18,225 research outputs found
Relying on storage or ICT? How to maintain low voltage grids' stability with an increasing feed-in of fluctuating renewable energy sources
Since the beginning of the new century our electricity system is changing rapidly. Distributed energy resources, such as wind or solar energies are becoming more and more important. These energies are producing fluctuating electricity, which is fed into low voltage distribution grids. The resulting volatility complicates the exact balancing of demand and supply. These changes can lead to distribution grid instabilities, damages of electronic devices or even power outages and might therefore end in deadweight losses affecting all electricity users. A concept to tackle this challenge is matching demand with supply in real-time, which is known as smart grids. In this study, we focus on two smart grids' key components: decentralized electricity storages and smart meters. The aim of this study is to provide new insights concerning the low diffusion of smart meters and decentralized electricity storages and to examine whether we are facing situations of positive externalities. During our study we conducted eight in-depth expert interviews. Our findings show that the diffusion of smart meters as well as decentralized electricity storages is widely seen as beneficial to society. This study identifies the most important stakeholders and various related private costs and benefits. As private benefits are numerous but widely distributed among distinct players, we argue that we face situations of positive externalities and thus societal desirable actions are omitted. We identify and discuss measures to foster diffusion of the two studied smart grid key components. Surprisingly, we find that direct interventions like subsidies are mostly not seen as appropriate even by experts from industries that would directly benefit from them. As the most important point, we identified well-designed and clearly defined regulatory and legal frameworks that are free of contradictions. --smart meter,decentralized electricity storage,smart grid,externality
Vulnerability analysis of satellite-based synchronized smart grids monitoring systems
The large-scale deployment of wide-area monitoring systems could play a strategic role in supporting the evolution of traditional power systems toward smarter and self-healing grids. The correct operation of these synchronized monitoring systems requires a common and accurate timing reference usually provided by a satellite-based global positioning system. Although these satellites signals provide timing accuracy that easily exceeds the needs of the power industry, they are extremely vulnerable to radio frequency interference. Consequently, a comprehensive analysis aimed at identifying their potential vulnerabilities is of paramount importance for correct and safe wide-area monitoring system operation. Armed with such a vision, this article presents and discusses the results of an experimental analysis aimed at characterizing the vulnerability of global positioning system based wide-area monitoring systems to external interferences. The article outlines the potential strategies that could be adopted to protect global positioning system receivers from external cyber-attacks and proposes decentralized defense strategies based on self-organizing sensor networks aimed at assuring correct time synchronization in the presence of external attacks
A Taxonomy of Workflow Management Systems for Grid Computing
With the advent of Grid and application technologies, scientists and
engineers are building more and more complex applications to manage and process
large data sets, and execute scientific experiments on distributed resources.
Such application scenarios require means for composing and executing complex
workflows. Therefore, many efforts have been made towards the development of
workflow management systems for Grid computing. In this paper, we propose a
taxonomy that characterizes and classifies various approaches for building and
executing workflows on Grids. We also survey several representative Grid
workflow systems developed by various projects world-wide to demonstrate the
comprehensiveness of the taxonomy. The taxonomy not only highlights the design
and engineering similarities and differences of state-of-the-art in Grid
workflow systems, but also identifies the areas that need further research.Comment: 29 pages, 15 figure
CoRide: Joint Order Dispatching and Fleet Management for Multi-Scale Ride-Hailing Platforms
How to optimally dispatch orders to vehicles and how to tradeoff between
immediate and future returns are fundamental questions for a typical
ride-hailing platform. We model ride-hailing as a large-scale parallel ranking
problem and study the joint decision-making task of order dispatching and fleet
management in online ride-hailing platforms. This task brings unique challenges
in the following four aspects. First, to facilitate a huge number of vehicles
to act and learn efficiently and robustly, we treat each region cell as an
agent and build a multi-agent reinforcement learning framework. Second, to
coordinate the agents from different regions to achieve long-term benefits, we
leverage the geographical hierarchy of the region grids to perform hierarchical
reinforcement learning. Third, to deal with the heterogeneous and variant
action space for joint order dispatching and fleet management, we design the
action as the ranking weight vector to rank and select the specific order or
the fleet management destination in a unified formulation. Fourth, to achieve
the multi-scale ride-hailing platform, we conduct the decision-making process
in a hierarchical way where a multi-head attention mechanism is utilized to
incorporate the impacts of neighbor agents and capture the key agent in each
scale. The whole novel framework is named as CoRide. Extensive experiments
based on multiple cities real-world data as well as analytic synthetic data
demonstrate that CoRide provides superior performance in terms of platform
revenue and user experience in the task of city-wide hybrid order dispatching
and fleet management over strong baselines.Comment: CIKM 201
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