【作者】 王远；

【导师】 杨永明；

【作者基本信息】 重庆大学 ， 电气工程， 2011， 硕士

【摘要】 发电机是电力系统中重要的电气设备,发电机故障主要是由绝缘引起,这些绝缘故障将威胁电力系统的安全稳定运行。通过对发电机定子绕组局部放电进行在线监测,可以判断发电机定子绝缘状况,并且可以提前发出警报,防止事故发生,对整个电力系统的稳定、安全、可靠运行有着重大意义。本文研究出一种发电机定子绕组局部放电在线监测系统。该系统是以超声波传感器作为现场敏感器件,测量局部放电产生的超声波信号,并对信号进行放大,滤波,电平抬升,A/D模数转换,以及通用串行总线传送数据,并对结果进行分析处理,提取出局部放电特征量。使用Keil C软件编写了下位机程序,完成单片机的初始化、A/D转换、下位机USB程序,并通过USBXpress软件来获取相关的驱动程序以及API函数,实现下位机和上位机之间的USB数据通信。基于虚拟仪器技术,结合超声波检测终端,在LabVIEW平台上开发了发电机定子绕组局部放电超声波检测软件系统。系统实现局部放电数据的接收、解码、分解和重组处理,在人机交互界面下图形化显示局部放电波形。开发了一套基于虚拟仪器的局部放电信号的小波分析软件,进行局部放电信号小波分析。建立局部放电数据库管理,实现数据库信息查询。利用该系统对模拟局部放电信号产生的超声波在发电机定子中传播情况和发电机定子绕组的局部放电超声信号进行检测,并对不同位置放电源的检测结果进行对比,分析局部放电产生的超声信号在发电机定子中传播特性。系统成功地检测出发电机定子线棒产生的局部放电超声波信号,并利用小波去噪提取出超声波信号。实验结果表明利用超声波检测发电机定子绕组局部放电是可行的,设计的检测系统具有较高的灵敏度和稳定性,为进一步得出局部放电产生的超声信号特征和绝缘故障之间的对应关系奠定基础。该系统进一步完善之后可指导相关人员检测发电机运行状态,及时发现故障点,有计划进行检查和维修,保证发电机正常安全运行,降低社会经济损失。更多还原

【Abstract】 Generator is extremely important electrical equipment in power systems. Generator failure is mainly caused by the insulation failure, which will also threaten the power system security and stability. By generator stator windings partial discharge (PD) on-line monitoring, the insulation condition of the generator stator can be judged, and the alarm can also be given to prevent accidents in advance, which will have great significance on stability, security and reliable operation of the entire power system.In the paper, on-line monitoring system of generator stator winding PD has been developed. The ultrasonic sensor has been used as system field-sensitive devices, which can gain ultrasonic signals generated by partial discharge.The ultrasonic signal is amplified, filtered, level lifted, A/D analog-digital convertered, and transfered by Universal Serial Bus(USB). The results are processed and analyzed, and then the characteristics of partial discharge have beeen extracted.The lower machine communication is programed by Keil C, including A/D converter of PD signal, the microcontroller initialization, the USB program. The relevant drivers and API functions are getten by USBXpress software and data communications between the USB and PC are realized.Based on virtual instrument technology and ultrasonic detection terminal, software system of generator stator windings PD ultrasonic testing is developed on the Lab VIEW platform. The software system realizes PD data receiving, decomposing and re-combining , and PD waveform is graphically displaied on human-computer interaction interface. The wavelet analysis software based on virtual instrument is developed and wavelet analysis of PD ultrasonic signal is done by the software. The database management of partial discharge is established to realize the database information inquiry.The propagation characteristics of PD ultrasonic from PD model and PD ultrasonic in generator stator winding are detected by using the detect system. Discharge sources in different position of the generator detected by the system are analyzed and compared. Propagation characteristic of ultrasonic signals in the generator stator is analysised.The system detects ultrasonic signals of generator stator bars successfully and PD ultrasonic signal is extracted by wavelet denoising method.Experimental results show that the proposed detection system is feasible and has high sensitivity and stability,which lay the foundations for further drawing the corresponding relationship between ultrasonic signals characteristics of PD and the insulation fault. With further improved, the system can detect operation state and failure point of the generator and realize planned inspection and maintenance, ensure that generators safely operate which will reduce the social economic losses effectively.更多还原