The work principle of all fiber optical current transducer (AFOCT) was introduced. By analyzing the characteristic of photo-detector's output, a measurement and signal processing scheme based on sine wave modulati...The work principle of all fiber optical current transducer (AFOCT) was introduced. By analyzing the characteristic of photo-detector's output, a measurement and signal processing scheme based on sine wave modulation and demodulation was put forward for eliminating the influence of light intensity change and modulation degree change. A digital signal processing system and a calibration scheme were also advanced. The experimental data show that the mean ratio error is 0.016 74% for direct current and 0.035% for alternating current, and the correlation coefficient of linearity is up to 0.999 982 4, meeting the precision requirement of 0.2 grade. Stability experiments and temperature drift experiments show the AFOCT has a better stable capability.展开更多
In order to improve the measurement precision of the optical current transducer （ OCT）, the adaptive optical transducing principle on independent variables is presented in this paper. And one of the adaptive optical...In order to improve the measurement precision of the optical current transducer （ OCT）, the adaptive optical transducing principle on independent variables is presented in this paper. And one of the adaptive optical current transducer（AOCT） on the independent variables of the output of the electricmegnet current transducer is introduced. According to IEC660044-8, the performance of AOCT was examined roundly applying the standard testing system authenticated by the state authority. The results indicate that the measurement precision of the AOCT has already reached 0. 2 class under the temperature from -40℃ to 60℃ ,which proves the feasibility of the method.展开更多
A high performance current and voltage measurement system has been developed in power system. The system is composed of two parts: one current measurement element and one voltage measurement element. A Rogowski coil ...A high performance current and voltage measurement system has been developed in power system. The system is composed of two parts: one current measurement element and one voltage measurement element. A Rogowski coil and a capacitive voltage divider are used respectively for the line current and voltage measurements. Active electronic components are used to modulate signal, and power supply for these components is drawn from power line via an auxiliary current transformer. Measurement signal is transmitted by optical fibers, which is resistant to electromagnetic induction and noise. With careful design and the use of digital signal processing technology, the whole system can meet 0.5% accuracy for metering and provides large dynamic range coupled with good accuracy for protective relaying use.展开更多
为提高光学电流互感器(Optical Current Transducer,OCT)在低信噪比环境下的测量准确度和长期稳定性,该文从影响OCT性能关键因素之一的算法入手,在分析现有的变步长自适应算法的基础上,结合OCT输出信号的特征和OCT工作的环境,提出一种...为提高光学电流互感器(Optical Current Transducer,OCT)在低信噪比环境下的测量准确度和长期稳定性,该文从影响OCT性能关键因素之一的算法入手,在分析现有的变步长自适应算法的基础上,结合OCT输出信号的特征和OCT工作的环境,提出一种改进的双Sigmoid函数变步长自适应算法,并将这种算法与现有的变步长自适应算法进行了仿真对比分析以及利用Active X技术将该算法在OCT中进行了应用测试,证明了该算法在低信噪比环境下提高OCT的测量准确度和长期稳定性的优势.展开更多
文摘The work principle of all fiber optical current transducer (AFOCT) was introduced. By analyzing the characteristic of photo-detector's output, a measurement and signal processing scheme based on sine wave modulation and demodulation was put forward for eliminating the influence of light intensity change and modulation degree change. A digital signal processing system and a calibration scheme were also advanced. The experimental data show that the mean ratio error is 0.016 74% for direct current and 0.035% for alternating current, and the correlation coefficient of linearity is up to 0.999 982 4, meeting the precision requirement of 0.2 grade. Stability experiments and temperature drift experiments show the AFOCT has a better stable capability.
文摘In order to improve the measurement precision of the optical current transducer （ OCT）, the adaptive optical transducing principle on independent variables is presented in this paper. And one of the adaptive optical current transducer（AOCT） on the independent variables of the output of the electricmegnet current transducer is introduced. According to IEC660044-8, the performance of AOCT was examined roundly applying the standard testing system authenticated by the state authority. The results indicate that the measurement precision of the AOCT has already reached 0. 2 class under the temperature from -40℃ to 60℃ ,which proves the feasibility of the method.
文摘A high performance current and voltage measurement system has been developed in power system. The system is composed of two parts: one current measurement element and one voltage measurement element. A Rogowski coil and a capacitive voltage divider are used respectively for the line current and voltage measurements. Active electronic components are used to modulate signal, and power supply for these components is drawn from power line via an auxiliary current transformer. Measurement signal is transmitted by optical fibers, which is resistant to electromagnetic induction and noise. With careful design and the use of digital signal processing technology, the whole system can meet 0.5% accuracy for metering and provides large dynamic range coupled with good accuracy for protective relaying use.
文摘为提高光学电流互感器(Optical Current Transducer,OCT)在低信噪比环境下的测量准确度和长期稳定性,该文从影响OCT性能关键因素之一的算法入手,在分析现有的变步长自适应算法的基础上,结合OCT输出信号的特征和OCT工作的环境,提出一种改进的双Sigmoid函数变步长自适应算法,并将这种算法与现有的变步长自适应算法进行了仿真对比分析以及利用Active X技术将该算法在OCT中进行了应用测试,证明了该算法在低信噪比环境下提高OCT的测量准确度和长期稳定性的优势.
