基于等效电路极化支路和特征量的油纸绝缘变压器老化诊断

Study on polarization branch and feature of equivalent circuit to evaluate transformer oil-paper insulation condition

回复电压法可以用于诊断油纸绝缘系统的绝缘状态,应用回复电压极化谱特征量构建的扩展德拜等效电路可以辅助分析油纸绝缘的老化状况,准确求解出等效电路参数是该项研究的关键。本文应用混合智能算法—粒子群遗传算法求解极化等效电路中的参数。将混合智能算法求解获得的回复电压极化谱与粒子群求解所得的结果进行对比,计算结果表明,应用混合智能算法求解获得的回复电压极化谱能更好地与现场测试的回复电压极化谱相吻合,从而说明粒子群遗传算法能更准确地计算出等效电路参数。在参数求解的基础上,本文还对油纸绝缘老化状况与极化支路数及支路时间常数的相互关系进行了探讨,结果表明,变压器油纸绝缘状态越差,极化支路数越多,对应支路的时间常数越小。同时提出综合利用极化支路数及较大时间常数这两个特征量来初步评估油纸绝缘状况。

Return voltage measurement is an effective non-destructive electrical testing method for diagnosis of oilpaper insulation equipment＇s insulation condition,and the oil paper insulation equivalent circuit model based on return voltage polarization spectrum characteristics is an effective way to analyze insulation aging. Calculating the equivalent circuit parameters accurately is the key to establish the equivalent circuit model of oil-paper insulation. In this paper,hybrid intelligent algorithm-Particle Swarm Genetic Algorithm is used to solve the polarization parameters of the equivalent circuit. Comparing the return voltage polarization spectra obtained by the hybrid intelligent algorithm and a single PSO,the results show that polarization spectra obtained by the application of hybrid intelligent algorithm obtained is better coincident with the testing return voltage polarization spectra,and that shows the feasibility and accuracy of using particle swarm genetic algorithm to calculate the equivalent circuit parameters. Meanwhile,the paper also discusses the relationship of oil-paper insulation aging status and the number of polarization branches,and the results show that more serious the transformer oil-paper insulation deterioration is,and the more number of the polarization branches exists,the smaller the time constant of the corresponding branch is. At the same time,combining the number of branches and the largest time constant can assess the condition of oil-paper insulation.