This paper proposes a novel approach for fault detection, classification, and distance estimation of five kinds of faults (ie, cable and Arc faults) in the PV-based DC-ring microgrid. The proposed approach is based on the Hilbert Huang Transform (HHT) and online sequential random vector functional link network (OS-RVFLN). Initially, differential current signals are passed through empirical mode decomposition (EMD) to yield intrinsic mode functions (IMFs). Among the series of IMFs, more efficient IMFs are selected based on the threshold of maximum weighted kurtosis index (M-WKI) value for fault diagnosis. The selected IMFs are passed through Hilbert transform (HT) for determining the instantaneous frequency, magnitude spectrum, and Hilbert energy. Then, the Teager energy operator (TEO) is applied to the more effective IMF among the selected IMFs of each DC fault for fault detection. The most suitable target features are extracted from the selected efficient IMFs. This feature set data is initialized to the proposed HHT-OSRVFLN algorithm for five kinds of faults classification and its location estimation. The performance of the proposed algorithm in the proposed microgrid is proved in terms of low fault detection time, superior classification accuracy, and low relative error through different case studies by consuming minimum computation time in MATLAB/Simulink environment. Finally, the digital architecture of the proposed method is designed and simulated in Xilinx ISE 14.5 software environment to estimate the fault location. The Chip scope hardware debugging output proves the correctness, simplicity, feasibility, practicability, and robustness of the proposed method for online fault diagnosis.List of Symbols and Abbreviations: R f , fault resistance; Idc 1 , Idc 2 , DC currents; Vdc 1 , Vdc 2 , DC voltages; α 1 , α 2 , attenuation constants; ωd 1 , ωd 2 , damping frequencies; ω n1 , ω n2 , natural frequencies; I 3 , differential current; I avg , average current; SD (k), squared difference; M e (t), mean envelope; E [C(t)], Teager energy of the signal; ω(t), instantaneous frequency; θ(t), phase angle; I b , best IMF; H, hidden layers; β 0 , output weight matrix; Z, output of the signal; d pfd , predicted fault distance; d actl , actual fault distance; t c , computation time; CC, correlation coefficient; EMD, empirical mode decomposition; FPGA, field programmable gate array; HHT, Hilbert Haung transform; ICON, integrator controller; ILA, integrated logic analyzer; IMF, intrinsic mode functions; KI, Kurtosis index; MAC, multiply and accumulate unit; OS-RVFLN, online sequential random vector functional link; TEO, Teager energy operator; VHDL, hardware description language; WKI, weighted kurtosis index.