Extending nearly Zero-Energy Buildings Load Matching Improvement to Community-Level

The nearly Zero-Energy Building (nZEB) concept is foreseen as a reference for the future of the European building stock. While several factors contribute to the introduction of legal instruments that promote a fast adoption of these buildings (e.g. energy efficiency), their relationship with Low Voltage distribution Grids (LVGs) is far more complex than the one of the regular buildings. In order to improve the grid interaction of nZEBs in particular, and of regular buildings equipped with distributed generation systems in general, Load Matching (LM) improvement incentives are being promoted worldwide. The literature shows that the existing LM improvement measures, that use the Energy Flexibility offered by controllable electricity demand devices, are only conducted at individual buildings (i.e. Building-Level) without taking into consideration the demand and on-site generation profiles of other buildings. Therefore, the first main objective of this research work refers to the assessment of impacts introduced by Building-Level LM improvement measures on existing LVGs. In order to improve the benefits offered to LVG operators and building owners (when compared to the existing Building-Level LM improvement measures), the second main objective concerns the development of a new LM improvement approach. For this purpose, the Cooperative Net-Zero Energy Community concept is introduced, extending the LM improvement to the Community- Level. A neighborhood made up of 33 buildings is considered to conduct the necessary experiments, where the benefits offered to LVG operators are quantified by three important Performance Indictors and the benefits offered to building owners are quantified by the respective electricity bills. The obtained results show that Building-Level LM improvement measures can be harmful to LVG operators when large amounts of controllable electricity demand are shifted to coincident periods. The conducted experiments also show that the proposed Cooperative Net-Zero Energy Community concept improves the benefits offered to LVG operators and building owners

Automated energy storage and curtailment system to mitigate distribution transformer aging due to high renewable energy penetration

UID/EEA/00066/2019.The increase of distributed generation units in low voltage distribution grids, stimulated by different mechanisms (mostly economic), like the Energy Performance of Buildings Directive in Europe and the associated nearly-Zero Energy Building concept, stresses in-depth research on the possible impacts that such generation may impose on fundamental grid equipment such as distribution transformers. Taking this into consideration, this paper has two main objectives: i) to analyze the impacts of distributed generation on a non-residential building supplied by a dedicated distribution transformer when this building is converted to a nearly-Zero Energy Building; and ii) to develop a Transformer Anti-Aging Protection System (TAAPS) that mitigates existing negative impacts in order to reduce transformer aging. The present study is based on 1-year, 1-min resolution, real electricity demand and weather data and uses the standard IEC 60076-7 (Loading Guide For Oil-immersed Power Transformers) to model the transformer aging. The collected results show that the introduction of distributed generation increases transformer aging and that the proposed protection system (TAAPS) fulfills its objectives preventing the excessive aging. An economic analysis, related with the proposed system, is also provided in this paper.authorsversionpublishe

Monitorização não intrusiva de cargas

Dissertação para obtenção do Grau de Mestre em Engenharia Electrotécnica e de ComputadoresAs previsões indicam que no período temporal decorrido entre 2004 e 2030 a procura energética global aumentará 53 por cento. Aliada a esta crescente procura, a progressiva diminuição dos recursos energéticos disponíveis provoca, nos vários sectores energéticos mundiais, sérios desafios relacionados com a satisfação da referida procura a preços acessíveis. O melhoramento da eficiência energética revela-se parte integrante da solução para este problema, uma vez que permite reduzir a quantidade de energia necessária para o cumprimento de um determinado nível de conforto, apresentando em simultâneo os menores custos associados. No caso da eficiência energética em edifícios (e.g., habitações ou serviços), o seu melhoramento pode ser alcançado através da mudança de alguns comportamentos dos seus utilizadores. O fornecimento de informação detalhada e em tempo real sobre o consumo de energia elétrica nos edifícios induz, nos utilizadores dos mesmos, a adoção de determinados comportamentos que resultam no referido melhoramento. Assim, com o intuito de melhorar a eficiência energética em edifícios, a presente dissertação concentra-se no desenvolvimento de um sistema de monitorização não intrusiva de cargas, capaz de colocar à disposição do utilizador informações detalhadas sobre os consumos energéticos de cada um dos dispositivos elétricos (e.g., ferro de engomar, televisão ou iluminação) presentes num determinado edifício. Estas informações dizem respeito aos horários de funcionamento de cada um dos dispositivos elétricos, bem como aos consumos energéticos, custos monetários e emissões de CO2 associados. Mediante este sistema de monitorização não intrusiva de cargas, o utilizador é também informado, em tempo real, sobre os dispositivos que se encontram em funcionamento. O reconhecimento dos dispositivos responsáveis pelas variações energéticas ocorridas no edifício baseia-se na utilização da transformada S. Nas experiências realizadas, o sistema computacional desenvolvido reconheceu corretamente a entrada e saída de funcionamento dos vários dispositivos elétricos utilizados em 96,43 porcento das ocorrências, num universo de 56 amostras

Investigating the potential for energy flexibility in an office building with a vertical BIPV and a PV roof system

ABSTRACT: Building Integrated Photovoltaics (BIPV) are becoming an attractive solution in the context of high penetration of photovoltaics (PV) in buildings caused by the strive to achieve net or nearly zero energy status. Besides retrieving solar radiation to produce electricity, BIPV also offers aesthetical advantages because of its architectural feature. This paper reports on the electrical energy performance of a passive solar office building, Solar XXI, located in Lisbon, Portugal, which has installed on the South façade a BIPV (12 kWp) and an additional photovoltaic roof system in a nearby car park facility (12 kWp) for electricity generation. The main objective is to investigate the potential to increase load matching between energy generation and consumption and improve grid interaction for two scenarios using the energy flexibility enabled by the integration of Battery Energy Storage Systems (BESS) with capacities ranging from 13.5 kWh to 54 kWh. To collect the required results, real consumption and generation data are used, together with numerical simulations related to the integration of the BESS. The results show that load matching and grid interaction related metrics can be significantly improved by using the energy flexibility provided by a BESS and that the implementation of such system can be economically viable for a 10-year period.info:eu-repo/semantics/publishedVersio

Implementation Framework for Energy Flexibility Technologies in Alkmaar and Évora

This research was funded by POCITYF, (FP7 grant agreement No 864400).As energy generation based on renewable resources does not always match energy consumption profiles, Positive Energy Districts (PEDs) should embody energy flexibility technologies to decrease possible negative impacts on existing grids due to, e.g., reverse power flows. As part of the EU H2020 Smart Cities and Communities project POCITYF, the cities Alkmaar (NL) and evora (PT) aim to support the deployment and market uptake of such districts and in doing so demonstrate innovative and integrated technologies to enable flexibility in the energy system. This paper addresses implementation conditions for energy flexibility technologies that help cities to engender the expected impact and ensure replication of these technologies to other sites. It aims to guide both urban planners and technology solution providers through pitfalls and opportunities that can appear during the design and implementation of PEDs. Taking this into consideration, the RUGGEDISED innovation and implementation framework for smart city technology was taken as a starting point to describe and analyze the experiences in Alkmaar and evora.publishersversionpublishe

Assessment of energy sharing coefficients under the new Portuguese renewable energy communities regulation

This research was partly funded by European Union's H2020 programme as part of the POCITYF project (a positive energy city transformation framework), Grant agreement ID 864400 and by the Portuguese “Fundação para a Ciência e a Tecnologia” ( FCT ) in the context of the Center of Technology and Systems CTS /UNINOVA/ FCT / NOVA , reference UIDB/00066/2020 . Publisher Copyright: © 2023The recent published European legal framework (Directives (EU) 2018/2001 and 2019/944) on renewable energy consumption, and its Portuguese transposition (the Decree-Law 15/2022), opens the possibility for buildings to operate as energy communities. One of the objectives is to increase the use of locally generated energy from renewable sources, by sharing available surplus among participants, using sharing coefficients defined by the entire community. Taking the actual legal framework into consideration, this paper presents an analysis of the energy sharing coefficients proposed by the newly published Portuguese legislation via the assessment of a renewable energy community, formed by public buildings, whose operation varies according to different sharing coefficient applied. Results show that time-variable energy sharing coefficients are the best option to the considered renewable energy community. Collected results also show that larger consumers can extract higher benefits from being integrated on a renewable energy community. These benefits decrease when buildings are allowed to self-consume local generated energy prior to the sharing process as demand inequalities become less important for the computation of the considered sharing coefficients. The entire community also presents better performance in this case.publishersversionpublishe

Stochastic nonlinear modelling and application of price-based energy flexibility

DSF1305-00027B 8090-00069B EP/S001670/1If CO2-emissions are to be reduced, the shares of renewable energy sources will have to be significantly increased. However, energy flexibility is required to cope with the increased share of renewable energy. Utilising it necessitates mathematical models of the operational response of energy flexible consumers. In this paper we present an accurate and general dynamic model of energy flexibility based on stochastic differential equations. The intuitive interpretation of the parameters is explained, to show the generality of the proposed model. To validate the approach, the parameters are estimated for three water towers and three buildings controlled by economic model predictive controllers. The model is then used to offer the energy flexibility on the current electricity market of Scandinavia, Nord Pool, using the so called “flexi orders”. Finally, the energy flexibility is used by controlling the demand of the water towers indirectly, through price signals designed based on the proposed model. Compared to having perfect foresight of electricity prices and future demand, between 63% and 98% of the potential savings were obtained in for these case studies. This shows that even without direct control of energy flexible systems, most of the potential can be reached under the current market conditions.publishersversionpublishe

Characterizing the energy flexibility of buildings and districts

The large penetration rate of renewable energy sources leads to challenges in planning and controlling the energy production, transmission, and distribution in power systems. A potential solution is found in a paradigm shift from traditional supply control to demand control. To address such changes, a first step lays in a formal and robust characterization of the energy flexibility on the demand side. The most common way to characterize the energy flexibility is by considering it as a static function at every time instant. The validity of this approach is questionable because energy-based systems are never at steady-state. Therefore, in this paper, a novel methodology to characterize the energy flexibility as a dynamic function is proposed, which is titled as the Flexibility Function. The Flexibility Function brings new possibilities for enabling the grid operators or other operators to control the demand through the use of penalty signals (e.g., price, CO2, etc.). For instance, CO2-based controllers can be used to accelerate the transition to a fossil-free society. Contrary to previous static approaches to quantify Energy Flexibility, the dynamic nature of the Flexibility Function enables a Flexibility Index, which describes to which extent a building is able to respond to the grid’s need for flexibility. In order to validate the proposed methodologies, a case study is presented, demonstrating how different Flexibility Functions enable the utilization of the flexibility in different types of buildings, which are integrated with renewable energies

An observational retrospective study of odontogenic cyst´s and tumours over an 18-year period in a Portuguese population according to the new WHO Head and Neck Tumour classification

Odontogenic cysts and tumours of the jaws represent one of the most prevalent groups of oral-maxillofacial lesions. We aimed to evaluate the clinical and pathological characteristics of a cohort of odontogenic cysts (OC) and odontogenic tumours (OT) of the jaws in a Portuguese population. This observational retrospective study analysed patients diagnosed with either an OC or OT of the jaws at a central hospital of Oporto, Portugal, between 1988 and 2006. Data collected from patients? files included demographic, clinical, radiological and histopathological information. Recurrence was evaluated using univariate and multivariate analysis. The sample consisted of 397 patients, 231 males (58.2%) and 166 females (41.8%), with a mean-age of 36.7±17 years. Twenty-seven patients (6.8%) presented with more than one lesion providing a total of 433 lesions. There were 396 (91.5%) OC, mostly represented by radicular cysts (n=257;59.4%), dentigerous cysts (n=79;18.2%), or odontogenic keratocysts (n=50;11.5%). There were 37 (8.5%) OT, mostly represented by ameloblastomas (n=16;3.7%), and odontomas (n=9;2.1%). The most common initial clinical manifestation was swelling (n=224;51.7%). Recurrence was observed in 30 cases (6.9%), mostly in ameloblastomas (n=6;37.5%) and odontogenic keratocysts (n=12;24%). In the multivariate analysis the diagnosis classification of the lesion was the only independent and significant variable related with the recurrence (P=0.04). Radicular cysts were the most commonly occurring type of OC and ameloblastomas the most commonly occurring OT. Amelobastomas and odontogenic keratocysts were the lesions with the highest rates of recurrence. This large sample provides useful information about the frequency profile and characteristics of OC and OT over a period of 18 years, allowing valuable comparison with data from other countries

Mapping flexibility of urban energy systems (FIRST) project: rationale and study design of an exploratory project

ABSTRACT: With the publication of the new Energy Performance of Buildings Directive, a large number of buildings are expected to become high energy performance and explore more the availability of renewable energy resources. Such buildings are often described in literature as nearly Zero-Energy Buildings (nZEB). Because renewable energy sources, such as wind and solar power, have an intrinsic variability, the zero-energy annual balance of nZEBs is difficult to reach at short time resolution (e.g. hourly). Thus, since electricity generation from small-scale solar renewable (typical case in Portugal) in individual households has limited capacity to be adjusted according to the power system needs, it is relevant to consider the demand flexibility potential, specially at community level (cluster of buildings). Unfortunately, there is a lack of studies on the impact of changes in electricity use at urban level on the future energy systems. Therefore, an approach addressing the energy flexibility (EF) in buildings may allow obtaining useful exploratory directions for the construction sector and related markets, policy makers and regulatory bodies. For these reasons, an exploratory project aimed at examining the potential of EF at the level of an existent neighbourhood in Lisbon was initiated. In this article we describe the objectives, design, and methods of the FIRST project, designed to map out the potential for EF in terms of benefits and costs in Lisbon.info:eu-repo/semantics/publishedVersio