Development of an improved microgrid-centralize power sharing scheme using fuzzy logic controller

Abstract

A microgrid is a local energy grid with control capability, which means it can be connected to or disconnected from the traditional grid and operate autonomously. Recently, the droop control techniques are widely used to solve the problem of load sharing in microgrid system. These techniques have been improved to resolve the rising issues such as system stability and power sharing. Although the improved droop techniques improvise the stability of microgrid operations, however the power sharing performance still not optimized and can be further improved. This thesis focuses on improving power sharing for parallel connected inverters in an islanded microgrid. A centralized power sharing scheme that utilizes Fuzzy Logic Controller (FLC) is proposed to improve the power sharing among parallel connected inverters in AC islanded microgrid. This proposed technique is implemented to control three parallel connected single-phase inverters in a microgrid. Central controller is used to process active and reactive output power information from all inverters and calculates the active and reactive output power references for each inverter based on the desired ratios of their output powers. The information from centralized control are then process by the FLC at each inverter to adjust the output voltage to an appropriate value to achieve the required power sharing. Several simulations have been conducted to verify the performance of the proposed power sharing scheme.