Multinodal Load Forecasting in Power Electric Systems using a Neural Network with Radial Basis Function

In this paper we present the results of the use of a methodology for multinodal load forecasting through an artificial neural network-type Multilayer Perceptron, making use of radial basis functions as activation function and the Backpropagation algorithm, as an algorithm to train the network. This methodology allows you to make the prediction at various points in power system, considering different types of consumers (residential, commercial, industrial) of the electric grid, is applied to the problem short-term electric load forecasting (24 hours ahead). We use a database (Centralised Dataset - CDS) provided by the Electricity Commission de New Zealand to this work.

Reference generator for voltage controlled power conditioners

Voltage reference generation is an important issue on electronic power conditioners or voltage compensators connected to the electric grid. Several equipments, such as Dynamic Voltage Restorers (DVR), Uninterruptable Power Supplies (UPS) and Unified Power Quality Conditioners (UPQC) need a proper voltage reference to be able to compensate electric network disturbances. This work presents a new reference generator's algorithm, based on vector algebra and digital filtering techniques. It is particularly suited for the development of voltage compensators with energy storage, which would be able to mitigate steady state disturbances, such as waveform distortions and unbalances, and also transient disturbances, like voltage sags and swells. Simulation and experimental results are presented for the validation of the proposed algorithm. © 2011 IEEE.

Estudos teóricos e experimentais da operação conjunta de um supressor eletromagnético e de um filtro ativo de potência

Pós-graduação em Engenharia Elétrica - FEIS

Implementação de microrredes residenciais em corrente contínua através da microgeração

This paper discusses the importance of energy efficiency and the use of alternative energy sources, facing to the increasing energy demand and the concomitant economic, social and environmental restrictions imposed by society. In this work, alternative sources are illustrated by photovoltaic, micro turbines and fuel cells microgeneration systems. Energy efficiency is presented by direct current microgrids because its uses excludes the conversions of direct current (DC) to alternating current (AC) losses made with the intention of injecting energy into the electric grid and then the inverse conversion, AC to DC, in order to feed residential loads. The object of this paper is to analyze a case study and evaluates the costs and technical feasibility of a Project that combines a DC microgrid and a microgeneration system

New integrated Zeta and Cuk inverters intended for standalone and grid-connected applications

This paper presents new inverter topologies based on the integration of a DC to DC Zeta or Cuk converter with a voltage source inverter (VSI). The proposed integration procedure aims to reduce the amount of components, meaning lower volume, weight and costs. In this context, new families of single-phase and three-phase integrated inverters are also presented. Therefore, considering the novelty for Zeta and Cuk integrated inverters structures, the proposed single-phase and three-phase inverters versions are analyzed for grid-tied and stand-alone applications. Furthermore, in order to demonstrate the feasibility of the proposal, the main simulation and experimental results are presented. © 2011 IEEE.

Power flow optimization for grid connected inverter using evolutionary algorithm and additional control loop

In this work it is proposed to validate an evolutionary tuning algorithm in plants composed by a grid connected inverter. The optimization aims the tuning of the slopes of P-Ω and Q-V curves so that the system is stable, damped and minimum settling time. Simulation and experimental results are presented to prove the feasibility of the proposed approach. However, experimental results demonstrate a compromising effect of grid frequency oscillations in the active power transferring. In addition, it was proposed an additional loop to compensate this effect ensuring a constant active power flow. © 2011 IEEE.

A multi-agent system with a percolation approach to simulate the driving pattern of Plug-In ELectric Vehicles

A multi-agent system with a percolation approach to simulate the driving pattern of Plug-In Electric Vehicle (PEV), especially suited to simulate the PEVs behavior on any distribution systems, is presented. This tool intends to complement information about the driving patterns database on systems where that kind of information is not available. So, this paper aims to provide a framework that is able to work with any kind of technology and load generated of PEVs. The service zone is divided into several sub-zones, each subzone is considered as an independent agent identified with corresponding load level, and their relationships with the neighboring zones are represented as network probabilities. A percolation approach is used to characterize the autonomy of the battery of the PVEs to move through the city. The methodology is tested with data from a mid-size city real distribution system. The result shows the sub-area where the battery of PEVs will need to be recharge and gives the planners of distribution systems the necessary input for a medium to long term network planning in a smart grid environment. © 2012 IEEE.

Improving the grid operation and reliability cost of distribution systems with dispersed generation

In this work, a mathematical model to analyze the impact of the installation and operation of dispersed generation units in power distribution systems is proposed. The main focus is to determine the trade-off between the reliability and operational costs of distribution networks when the operation of isolated areas is allowed. In order to increase the system operator revenue, an optimal power flow makes use of the different energy prices offered by the dispersed generation connected to the grid. Simultaneously, the type and location of the protective devices initially installed on the protection system are reconfigured in order to minimize the interruption and expenditure of adjusting the protection system to conditions imposed by the operation of dispersed units. The interruption cost regards the unsupplied energy to customers in secure systems but affected by the normal tripping of protective devices. Therefore, the tripping of fuses, reclosers, and overcurrent relays aims to protect the system against both temporary and permanent fault types. Additionally, in order to reduce the average duration of the system interruption experienced by customers, the isolated operation of dispersed generation is allowed by installing directional overcurrent relays with synchronized reclose capabilities. A 135-bus real distribution system is used in order to show the advantages of using the mathematical model proposed. © 1969-2012 IEEE.

Optimal charging of electric vehicles considering constraints of the medium voltage distribution network

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Determining spatial resolution in spatial load forecasting using a grid-based model

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A NS-2 simulation model for DNP3 protocol over IEEE 802.15.4 wireless protocol toward low cost simulation of Smart Grid applications

Faced with an imminent restructuring of the electric power system, over the past few years many countries have invested in a new paradigm known as Smart Grid. This paradigm targets optimization and automation of electric power network, using advanced information and communication technologies. Among the main communication protocols for Smart Grids we have the DNP3 protocol, which provides secure data transmission with moderate rates. The IEEE 802.15.4 is another communication protocol also widely used in Smart Grid, especially in the so-called Home Area Network (HAN). Thus, many applications of Smart Grid depends on the interaction of these two protocols. This paper proposes modeling, in the traditional network simulator NS-2, the integration of DNP3 protocol and the IEEE 802.15.4 wireless standard for low cost simulations of Smart Grid applications.

Smart Grid e Carros Elétricos - Influência da Carga de Carros Elétricos Sobre o Sistema Elétrico

The technologies are advancing at a pace so expressive that allow the increase of the power quality from generation until the distribution to end customers. This improvement has been made possible through the automation of the energy that follows to a better quality of the energy provided, a lower energy supply disruptions and a very short recovery time. The trend of today and the near future is the distributed energy generation. To keep the automated control of the chain, the presence of Smart Grids is needed and that will be the most efficient and economical way to manage the entire system. Within this theme, is going to be necessary analyze the electric cars that promise to promote a more sustainable transport because it doesn’t uses fossil fuels, and more healthy because it does not emit pollutants into the atmosphere. The popularization of this type of vehicle is estimated to happen in a few decades and the case study analyzing its influence on the demand of the electrical system is something that will be very important in the near future. This paper presents a study of the influence of the inclusion of charges refering to electric cars

Desenvolvimento de um sistema de gerenciamento de energia (EMS - Energy Management System) para a rede elétrica inteligente (Smart Grid)

Pós-graduação em Engenharia Elétrica - FEIS

Análise de desempenho de redes de comunicação wireless em aplicações de Smart Grid

Pós-graduação em Engenharia Elétrica - FEIS

Activation of bovine oocytes by strontium combined or not with an electric pulse

O objetivo deste trabalho foi avaliar as taxas de ativação e de clivagem de oócitos bovinos tratados com estrôncio (10mm de SrCl2), após maturação in vitro por 27-28 horas. No experimento 1, os tratamentos foram: S4 - ativação pelo estrôncio por 4 horas; S12 - ativação pelo estrôncio por 12 horas; S30 - ativação pelo estrôncio por 30 horas; e P - ativação por pulso elétrico (3 pulsos de 1,0kv/cm). No experimento 2 os tratamentos foram: PS4 - ativação combinada pelo pulso elétrico e pelo estrôncio por 4 horas; S4P - ativação pelo estrôncio por 4 horas e pelo pulso elétrico; e PS30 - ativação pelo pulso elétrico e pelo estrôncio por 30 horas. No experimento 1, todos os tratamentos apresentaram taxas similares de ativação (83-90%; P>0,05). Para clivagem, P foi melhor (53%; P<0,05) do que todos os tratamentos com estrôncio (6 a 28%). No experimento 2, o tratamento S4P apresentou melhor taxa de ativação (88%; P<0,05) do que PS4 e PS30 (60 e 68%, respectivamente). Para clivagem, observou-se o mesmo padrão, S4P (65%; P<0,05) e PS4 e PS30 (37% e 44%, respectivamente). Conclui-se que o estrôncio é capaz de ativar oócitos bovinos e sua combinação com pulso elétrico não melhora a ativação. Este é o primeiro relato demonstrando que o estrôncio ativa oócitos bovinos.