Search

In this paper, we present a two-stage model of zonal electricity markets with day-ahead market clearing, and real-time re-dispatch and balancing that accounts for transmission line switching at both stages. We show how the day-ahead problem with switching can be formulated as an adaptive robust optimization problem with mixed integer recourse, and present a new algorithm for solving the adversarial max-min problem that obeys the structure of an interdiction game. We apply the model on a realistic instance of the Central Western European system, and comment on the impacts of both proactive, and reactive transmission switching on the operating costs of the system. Part I presents day-ahead models of a short-term zonal electricity market with switching, and describes our algorithmic approach for solving these models efficiently. Part II describes variants of the real-time model, and presents the results of our case study on the Central Western European market. [ABSTRACT FROM AUTHOR]

A European efficiency enhancement strategy for the grid-tied inverters with common dc bus and ac bus in parallel operation is proposed in this paper. Based on the inherent relationship between the dc bus voltage and the grid-feeding power, two dc bus voltage regulators with different output limits are employed in each grid-tied inverter. The operation of the dc bus voltage regulators depends on the grid-feeding power level. Therefore, the grid-tied inverter has priority up to the maximum efficiency operation point, and then, to operate at full load mode with the increase of the grid-feeding power. As a result, the European efficiency of the grid-tied system is improved without any communication link and extra hardware cost. The operation principle of the grid-tied inverter system is analyzed in detail with the implementation of the proposed control, and the design guidelines for key parameters are given and discussed. A prototype with three grid-tied inverters in parallel operation is built and experimental tests have been conducted on it in terms of steady-state performances and dynamic performances. The experimental results show that the operation modes of each grid-tied inverter depend on its sensing gain of the dc bus voltage. The European efficiency of the grid-tied inverter system with the conventional control and with the proposed control are 94.74% and 95.17%, respectively, which means the European efficiency has been enhanced by 0.43%. These results verify the feasibility and effectiveness of the proposed control strategy. [ABSTRACT FROM AUTHOR]

Voltage-source-converter (VSC) technologies present a bright opportunity in a variety of fields within the power system industry. New modular multilevel converters (MMCs) are expected to supersede two- and three-level VSC-based technologies for HVDC applications due to their recognized advantages in terms of scalability, performance, and efficiency. The computational burden introduced by detailed modeling of MMC-HVDC systems in electromagnetic-transients (EMT)-type programs complicates the study of transients especially when these systems are integrated into a large network. This paper presents a novel average-value model (AVM) for efficient and accurate representation of a detailed MMC–HVDC system. It also develops a detailed 401-level MMC-HVDC model for validating the AVM and studies the performance of both models when integrated into a large 400-kV transmission system in Europe. The results show that the AVM is significantly more efficient while maintaining its accuracy for the dynamic response of the overall system. [ABSTRACT FROM AUTHOR]

Energy transition toward smart grids with deep impact of renewables, energy storage systems, and electric vehicle charging stations will increasingly promote the establishment of energy communities that own portions of the electricity grid. The energy communities will consist of clusters of multiunit buildings and or single residential units aggregated sharing a common or multiple medium and low voltage (MV/LV) electrical substations. The size and impact of the location of these MV/LV substations can constitute a barrier especially for highly urbanized contexts where it is very complicated to provide technical spaces inside buildings for large technical systems like transformers, MV switchgear, etc. The idea of this work consists of developing a compact outdoor MV/LV substation to reduce the overall dimensions and to make the execution modularized to facilitate management and maintenance. Also an investigation of energy exchange between multiunit buildings, which are considered as the real energy community case study. The main objective for this case study is to minimize the operation cost of the system by maximizing the self-consumption. [ABSTRACT FROM AUTHOR]

Resistive-switching random access memory (RRAM) devices based on filamentary switching are attracting widespread interest for their unique properties, such as high ON–OFF ratio, ultrasteep slope, good endurance, and low-current operation. Recently, volatile RRAMs based on Ag drift and diffusion were also demonstrated for possible applications such as crosspoint array selectors and neuromorphic computing. However, the mechanism of the volatile switching, namely, the spontaneous dissolution of the Ag filament, is still not clear. A deep understanding of the metallic filament formation and spontaneous disruption would strongly help the engineering of the device for optimized performances. Here, we present a numerical physics-based drift/diffusion modeling framework to describe the threshold switching, ${I}$ – ${V}$ characteristics, and morphological evolution of the metallic filament. The model can support TCAD-type device simulations for scaling, reliability, and variability studies. [ABSTRACT FROM AUTHOR]