基于单总线及磁调制传感技术的直流接地故障监测装置

直流系统接地故障的诊断技术随着新原理、新手段的出现而不断地有所发展,大体上可归纳为电桥法、低频信号注入法、直流信号注入法、直流漏电流检测法等几种。电桥法依据电桥平衡原理,结构简单,成本低廉,但功能单调,仅能对系统接地给予报警。低频信号注入法是将低频信号注入直流系统母线,通过检测各个支路的低频分量来判断是否该支路发生接地。为了排除分布电容的干扰,又发展出了变频探测法、载波相位法、复值小波变换等方法,但实际使用效果并不理想。直流信号注入法是向直流母线注入一个直流信号,再监测各支路的对地电流判断是否接地。无论是注入直流还是低频交流信号,为了提高检测的灵敏度,信号幅值都很大,对直流系统会造成一定的干扰,因此信号注入法并不受欢迎。直流漏电流检测法是直接将高灵敏度的直流传感器套在各支路上,检测漏电流,判断是否存在接地,由于该方法对直流系统无任何干扰,因此已经得到广泛应用。

Magnetic sensitivity technology based on microwave modulation of solid state spin system NV center

In view of the low resolution and accuracy of traditional magnetometer,a method of microwave frequency modulation technology based on nitrogen-vacancy(NV)center in diamond for magnetic detection was proposed.The magnetometer studied can reduce the frequency noise of system and improve the magnetic sensitivity by microwave frequency modulation.Firstly,ESR spectra by sweeping the microwave frequency was obtained.Further,the microwave frequency modulated was gained through the mixed high-frequency sinusoidal modulation signal generated by signal generator.In addition,the frequency through the lock-in amplifier was locked,and the signal which was proportional to the first derivative of the spectrum was obtained.The experimental results show that the sensitivity of magnetic field detection can reach 17.628 nT/Hz based on microwave frequency modulation technology.The method realizes high resolution and sensitivity for magnetic field detection.