Evaluating Future Challenges and Possibilities for Electrical Substations

Abstract

Abstract The future entails a significant expansion of the electrical power system in every aspect from production to distribution. The electrification is a necessity for addressing the future environmental challenges. With the electrification and expansion of the electrical power production comes the integration of high amounts of renewableenergy sources. This thesis aims to evaluate what challenges arise from such an integration. Furthermore, the thesis aims to review the alternatives to the insulating gas SF6 and the consequences of the alternatives on a substation design level. It was found that renewable energy sources impact the frequency stability, voltage stability, rotor-angle stability, system protection while also injecting harmonic content to the system. These challenges may be mitigated using Flexible AC Transmission System (FACTS) -devices, battery energy storage and digitization of substations. The fluorinated gas SF6, one of the strongest green house gases known, is heavily used as insulating medium in high voltage switchgear. Due to its superior insulating and electronegative characteristics, the quest for an alternative insulating material in high voltage applications is, and will continue to be, a major challenge. Several alternatives to SF6 circuit breakers are highlighted in the thesis. Gas mixtures containing the compound C4-FN is found to be the most promising alternative. Electrostatic simulation on gas mixtures containing C4-FN and CO2 found that the gas mixtures containing C4-FN was able to perform at the same level as SF6 while maintaining the demanded size constraints.