Power flow and faults analysis of a hybrid DC Microgrid : PV system and wind energy

Abstract

Rural electrification has become a very important means of improving the standard of living of rural dwellers, a process which also helps in the electrification of remote and isolated regions. Presently, the electrification of such regions can be achieved through the use of renewable energy. The use of renewable energy sources such as PV and wind energy is gaining popularity as the solution to achieving the electrification of rural areas, such as the use of the microgrid, which can be in the form of an AC or DC microgrid. The DC microgrid can be used to connect distributed energy resources and its energy storage is considered to be an economical system to meet consumer demand due to its benefits, namely environmental friendliness, reliability and good performance in load distribution. The power system may experience many faults when transferring power via overhead transmission lines to the load. When these faults occur, it is important to detect the location and isolate the part that had experienced the fault quickly, without de-activating the whole microgrid. The main aim of this study was to conduct a power flow and faults analysis on a hybrid DC microgrid model with battery storage. The hybrid energy sources for the DC microgrid are the PV system and wind energy system. Firstly, this research conducted a power flow analysis for the hybrid DC microgrid. Secondly, a fault analysis was carried out on the system and both the power flow and the fault analysis were formulated through implementation in a MATLAB/Simulink environment under various conditions in order to ascertain the stability and reliability of the system. Various MATLAB/Simulations were carried out, including the DC single-line-ground fault and DC line-line fault and are analysed in a designed hybrid DC microgrid power system. The results showed that DC line-to-line and DC line-to-ground faults lead to the imbalance of DC voltage, which is difficult to re-balance and stabilize in the system after the existence of these faults. When these faults occurred in the system, there was immense fluctuation and unsteadiness of output load power delivered to consumers. Moreover, wind-generated power on the generation side was severely affected. Based on the results and analysis of those results, the hybrid DC microgrid is seen as a satisfactory and optimum concept for the generation and transmission of power for rural and isolated area electrification, i.e. it can provide power to remote areas that cannot be reached by the national grid. The study revealed, based on the analysis of results, that it has an effective response under fault conditions. Results for a hybrid DC microgrid revealed that high quality of power is experienced in load distribution. Also based on the results, when DC faults occurs there is disturbance to output.