Eco-friendly alternatives to replace SF6 in high voltage Gas-Insulated Transmission Lines: a comparative study

This project focuses on the research of an eco-friendly alternative that could replace SF_6, which is a strong greenhouse gas, in high voltage Gas-Insulated Transmission Lines, reducing the environmental impact but at the same time maintaining the excellent dielectric properties that make GIL the most reliable power transmission line

Study of Environmentally Friendly Arc Extinguishing Media as Alternatives to Sf6 in High-Voltage Circuit Breakers

Работа посвящена сравнению характеристик элегаза и альтернативных экологичных ему смесей в качестве изоляционных сред в высоковольтных выключателях. Произведен сравнительный анализ диэлектрических и дугогасящих свойств газов по основным физическим характеристикам выбрана наиболее перспективная смесь C4F7N/CO2. Выполнен аналитический расчёт изоляционных промежутков и газодинамических характеристик для элегаза и его альтернативы. Произведён численный расчет электрических полей исследуемых газов для колонкового высоковольтного выключателя ВГТ-110.The paper is devoted to comparing the characteristics of SF6 and alternative environmentally friendly mixtures as insulating media in high-voltage circuit breakers. A comparative analysis of the dielectric and arc-extinguishing properties of gases was carried out according to the main physical characteristics ¬ the most promising mixture C4F7N/CO2 was chosen. An analytical calculation of insulation gaps and gas-dynamic characteristics for SF6 and its alternative has been performed. A numerical calculation of the electric fields for the live-tank circuit breaker VGT-110 with insulation media under study was carried out

The insulation performance of novel refrigerant gas as an alternative to SF6 for medium voltage switchgear

Gas-insulated systems are widely utilized in the electric power sector to transmit and distribute electrical energy. Sulphur-hexafluoride (SF6) has dominated gas insulation in high-voltage insulation technology since the early 60s. It is a greenhouse gas with a protracted lifespan in the atmosphere. This paper proposes an economical and comparatively more environmentally friendly R507 gas alternative to SF6 for medium-voltage applications. R507 has been analyzed experimentally through power frequency breakdown and lightning impulse testing to validate the performance and theoretical concepts. R507 has a very low liquefication temperature of −46.7∘C , but it must still be mixed with buffer gases such as CO2, N2, or dry air to meet the diverse liquefaction temperature applications. Various field utilization factors under AC and lightning impulse voltages are used in the experiments, along with different electrode geometries, including sphere-to-plane and rod-to-plane (i.e., quasi-homogeneous and inhomogeneous electric field distribution). For comparison, identical experiments are conducted with pure SF6. R507 gas was found to be a promising substitute for SF6 gas, with its dielectric strength being approximately 0.95 times that of SF6 gas. A positive synergistic effect is present between R507 and CO2, along with the good self-recoverability property of the gas mixture. The current research study serves as a fundamental resource for characterizing the R507/CO2 gas mixture insulation properties to be utilized in practical applications

Investigation of surface discharges in insulation gases through synchronisation of improved electrical and fast enhanced-imaging techniques

This thesis investigates the generation of discharge activity in the regions where gaseous and solid dielectrics meet with energised conductors, frequently referred to as triple points/junctions. Such conditions are frequently met in practical complex assemblies of equipment and apparatus used in medium- and high-voltage applications, and the common discharge phenomena to appear are known as surface discharges. An optimised test configuration which replicates strongly non-uniform field conditions on the surface of solid dielectric samples was developed. As gaseous insulation, atmospheric gases are considered namely, technical air (21/79 % O2 /N2), nitrogen (N2) and carbon dioxide (CO2 ), and the eco-friendly mixture of trifluoroiodomethane (CF3 I)with carbon dioxide (30/70 % CF3 I/CO2). The examined solid dielectric materials include polytetrafluoroethylene (PTFE), epoxy resin and silicone rubber, all of which are frequently found in electric power industry applications of different types. The experimental investigation included the electrical detection of surface discharge activity in various gaseous compound/solid dielectric type combinations with the use of optimally developed current sensing circuits. Furthermore, a new enhanced performance high-speed camera system was developed synchronised with the electrical detection system for the study of the propagation patterns and morphology of the discharges. From both electrical and optical detection methods, it could be concluded that the 30/70 % CF3 I/CO2 mixture performed the best with N2 being the least effective. Technical air was found to withstand flashover better compared to CO2 however, the latter showed better performance in suppressing the inception of partial discharge activity and the extension of surface streamers. A list of more detailed conclusions and discussion points are presented at the end of each chapter and which are further developed in the last chapter of this thesis. Suggestions that can potentially be implemented in future works, experimental and theoretical, are also listed

Environmental Compatible Circuit Breaker Technologies

Recent research and development in the field of high-current circuit breaker technology are devoted to meeting two challenges: the environmental compatibility and new demands on electrical grids caused by the increasing use of renewable energies. Electric arcs in gases or a vacuum are the key component in the technology at present and will play a key role also in future concepts, e.g., for hybrid and fast switching required for high-voltage direct-current (HVDC) transmission systems. In addition, the replacement of the environmentally harmful SF6 in gas breakers and gas-insulated switchgear is an actual issue. This Special Issue comprises eight peer-reviewed papers, which address recent studies of switching arcs and electrical insulation at high and medium voltage. Three papers consider issues of the replacement of the environmentally harmful SF6 by CO2 in high-voltage gas circuit breakers. One paper deals with fast switching in air with relevance for hybrid fault current limiters and hybrid HVDC interrupters. The other four papers illustrate actual research on vacuum current breakers as an additional option for environmentally compatible switchgear; fundamental studies of the vacuum arc ignition, as well as concepts for the use of vacuum arcs for DC interruption

Optical In-Process Measurement Systems

Information is key, which means that measurements are key. For this reason, this book provides unique insight into state-of-the-art research works regarding optical measurement systems. Optical systems are fast and precise, and the ongoing challenge is to enable optical principles for in-process measurements. Presented within this book is a selection of promising optical measurement approaches for real-world applications