摘要
电力设备长期受温度、雷击及内部过电压的作用,绝缘会逐步老化,导致内部产生微弱放电(称局部放电),如果不采取措施,它会逐步扩大而导致设备绝缘击穿。近年来,在线监测技术的发展使得及时发现这些缺陷成为可能,它能对被监测设备的绝缘参数随时进行测量,为电力系统的安全运行提供可靠的保证。
基于无线传输的特殊优点,本文提出在线监测系统采用无线传输的方式,为防止局部放电的无线干扰信号,选择通信频率为433MHz的短距离通信芯片nRF9E5。在此基础上,本文开发了通信芯片与PC机之间的通信以及通信芯片间的点对点通信系统。
本文构建了四种典型的局部放电模型来模拟电力设备内部的放电,并利用罗可夫斯基线圈、已有的采集系统和开发的点对点通信系统对其进行了传输试验,对接收到的数据进行了复原,使得其能较真实地反映放电模型的局部放电特征。为验证通信系统的可靠性,将利用传输系统得到的数据放电波形图和示波器采集到的波形图进行了比较,得到了很好的结果。
在对四种局部放电模型传输试验的基础上,对接收到的数据进行了处理,根据工频电压信号数据得到了局部放电信号的相位特征,根据局部放电电压信号数据得到了其放电量。据此选取一个工频周期对其相位φ、放电量q和放电重复率n进行了统计,绘制了四种局部放电模型的φ-q-n三维谱图,并对其进行了分析和比较。
Under temperature/lightning strike and internal voltage for long time, insulation of power equipment becomes aged, which leads to partial discharge. If the messures cannot be adopted, insulation breakdown may come along. The development of on-line monitoring makes it possible to find these faults. It can make sure the safe of power system by messuring the state of power equipment monitored.
Based on the special merits of wireless communication, wireless transmission is pointed out for monitoring system. We choose nRF9E5 to avoid wireless interference. By studying the inner structure of nRF9E5, the software support is programmed for point-to-point communication system.
This paper creates four relevant PD models upon the peculiar PD patterns of power equipment. PD experiment is done and the data is transmitted by system of data acquisition and point-to-point communication. The information received by controller center is treated and made a comparison with the primary signal of PD and we get a good result.
On the basis of experiment on four relevant PD midels, the received data is treated. The characteristic of phase (φ) is got by the signal of power frequency voltage and the characteristic of PD magnitude (q) is got by the signal of PD.φ-q-n of PD is numbered in 20 millisecond. Andφ-q-n 3-D plots are made for four PD models by data treated. The results are analyzed and compared based on the plots.
引文
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