Design and simulation of photovoltaic, diesel hybrid AC mini-grid system for rural electrification

Abstract

A hybrid photovoltaic-diesel-battery mini-grid model has been designed and simulated in MATLAB/Simulink for study and analysis purposes. Each component of the mini-grid model has been designed to simulate the model accurately. These include PV array, battery, diesel generator, inverter, maximum power point tracking (MPPT) based charge controller and loads. To make the model more realistic, a detailed load model has been presented where each type of load has been configured with its individual load profile. Some household appliances have been designed to investigate their different characteristics. An MPPT based on incremental conductance (INC) algorithm has been implemented for maximum power extraction from the PV array. A three-phase four-wire inverter with filter has been designed to generate a 400V 50Hz AC for distribution system. For AC distribution system, a 3-phase 4-wire network is designed using PI section block considering distribution line parameters to simulate voltage drop and line loss in the network. To control power flow from/to the battery, a bidirectional buck/boost converter with controller has been designed. Based on the daily energy consumption and load profile, appropriate size of PV array and energy storage system has been designed. A power management algorithm has also been developed and simulated to control power flow from PV array, diesel and battery. Grid voltage, current and frequency have been observed using the simulation results. Characteristics of balanced/unbalanced, fixed/variable loads have been studied here. The daily mini-grid load profile has also been simulated and studied. The placement of PV array and diesel generator has an impact on a mini-grid's efficiency, and also introduces the possibility of different technical issues. Hence, the PV array and diesel have been connected to different locations of the mini-grid to determine the optimal place with minimum voltage drop and line loss. On the other hand, fault analysis is an important consideration for design and operation of a mini-grid. Faults in different locations of mini-grid model have been simulated to investigate the characteristics and its effects on mini-grids. The designed model can be a useful tool for study and analysis of mini-grid system.