This thesis aimed to characterize partial discharges in DC gas-insulated substations, and to develop an automatic defect identification tool. The first step of this work was the development of a partial discharge measuring bench. The complete study has been performed in a GIS section, so that the results can be directly applied to industrial equipment.
The study involves first the building of an experimental setup where arcs, created between two fixed CuCr25 contacts, were visualized using a high-speed camera in a vacuum demountable chamber.
Multi-terminal high voltage direct current (MTDC) grids, or supergrids, are considered an interesting solution to integrate large amounts of renewable power and release congestion of existing AC power grids. Nonetheless, safe and reliable operation of such grids require the development of new DC protection systems.
The scope of this thesis includes control and management of the Modular Multilevel Converter (MMC)-based Multi-Terminal Direct Current (MTDC).
Large offshore wind farms will be important players within the future energy landscape. What is the expected benefit for a project is an essential issue from Investor side, considering both technical and economic aspects. Levelized Cost Of Energy - LCOE - is a standard economic indicator which allows to assess the economic viability of a project.
Common understanding today is that the challenges to develop the SuperGrid are huge at many levels (e.g.: political, societal, economical, financial, scientific, technical…). It is also commonly accepted that the SuperGrid will require novel technologies (breakers, cables, converters…) and operating principles (e.g.: transition from a more passive essentially AC-based power system to a more active AC/DC-based one). This thesis deals with the development of a key actor for SuperGrid technology, that is, AC/DC converters.
To connect the different points of the network, the transmission and distribution of electric power used cables. Since few years, cables and especially their insulation part are evolving, going from paper insulation to a synthetic insulation. Nowadays, the insulation part of HVDC cables is in crosslinked polyethylene or XLPE.
To connect the different points of the network, the transmission and distribution of electric power used cables. Since few years, cables and especially their insulation part are evolving, going from paper insulation to a synthetic insulation. Nowadays, the insulation part of HVDC cables is in crosslinked polyethylene or XLPE.
High Voltage Direct Current (HVDC) converters are composed of hundreds of semiconductor switches connected in series to sustain the rated voltage of the converter (several hundred of kilovolts). Because of the large number of switches, it is highly probable that at least one of them will fail during the lifetime of the converter. Such failure should not cause the entire converter to shut down, despite the series connexion of the switches. As a consequence, each switch should be designed so that upon failure, it becomes a short circuit and keeps carrying the current (“fail-to-short” behaviour).
High Voltage Direct Current (HVDC) converters are composed of hundreds of semiconductor switches connected in series to sustain the rated voltage of the converter (several hundred of kilovolts). Because of the large number of switches, it is highly probable that at least one of them will fail during the lifetime of the converter. Such failure should not cause the entire converter to shut down, despite the series connexion of the switches. As a consequence, each switch should be designed so that upon failure, it becomes a short circuit and keeps carrying the current (“fail-to-short” behaviour).
