电子式互感器数字输出校验系统的研究

An All-digital and High-accuracy System for Calibration of Electronic Transformers with Digital Output

电子式互感器数字输出校验系统一般采取构建标准信号通道且数字化技术,同步接收被校验互感器合并单元的数字输出,再进行两路信号误差计算的方法。本文针对影响校验系统精度的主要因素进行了详细分析,研究了一种基于PCI高精度采集卡的数字输出电子式互感器校验系统。该系统采用24位A/D保证了标准通道采集单元的精度和动态范围,通过路由采样时基的同步方法将同步误差控制在纳秒级,加二阶汉宁卷积窗的误差修正算法有效抑制频率波动及间谐波干扰的影响。在国家电网武汉高压研究院进行了该系统的误差校准,结果表明该系统具有0.05级以上的精度,并已在现场校验中实际应用。

Normally, calibration system of electronic transformers with digital output which includes construction of standard channel, digital processing of analog output signal of standard channel, receives the digital output of MU synchronous and error calculation. In this paper, an all-digital calibration system with digital output based on PCI high-accuracy DAQ card is proposed considering the factors influencing accuracy. Precision and dynamic range are guaranteed by A/D converter with 24 resolution and synchronization error limit is nanosecond by using the novelty synchronization method. Inaddition, an error correction algorithm based on the two-order Hanning convolution window has good inhibition of frequency fluctuation and inter-harmonics interference. Error calibration was carried out in the State Grid Electric Power Research Institute of China and results show that the proposed system can reach the precision class up to 0.05.