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Nowadays, it is possible to notice a growth in the integration of distributed energy resource (DER) in the distribution systems. Despite the many benefits caused by this integration, there are some changes in the load and short-circuit current, which may lead to mis-coordination between protective devices. Moreover, an improper DER integration can generate problems regarding the levels of current, voltage, and power factor of the network. Therefore, in this study, the authors conducted a specific study to optimise the size and location of DER in a distribution feeder, to reduce investment and operation costs, regarding the operational and physical limits of the system and generators. In addition, the optimised recloser-fuse coordination was performed to reduce the actuation time of these protective devices, taking into account the generation and load variation during the day, DER operating modes, and all the fault types. In this study, the optimisation method adopted was genetic algorithms and the IEEE 34-node test feeder was used to validate the proposed methodology. Thus, it was possible to achieve a single protection scheme based on the fuse saving scheme, which is able to coordinate the protective devices for all the analysed cases simultaneously.

A fim de minimizar os custos da operação do sistema de transmissão e de criar uma análise justa de remuneração dos serviços ancilares (SA), neste artigo, apresenta-se um esquema de otimização do mercado de energia considerando os custos de operação para satisfazer a demanda e as perdas de potência ativa do sistema elétrico de potência, junto aos custos dos SA de reserva de potência operativa e compensação síncrona. Foi resolvido o problema de otimização do mercado brasileiro de energia elétrica e o modelo, desenvolvido neste artigo, é baseado nas regras e procedimentos de operação do Operador Nacional do Sistema Elétrico e da Câmara de Comercialização de Energia Elétrica. Propõe-se uma nova modelagem de mercado para o sistema brasileiro, na qual a remuneração da geração de potência reativa seja estruturada de forma mais precisa e atrativa para o mercado. Para demonstrar a eficácia da nova estrutura proposta, o sistema de transmissão IEEE 30 é empregado para teste e análise no software AMPL, utilizando o solver KNITRO. Por fim, pode-se demonstrar que o operador do sistema é mais beneficiado com o modelo de mercado proposto neste trabalho, devido à redução dos custos de operação e reserva e a melhor precificação dos custos de potência reativa.

In search of greater diversity in energy sources, to meet the demand of the electricity power, the use of photovoltaic generators is increasing. Such components have their power generation specified by IEEE 1547/2018, which limits the power parameters of each one. In a situation of high penetration of distributed generation, generators can contribute to the electric current that will circulate within the system in case of a fault, causing major disruption to the mesh and the users. Seeking to reduce this impact, the paper will minimize the value of the short circuit current by adjusting the parameters of the photovoltaic generators. The analysis will be done on IEEE Test Feeder 13 and 34 nodes and will refer to generators from category A, B and without reactive power injection in the mesh.

A maior necessidade de fontes de energia e sistemas sustentáveis resultou no surgimento de novas tecnologias e modelos de sistemas, como geração eólica e solar; sistemas de Geradores Distribuídos (GDs); Veículos Elétricos (VEs); e muitos outros. Contudo, devido ao grande impacto desses ativos no sistema de energia existente, é importante saber a forma mais sábia para inserí-los objetivando maximizar seus prós e minimizar seus contras. Assim, o presente trabalho tem como principal objetivo introduzir um método de otimização híbrido para alocar Estações de Carregamento de VEs (ECVEs) e GDs síncronos e realizar o despacho de energia para minimizar os custos operacionais da rede. O método consiste em duas etapas, a primeira via otimização pelo método de Algoritmos Genéticos (AG), utilizando o software MATrix LABoratory (MATLAB), para resolver o problema de alocação, e o segundo via método de Pontos Interiores (PI), utilizando o software A Mathematical Programming Language (AMPL), para resolver o problema de programação não linear que é o despacho econômico de energia dos geradores. O método se mostrou eficaz em sua aplicação, reduzindo os custos operacionais em cerca de 13.47%.

The Federal University of Espírito Santo has acquired 5,441 kWp of solar photovoltaic distributed energy resource (DER), which is being installed on the rooftoop of the buildings of the Goiabeiras Campus in the city of Vitória, Espírito Santo, Brazil. Knowing that the solar plant would decrease the metered power factor, this paper analyzed whether the finance revenue of the DER installation may be increased by the injection of reactive power using the DER inverters. Results allow to state that the revenue may be lightly increased. Nevertheless, the costs of a real implementation are not addressed.

Currently, it is evident a great increase in the integration of distributed generation in the electric power system. However, despite the several benefits caused by distributed generation, this integration causes many modifications in the electrical system parameters, such as the charging and the fault current. Thus, the power system protection may not operate as desired, reducing the reliability and safety. Therefore, this paper analyzes the influence of the distributed generation insertion, based on the addition of the photovoltaic system in the IEEE 13-Node Test Feeder, by using Genetic Algorithms to coordinate directional overcurrent relays in this feeder. From the results, it was possible to notice a considerable modification in the load and fault current, besides that, the developed Genetic Algorithm was able to reduce the objective function effectively respecting the established constraints. So the relays presented in the IEEE 13-Node test feeder with high integration of distributed generation were optimally coordinated.

This article proposes the use of a controlled current source as a photovoltaic generator, due the fact that recent work shows that this choice provides faster processing speed and agile implementation to obtain the power flow. This phasorial analysis will be tested using, with some considerations, the 13-Node Test Feeder topology and its input data. Initially, no distributed generation will be considered connected to the feeder and, for a second analysis, photovoltaic distributed generation will be inserted in the system to perform the power flow calculation with the proposed model. The reference simulator will be the Knowledge’s Virtual Academy (KVA), because it is a free-access software with a high-level solver to perform the numerical calculation. While the proposed methodology will be implemented in the sotfware Matlab. This study compares and analyze the voltage magnitude, mainly, and angle values obtained for both methods, the KVA result and the proposed method, for the scenarios with and without distributed generation.

Made available in DSpace on 2018-12-11T17:33:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-08-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) The distribution systems planning consists of finding an optimized configuration, at a low cost, which allows to keep the quality and reliability of energy supply. Distributed generators (DGs) make the planning problem more complex to be solved. Therefore, it is important to develop efficient computational tools to reduce costs and time in decision making, indicating where, when, and what types of components should be installed and/or replaced in the medium voltage electric distribution system in the presence of DGs. This paper proposes a short-term planning methodology for allocation of DGs, capacitor banks, control and protection devices, as well as the possibility of reconductoring of branches for the distribution network, while maintaining the quality of energy supply. The formulated multi-objective problem consists of minimizing the costs associated with investment, technical losses, and non-supplied energy of the distribution system, subject to physical, economic, and operational constraints. The reliability of the system is improved through allocation of control and protection devices and compact aerial structures. This problem is solved through an approach based on the non-dominated sorting genetic algorithm (NSGA-II). Tests were performed in a 135-bus distribution system, and the obtained results show the effectiveness of the proposed methodology. IFMT - Campus de Cuiabá FEIS UNESP FEIS UNESP FAPESP: 2012/15210-8 FAPESP: 2013/23590-8 CNPq: 305371/2012-6

This paper presents a mixed-integer linear programming approach to solving the problem of optimal type, size and allocation of distributed generators (DGs) in radial distribution systems. In the proposed formulation, (a) the steady-state operation of the radial distribution system, considering different load levels, is modeled through linear expressions; (b) different types of DGs are represented by their capability curves; (c) the short-circuit current capacity of the circuits is modeled through linear expressions; and (d) different topologies of the radial distribution system are considered. The objective function minimizes the annualized investment and operation costs. The use of a mixed-integer linear formulation guarantees convergence to optimality using existing optimization software. The results of one test system are presented in order to show the accuracy as well as the efficiency of the proposed solution technique.

Traditionally, ancillary services are supplied by large conventional generators. However, with the huge penetration of distributed generators (DGs) as a result of the growing interest in satisfying energy requirements, and considering the benefits that they can bring along to the electrical system and to the environment, it appears reasonable to assume that ancillary services could also be provided by DGs in an economical and efficient way. In this paper, a settlement procedure for a reactive power market for DGs in distribution systems is proposed. Attention is directed to wind turbines connected to the network through synchronous generators with permanent magnets and doubly-fed induction generators. The generation uncertainty of this kind of DG is reduced by running a multi-objective optimization algorithm in multiple probabilistic scenarios through the Monte Carlo method and by representing the active power generated by the DGs through Markov models. The objectives to be minimized are the payments of the distribution system operator to the DGs for reactive power, the curtailment of transactions committed in an active power market previously settled, the losses in the lines of the network, and a voltage profile index. The proposed methodology was tested using a modified IEEE 37-bus distribution test system.

In a smart grid environment, attention should be paid not only to the power supplied to satisfy loads and system losses but also to the services necessary to provide security and stability to the system: the so-called ancillary services. As they are well known the benefits that distributed generation can bring to electrical systems and to the environment, in this work the possibility that active power reserve for frequency control could be provided by distributed generators (DGs) in an efficient and economical way is explored. The proposed methodology was tested using the IEEE 34-bus distribution test system. The results show improvements in the capacity of the system for this ancillary service and decrease in system losses and payments of the distribution system operator to the DGs.

The scope of this work is to optimize the charging of electric vehicles (EVs) in a controlled environment. The method uses a linear optimization technique, which determines the electrical power that will be delivered to each EV considering as constraints the operating levels of the medium voltage distribution network. The proposed method was tested using the IEEE 34 bus distribution test system considering a level of penetration of EVs of 15%. The results show that, using the optimization process, it is possible to attend the demand of all considered PHEVs without violating any constraints.

Usually, ancillary services are provided by large conventional generators; however, with the growing interest in distributed generation to satisfy energy and environmental requirements, it seems reasonable to assume that these services could also be provided by distributed generators in an economical and efficient way. In this paper, a proposal for enhancement of the capacity of active power reserve for frequency control using distributed generators is presented. The goal is to minimize the payments done by the transmission system operator to conventional and distributed generators for this ancillary service and for the energy needed to satisfy loads and system losses, subject to a set of constraints. In order to perform analysis, the proposal was implemented using data of the IEEE 30-bus transmission test system. Comparisons were performed considering conventional generators without and with distributed generators installed in the system.

A high degree of variability reduces the available capability of Distributed Generators (DGs) based on renewable energy sources because their power output is uncertain. To determine the true available capability of this kind of DG, this uncertainty must be reduced so that these DGs can be regarded as a reliable alternative. In this work, an efficient forecast system for DGs with uncertainties in the primary energy source is proposed. The power generation uncertainty of these DGs is reduced by running a multiobjective optimization algorithm in multiple probabilistic scenarios combining the Monte Carlo method and the Markov models. (4 pages)

This paper presents a comparison of reactive power support in distribution networks provided by switched Capacitor Banks (CBs) and Distributed Generators (DGs). Regarding switched CBs, a Tabu Search metaheuristic algorithm is developed to determine their optimal operation with the objective of reducing the power losses in the lines on the system, while meeting network constraints. On the other hand, the optimal operation of DGs is analyzed through an evolutionary Multi-Objective (MO) programming approach. The objectives of such approach are the minimization of power losses and operation cost of the DGs. The comparison of the reactive power support provided by switched CBs and DGs is carried out using a modified IEEE 34 bus distribution test system.

Distributed Generation, microgrid technologies, two-way communication systems, and demand response programs are issues that are being studied in recent years within the concept of smart grids. At some level of enough penetration, the Distributed Generators (DGs) can provide benefits for sub-transmission and transmission systems through the so-called ancillary services. This work is focused on the ancillary service of reactive power support provided by DGs, specifically Wind Turbine Generators (WTGs), with high level of impact on transmission systems. The main objective of this work is to propose an optimization methodology to price this service by determining the costs in which a DG incurs when it loses sales opportunity of active power, i.e, by determining the Loss of Opportunity Costs (LOC). LOC occur when more reactive power is required than available, and the active power generation has to be reduced in order to increase the reactive power capacity. In the optimization process, three objectives are considered: active power generation costs of DGs, voltage stability margin of the system, and losses in the lines of the network. Uncertainties of WTGs are reduced solving multi-objective optimal power flows in multiple probabilistic scenarios constructed by Monte Carlo simulations, and modeling the time series associated with the active power generation of each WTG via Fuzzy Logic and Markov Chains. The proposed methodology was tested using the IEEE 14 bus test system with two WTGs installed.

Problems as voltage increase at the end of a feeder, demand supply unbalance in a fault condition, power quality decline, increase of power losses, and reduction of reliability levels may occur if Distributed Generators (DGs) are not properly allocated. For this reason, researchers have been employed several solution techniques to solve the problem of optimal allocation of DGs. This work is focused on the ancillary service of reactive power support provided by DGs. The main objective is to price this service by determining the costs in which a DG incurs when it loses sales opportunity of active power, i.e, by determining the Loss of Opportunity Costs (LOC). The LOC will be determined for different allocation alternatives of DGs as a result of a multi-objective optimization process, aiming the minimization of losses in the lines of the system and costs of active power generation from DGs, and the maximization of the static voltage stability margin of the system. The effectiveness of the proposed methodology in improving the goals outlined was demonstrated using the IEEE 34 bus distribution test feeder with two DGs cosidered to be allocated.

Due to the renewed interest in distributed generation (DG), the number of DG units incorporated in distribution systems has been rapidly increasing in the past few years. This situation requires new analysis tools for understanding system performance, and taking advantage of the potential benefits of DG. This paper presents an evolutionary multi-objective programming approach to determine the optimal operation of DG in distribution systems. The objectives are the minimization of the system power losses and operation cost of the DG units. The proposed approach also considers the inherent stochasticity of DG technologies powered by renewable resources. Some tests were carried out on the IEEE 34 bus distribution test system showing the robustness and applicability of the proposed methodology.

In this paper, a novel methodology to price the reactive power support ancillary service of Distributed Generators (DGs) with primary energy source uncertainty is shown. The proposed methodology provides the service pricing based on the Loss of Opportunity Costs (LOC) calculation. An algorithm is proposed to reduce the uncertainty present in these generators using Multiobjective Power Flows (MOPFs) implemented in multiple probabilistic scenarios through Monte Carlo Simulations (MCS), and modeling the time series associated with the generation of active power from DGs through Markov Chains (MC).

Made available in DSpace on 2019-03-11T13:02:34Z (GMT). No. of bitstreams: 1 tese_11414_Dissertação_Raisa_corrigido_final.pdf: 4785169 bytes, checksum: 24a66ff43fd0ce388e85e1ea16afc943 (MD5) Previous issue date: 2018-12-06 Não consta.

Made available in DSpace on 2018-09-11T12:38:31Z (GMT). No. of bitstreams: 1 tese_10905_DissetacaoLuan-posdefesa.pdf: 3112051 bytes, checksum: 7548c7bc51921f7c556402e44224c464 (MD5) Previous issue date: 2018-06-08 Não disponível.

Made available in DSpace on 2018-03-22T15:50:41Z (GMT). No. of bitstreams: 1 tese_11641_[dayane] abntex2-modelo-trabalho-academico (1).pdf: 1864556 bytes, checksum: 908b1da8a6184a0cef37b31b75f12fe5 (MD5) Previous issue date: 2017-12-20 Sistemas elétricos de potência devem fornecer eletricidade em frequência e tensão sincro-nizados para serem considerados confiáveis. Sistemas de controle de tensão podem usar diferentes estratégias para que a mesma seja regulada, sendo que o método de compensação de potência reativa é uma das possíveis maneiras. Por outro lado, o controle de frequência é tradicionalmente obtido por regulação de operações de máquinas síncronas em larga escala. Entretanto, a crescente utilização de fontes alternativas de energia e a operação desses geradores em paralelo com os sistemas elétricos de potência tradicionais ressaltam a importância do estudo da integração destas unidades com o sistema. Um fator a ser analisado é o impacto na redução da inércia total da rede, que pode causar o aumento de variações de frequência e de tensão, de forma a afetar a estabilidade do sistema frente distúrbios. Nesse contexto, este trabalho propõe-se a discutir a utilização do conceito de inércia adicional virtual, onde cada unidade de geração se comporta como um gerador síncrono virtual, em comparação com a tradicional técnica PQ para o controle de potência de inversores que fazem a interface de unidades de geração tradicionalmente não inerciais com o sistema. Os resultados de simulação apresentados comprovam a contribuição do gerador síncrono virtual para a estabilidade de uma rede conhecida, o sistema IEEE-14 Barras. Palavras-chave: IEEE 14-barras. Controle de Potência. Estabilidade em Sistemas Elétricos de Potência. Gerador Síncrono Virtual

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