This paper evidences the influence of different parameters on the electric field on DC spacers in GIS/GIL and thus their dielectric withstand under S/IMP tests. A notable difference in term of electric field can be observed in function of impulse polarity, load condition (with/without heating current) and insulating material’s properties. For example, an overstress of 0.3pu was obtained on spacer’s surface in case of superimposed impulse test with opposite impulse polarity, high load condition and high leakage current in gas. Contrary to AC system where the simple LI tests were enough, S/IMP tests with both impulse polarity, ZL and HL conditions are mandatory to verify the insulating performance of HVDC GIS/GIL spacer. This paper gives a better understanding of the electric field distribution in HVDC GIS/GIL and helps for the design and tests
The article presents a three-phase Medium Frequency Transformer being a part of a 100kW 1.2kV 20kHz Dual Active Bridge DC-DC converter. The transformer design is detailed focusing on winding and core power loss calculation. The high power three-phase MFT prototype is presented. The experimental results include the transformer impedance characteristics, no load test and three-phase DAB full load test waveforms.
Cost-performance framework for the assessment of Modular Multilevel Converter in HVDC transmission applications
This article proposes a methodology of Cost-Performance Assessment (CPA) enabling the efficient cost evaluation required for the Cost-Benefit Analysis (CBA). The proposed method is applied for the Modular Multilevel Converter (MMC) in offshore wind high voltage direct current (HVDC) transmission. Thanks to the developed model, an analysis of submodule voltage rating is performed demonstrating the interest of this methodology in the evaluation of new technologies for HVDC transmission. The analysis shows that increasing the submodule (SM) voltage could lead to savings in the MMC cost and weight.
The number of high voltage direct current (HVDC) links continue to increase over the years, most of them, for offshore applications or bulk power transmission over long distances. The present paper evaluates the possible development of a direct current (dc) grid in Europe given the present, and future, HVDC links. Eight potential cases for the interconnection between close links are suggested as starting scenario for a multiterminal network. The need of a dc-dc converter and its special requirements are evaluated in function of suggested interconnections. As an example, a case study is chosen to evaluate the behavior of an interconnection between line commutated converter (LCC) and voltage source converter (VSC) link using a front-to-front (F2F) isolated converter.
This paper deals with the opportunities to introduce split storage into an MMC. The analysis is focused on the internal energy exchange to maintain the proper function of the converter by using circulating current. Analysis shows that, SM capacitor voltage ripple or semiconductors load are greatly influenced by additional circulating current injection. This study helps to design Embedded ESSs in the converter to provide new function like ancillary services for power system operation. Finally, a simulation of an MMC with ESS confirms analytical calculations.
The thinking caps are on this week at SuperGrid Institute with the “Fête de la Science” event! Over the last few days the institute has welcomed four classes of high school students who learnt about the work that we do through fun, interactive activities. This Saturday afternoon, we are opening our doors to the public to round of the week in style! Come along and see us!
Every year the French chapter of IEEE Power & Energy Society (PES), in collaboration with SEE (Society of Electricity, Electronics and Information and Communication Technologies), recognises outstanding PhD theses and hands out the “outstanding engineer of the year” prize at an annual evening ceremony. This Wednesday the 9th of October, Ahmed Zama was honoured with the IEEE “Doctorate Award” for his thesis work on “Modeling and Control of Modular Multilevel Converters (MMCs) for HVDC applications”.
Use of Unbalanced Insulation for the Limitation of Double-Pole Lightning Flashovers in Double Circuit HVDC Overhead Lines
Lightning studies are a critical part of any system involving overhead lines. As HVDC technologies develop, new problems and questions arise regarding the lightning performance of HVDC overhead lines. For instance, the installation of two separate HVDC circuits on the same transmission tower may become a popular alternative for the uprating of old AC lines to take advantage of the already existing Right-of-Ways. Double-pole flashovers may be particularly constraining in double circuit HVDC systems, since they could lead to the loss of both circuits at the same time due to the flashover of both poles of the same polarity having the same amplitude at all times (which is not the most likely case in AC systems). This corresponds to a 100% of loss of transmitted power, which could represent a threat for the system stability. This constitutes the main motivation for this work.
Stage dating is back at SuperGrid Institute! Get your CV ready and come along to apply for one, or several, of our internships on Thursday the 24th October at our premises in Villeurbanne (69). Our internship tutors will be available for a whole afternoon, seeking new talents to help us shape the power transmission system of tomorrow!
Interest of using a micro-meter spatial resolution to study SiC semi-conductor devices by Optical Beam Induced Current (OBIC)
In this paper we present a new test bench called micro-OBIC used to characterized wide band gap semi-conductor. Micro-OBIC allows to scan an Optical Beam Induced Current (OBIC) signal with a microscopic spatial resolution. We used micro-OBIC to characterize peripheral protection such as MESA, JTE or JTE in high voltage SiC device.