直流局部放电试验系统的研制及应用

随着中国特高压直流输电工程的发展，换流变压器等电力设备的安全可靠性问题显得尤为重要。由于直流局部放电试验能够提早发现绝缘缺陷、有效预防直流输电设备绝缘击穿事故的发生，根据直流局部放电机理，研制出一套可用于换流变压器直流耐压过程的局部放电检测的试验系统。该系统具有抗干扰能力强，高速、持续、实时采集的特点，能够保证系统检测的直流局部放电信号的有效性和完整性，并通过典型油纸复合绝缘模型验证了其性能。实践结果表明，它能有效、便捷地测量油纸绝缘直流局部放电的时域信号。对时域信号进行的时频分析和统计分析结果表明：同一电极模型中，统计特征参量的数值上随加压时间变化明显，可实现局部放电发展严重程度的预测；不同电极模型中，统计特征参量分布规律一致，可有效判断缺陷类型，该系统有望广泛地应用于直流输电设备检测。

Development and Application of Measurement Device for DC Partial Discharge

With the development of UHVDC transmission engineering in China, the safety and reliability of such electrical equipment as converter transformer is particularly important. DC partial discharge is a prominent indicator of insulation defects, and its test can help prevent dielectric breakdown of DC power transmission equipment. Based on the DC partial discharge principle, a DC partial discharge test system was established to monitor the insulation status of converter transformers. Characterized by strong anti-interference ability, and high-speed, persistent and real-time capability in data acquisition, the proposed system can record the DC partial discharge signal efficiently and entirely. The system’s performance was verified through a typical oil-paper compound insulation model. The practical results show that the proposed system can effectively and conveniently measure the DC partial discharge time-domain signal of oil-paper insulation. Time-frequency analysis and statistical analysis of DC partial discharge signal indicates that the statistical characteristic parameters in the model of same electrodes varies significantly with time and can be used to forecast the severity caused by partial discharge, and the the statistical characteristic parameters in the model of different electrodes have the similar distribution tendency and can be used to estimate the defect types. The measuring systemt is expected to be implemented widely in testing DC power transmission devices in China.