Comparative Study of the Traditional, Arctan and Universal Droop Control Techniques for Proper Power Sharing in an Islanded Micro-Grid

Abstract

Distributed generation (DG) sources together with loads, storage devices and a controller form a micro-grid (MG). The micro-grid can operate in grid-connected or islanded mode. A controller is needed for islanded mode operation to ensure voltage and frequency stability and proper power sharing among DG units. Droop, average current-sharing, and master-slave controls are among approaches that have been developed. Droop control has recently gained popularity due to the fact that it does not require a communication path, has high stability, and is relatively inexpensive. Therefore, this paper aims to offer a comparative study of three droop control techniques, namely, the traditional, arctan and universal droop control approaches. Using MATLAB/SIMULINK software, a simple MG made of two parallel-connected inverters with resistive-inductive load is used to compare the performance of these three methods. Results showed that the universal droop control (UDC) provides the best voltage regulation at 0.45% followed by the traditional droop control (TDC) at 3.37% and lastly the arctan droop control (ADC) at 3.85%. Also, regarding real power sharing between parallel connected inverters, UDC again provides the performance (49.36%, 49.53%) followed by TDC (46.30%, 46.30%) and lastly ADC (46.31%, 46.11%). For reactive power sharing, UDC has again the best performance (49.13%, 49.33%) followed by ADC (50.03%, 50.43%) and lastly TDC (50.43%, 41.83%). Finally, ADC provides the best frequency regulation at 0.02% followed by TDC at 0.34% and lastly UDC at 0.36%. Therefore, according to the results a hybrid of the universal and arctan droop control is recommended to gain the performance of two controller for the future works.