Voltage Harmonics-Based Islanding Detection for Grid-Tied Photovoltaic Systems

Abstract

Renewable energy sources (RES) are pollution free, inexhaustible as well as sustainable and their penetration is proliferating globally. Among the RES, solar photovoltaic (PV) systems possess key advantages like the absence of fuel cost, modular and static structure, longer life with reduced maintenance, and high power capability. Grid-tied PV systems have become prevalent due to the benefit of extremely effectual utilization of produced power. However, the grid integration of solar PV systems creates issues like voltage, frequency fluctuations, harmonic distortion and islanding. Islanding is a paramount issue in grid-tied PV systems, in which a part of the utility system, that encompasses both distributed generation sources and loads, remains energized while disconnected from the rest of the utility system. In an attempt to maintain the quality of delivered power as well as assure the safety of personnel and equipment, the solar PV inverters must be able to detect and prevent islanding. Hence, this paper investigates the efficacy of voltage harmonics-based islanding detection as a simple and low cost technique of implementing islanding protection for grid-tied PV systems. The dynamic performance of the suggested strategy is investigated for a 25 kW grid integrated PV system under islanding conditions utilizing the MATLAB/Simulink platform. The simulation results demonstrate that the voltage harmonics-based islanding detection scheme offers the advantages of fast response with smaller non-detection zone and no degradation of system stability and power quality compared to other state-of-the-art methods. The suggested strategy provides reliable islanding protection even in the presence of high Q-factor loads and during conditions of load and PV generation reactive power balance.