Indonesian Journal of Electrical Engineering and Computer Science Vol. 30, No. 3, June 2023, pp. 1308~1320 ISSN: 2502-4752, DOI: 10.11591/ijeecs.v30.i3.pp1308-1320  1308 Journal homepage: http://ijeecs.iaescore.com Voltage and frequency stabilization by fuzzy integrated droop control of a multi renewable source micro grid Savitri Swathi 1 , Bhaskaruni Suresh Kumar 2 , Jalla Upendar 1 1 Department of Electrical Engineering, University College of Engineering, Osmania University, Hyderabad, India 2 Department of Electrical and Electronics, Osmania University, Hyderabad, India Article Info ABSTRACT Article history: Received Oct 16, 2022 Revised Jan 19, 2023 Accepted Feb 4, 2023 A multi renewable source micro-grid system has many power quality issues when it is operated in grid islanding condition. During grid connected mode the voltage and frequency of the system will remain stable for small disturbances like load changes or environmental changes. During these sudden variations in the system, the grid supports the load maintaining the system stable. In this paper a droop control is introduced for the renewable source module 3-ph inverter during standalone mode supporting the load. For detection of grid islanding, an active islanding detection control is adopted which makes the 3-ph inverter to shift from synchronous reference frame (SRF) control to droop control. The performance of the droop control is improvised with fuzzy interference structure (FIS) module replacing the conventional proportional integral and derivative (PID) control. A comparative analysis is done in this paper with different controllers in droop control scheme using matrix laboratory (MATLAB) Simulink software. Stability analysis is carried out on the system determining the voltage and frequency fluctuations during grid disturbances. There is an improvement in load compensation, voltage ripple, voltage magnitude, frequency ripple and settling time with the introduced fuzzy droop controller. Keywords: Droop control Fuzzy interference structure MATLAB Proportional integral and derivative Simulink Synchronous reference frame This is an open access article under the CC BY-SA license. Corresponding Author: Savitri Swathi Department of Electrical Engineering, University College of Engineering, Osmania University Hyderabad, India Email: eee.swathi48@gmail.com 1. INTRODUCTION For clean and green electrical power generation most of the grids as of today and in future are adopting renewable sources. The grid is bifurcated into multiple micro-grids [1] where each micro-grid is introduced with local renewable sources. Different renewable source like photovoltaic (PV) system, wind farms or fuel cells can be used for compensation of local load demand. In most of the previous research the renewable sources are always grid connected which share power to the load along with main grid. The grid connected condition have very less power quality issues as the main grid always supports the system for any sudden or intermittent disturbances. The major issues transpire when the system is alienated [2] from main grid making it to work in standalone condition during main grid failure. During grid connected mode the renewable source module 3-ph inverter is operated using synchronous reference frame (SRF) control which takes feedback from the grid side 3-ph voltages. The SRF control uses phase locked loop (PLL) unit for the operation of the 3-ph inverter to synchronize with the grid voltages for sharing of renewable power [3]. In the grid connected mode the system has better stability even during sudden load changes or renewable power disturbances as the main source supports the system. The voltage, frequency, and powers of all the modules are maintained with less