1,721,132 research outputs found
A Novel Community-based Photovoltaic Energy Sharing Business Model Incorporated in Decentralized Energy Markets
No full textAs a promising solution to energy transition and energy cost reduction, distributed photovoltaic (PV) has become one of the key technologies for low-carbon energy system. However, due to the long financial return cycle, space constraints, policy uncertainty, and inefficient current management schemes, etc, its potential for acting as an energy supply alternative are yet to be manifested and implemented in practice, especially for the individual community residents. this paper presents a community-based PV energy sharing business model based on a shareholding system, which can stimulate the participation of residents in distributed PV capacity sharing under the regulation of a PV service provider. Specifically, the residents can obtain the usufruction of PV capacity on-demand through shares transfer, and energy generated by shared PV can be shared via decentralized peer-to-peer (P2P) transactions and local energy community market (LECM). On this basis, an incentive and penalty mechanism is designed to ensure the efficient use of the PV capacities and a day-ahead decision-making strategy is established to maximize the individual resident's benefits. Finally, extensive case studies are conducted to validate the effectiveness and feasibility of the proposed model
Seamless transition between grid forming and grid following inverters based on online grid impedance estimation
No full textThe rapid increase in the penetration of inverterbased resources (IBRs) into the distribution network causes thepower system to behave as a weak grid and often alters system strength. IBRs operate as either grid-following (GFL) or grid forming (GFM) inverters, differing in both control stability and inertia support capabilities under varying operating conditions. To maintain system stability across different grid strengths, IBRs need to support smooth switching between GFL and GFM modes. This paper presents an automatic smooth-switching control strategy based on online grid impedance estimation to enhance operational stability. Ordinary Least Squares (OLS) regression is used to estimate grid impedance, and hysteresis switching is applied to prevent continuous switching when grid strength fluctuates near boundary conditions. The effectiveness of the proposed control strategy is verified through case studies under varying grid strengths
MIMO impedance modelling of grid following inverter with local voltage control
No full textIn recent years, in response to the global climate crisis, inverter-based energy resources (IBRs) have been massively integrated into power systems. Their effective operation and control lie on a wide variety of inner, outer, and synchronization control loops which have been reported to interact and compromise power system’s stability. In this study, a Multi-Input-Multi-Output (MIMO) impedance model for a three-phase grid following inverter with local voltage control has been proposed. This linear time invariant model takes into consideration the delay and the coupling between the control blocks and serves as a simpler and more computationally efficient method to capture oscillations and interactions in time and frequency domain. It can predict instabilities caused by the different control layers along with the frequencies of the oscillations. The effect of the delay, the current control tuning parameters and the interactions between the current controller and the local voltage controller have been highlighted. The results have been validated in time and frequency domain simulations in SIMULINK environment
Boundary analysis of damping methods for virtual synchronous generators
No full textVirtual synchronous generators (VSGs) imitate traditional synchronous generators to provide virtual inertia and damping for inverter-based resources. The emulated damping relates to the power synchronization, therefore, has a major impact on system stability. Although various damping methods exist, phase-locked loop (PLL) integration is particularly concerning, as it is a key component in grid-following (GFL) control but now is being applied to grid-forming (GFM). This paper analyzes the typical VSG control and PLL damping unit by mapping stability boundaries and feasibility range. The boundaries are mapped in two dimensions to determine the relationship between the control parameters and the grid impedance. A comprehensive sensitivity analysis of controller parameters for VSG stability is conducted, drawing parallels with the equivalence of droop-based GFM stability. Finally, the boundary analysis is verified by time-domain simulation results and demonstrates the reliability of damping-switching method
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Complex terrains and wind power : enhancing forecasting accuracy through CNNs and DeepSHAP analysis
Get PDFAccurate prediction of wind power generation in regions characterised by complex terrain is a critical gap in renewable energy research. To address this challenge, the present study articulates a novel methodological framework using Convolutional Neural Networks (CNNs) to improve wind power forecasting in such geographically diverse areas. The core research question is to investigate the extent to which terrain complexity affects forecast accuracy. To this end, DeepSHAP—an advanced interpretability technique—is used to dissect the CNN model and identify the most significant features of the weather forecast grid that have the greatest impact on forecast accuracy. Our results show a clear correlation between certain topographical features and forecast accuracy, demonstrating that complex terrain features are an important part of the forecasting process. The study’s findings support the hypothesis that a detailed understanding of terrain features, facilitated by model interpretability, is essential for improving wind energy forecasts. Consequently, this research addresses an important gap by clarifying the influence of complex terrain on wind energy forecasting and provides a strategic pathway for more efficient use of wind resources, thereby supporting the wider adoption of wind energy as a sustainable energy source, even in regions with complex terrain.© 2024 Konstantinou and Hatziargyriou. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright
owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does
not comply with these terms.fi=vertaisarvioitu|en=peerReviewed
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Microgrids: architectures and control
No full textMicrogrids are the most innovative area in the electric power industry today. Future microgrids could exist as energy-balanced cells within existing power distribution grids or stand-alone power networks within small communities. A definitive presentation on all aspects of microgrids, this text examines the operation of microgrids - their control concepts and advanced architectures including multi-microgrids. It takes a logical approach to overview the purpose and the technical aspects of microgrids, discussing the social, economic and environmental benefits to power system operation. The b
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