Research On Intelligent Adaptive Residual Current Operated Protective Device

In the low-voltage grid, the residual current operated protective device can prevent electrical fires, personal electric shock and damage to electrical equipment caused by residual current, playing an important role in the guarantee of electricity safety.Currently, the application environment of residual current operated protective device has become increasingly complex. With the application of electronic devices, DC component and the level of power harmonics problems are more and more serious. The normal residual current levels of different grids are widely different, and the normal residual current of the same grid even changes a lot due to the different seasons, humidity and temperature. If residual current operating value is fixed, the protector is easy to malfunction when the grid normal residual current is large, reducing the commissioning rate.To solve the above problems, this paper proposes an adaptive residual current protection technology to improve the adaptation and reliability of the residual operated protective device.This paper converts the residual current signal from the time domain to the frequency domain using FFT transform, and the residual current signal RMS is calculated. The implementation process of adaptive residual current protection is discussed. Moreover, it researches and designs microcontrollerbased hardware systems, including the MCU module of the system, the drive modules, power modules, signal conditioning modules and others. The software system is designed, and the flowcharts are presented. At the end, related experiments are conducted to verify the feasibility of the system and achieve the desired results which prove the device can adapt to complex work environment and operate reliably.