In the past three years, a number of oil-immersed ultra-high-voltage shunt reactors have experienced discharge defects when being put into operation, resulting in an overload of acetylene. However, detecting and identifying these discharge defects caused by switching impulse voltage is challenging under steady-state conditions. This poses unpredictable and difficult-to-assess safety risks for the longterm operation of the equipment and subsequent transient processes. Hence, comprehending the discharge behavior of oil-pressboard (PB) insulation under switching impulse voltage and devising a method to identify defects becomes crucial. This study focuses on investigating the frequent arc reignition (FAR) pattern exhibited by typical defects under both standard and oscillation switching impulse voltages. The objective is to uncover the mechanism behind FAR and propose a defect recognition strategy suitable for transient processes. The study reveals the FAR process will occur at least once during the breakdown process; the FAR phenomenon is the weakest in the surface defect with a weak vertical electric field. The average recovery voltage percentage and the average discharge interval of the FAR process decrease with increasing impulse amplitude or oscillation frequency. Additionally, the average number of discharges decreases with higher oscillation frequency, while it initially increases and then decreases with increaseing amplitude. Based on the analysis of the number of FAR processes and their variation in terms of amplitude or discharge interval, a method for recognizing oil-PB defects during switching transient processes is developed and successfully applied to a case study involving acetylene overload in a 1000 kV shunt reactor.

中文翻译：

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基于操作冲击电压下频繁电弧重燃现象的油压板绝缘缺陷识别

近三年来，多座油浸式超高压并联电抗器在投入运行时出现放电缺陷，导致乙炔过载。然而，在稳态条件下检测和识别这些由开关脉冲电压引起的放电缺陷具有挑战性。这给设备的长期运行和随后的瞬态过程带来了不可预测且难以评估的安全风险。因此，了解油压板（PB）绝缘在开关脉冲电压下的放电行为并设计一种识别缺陷的方法变得至关重要。本研究重点研究标准和振荡开关脉冲电压下典型缺陷所表现出的频繁电弧重燃 (FAR) 模式。目标是揭示 FAR 背后的机制并提出适合瞬态过程的缺陷识别策略。研究表明，FAR过程在击穿过程中至少会发生一次；FAR现象在垂直电场弱的表面缺陷中最弱。FAR过程的平均恢复电压百分比和平均放电间隔随着脉冲幅度或振荡频率的增加而减小。此外，平均放电次数随着振荡频率的增加而减少，而随着振幅的增加，平均放电次数先增加然后减少。基于对FAR过程的数量及其在幅度或放电间隔方面的变化的分析，开发了一种在切换瞬态过程中识别油-PB缺陷的方法，并成功应用于涉及1000 kV分流器中乙炔过载的案例研究反应堆。