Voltage Positive Feedback based Islanding Detection Algorithm for Power Quality Assessment

Abstract

During electrical separation from the power grid, Distributed Generators (DGs) inject power exclusively to the local load, which is known as Islanding. Several IslandingDetection Methods (IDMs) have been reported to identify this unwanted situation, which are divided into three categories: remote, active, and passive.In active approaches, a disturbance is introduced into the DG's controller, which causes a local measure to deviate outside of the acceptable range. Even in well-balanced islands, this perturbation contributes to more effective detections, but it worsens the Total Harmonic Distortion (THD) of the output current under normal operation conditions. The modified sliding mode controller as a novel Active IDM for Grid-Connected Photovoltaic Systems (GCPVS) with a string inverteris investigated in this work.Its performance is compared to that of a well-known active IDM, the Voltage Positive Feedback (VPF) approach. The output current harmonics and THD,as well as the efficiency, are measured for a1 kWp GCPVS in the MATLAB/Simulink platform at varied penetration and disturbance levels.The output data shows that the proposed disturbance does not generate harmonics or subharmonics since it adjusts the amplitude of the output current. As a result, it has a minor negative impact on power quality. Finally, the behaviour of the sliding mode-based IDM is deemed reliable in terms of Islanding detection and power quality.A modified Sliding Mode Controller(SMC) is combined with Fuzzy LogicController(FLC) and Artificial Neural Network(ANN) controller, which are implemented in a SIMULINK platform and simulation results are compared to further reduce THD percent of load currents and enhance power quality.