Harmonic disturbance control in islanded smart grids

The paper proposes a computational procedure able to control in real-time the harmonic disturbance injected by nonlinear loads in an islanded MV/LV Smart Grid, characterized by low short circuit power. Aim of the proposed procedure is to keep automatically under acceptable values the penetration of harmonic disturbances caused by different loads, by means of a control algorithm suitable to a Smart Grid context. The control logic has been developed to perform detachments/controls in realtime in function of non-linear loads and their harmonic injection, starting from the assessment of voltage total harmonic distortion (THDv). In order to not exceed the harmonic disturbance thresholds, imposed by the Standard, the smart grid loads are scheduled by means of delayed activations over time, also using energy storage systems. The procedure is able to simulate load variability taking into account power consumption and harmonic profile changes in time. Electrical network, linear and non-linear loads and control algorithm have been implemented in a Simulink model. A case study representing a typical smart grid with residential and tertiary users, electric vehicle charging points and renewable sources is presented.