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Handling Ground Faults in Meshed MVDC Grids by Fast Redistribution of Power Flow
No full textInternational audienceIn case of ground faults, the power flows within multiterminal DC grids must be redistributed to drive the current in faulty lines to zero. This paper completes a previously presented method for generating such transitions by a central component, a new feedback control to correct undesirable deviations from the desired behavior
CO2 Footprint of DC Solid State Transformer for Linear PV Power Plant
No full textInternational audienceThis paper presents a comparison of the carbon footprint of a DC SST designed for a linear PV application with MVDC collection network, and its counterpart for a traditional MVAC architecture. A method is proposed, allowing to calculate the CO2 footprint of the DC SST accounting for the manufacturing emissions of the PV modules. It is found that the energy efficiency of the conversion chain tends to be less and less significant to the overall carbon footprint as the energy mix shifts towards renewable energy sources. The manufacturing emissions of the conversion chain are thus to be reduced in the future. For PV power plants this can be achieved thanks to MVDC collection network
Measurement Techniques of Threshold Voltage Shift and Recovery in GaN e-HEMTs
No full textInternational audienceThis paper presents two different techniques of threshold voltage shift (ΔVTH) and recovery characterisation in GaN e-HEMTs. The first technique applies a stressing gate voltage (VGS) of defined magnitude and duration and then measures a ΔVTH at different time intervals by shorting the gate-to-drain terminals of the e-HEMT while passing a sensing current trough the drain-source. In the second technique, after the VGS stress, a sensing current through the 3 rd quadrant of the GaN e-HEMT is used to measure the 3 rd quadrant voltage as an indicator of ΔVTH. Both measurements show the same trends. With positive VGS stress, ΔVTH is positive (due to electron capture at the p-GaN/AlGaN interface) and then becomes negative over time due to faster electron release than hole release. The magnitude of the initial positive ΔVTH is proportional to the VGS stress while the recovery rate is inversely proportional of VGS stress
LTO BATTERY USEFUL LIFE PREDICTION FOR ALWAYS ON EDGE AIoT BASED STRUCTURAL HEALTH MONITORING
No full textInternational audienceAlthough many high-sampling sensor systems tend to be power-hungry, critical monitoring applications require reliable battery-powered sensor nodes that can retrieve and compute data on the edge for years. With the advent of Tiny Machine Learning (TinyML), it is becoming increasingly feasible to deploy always-on inference Machine Learning models on constrained battery-powered microcontrollerbased nodes. However, owing to unpredictable and dynamic energy harvesting availability conditions and the limitations of battery technology, long-term operation is still challenging.In this paper, we present a hardware and software solution for long term continuous solar operation of power-hungry wireless sensor nodes with Lithium titanate oxide (LTO) batteries.</p
Reconfigurable Interleaved LLC Resonant Converter Using Hybrid Modulation for Ultrawide Output Voltage Range
No full textInternational audienceApplications such as renewable energy, electric vehicle (EV) battery charger, EV electronic Components, energy storage system, and electrolyzer demand DC/DC converters with a wide voltage range. The LLC resonant converter is widely applied due to their high efficiency advantage. This paper proposes a reconfigurable interleaved LLC resonant converter with hybrid modulation for ultra-wide output voltage range applications. The proposed converter achieves three operating modes with extended voltage gain within a narrow frequency range by regulating the switching frequency and phase-shift angle. This allows the selection of a large magnetizing inductance and reduces circulating current and conduction losses. Additionally, the converter achieves zero voltage switching of the MOSFETs at full load. To verify the performance of the proposed converter, a 3.3kW rated converter with 400V input and 150V-800V output is designed
Small-Signal Analysis of Grid-Forming Vector Current Control
No full textInternational audienceGrid-Forming Vector Current Control (GFVCC) is a novel control strategy that enables gridconnected converters to provide stiff voltage regulation, inertia emulation, and power sharing. It enhances conventional Phase-Locked Loop (PLL)-based vector current control by incorporating a special PLL tuning strategy and virtual admittance, thus enabling the grid-forming functionalities. Although previous studies have validated its technical feasibility, further analysis of its behavior and its tuning are necessary. This work first develops a comprehensive Differential-Algebraic Equation (DAE) model of GFVCC in the dq-domain. Subsequently, the DAEs are numerically linearized to perform small-signal analysis and uncover additional properties. Our findings are established through modal and parameter sensitivity analysis in a single machine, infinite bus setup
Development of Energy Management Strategies for a MG with Distributed Energy Generation and Storage
No full textInternational audienceIn this paper, energy management strategies are developed and compared for a microgrid connected to the grid, composed of solar panels, a storage system and a load profile. Three rule-based strategies and one strategy based on dynamic programming were implemented and compared in simulation. The first ruled-based strategy is based on self sufficiency principle and tries to use the grid as last resort. The second aims to use the battery in peak times. The third is predictive and uses weather and demand forecasts in order to limit the battery charging to be able to absorb all the surplus of solar energy. The paper shows that none of these rule-based strategies can reach the optimal solution. This is why an optimal strategy was developed as a reference for results comparison, using dynamic programming. After explaining the different strategies, a comparison is done between them using results of a case simulation
Characterization of an Integrated GaN Driver for Power Switching Applications
No full textInternational audienceModern GaN-HEMTs require appropriate driving circuits to enable fast switching. Thus, monolithic integration of power switches and gate drivers is necessary. Therefore, this paper demonstrates a GaN driver to control a GaN power switch. Besides static and pulsed characterization, the driver's performance is validated through continuous switching tests, demonstrating effective operation with turn-on and turn-off times of an emulated load of 1.68 ns and 1.84 ns, respectively
A framework for smart charging strategies to further the adoption of electric buses in cities
No full textInternational audienceThe increasing deployment of electric buses in cities can create opportunities for bus operators to provide flexibility to the electrical grid and to reduce their operational costs. However, charging sessions must be properly monitored to maximize externalities while ensuring energy requirements of the fleet for their trips. This paper proposes a framework for analyzing the relevant charging strategies for a fleet of electric buses. After reviewing possible charging strategies in cooperation with grid ecosystem, a framework of interactions between actors is proposed. Modeling methods enabling to implement several charging strategies in a mathematical model are finally presented