Cookies
O website necessita de alguns cookies e outros recursos semelhantes para funcionar. Caso o permita, o INESC TEC irá utilizar cookies para recolher dados sobre as suas visitas, contribuindo, assim, para estatísticas agregadas que permitem melhorar o nosso serviço. Ver mais
Aceitar Rejeitar
  • Menu
Publicações

Publicações por CPES

2016

Smart grid energy storage controller for frequency regulation and peak shaving, using a vanadium redox flow battery

Autores
Lucas A.; Chondrogiannis S.;

Publicação
International Journal of Electrical Power and Energy Systems

Abstract
Grid connected energy storage systems are regarded as promising solutions for providing ancillary services to electricity networks and to play an important role in the development of smart grids. Thus far, the more mature battery technologies have been installed in pilot projects and studies have indicated their main advantages and shortcomings. The main concerns for wide adoption are the overall cost, the limited number of charging cycles (or lifetime), the depth of discharge, the low energy density and the sustainability of materials used. Vanadium Redox Flow Batteries (VRFB) are a promising option to mitigate many of these shortcomings, and demonstration projects using this technology are being implemented both in Europe and in the USA. This study presents a model using MATLAB/Simulink, to demonstrate how a VRFB based storage device can provide multi-ancillary services, focusing on frequency regulation and peak-shaving functions. The study presents a storage system at a medium voltage substation and considers a small grid load profile, originating from a residential neighbourhood and fast charging stations demand. The model also includes an inverter controller that provides a net power output from the battery system, in order to offer both services simultaneously. Simulation results show that the VRFB storage device can regulate frequency effectively due to its fast response time, while still performing peak-shaving services. VRFB potential in grid connected systems is discussed to increase awareness of decision makers, while identifying the main challenges for wider implementation of storage systems, particularly related to market structure and standardisation requirements.

2016

The influence of UK emissions reduction targets on the emissions of the global steel industry

Autores
Serrenho A.; Mourão Z.; Norman J.; Cullen J.; Allwood J.;

Publicação
Resources, Conservation and Recycling

Abstract
The steel industry is the world's largest industrial source of CO2 emissions. Recent UK economic policies have led to reduced domestic steel production giving an apparent reduction in national emissions. However, demand for goods made from steel has not reduced. Emissions have thus been transferred not reduced and implementation of UK climate policies may in future expand this 'carbon leakage.' This paper explores how future UK demand for goods made from steel might be supplied while satisfying national climate policies, and how this will influence global CO2 emissions. Current flows and stocks of steel are estimated from existing databases. Evidence from other developed economies suggests that per capita stocks are tending towards a saturation level so future demand is forecast from population growth and the expected rate of replacement of a stable stock. The carbon intensities of five different steel-making routes are used to predict the allowed scale of future domestic steel production within the industrial emissions allowances set in four energy pathways defined by the UK Government. The remaining requirement for steel must be sourced offshore and the associated emissions are predicted, to give an estimate of the global emissions arising from final demand in the UK. The results show that current UK climate strategy may have a limited effect in reducing the CO2 emissions of the global steel industry, unless the UK shifts towards producing more of its own steel products with domestic secondary steel-making. This option would also increase the security of UK supply and support an expansion of UK manufacturing.

2016

Greenhouse with Sustainable Energy for IoT

Autores
Oliveira, FT; Leitao, SA; Nabais, AS; Ascenso, RM; Galvao, JR;

Publicação
TECHNOLOGICAL INNOVATION FOR CYBER-PHYSICAL SYSTEMS

Abstract
In order to support the intensive development of agricultural crops and, in particular the floricultural inside a greenhouse, with the perspective of a quick distribution in the market, increasing the economic benefits and supported on efficient and intelligent management systems energy, it is mandatory to conceive a model based on Cyber-Physical Systems (CPS) This implies, accordingly, increases in renewable primary energy sources utilization coupled with sensing technologies, include developments on Internet of Things (IoT) and Cloud Computing (CC), supported with Information and Communication Technologies (ICT) that will lead to new architectural approach applied to a proposed energy system, based on a sustainable and more engineering autonomous process. This work comes up with a new energy model that retrofits the system of a greenhouse supported with multiple sensors in one grid, to expand into CPS concept to manage sensors and controllers that will improve a profitable energy system.

2016

Control criteria of electrochromic glasses for energy savings in mediterranean buildings refurbishment

Autores
Tavares, P; Bernardo, H; Gaspar, A; Martins, A;

Publicação
SOLAR ENERGY

Abstract
During the next decades the refurbishment of old buildings will be an essential way to contribute to the global improvement of buildings energy performance indicators. Within this context, the present paper is focused on the use of electrochromic (EC) windows, an emerging technology alternative to shading devices, to control solar gains in buildings located in Mediterranean climates. The optical properties adjustments of the EC glasses are discussed based on the incident solar radiation. The ESP-r building energy simulation software was used to study the energy savings resulting from the application of electrochromic windows, considering the comparison of several windows solutions (single, double-glazing and EC windows) and windows orientations (East, South and West). In addition, different transition ranges for the optical properties of the EC glasses are assessed through the analysis of the energy needs for space heating and cooling. The main conclusion is that EC technology is an effective option in cooling dominated buildings. The impact of EC windows is highly dependent on facade orientation, being a valid option particularly in the cases of the East and West facades. For these facades, the control set point found to be effective corresponds to an incident solar radiation on the glass of 150 W/m(2) to impose a total coloured state. For the South facade the results show no significant advantage of using EC windows.

2015

A Modified Negative Selection Algorithm Applied in the Diagnosis of Voltage Disturbances in Distribution Electrical Systems

Autores
Lima, FPA; Minussi, CR; Bessa, RB; Fidalgo, JN;

Publicação
2015 18TH INTERNATIONAL CONFERENCE ON INTELLIGENT SYSTEM APPLICATION TO POWER SYSTEMS (ISAP)

Abstract
This paper presents a modified negative selection algorithm for the diagnosis of disturbance in distribution electrical systems. This study analyzes voltage disturbances and high-impedance faults, based on three phase current and voltage electric measures, which are obtained at the substations. The principal application is to support operation decision aid during faults, as well as to supervise the protection system. To evaluate the performance of the proposed method, simulations were executed using the EMTP software for a distribution test system containing 134 bus. The results obtained were compared with the specialized literature.

2015

Forecast of the Bidding Curve of Generation Players in the Iberian Electricity Market

Autores
Soares, RA; Saraiva, JT; Fidalgo, JN; Martins, BC;

Publicação
2015 12TH INTERNATIONAL CONFERENCE ON THE EUROPEAN ENERGY MARKET (EEM)

Abstract
This paper reports the research that was developed to predict biding curves submitted by generation players to the Market Operator of the Iberian Electricity Market. In this scope, we used a data set based on publicly available information from the website of the Market Operator to develop a two-step ANN prediction model. The first step involves the prediction of the amount of energy bidden at zero price and the second ANN predicts the parameters of the equation of the line that better approximates the remaining bid curve. The tests were done using information of a large generation player but this approach can be replicated to other players so that the individual predicted curves can be composed in order to obtain the aggregated selling curve for each hour of the next day.

  • 162
  • 317