A Novel Multilayer N-LMS Adaptive-Filter-Based Control for Synchronization and Power Quality Improvement in Grid-Tied SPV System

Abstract

In the power distribution grid, a solar photovoltaic (SPV) system may experience voltage sag, swell, harmonics distortion, unbalance, and DC offset at its point of interconnection (POI). These conditions decline the power quality indices, which are escalated when the SPV system supplies power to unbalanced/ distorted loads. In this context, a multilayer normalized least mean square (N-LMS) adaptive filter-based control is proposed for the grid-tied SPV system, where the sensed grid voltages and load currents are filtered using the proposed method. Then, their dq-axis components are estimated and used to resolve synchronization issues. The estimated components are immune to negative sequence components, distortion, low-order odd harmonics (3 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rd</sup> , 5 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> , 7 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> , 9 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> ), and DC offset. The proposed control scheme has a simple structure with two tuning parameters. Moreover, it has no integrator compared with the generalized-integrator-based algorithm and only has three delay units compared with the methods based on the cascaded delay signal cancellation (CDSC). Hence, it is computationally faster than the advanced CDSC and other multilayer structure-based algorithms. Performance of the proposed method is demonstrated experimentally by implementing it on a laboratory setup of a grid-tied SPV system operating under non-ideal voltages and currents.