For actively modulated In-line Sagnac interferential all optic fiber current transformers (AOFCTs), the accuracies are directly affected by the amplitude of the modulation signal. In order to deeply undertand the func...For actively modulated In-line Sagnac interferential all optic fiber current transformers (AOFCTs), the accuracies are directly affected by the amplitude of the modulation signal. In order to deeply undertand the function of the modulator, a theoretical model of modulation effect to AOFCTs is built up in this paper. The effect of the amplitude of the modulation signal to the output intensity of AOFCTs is theoretically formulated and numerical calculated. The results show that the modulation voltage variation could affect the output accuracies significantly. This might be some references on the investigation for practical applications of AOFCTs.展开更多
An optical fiber transmitting photoelectric coupling current transformer has been developed. In the environment of high voltage and electromagnetic fields, this device is characterized by high insulation, high reliabi...An optical fiber transmitting photoelectric coupling current transformer has been developed. In the environment of high voltage and electromagnetic fields, this device is characterized by high insulation, high reliability, small mass and high anti-interference. The structure design and operating principle of the system are introduced, measurement errors are analyzed and experimental results are given.展开更多
The advantages of the all-fiber optical current transformer include but are not limited to being small in size,having no magnetic saturation,exhibiting high measurement accuracy,and boasting strong electromagnetic int...The advantages of the all-fiber optical current transformer include but are not limited to being small in size,having no magnetic saturation,exhibiting high measurement accuracy,and boasting strong electromagnetic interference resistance.However,the high cost of the all-fiber optical transformer limits its promotion and application in engineering.This paper proposes a design scheme of an independent double acquisition loop for the all-fiber optical current transformer based on the single optical path.Firstly,based on the closed-loop control mode and open-loop control mode,the twochannel sampling signal demand for relay protection,and the independent dual-acquisition loop design scheme of the all-fiber optical current transformer are proposed.Secondly,the reliability and economic feasibility of the scheme are demonstrated by an analysis of system failure and cost.The results show that the scheme can actualize the acquisition function of two independent all-fiber optical current transformer products on a single all-fiber current transformer in an integrated manner,which greatly reduces the cost of the all-fiber optical current transformer in engineering applications.展开更多
为了更有效的提高光纤电流互感器FOCT(Fiber-Optical Current Transformer)的信噪比,在分析FOCT输出信号特性的基础上,结合变步长自适应算法和小波变换理论,提出一种针对处理FOCT输出信号的改进多尺度域变步长自适应滤波算法,并设计了...为了更有效的提高光纤电流互感器FOCT(Fiber-Optical Current Transformer)的信噪比,在分析FOCT输出信号特性的基础上,结合变步长自适应算法和小波变换理论,提出一种针对处理FOCT输出信号的改进多尺度域变步长自适应滤波算法,并设计了一种基于Active X技术的变步长自适应滤波系统,通过该系统将改进算法与现有的变步长自适应算法进行了对比,结果表明此算法的收敛速度和稳态精度都得到了很大的改善。然后将此算法在FOCT中进行了应用测试,测试结果反映了该算法能有效提高FOCT的检测信噪比和抗噪声干扰能力。展开更多
Based on the transverse electro-optic effect of lithium niobate crystal,combined with polarizers and Faraday rotator,this paper presents a collinear closed-loop fiber optic current transformer with spatial non-recipro...Based on the transverse electro-optic effect of lithium niobate crystal,combined with polarizers and Faraday rotator,this paper presents a collinear closed-loop fiber optic current transformer with spatial non-reciprocity modulation method,and the feasibility of the scheme is verified by both the theoretical and experimental evidences.The detection scheme avoids the limitation of the transition time of the sensing fiber coil on the phase modulation frequency,improves the sensitivity and stability of the system,and reduces the volume and cost of fiber optic current transformer.The sawtooth wave modulation scheme is adopted to realize phase bias modulation and feedback modulation through phase shift of sawtooth wave to achieve closed-loop detection effect,which enhances the signal to noise ratio and simplifies demodulation mode.The experimental results show that the current ratio errors measured at room temperature range from 1%to 120%of rated current meet the requirements of national standard GB/T 20840.8-2007 and reach the accuracy level of 0.2S.The temperature stability of the current transformer is also tested,and the ratio error measured at the rated current does not exceed±0.2%in the range of-30℃to 50℃.展开更多
为探究全光纤电流互感器(fiber optical current transformer,FOCT)调制回路故障对探测器输出信号影响,便于故障预测与故障诊断,文中首先建立包含光电回路相位延迟的正弦波调制FOCT输出信号数学模型,给出调制深度与驱动电压、二次谐波...为探究全光纤电流互感器(fiber optical current transformer,FOCT)调制回路故障对探测器输出信号影响,便于故障预测与故障诊断,文中首先建立包含光电回路相位延迟的正弦波调制FOCT输出信号数学模型,给出调制深度与驱动电压、二次谐波、四次谐波的数学关系式,分析定目标值调制器闭环调制、解调的基本方法。在此基础上通过建立数学模型分析调制深度对探测器输出光强峰值、平均光强、二次谐波、四次谐波的影响。据此提出发生调制回路故障时调制深度降低是导致探测器输出信号异常的关键因素,探测器输出平均光强增大、四次谐波降低、二次/四次谐波比值增加应作为调制回路故障的典型特征。最后开展实际FOCT模拟试验证明理论研究的有效性。展开更多
文摘For actively modulated In-line Sagnac interferential all optic fiber current transformers (AOFCTs), the accuracies are directly affected by the amplitude of the modulation signal. In order to deeply undertand the function of the modulator, a theoretical model of modulation effect to AOFCTs is built up in this paper. The effect of the amplitude of the modulation signal to the output intensity of AOFCTs is theoretically formulated and numerical calculated. The results show that the modulation voltage variation could affect the output accuracies significantly. This might be some references on the investigation for practical applications of AOFCTs.
文摘An optical fiber transmitting photoelectric coupling current transformer has been developed. In the environment of high voltage and electromagnetic fields, this device is characterized by high insulation, high reliability, small mass and high anti-interference. The structure design and operating principle of the system are introduced, measurement errors are analyzed and experimental results are given.
基金supported by the National Natural Science Foundation of China (No. U1866203)
文摘The advantages of the all-fiber optical current transformer include but are not limited to being small in size,having no magnetic saturation,exhibiting high measurement accuracy,and boasting strong electromagnetic interference resistance.However,the high cost of the all-fiber optical transformer limits its promotion and application in engineering.This paper proposes a design scheme of an independent double acquisition loop for the all-fiber optical current transformer based on the single optical path.Firstly,based on the closed-loop control mode and open-loop control mode,the twochannel sampling signal demand for relay protection,and the independent dual-acquisition loop design scheme of the all-fiber optical current transformer are proposed.Secondly,the reliability and economic feasibility of the scheme are demonstrated by an analysis of system failure and cost.The results show that the scheme can actualize the acquisition function of two independent all-fiber optical current transformer products on a single all-fiber current transformer in an integrated manner,which greatly reduces the cost of the all-fiber optical current transformer in engineering applications.
文摘为了更有效的提高光纤电流互感器FOCT(Fiber-Optical Current Transformer)的信噪比,在分析FOCT输出信号特性的基础上,结合变步长自适应算法和小波变换理论,提出一种针对处理FOCT输出信号的改进多尺度域变步长自适应滤波算法,并设计了一种基于Active X技术的变步长自适应滤波系统,通过该系统将改进算法与现有的变步长自适应算法进行了对比,结果表明此算法的收敛速度和稳态精度都得到了很大的改善。然后将此算法在FOCT中进行了应用测试,测试结果反映了该算法能有效提高FOCT的检测信噪比和抗噪声干扰能力。
基金This work was supported by the National Natural Science Foundation of China(Grant No.61735011)the Science and the Key Research and Development Program of Hebei Province(Grant No.19251703D)the Local Science and Technology Development Projects of the Central Committee(Grant No.19941708G).
文摘Based on the transverse electro-optic effect of lithium niobate crystal,combined with polarizers and Faraday rotator,this paper presents a collinear closed-loop fiber optic current transformer with spatial non-reciprocity modulation method,and the feasibility of the scheme is verified by both the theoretical and experimental evidences.The detection scheme avoids the limitation of the transition time of the sensing fiber coil on the phase modulation frequency,improves the sensitivity and stability of the system,and reduces the volume and cost of fiber optic current transformer.The sawtooth wave modulation scheme is adopted to realize phase bias modulation and feedback modulation through phase shift of sawtooth wave to achieve closed-loop detection effect,which enhances the signal to noise ratio and simplifies demodulation mode.The experimental results show that the current ratio errors measured at room temperature range from 1%to 120%of rated current meet the requirements of national standard GB/T 20840.8-2007 and reach the accuracy level of 0.2S.The temperature stability of the current transformer is also tested,and the ratio error measured at the rated current does not exceed±0.2%in the range of-30℃to 50℃.
文摘为探究全光纤电流互感器(fiber optical current transformer,FOCT)调制回路故障对探测器输出信号影响,便于故障预测与故障诊断,文中首先建立包含光电回路相位延迟的正弦波调制FOCT输出信号数学模型,给出调制深度与驱动电压、二次谐波、四次谐波的数学关系式,分析定目标值调制器闭环调制、解调的基本方法。在此基础上通过建立数学模型分析调制深度对探测器输出光强峰值、平均光强、二次谐波、四次谐波的影响。据此提出发生调制回路故障时调制深度降低是导致探测器输出信号异常的关键因素,探测器输出平均光强增大、四次谐波降低、二次/四次谐波比值增加应作为调制回路故障的典型特征。最后开展实际FOCT模拟试验证明理论研究的有效性。
