电子式互感器高频数据采集与传输方案

针对当前电力系统电子式互感器采样率偏低,难以满足行波测距装置准确定位电力故障的问题,提出了电子式互感器高频信号采集与传输方案；电子式互感器内部为Rogowski 线圈,电网电流信号被其微分作用转换为小电压信号并附加了90°超前相差,设计积分电路补偿该相差；设计采样率为2 MSps的高频信号采集电路,FPGA通过LVDS接口读取采样数据,并进行幅值处理,最后利用大容量FIFO(先入先出单元)进行缓存；由于百兆网数据传输速率有限,利用FPGA设计吉比特光纤以太网传输特定格式报文,把电流数据传输至电力行波测距装置；解决了积分电路由于运放输入偏置电压带来的积分饱和问题,以及高速ADC输入量程小于输入信号幅值等技术难点；试验结果表明,高频信号采集及传输方案能够满足行波测距装置百米级别的测距精度要求,具有一定工程应用价值。

A Design Scheme of Electronic Transformer High-frequency Signal Acquisition and Transmission

As electronic transformer with low sample rate cannot meet the needs of power fault location accuracy, high-frequency signal acquisition and transmission technology is introduced. Current signal of power grid was converted to low voltage signal with 90°angle ahead by Rogowski coil in electronic transformer, which was compensated by the subsequent integrator circuit. Sample rate of signal acquisition circuit was designed to be 2 MSps. Sample data were read via LVDS interface, processed and buffered with FIFO by FPGA. Due to the mass traveling-wave data, instead of 100 M Ethernet, gigabit Ethernet was used. Frames of special form were transmitted to traveling-wave location devices. Technical difficulties such as integration saturation due to input bias voltage of operational amplifier, and small measuring range of high-speed ADC, were solved. Experiment result showed that this design of signal acquisition and transmission meet the needs of location accuracy and has some engineering value.