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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。
Aiming at the low sampling rate of electronic transformer in power system, it is difficult to meet the problem of locating power fault accurately by traveling wave distance measuring device. A high frequency signal acquisition and transmission scheme of electronic transformer is put forward. The internal of electronic transformer is Rogowski coil, The grid current signal is converted into a small voltage signal by its differential function and added with a 90 ° lead difference. The integration circuit is designed to compensate for the phase difference. The high-frequency signal acquisition circuit with a sampling rate of 2 MSps is designed. The FPGA reads the sampling data through the LVDS interface And then use large-capacity FIFO (first-in first-out unit) for buffering. Due to the limited data transmission rate of Fast Ethernet, Gigabit Ethernet is used to transmit specific formatted messages by using FPGA, and the current data is transmitted to power traveling wave The invention solves the integral saturation problem caused by the input bias voltage of the op amp and the technical difficulty that the input range of the high speed ADC is smaller than the amplitude of the input signal. The experimental results show that the high frequency signal acquisition and transmission scheme can meet the requirements of line Wave distance measuring device 100 meters ranging accuracy requirements, with some engineering value.