用于发电机保护的柔性全光纤电流互感器

介绍了采用柔性全光纤电流互感器(FFOCT)的发电机保护总体方案和系统结构以及FFOCT结构和工作原理。详细介绍了FFOCT的关键技术难题并给出了对应的解决方案:采用旋转高双折射(Spun Hi-bi)光纤制作可现场缠绕在导体周围的传感光缆,并对采用Spun Hi-bi光纤的FFOCT的电流检测灵敏度和抵御外界干扰的能力进行了理论分析;采用四态方波调制和阶梯波反馈的全数字双闭环解调方案改善FFOCT动态范围、测量精度以及系统的长期稳定性。测试结果表明研制的FFOCT满足测量0.2级、保护5TPE的精度要求。最后简单介绍了用于观音岩水电站发电机保护的FFOCT的现场安装与应用情况。

FFOCT for generator protection

The structure and working principle of FFOCT(Flexible Fiber Optical Current Transducer) as well as the overall scheme and system structure of generator protection adopting FFOCT are introduced. The key technical issues of FFOCT are introduced in detail and corresponding solutions are given. Spun Hi-bi(Spun Highly-birefringent) fiber is used to manufacture the sensing optical cable, which can wind around the conductor in field. The current detection sensitivity and anti-interference ability of FFOCT using Spun Hi-bi fiber are analyzed. The all digital dual close-loop demodulation scheme with four-state bias modulation and digital ramp feedback is adopted to enhance the dynamic range, measurement accuracy and long-term stability of FFOCT. The test results show the developed FFOCT meets IEC accuracy class 0.2 and 5TPE. The site installation and application of FFOCT for the generator protection of Guanyinyan hydropower station are briefly introduced.