Improved Reweighted Zero-Attracting Quaternion-Valued LMS Algorithm for Islanded Distributed Generation System at IM Load

Sudden start of an IM load and frequent change of nonlinear load in a standalone distributed generation system (DGS) cause the dip in ac voltage and frequency. Moreover, these loads distort DGS currents. Therefore, in this paper, an improved-reweighted zero-attracting quaternion-valued least mean square (I-RZA-LMS)-algorithm-based voltage source converter (VSG) control is proposed for voltage and frequency regulation, and power quality improvement in DGS. Moreover, the control algorithm of dc–dc bidirectional converter (BDC) is used for dc link voltage regulation and MPPT of the solar photovoltaic array at IM starting and nonlinear loading. In this DGS, the I-RZA-LMS-based control algorithm estimates the active and reactive component currents of distorted load currents for effective harmonics mitigation, reactive power compensation, and point of common coupling voltages regulation. The proposed control algorithm rejects the dc-offset component from load currents and gives the fundamental load component. The dc link voltage of VSC is regulated using BDC with a solar feedforward term, which is used to enhance the capability of dc link voltage control under solar power variation, IM starting, and unbalanced loading. The effectiveness of the proposed DGS is validated through the simulation as well as experimental results obtained on a developed prototype of DGS.