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Orientadora: Profa. Dra. Ahda Pionkoski Grilo Pavani Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Energia, Santo André, 2022. Os sistemas fotovoltaicos estão ficando cada vez mais populares no Brasil, este fato se deve a resolução normativa nº 482/2012 (atualizada pela resolução normativa nº 687/2015) da ANEEL que criou as regras de conexão e o sistema de compensação de energia, que permitem que o consumidor gere sua própria energia e injete a energia excedente na rede em troca de créditos. Devido sua característica intermitente, a penetração massiva dos sistemas de geração fotovoltaica na rede de distribuição apresenta impactos nas tensões de alimentadores de média tensão, especialmente, em dias parcialmente nublados. A passagem rápida de nuvens resulta em variações rápidas da potência injetada pelos geradores fotovoltaicos o que impacta em variações de tensão nos alimentadores da rede de média tensão. De forma geral, a conexão de geração fotovoltaica é associada com armazenamento para compatibilizar a curva de carga com a curva de geração fotovoltaica. Como o armazenamento local não é prática em função da possibilidade de injeção da potência na rede da concessionária, uma solução que algumas concessionárias estão adotando é conectar o Battery Energy Storage Systems (BESS) no nível da rede para minimizar esses impactos. Estas baterias são conectadas à rede elétrica através de conversores, os quais podem ser utilizados também para injetar potência reativa na rede. Eles apresentam uma resposta bastante rápida para variação da potência reativa injetada na rede e, dessa forma, podem ser utilizados para suavizar variações rápidas de tensão devido à passagem de nuvens. Neste contexto, é proposto neste trabalho a análise da utilização do controle da potência reativa de unidades de armazenamento em redes de distribuição para melhorar as variações de tensão de rápida duração devido à passagem de nuvens em redes de distribuição com geração fotovoltaica. A proposta é validada utilizando simulações computacionais no software OpenDSS empregando uma rede de distribuição de média tensão. Com este trabalho, verificou-se que o perfil de tensão do sistema é afetado, em maior ou menor grau, dependendo da variação da irradiância, do nível de carregamento do sistema, do local de conexão do GF, local da carga associada à barra, da topologia da rede e do nível de penetração fotovoltaica. Constatou-se que o emprego do controle de unidades de armazenamento para melhoria das variações rápidas de tensão devido á geração fotovoltaica objeto deste estudo é eficiente. Espera-se que a mudança de operação de controle do BESS para regulação da tensão da rede ocorra de maneira muito mais rápida do que o sombreamento causado por nuvens transitórias de um dia parcialmente nublado. Desta forma, o controle do BESS pode acontecer de forma escalonada, buscando ponto a ponto qual o melhor FP para minimizar a variação que está acontecendo naquele momento. Photovoltaic systems are becoming more and more popular in Brazil, due to normative resolution nº 482/2012 (updated by normative resolution nº 687/2015) of ANEEL that created the connection rules and the system of energy compensation, which allow the consumer to generate their own energy and inject the excess of energy into the grid in exchange for credits. Due to its intermittent characteristic, the massive penetration of photovoltaic generation systems in the distribution network impacts the voltages of medium voltage feeders, especially on partially cloudy days. The rapid passage of clouds results in rapid variations in the power injected by photovoltaic generators, which impacts voltage variations in the medium voltage network feeders. This impact could be avoided with the use of photovoltaic generation associated with storage to match the load curve with the photovoltaic generation curve. However, due to the possibility of injecting power into the utility grid local storage is not employed. Thus, a solution that some utilities are adopting is to connect Battery Energy Storage Systems (BESS) at the grid level to minimize these impacts. These batteries are connected to the electrical network through converters, which can also be used to inject reactive power into the network. They present a very fast response to the variation of the reactive power injected into the network and, therefore, they can be used to smooth out fast voltage variations due to the passage of clouds. In this context, this work proposes the analysis of the use of reactive power control of storage units in distribution networks to improve voltage variations of rapid duration due to the passage of clouds in distribution networks with photovoltaic generation. The proposal is validated using computer simulations in OpenDSS software using a medium voltage distribution network. With this work, it was verified that the system voltage profile is affected, to a greater or lesser extent, depending on the irradiance variation, the system loading level, the location of the photovoltaic generation connection, the location of the load associated with the bus, network topology and photovoltaic penetration level. It was found that the use of storage units control to improve the rapid voltage variations due to the photovoltaic generation object of this study is efficient. The change from BESS control operation to grid voltage regulation is expected to occur much faster than the shading caused by transient clouds of a partially cloudy day. In this way, the BESS control can happen in a staggered way, searching point by point for the best PF to minimize the variation that is happening at that moment.

Natural evolution has chosen the localization of biomolecular processes into crowded sub-cellular femtoliter (fL) scale compartments for organizing complex biological processes. [1] Many synthetic biology platforms with life-like activities have been able to mimic these systems under different compartment sizes regimes. [2] However, the fabrication of crowded compartments down to sub-cellular scales is challenging, mainly because of high surface-volume ratio of these systems, finally compromising the stability of the encapsulated biomolecules. In this regard, we here bridge this gap by showing the possibility to produce femtoliter-scale aqueous droplets using a novel inkjet printing approach reproducing a theoretical model from Eggers et al. [3] The fL-scale droplets are spiked with non-ionic surfactants to stabilize the water/oil interface whilst not compromising ink viscosity and surface tension. [4] When injected into nL-scale mineral oil droplets, the fL-droplets form an almost-regular circular pattern at the border of mineral oil drops due to Marangoni flows (see Figure). Remarkably, downscaling at the fL-size induces the spontaneous formation of molecularly crowded shell structures at the water/oil interface, as observed by fluorescence microscopy, showing typical thickness in order of hundreds of nanometers, in accordance with previously reported models. [5] Molecular crowding effects are tested by using fluorescence lifetime imaging under the convenient phasor plot approach, [6] revealing different characteristic lifetimes of specific probe molecules in the confined volumes with respect to macroscopic solutions. The fL-scale compartments autonomously trigger the formation of unique features (e.g., spatial heterogeneity, up-concentration, molecular proximity) that are mediated by the intermolecular interactions in these novel environments. Remarkably, the crowding conditions are observed not to affect the conformation variation of a model DNA hairpin in presence of molecular triggers and of a CYP2E1-catalyzed enzymatic reaction. Our results can be a first step towards the fabrication of lab-on-a-chip compartments for molecularly crowded confinement mimicking sub-cellular environments. Bibliography 1. S. F. Banani et al., Nat. Rev. Mol. Cell Biol. 2017, 18, 285. 2. B. C. Buddingh’, J. C. M. Van Hest, Acc. Chem. Res. 2017, 50, 769. 3. G. Arrabito, F. Cavaleri et al. Adv. Biosys. 2019, 1900023 4. J. Eggers, Phys. Rev. Lett. 1993, 71, 3458. 5. M. Staszak, J. Surfactants Deterg. 2016, 19, 297. 6. C. Stringari et al. Proc. Natl. Acad. Sci. USA 2011, 108, 13582.

The fabrication of size-scalable liquid compartments is a topic of fundamental importance in synthetic biology, aiming to mimic the structures and the functions of cellular compartments. Here, inkjet printing is demonstrated as a customizable approach to fabricate aqueous compartments at different size regimes (from nanoliter to femtoliter scale) revealing the crucial role of size in governing the emerging of new properties. At first, inkjet printing is shown to produce homogenous aqueous compartments stabilized by oil-confinement with mild surfactants down to the hundreds of picoliter scale [1]. Raster Image Correlation Spectroscopy allows to monitor few intermolecular events by the involvement of protein-binding assays within these compartments [2]. Subsequently, in order to reduce droplet size at values below the nozzle size, a theoretical model from Eggers et al. [3] is experimentally reproduced permitting to obtain femtoliter-scale aqueous droplets from picoliter-scale microchannels [4]. As a remarkable difference to picoliter scale droplets, downscaling at the femtoliter-size triggers the spontaneous formation of molecularly crowded shell structures at the water/oil interface stabilized by a mixture of biocompatible surfactants. The shells have typical thickness in order of hundreds of nanometers, in accordance with theoretical models [5]. Molecular crowding effects in these systems are tested by using fluorescence lifetime imaging under the phasor plot approach [6], revealing different characteristic lifetimes of specific probe molecules in the confined volumes with respect to bulk solutions. The femtoliter-scale compartments autonomously trigger the formation of unique features (e.g., up-concentration, spatial heterogeneity, molecular proximity) that are mediated by the intermolecular interactions in these novel environments, ultimately permitting to mimic the native conditions of sub-cellular scale compartments. The crowding conditions in femtoliter-scale droplets do not to affect the conformation variation of a model DNA hairpin in presence of molecular triggers and of a CYP2E1-catalyzed enzymatic reaction. Our results can be a first step towards the fabrication of size-scalable lab-on-a-chip compartments mimicking sub-cellular environments. References 1. G. Arrabito, F. Cavaleri, V. Montalbano, V. Vetri, M. Leone, B. Pignataro, Lab on Chip, 2016, 16, 4666. 2. M.A. Digman, C. M. Brown, A. R. Horwitz,W.W. Mantulin, and E. Gratton, Biophysical Journal, 2016, 94, 2819. 3. J. Eggers, Phys. Rev. Lett. 1993, 71, 3458. 4. G. Arrabito, F. Cavaleri, A. Porchetta, F. Ricci, V. Vetri, M. Leone, B. Pignataro, Adv. Biosys. 2019, 1900023. 5. M. Staszak, J. Surfactants Deterg., 2016, 19, 297. 6. C. Stringari, A. Cinquin, O. Cinquin, M. A. Digman, P.J. Donovan, and E. Gratton, Proc. Natl. Acad. Sci. USA 2011, 108, 13582.