Schurch Roger, Munoz Osvaldo, Ardila-Rey Jorge, Donoso Pablo, Peesapati Vidyadhar
Department of Electrical Engineering, Universidad Tecnica Federico Santa Maria, Valparaiso 2390123, Chile.
Department of Engineering and Design, Chilean Independent System Operator, Santiago 9020000, Chile.
Polymers (Basel). 2023 May 26;15(11):2461. doi: 10.3390/polym15112461.
Electrical treeing is one of the main degradation mechanisms in high-voltage polymeric insulation. Epoxy resin is used as insulating material in power equipment such as rotating machines, power transformers, gas-insulated switchgears, and insulators, among others. Electrical trees grow under the effect of partial discharges (PDs) that progressively degrade the polymer until the tree crosses the bulk insulation, then causing the failure of power equipment and the outage of the energy supply. This work studies electrical trees in epoxy resin through different PD analysis techniques, evaluating and comparing their ability to identify tree bulk-insulation crossing, the precursor of failure. Two PD measurement systems were used simultaneously-one to capture the sequence of PD pulses and another to acquire PD pulse waveforms-and four PD analysis techniques were deployed. Phase-resolved PD (PRPD) and pulse sequence analysis (PSA) identified tree crossing; however, they were more sensible to the AC excitation voltage amplitude and frequency. Nonlinear time series analysis (NLTSA) characteristics were evaluated through the correlation dimension, showing a reduction from pre- to post-crossing, and thus representing a change to a less complex dynamical system. The PD pulse waveform parameters had the best performance; they could identify tree crossing in epoxy resin material independently of the applied AC voltage amplitude and frequency, making them more robust for a broader range of situations, and thus, they can be exploited as a diagnostic tool for the asset management of high-voltage polymeric insulation.
电树枝化是高压聚合物绝缘中的主要劣化机制之一。环氧树脂被用作旋转电机、电力变压器、气体绝缘开关设备和绝缘子等电力设备中的绝缘材料。电树枝在局部放电（PD）的作用下生长，局部放电会逐渐使聚合物劣化，直到树枝穿过整体绝缘，进而导致电力设备故障和能源供应中断。这项工作通过不同的局部放电分析技术研究环氧树脂中的电树枝，评估并比较它们识别树枝穿过整体绝缘（故障前兆）的能力。同时使用了两个局部放电测量系统——一个用于捕获局部放电脉冲序列，另一个用于获取局部放电脉冲波形——并采用了四种局部放电分析技术。相位分辨局部放电（PRPD）和脉冲序列分析（PSA）识别出了树枝穿过；然而，它们对交流激励电压的幅度和频率更为敏感。通过关联维数评估了非线性时间序列分析（NLTSA）特性，结果表明从树枝穿过前到穿过后关联维数降低，这表明动态系统变得不那么复杂。局部放电脉冲波形参数表现最佳；它们能够独立于所施加的交流电压幅度和频率识别环氧树脂材料中的树枝穿过情况，使其在更广泛的情况下更具鲁棒性，因此，它们可被用作高压聚合物绝缘资产管理的诊断工具。
