1,721,110 research outputs found
Real-Time Control of Renewable Community Energy Resources Including Demand Response Providers
No full textThis paper proposes a tool for the optimal real-time management of the resources of a renewable energy community. According to Italian Regulations, the renewable energy community members are fed by distribution networks connected to the upstream high-voltage network through the same substation. The community includes renewable energy systems, battery energy storage systems, and controllable and non-controllable loads. The proposed approach implements the optimal operation within a probabilistic framework and is aimed at maximising the community's shared energy, providing demand response to the distribution network, and providing available capacity for delivering services to the distribution grid and/or to the upstream grid. Numerical applications allow testing of the proposed real-time control tool showing its potential in terms of monitoring and control of the resources and of the required services
Caputo derivative applied to very short time photovoltaic power forecasting
No full textIntra-hour photovoltaic power forecasting provides essential information for real time optimal control of microgrids. At this purpose, a critical issue is the selection of the forecasting method. The choice of a forecasting method depends on many factors such as the availability of historical data, the time horizon, the lag period, and the time available for the forecast. Persistence based methods are particularly tailored for real time forecasting which require fast information and are typically a good trade-off choice when dealing with real time operation of microgrids. Their accuracy, however, could be not satisfactory in some cases such as when it appears critical to consider the trend of the power output in the last few minutes rather than only the last measured value. Derivatives help reach this goal, but fractional derivatives seem to be a more accurate choice in order to take into account the history of the variable to be forecasted as they are a promising tool for describing memory phenomena. In this paper, a novel intra-hour forecasting method is proposed based on the Caputo derivative. Numerical applications are carried out to show the efficacy of the proposed approach. Also, the accuracy of the proposed approach is tested through comparison with three models namely, persistence, derivative-persistence and auto regressive moving average models. The strength of the proposed forecasting tool is strictly related to its low computational burden without compromising accuracy. This makes of it an interesting means for real time grid operation strategies and can be of interest for the grid operators especially in vision of the changes distribution grids are witnessing with the transition to the smart grid paradigm
Contribution of Renewable Energy Communities to Grid Operation: Sensitivity and Statistical Analyses
No full textThis paper deals with renewable energy communities including energy storage systems, controllable and non-controllable loads, and electrolyzers for hydrogen production. The community's resources are connected to different nodes of a distribution network and their contribution to network operation is analysed. The resources provide flexibility services to the grid in terms of demand response and reactive power support and optimize their operation by maximizing their economic benefits. Uncertainties due to renewable energy production and load demand strictly affect the obtainable economic benefit of the community members and the operation of the distribution network. For this reason, this paper proposes an analysis concerning community resource configuration and uncertain operation scenarios. Particularly, community self-consumption performance including hydrogen production potential is analyzed within the Italian incentive scheme
Minimizing power losses in distribution systems using GA in planning and operation: A case study for DGs and SCs
No full textThis paper proposes a relevant method to plane the optimal location and size of the multiple distributed generators (DGs) and shunt capacitors (SCs) as well as the optimal operating power factor for each DG in the distribution systems. The proposed method is aimed at minimizing the power losses. Based on Genetic Algorithm (GA), the proposed method is developed to solve the optimization problem applying the nonlinear objective function and considering the parameter values as the placement and size of DGs and SCs and the power factor of DGs for minimizing power losses of the system subjected to both equality and inequality constraints. In order to check the feasibility, the outlined method is analyzed and tested on IEEE 37-node radial distribution system and the results compared with other tested cases based on the total power losses and the voltage profile at nodes
Environmental and economic issues for the sizing of battery energy storage combined with renewable generation in an industrial facility
No full textThis paper analyzes the inclusion of a battery energy storage system equipping a photovoltaic generation system in an industrial facility. The main objective of the analysis is the evaluation of the economic and environmental implications related to the design choices. Besides the economic viability evaluation, two indices have been used for the analysis, namely the self-consumption rate and self-sufficiency rate, which allowed evaluating the ability of the system to reduce energy request to the grid. As an economic indicator, a modification of the levelized cost of use index is proposed and its application on a prosumer facility is consider so assessing also the benefit derived from selling energy to the grid. A total cost analysis has been carried out in order to discuss the optimal battery sizing solution
Probabilistic planning of a battery energy storage system in a hybrid microgrid based on the Taguchi arrays
No full textThe transformation of electrical networks in the context of the new smart grid paradigm unavoidably involves new challenges for electrical component planning. This paper provides a tool for the probabilistic sizing of a battery energy storage system in a hybrid AC/DC microgrid (i.e., a microgrid including AC and DC subsections with AC and DC loads and renewable power generation). The procedure is based on an analytical formulation to assess the total costs sustained by the microgrid for the inclusion of the battery energy storage system. The total costs depend on the random nature of the load demand, the electrical energy prices, and the renewable power generation, therefore, a probabilistic approach has been used. Furthermore, to account for uncertainties that affect the input data, the Taguchi orthogonal arrays are applied which allow significantly reducing the computational efforts while guaranteeing the desired accuracy of the results. The proposed analytical formulation along with the use of the Taguchi orthogonal arrays allows limiting the computational complexity even in presence of a large number of random inputs and discretization levels. A case study based on an industrial hybrid microgrid is presented to analyse the results obtained in terms of the optimal sizing of the battery energy storage system and to investigate the sensitivity with respect to some inputs
Electrical Energy Storage in a Renewable Energy Community: a Planning Approach
No full textRenewable energy communities are an important means to encourage the participation of citizens in the energy transition. The ownership of generation plants by the community citizens allows for lowering investments and thus energy costs, as well as increasing decentralized power plants at the local level. Also, sector-coupling energy services within a community, such as charging/discharging of electric vehicles, allow for providing flexibility services to the power system. In this framework, electrical energy storage systems have a central role. High shares of renewable energy imply the need to store electricity due to the variability of the energy source. Also, the use of electrical energy storage in electric vehicles or total renewable microgrids represent a step forward to decarbonizing systems that were heavily reliant on fossil fuel. From the end-user point of view, consumers can reduce their electricity bills, lowering peak demand charges as well as increasing self-consumption. In this context, the planning of energy storage systems for an energy community is a critical task which needs to be dealt with considering the regulatory framework. In this paper, a planning approach is proposed for optimally sizing both the storage and photovoltaic system in an energy community considering the incentive mechanism which is applied with reference to the shared community energy. The proposed approach properly accounts for a probabilistic characterization of the variables affecting the charging/discharging of storage systems, such as demand and renewable energy production. A case study referring to the Italian regulatory framework is proposed
Design and control of coupled inductor DC–DC converters for MVDC ship power systems
No full textThis paper deals with the design and control aspects of modern ship power systems within the paradigm of an all-electric ship. The widespread use of power electronic converters is central in this context due to the technological advances in automation systems and the integration of the electrical propulsion systems and other components, such as electrical energy storage systems and renewable energy sources. The issue to address in this scenario is related to the request of increased performances in dynamic operation while pursuing advantages in terms of energy savings and overall system security. In addition, the presence of large load changes requires providing robustness of the control in terms of system stability. This paper is focused on medium voltage direct current (MVDC) ship power systems and the design and control of coupled inductor DC-DC converters. The load is handled in terms of a constant power model, which generally is considered the most critical case for testing the stability of the system. The robustness of the design procedure, which is verified numerically against large and rapid load variations, allowed us to confirm the feasibility and the attractiveness of the design and the control proposal
I frammenti in beneventana e carolina nell'archivio di Corfinio
No full textI frammenti, appartenuti a cinque codici diversi, permettono lo studio delle scritture librarie (secc. XI-XII) e arrecano un piccolo ma importante contributo alla conoscenza filologica dei testi in un’area povera di documentazione. Seguono l’edizione e 9 tavv. f.t
Single-objective approaches for microgrid scheduling in the presence of plug-in vehicle fleets and datacenters
No full textIn the paper different strategies are presented which are able to manage the operation of a microgrid characterized by the presence of datacenters, electric vehicles and distributed generation. Datacenters are considered to use the batteries within the uninterruptible power sources for providing active power support. The electric vehicles are considered to control their charge in the most convenient way. Distributed generation units are considered to maximize the use of renewable energy within the grid operation constraints. Also the reactive power support of all the resources is considered. Based on single-objective formulations, the proposed strategies allow to operate these resources in order to gain some services such as cost minimization, power quality or energy savings. Several numerical applications are made and the results demonstrate the effectiveness of each single-objective strategy
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