power frequency phase generator, wideband signal amplifiers, filters, a digital oscilloscope and a computer. The propagation law and coupling mechanism of wideband partial discharge pulse in the real transformer are studied on3three-phase-double-winding real transformers and1three-phase-three-winding transformer model in this paper, which can provide guidance for partial discharge on-line monitoring and positioning of transformers.In this paper, we collected the partial discharge signals from several transformers’core grounding lines within the substation of somewhere using the wideband partial discharge on-line monitoring system, and then analyzed the signals’ frequency spectrum of each substation in order to study the law of partial discharge in frequency domain. Then we also conducted a statistical analysis based on the phase distribution, and identified the types of discharge which is suspected to be real partial discharge based on the equivalent time-frequency method.更多还原