基于PEA的XLPE电缆测试信号处理的研究

发布时间：2019-03-29 12:36

【摘要】：XLPE电力电缆因其优越的电气和机械性能而大量在地下输配电网络中使用。然而XLPE等聚合物材料中空间电荷的积聚会使得局部场强发生畸变,严重影响其绝缘性能,因此,研究这些绝缘介质中的空间电荷分布具有重大意义。目前,在空间电荷的测量方法中,电声脉冲法(PEA)的应用最广泛,能用于测量切片状固体和电缆本体试样中的空间电荷分布,但如何根据PEA测得的电压信号求出试样中空间电荷量的准确分布是一个重要问题。本文基于XLPE电缆PEA测试系统,从硬件电路和PEA系统中声波在介质中的传播特性两个方面分析了空间电荷测试信号受到的影响,前者包括硬件电路的频率响应引起的信号过冲、温度梯度场下压电传感器和放大器性工作性能的改变,后者包括介质摩擦阻尼及声波辐射形状对声脉冲形成的衰减色散、温度梯度场下声脉冲在XLPE绝缘中的传播速度和幅值的变化等。在这些因素中,针对能够影响空间电荷量及分布判断的部分,提出了空间电荷测试波形恢复的方法,开发了一套基于XLPE电缆的PEA测试信号处理程序,程序主要包含三大模块,分别是测试信号过冲恢复模块、衰减恢复模块以及单位校正模块,其中过冲恢复采用了频域下的反卷积技术,并通过高斯函数对反卷积中的病态问题进行约束,衰减恢复模块包含三个分支,分别针对切片试样,XLPE电缆本体以及温度梯度场下的XLPE电缆本体,对程序有效性进行了实例分析验证。为空间电荷对XLPE等绝缘材料老化特性的研究提供了数据分析基础。
[Abstract]:XLPE power cables are widely used in underground transmission and distribution networks due to their superior electrical and mechanical properties. However, the accumulation of space charges in polymer materials such as XLPE will cause local field strength distortion and seriously affect their insulation properties. Therefore, it is of great significance to study the distribution of space charges in these insulating media. At present, the electro-acoustic pulse method (PEA) is the most widely used method in the measurement of space charge, and it can be used to measure the space charge distribution in sliced solid and cable body samples. However, it is an important problem that how to calculate the accurate distribution of the space charge in the sample according to the voltage signal measured by PEA. Based on the XLPE cable PEA test system, this paper analyzes the influence of space charge test signal from two aspects: the hardware circuit and the propagation characteristic of acoustic wave in the medium of the PEA system. The former includes the signal overshoot caused by the frequency response of the hardware circuit, and the signal overshoot caused by the frequency response of the hardware circuit. Changes in the performance of piezoelectric sensors and magnifiers under temperature gradient fields, which include dielectric friction damping and attenuation dispersion of acoustic pulses formed by acoustic radiation shapes. The variation of propagation velocity and amplitude of acoustic pulse in XLPE insulation under temperature gradient field. In these factors, aiming at the part that can influence the space charge quantity and the distribution judgment, this paper puts forward the method of restoring the space charge test waveform, and develops a set of PEA test signal processing program based on XLPE cable. The program mainly includes three modules. The signal overshoot recovery module, attenuation recovery module and unit correction module are respectively tested. The over-impulse recovery adopts deconvolution technology in frequency domain, and the ill-conditioned problem in deconvolution is constrained by Gao Si function. The attenuation recovery module consists of three branches. For slice sample, XLPE cable body and XLPE cable body under temperature gradient field, the validity of the program is analyzed and verified by an example. It provides the basis of data analysis for the study of aging characteristics of insulating materials such as XLPE by space charge.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM247

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