【作者】 曹娟；

【导师】 蒋兴良；

【作者基本信息】 重庆大学 ， 电气工程， 2003， 硕士

【摘要】 对覆冰地区的超高压线路，绝缘子覆冰引起的闪络已经成为最主要的故障之一，对电力系统的安全运行造成了极大的威胁。覆冰是一种特殊形式的污秽。覆冰绝缘子的闪络也是由泄漏电流引起的，泄漏电流的变化与发展是导致其是否能发展成完全闪络的主要因素之一。因此，对覆冰闪络过程中泄漏电流的检测具有非常重要的工程应用价值和学术意义。绝缘子覆冰后在运行电压作用下，由于环境条件的变化引起的表面覆冰状态的变化，从而造成泄漏电流的变化范围大，通常在μA到300~600mA之间。并且泄漏电流的持续时间长，试验中利用现有仪器观测和记录整个闪络过程难以实现。至今为止，虽然对绝缘子泄漏电流的检测和记录已进行了大量研究，但针对覆冰绝缘子闪络过程中泄漏电流变化全过程的测量和记录的研究仍然是空白。本文在国内外现有研究成果的基础上，根据覆冰绝缘子闪络过程中泄漏电流特性和测量要求，应用图形化编程语言LabVIEW设计了基于虚拟仪器的绝缘子冰闪过程泄漏电流检测系统。完成了硬件电路和软件的设计、制作及系统的模拟调试工作。在硬件电路的实现上，合理设计了保护电路和前置放大电路；结合前置电路选择了参数合适的数据采集卡。在软件设计上，设计了与普通数据采集卡的接口，实现了在LabVIEW环境中应用普通数据采集卡的功能；运用双缓冲和内存直接映射的设计方法实现对连续、大容量泄漏电流信号的实时采集和存储；设计了数字滤波器对采集后的原始数据滤去高频干扰。最后设计出虚拟测试仪器，通过与示波器进行对比测试表明该仪器稳定性和精度都比较高，还具有普通示波器所不具备的信号连续存储和回放功能。可以用于对覆冰绝缘子交直流临闪前泄漏电流过程进行检测，也可以用于污秽绝缘子泄漏电流的测量。通过在高压实验室人工气候室内对覆冰绝缘子闪络过程中泄漏电流测量表明：该系统可以全面的测量覆冰绝缘子泄漏电流变化和局部电弧的发展过程的整个过程。更多还原

【Abstract】 The iced insulators flashover is one of the main faults of the EHV transmission lines in icing regions. Icing is especial form of pollution. The flashover of iced insulators is also caused by the leakage current. The variety and development of the leakage current is one of the main factors to cause the iced insulators flashover. Therefore, leakage current measurement on flashover process during the insulators icing has both important academic meaning and engineering value.During the insulators are carried out working voltage after it was iced, the surface states of iced insulators would variety according to the environment conditions. Therefore, The amplitude of leakage current would vary from several μA to 300~600mA. And it would last a long time because of the flashover development, it’s difficult to data acquisition or logging the leakage current waveform by currently instruments. And so far, lots of investigation was conducted on the insulators’ leakage current measurement and logging, but the investigation of the entireness process measurement and logging of the iced insulators flashover is also vacancy.Based on the currently laboratory investigation results and the iced insulators leakage current performance during icing process, in this paper a leakage current measurement system is designed with graphical programming language laboratory virtual instrument engineering workbench. Designs, manufacture and test for hardware and software of the whole system are finished.When signal-conditioning circuit is in consideration, attention is paid to design safeguard circuit and magnify circuit. A proper parameter data acquisition card is selected according to the signal-conditioning circuit. A common data acquisition card can be used on laboratory virtual instrument engineering workbench through designing the external interface between LabVIEW and common date acquisition card on the software design; Used the idea of the double buffer and direct memory access, a real time data acquisition and logging about the succession, big capacitance leakage current is realized; A digital filter is designed to filter high frequency signals. Finally, a kind of virtual instrument is designed to detect leakage current. It has high precision and high stability performance through comparison measurement between virtual instrument and oscillograph. It also can log and reading continues data while a common oscillograph can’t. It offered a feasible way not only for iced insulators<WP=6>to detect leakage current during flashover on AC and DC, but also for polluted insulators.The iced insulators leakage current measurement results during flashover process in the multi-function artificial climate chamber of Chongqing University indicate that it cans acquisition and logging of iced insulator’s leakage current and partial arc exactly.更多还原