Improvement of a power system security by fault current reduction

Abstract

The generation of electricity from Renewable energy sources (RES) (wind, solar, hydro, etc.) has grown at an exponential rate in recent years. This is due to the global energy industry becoming even more mindful of the environmental impact caused by the generation of electricity from fossil fuel energy sources (coal, nuclear, diesel, etc.). Distributed generation and micro-grids are some of the topologies that are employed by many grid designers around the world to work towards achieving a 100% green energy network. Solar and wind energy are the dominating energy sources in the renewable energy industry and grid codes of many countries require fault ride-through capabilities for all inverter-based RES. Consequently, the bulk integration of renewable energy sources into the conventional power grid significantly compromises the power system's security. The fault current levels increase, and the direction of the power flow changes significantly. This poses a risk of exceeding the fault current rating of the installed power system apparatus and would result in major power system outages or much worse cause devastating damages to the apparatus. Hence, this dissertation analyses different fault current limiting measures, techniques, and technologies that are used to reduce the intermittent and inevitable fault currents. An extensive literature review is caried out and Resistive Superconducting Fault Current Limiter (rSFCL) is found to be a preferred technology. A MATLAB Simulink model of rSFCL is designed and simulated. The rSFCL model is further integrated into an IEEE 9 bus power system to test its impact on fault current levels at different buses. Through different simulation scenarios, the results shows that the rSFCL model does indeed reduce the fault current levels. When the rSFCL model is installed in the power system model near the energy source the fault current peak levels are reduced by approximately 27.05 %.