Rafael Kotchetkoff Carneiro

The article presents field results and discusses the harmonic measurement errors of power quality analyzers (PQA) due to sampling aliasing of currents and voltages in grids with the presence of power electronics converters (PEC). The PQA may imply non-existing harmonic components incorrectly depending on the sampling rate of the PQA and the switching frequency of the PEC. Such phenomenon is prone to become more common and unpredictable due to the amplification of high-frequency components in voltages and currents due to interactions between PEC, loads, and grid elements. The conclusion is that PQAs, as required by standards in use currently, are not prepared to identify and quantify, when necessary and correctly, the high-frequency components that are present in modern electric networks with multiple PECs.

Residential condominium microgrids are characterized by agglomerations of consumers with typically residential loads, which may have individualized or centralized distributed generation units, as well as storage systems. Associated with spaces of common use in condominium microgrids, there may be own generation systems, to meet the demand of these areas and/or the public lighting system of the condominium, as well as a common energy storage system. In this paper, the modeling and the results of the analysis of scenarios for the operation of the electrical grid that are part of an existing condominium microgrid are simplified, through a representation in the software PSCAD/EMTDC, composed of photovoltaic generation, residential loads and storage system. Simulation results considering islanded and grid-connected operation scenarios are presented and discussed. In on-grid mode, the generation mix injects energy into the driver’s grid and there is no violation of voltage limits. In off-grid mode, voltage overshoots occur during the transient regime.

One of the challenges faced by Brazilian distribution utilities to enable the connection and operation of microgrids (MGs) is the absence of a solid set of technical standards in the country. An alternative has been to use and adapt existing standards applied to micro- and mini-distributed generation. In this context, this paper presents an analysis of the development status of norms, standards, and general requirements for the connection and operation of microgrids, as well as a proposal for the regulation and structuring of technical and operational requirements related to the implementation of microgrid projects. Some critical points highlighted in the paper include: the modes of operation, the minimum requirements for the different modes of operation, interoperability of systems, a conceptual model with attribution of responsible actors for the decentralized management of microgrids adapted to the institutional standards of the Brazilian sectorial model, a proposal for a standard connection structure considering the point of connection (PoC) implanted using multifunctional relay and recloser, procedures for technical feasibility assessment (operational studies) of MGs connection, and, finally, a discussion of operational issues of storage systems in a microgrid environment.

Investigating the capacity of the solar resource in a given region is the first and most important step in the process of making investments viable and implementing photovoltaic generation systems. The present work aims to visually analyze the main squares of solar energy production in Bahia. For this, a review of the basic concepts, variables involved and works related to the proposed theme was carried out. Furthermore, regional data from Bahia on normal direct irradiation and diffuse irradiation were presented, seeking to assess the contrasts between these locations. As a result of the analysis, there was a finding of the great potential for solar production, respectively, in the mesoregions, microregions and municipalities of the state, with the presentation of the highest and lowest rates of these irradiations. At the end of the work, it was concluded that photovoltaic generation is a good financial investment in Bahian locations, in addition to contributing to the sustainable development of the country, being necessary to identify the best suitable technology for frequent solar irradiation in the place where it will be installed.

Devido ao crescimento expressivo no número de instalações fotovoltaicas no Brasil, tem-se a necessidade de equipamentos que realizem diagnósticos e auxiliem nas atividades de operação e manutenção (O&M) desses geradores. Este artigo descreve o desenvolvimento de um traçador de curva I-V portátil, para arranjos fotovoltaicos com tensões de circuito aberto até 400V e correntes de curto-circuito até 10A. Foi desenvolvido um protótipo de baixo custo relativo, utilizando controle por Arduino Mega e com o projeto e construção do circuito de chaveamento e de potência utilizando carga capacitiva e chaves MOSFET. A aplicação visada é a caracterização, comissionamento através da ABNT NBR 16274/2014 e diagnóstico de arranjos fotovoltaicos de baixa escala, através de um equipamento nacional facilmente implementável, evitando assim os altos custos com os quais equipamentos semelhantes chegam ao Brasil e possibilitando que a setor solar nacional tenha capacidade de execução de sistemas fotovoltaicos com qualidade e que possibilite as atividades de O&M.