A battery energy storage system (BESS) with the ability to provide ancillary services to the electricity distribution network

Non-linear loads are a major contributor to harmonics in the power system. Harmonics harm electrical network components by destroying the sinusoidal waveform of current and voltage. The goal of this article is to provide and control active and reactive power, as well as to reduce network harmonic currents caused by non-linear loads. As a result, the proposed method decreases grid current harmonics by employing a battery energy storage system and providing a control mechanism for it, in addition to managing and supplying the amount of active and reactive power of the nonlinear load individually. Power control and harmonic reduction are the two parts of the proposed control system. Power control is done with classic PI controllers, whose coefficients are obtained with Ziegler-Nichols method, while harmonic reduction is done with PI-Fuzzy controllers. The current harmonic signal is sent into the PI-Fuzzy controller, while the main component (50 Hz) is isolated from it. The simulation results in three distinct scenarios demonstrate that the proposed approach can regulate the active and reactive powers of the nonlinear load under different charging and discharging situations, as well as reduce current harmonics up to the 31st harmonic.