电容型高压设备介损在线监测系统的现场采集单元设计

Design of Field Sampling Unit of an On-line Monitoring System of Dielectric Loss in Capacitive High-voltage Apparatus

在线监测电容型高压设备的介质损耗(简称介损)是判断其绝缘状况的有效手段;为了提高电力系统高压电气设备监测的安全性、可靠性及信息化指标,设计了一种基于新型电容型高压设备介损在线监测系统的现场采样单元(监测终端);针对相对比较法,提出了利用GPS授时实现异地高精度同步采样,并采用GPRS无线网络实现远程控制和通信的相对介损测量方案,系统采用内嵌处理器软核Nios Ⅱ的现场可编程门阵列(FPGA)器件EP1C6Q240C8完成对芯片ADS8505的采样控制;利用Quartus Ⅱ软件进行逻辑设计时,使用硬件描述语言VHDL和Verilog设计工频测量和采样逻辑模块的逻辑时序并完成数字信号的提取和存储;监测终端将数据信息打包后通过GPRS无线网络、Internet、服务器传输到客户端;最后又引入了相关诊断策略的专家软件对设备的绝缘性能进行判断;试验结果表明,该系统相对介损测量的可信度、精确度和稳定度比传统仪器有很大提高。

To assess the insulation condition of capacitive high-voltage apparatus, on-line monitoring of dielectric loss angle （3） is an effective measure. A type of field sampling unit （monitoring terminal） based on a new style on-line monitoring system of dielectric loss in capacitive high-voltage apparatus is designed, with which the safety, reliability and information-based standard of monitoring high voltage apparatus in power systems can be improved greatly. An approach using GPS to implement high-accuracy synchronization sampling in different places, and using GPRS to implement remote control and communication is presented in order to achieve relative comparison method. The accurate acquisition and control of ADS8505 is realized by EP1C6Q240C8 that includes Nios II embedded soft core processors. The logic se quential control of frequency measurement and a sampling logic modules are designed by using hardware description language VHDL as well as Verilog, and the extraction and storage of digital signal is completed in the period during which the logic design is realized by Quartus II. Then the digital information is packed and transmitted through the GPRS wireless network, Internet, the server to the client by monitoring terminal. Finally, the expert software assesses the insulation condition of the apparatus according to the relevant insulation diagnosis strategies. Testing results show that the monitoring system can improve the measurement of dielectric loss angle greatly with regard to confidence, accuracy and stability compared with conventional equipment.