1,721,188 research outputs found

    Evaluation of Requirements for Volt/Var Control and Optimization Function in Distribution Management Systems

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    To meet the requirement from new visions within “smart grid” and to provide solutions for many challenges that DSOs (Distribution System Operators) are facing today, we need to develop advanced DMS (Distribution Management System) applications. A centralized Volt/Var Control (VVC) is one of the most desirable and important functions within Distribution Automation systems and DMSs. The overall Volt/Var control function is concerned with maintaining system voltage profile within a desired range and minimizing system losses by controlling the reactive power flow. The main objective of this paper is to review and evaluate the existing and recent techniques and algorithms for advanced VVC applications and identify the requirements for integrated Volt/Var control and optimization function in distribution management systems within the smart grid concepts

    Modeling of DFIG Wind Turbine and Lithium Ion Energy Storage System

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    The paper is aimed at describing the dynamic models of DFIG equipped wind turbine and Lithium Ion EnergySystem. The purpose of the energy storage system is to be coupled to the wind generation system in order to smooth its power output. Depending on the size of the storage system different task can be performed, starting from short term fluctuation leveling and power quality, getting to primary frequency-power regulation and, in case on large sizing, granting day-ahead turbines dispatching

    Phase Balancing by Means of Electric Vehicles Single-Phase Connection Shifting in a Low Voltage Danish Grid

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    In Denmark, household consumers are supplied with three phase with neutral cable. In addition, the distribution service operator cannot decide to which phase electrical appliance are connected. The technician who realizes the installation connects the loads according to his technical expertise. This may results in heavy imbalances. This paper uses a real Danish distribution system with household consumers, photovoltaic installation and electrical vehicles (EV). In this paper the possibility to use EVs’ charging spots in order to reduce grid’s imbalances will be investigated. Usually, charging stations are equipped with single-phase converters. According to the designed control strategy, the charging spot can select the phase to be used for the charge. The selection is done according to a phase voltage measurement

    Going Beyond Counting First Authors in Author Co-citation Analysis

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    The 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
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