Filter Capacitor Current Dynamics-Based Frequency-Domain Fault Detection Approach for Grid-Connected Low-Voltage DC Microgrid

Abstract

This paper proposes a cost-effective short circuit fault detection method for a distribution network in the ac grid-connected low-voltage dc (LVDC) microgrid. In this method, a typical dc system is considered where a number of dc/dc, ac/dc power converters and loads are interfaced to the dc link. Further, these loads are dedicated as local loads to the converter based on the locality of the same. The discharge of a filter capacitor (FC) in power converters in the dc system is the foremost indicator of a fault. Such dynamic behavior of FC can be utilized in the identification of a fault. This method is a time-frequency domain-based wavelet transform (WT), which utilize the current dynamics of an FC for quantitative analysis of a fault current. Additionally, a detailed thresholds selection process is also explained. MATLAB/Simulink model is used to carry out simulation studies. The experimental validation of WT based fault detection method is executed on the ac grid-connected LVDC microgrid testbed interfaced to the dSPACE 1104 controller.