This paper proposes a new approach to tuning voltage droop parameters in an MMC-based multi-terminal HVDC system. Using the new degree of freedom offered by the virtual capacitor control, the transient behavior of the DC voltage can be improved without adverse effects on the connected AC grids.
Space charge accumulation on High Voltage Direct Current Gas Insulated Substations can produce electrical field reinforcements in the insulation that need to be taken into account in the equipment design. The TSM (Thermal Step Method) is one of the experimental techniques allowing to determine space charge distributions in insulating materials. However localized defects (i.e. microvoids, delaminations etc) cannot usually be detected by this technique. A new numerical approach to study the influence of structural defects on Thermal Step Method currents is proposed. The method is based on a Finite Element numerical simulation allowing to simultaneously solve electrical and thermal equations. The effect of three different defects were studied. It results that ring defects, with diameters smaller than 0.4 mm, produce less than 10% of change on TSM current signals. This confirms the difficulty to detect small defects by this method. It was also observed that delaminations can produce variations in signal as high as 70%, and even generate signals of opposing sign from the case without defect.
SuperGrid Institute is going global! Next week, Arthur Boutry will be crossing the Atlantic to collaborate with the Center for Power Electronics Systems (CPES), a laboratory at Virginia Tech (listed by The Times as one of the top 300 universities in the world in 2019!). During his time in the USA, Arthur will continue his work on designing MMC sub-modules for HVDC applications as part of his PhD which he began in 2018 at SuperGrid Institute, in collaboration with the Laboratoire Ampère. Arthur received a grant from the American government for his exchange year in the form of a Fulbright scholarship, one of the most prestigious and competitive fellowship programs in the world. An impressive accomplishment!
Since October 2016, SuperGrid Institute has been involved in the NanocompEIM 2 project. The goal of the project is to develop nanocomposites (Nanocomp) for electrical insulation materials (EIM) in order to reduce CO2 emissions and improve system reliability and availability. Financed at 50% by Innovate UK, a government organisation dedicated to research and innovation in the United Kingdom, the overall budget of the project is around 1M£ (1.1M€).
In this article, we focus on the condenser of a loop thermosiphon designed to cool power electronic component. The objective here is to condense Novec 649, our chosen working fluid for this loop. It is a fluid recently developed by 3M, which is known for having low environmental impact and non-flammable. We first present a theoretical analysis with the calculation and the hypotheses leading to the design of the multi-tubular condenser. Then we present a full size thermosiphon built for experimental validation. A discussion then addresses some of the design hypotheses. Three main parameters are studied : the tilting angle of the condenser (from horizontal to vertical orientations), the temperature of the coolant and finally the mass flow effect at different saturation temperatures. In our setup, we dissipate up to 2.4 kW at the evaporator level. The produced vapor is then condensed in the heat exchanger using cold water flowing at countercurrent. A number of measurements are made via thermocouples and pressure sensors located at both ends of the condenser to measure the average heat exchange coefficient.
Last year, SuperGrid Institute signed a framework agreement with the Digital Department of Edouard Branly School with the aim of developing educational modules in the field of electrical engineering. This year for their final project the undergraduate students from the Digital Department worked on an interactive learning application based on High Voltage Direct Current cable systems and junctions. The final project counts for a significant proportion of the students’ overall credits for the year.
This Tuesday the 10th of July, Michel MERMET-GUYENNET presented a keynote speech at the 13th IEEE International Conference on Power Electronics and Drive Systems (PEDS 2019) in Toulouse, following the invitation of Bernado COGO from the Antoine de Saint Exupéry Institute of Technology (IRT Saint Exupéry). In his paper, Michel MERMET-GUYENNET presented power electronics technologies for MV and HV grids.
The Association Grand Projects 21 – Major Programmes and Projects for the 21st Century (AGP21) met this Thursday in Versailles to discuss the development of interconnected electricity networks on a global scale. SuperGrid Institute was invited to present its vision and discuss the appeal of multi-terminal HVDC technologies in the design and construction of future energy highways. The subsea node concept developed at SuperGrid Institute was also introduced as an essential building block for extending offshore networks and integrating renewable energies on a wide-scale.
This study aims to examine possible impact of these harmonics in presence of microcavities. Depending on their size and on the electrical field, partial discharges (PD) can occur in these microcavities. Two types of cables have been aged: a medium voltage AC (MVAC) cable with millimetric cavities induced artificially and a model cable with an HVDC XLPE grade.
Raphaël CHASSAGNOUX received the best student presentation prize for his « Prebreakdown and Breakdown in Liquid Nitrogen under Pulsed Heating for Superconducting Applications » at IEEE ICDL 2019.
Subscribe to our newsletter:
