IMPROVED POWER CONTROLLER FOR MICROGRID WITH NONLINEAR AND LINEAR LOADS

Abstract

The main objective of this control is to maintain the stability of the microgrid frequency and voltage by forcing the inverters to operate at their rated power, while eliminating unwanted currents such as circulating currents and noise currents arising from output parameter inconsistencies. However, the presence of non-linear or unbalanced loads poses serious challenges, negatively affecting the effectiveness of this control mechanism. These harmonics will cause the power sharing control between inverters to become inaccurate, thereby creating circulating currents between inverters, causing overheating and potentially damaging the inverters. This paper proposes a control strategy that enhances the accuracy of power sharing between inverters and improves the voltage quality in the microgrid. The proposed method can accurately distribute power to the inverters in the microgrid by using a virtual impedance block, which can automatically adjust its value according to the load conditions, the ambient temperature conditions, and the structure changes of the microgrid. In addition, the power sharing accuracy of the proposed method is not affected by nonlinear or unbalanced loads, improving the voltage quality in the microgrid. The proposed controller overcomes the limitations of the conventional controller. The simulation and experimental results demonstrate the suitability of the proposed control method.