Robust Adaptive Active Islanding Detection With $\alpha$-Axis Disturbance Injection Under High Impedance Fault, Unbalanced Loading, and Phase Failure in Grid Tied PV System

Abstract

Power generation with photovoltaic technology is growing expeditiously. With the high penetration of solar-based generation, a concern of islanding detection is always by the distributors due to grid side faults and abnormality. It is the demand of the situation to equip the PV-connected inverter with an islanding detection mechanism to avoid any catastrophe. In the present work, an active islanding detection technique utilizing a smaller magnitude current injection through <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\alpha$</tex-math></inline-formula> -axis current controller of grid side voltage source converter (VSC) is proposed. Due to injection of current through VSC, point of common coupling (PCC) voltage is having different harmonic component in the grid connected and islanded mode. In the proposed detection method, the sensed PCC voltage is used to derive the three signals i.e. AVVM(absolute <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$v_{mag}$</tex-math></inline-formula> variation mean), AMSVV(absolute mean of square variation of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$v_{mag}$</tex-math></inline-formula> ), & FAVVM(Frequency of absolute <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$v_{mag}$</tex-math></inline-formula> variation mean). These three derived signals is used to take the decision for islanding detection. Further, Complex Co-efficient Filter-Second Order Frequency Locked Loop (CCF-SOFLL) is proposed for three phase grid synchronization and frequency estimation. The proposed Strategy is tested under high impedance fault, phase failure and unbalanced loading conditions. It is found that the proposed work clearly differentiates the islanding and faults condition. The Non- detection zone (NDZ) of the proposed strategy is verified under different quality factors ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$Q_{f}$</tex-math></inline-formula> ) of the load. To evaluate the effectiveness of the suggested strategy, MATLAB Simulation and experimental validation is performed. The obtained islanding detection time is within the IEEE-1547 standard.