Raimundo Furtado Sampaio

Multiobjective Optimization Algorithm for Switch Placement in Radial Power Distribution Networks

Customer satisfaction counts very much to the electric power distribution companies. The improvement of reliability indices is an effective way to achieve this goal. The optimal placement of power switches is a desirable procedure because while it reduces investment in network assets, it also reduces the number of customers not supplied by outages and, accordingly, improves system reliability. This paper proposes a multiobjective optimization approach for switch placement based on the particle swarm optimization method applied to radial distribution networks of power utilities. The proposed algorithm gives a set of solutions instead of a single one. It intends to be a valuable and flexible tool for planning modern and reliable power distribution networks. Simulation results when using the IEEE 123-node test system and the Roy Billinton Test System are presented as testbeds.

Modeling and simulation of a microgrid with multiple energy resources

This work presents the modeling, control and operation of a microgrid with three power sources and a storage system. The sources are solar photovoltaic, fuel cell and wind turbine. The objective of this work is to describe useful models of typical sources, the calculation of its parameters and control design of the power electronic converters of the energy sources. The modeling of the full system including all the stages of the converters is performed using PSCAD/EMTDC software package. The microgrid was designed to operate connected to the main network. The microgrid operated appropriately for different steady state operating conditions.

A multiagent approach to automatic restoration of distribution network

This paper proposes an application of multiagent systems to automatic restoration of distribution network. The system proposed consists of three types of agents: Device Agent, Feeder Agent and Substation Agent. The Device Agents are associated with equipment installed on the grid, the Feeder Agents are responsible to manage the feeders and Substation Agents are responsible to manage the substations. The behavior of agents is presented to a condition of automatic restoration of a distribution network subjected on fault condition. The approach using multiagent indicates that the proposed system is able to locate the fault, isolate and restore the system, considering operating limits and uncoordinated system protection.

Método de implementação de Sistema de Diagnóstico de Falta para subestações baseado em Redes de Petri

This paper presents a methodology for the development of a Fault Diagnosis System (FDS) based on Hierarchical Colored Petri Nets. The proposed FDS aims to evaluate the information from the SCADA and to present a fault diagnosis sucint and accurate to the power system operators, causing the task of fault diagnosis faster, reliable and less stressful. The proposed methodology is developed and applied to a typical distribution substation with digital relays, 15 MVA, 69 kV/13,8 kV, owned by the local distribution utility, Companhia Energetica do Ceara (Brazil).

Application of Multi-objective Evolutionary Algorithms in automatic restoration of radial power distribution systems

When a permanent fault occurs in a power distribution system, the network can be reconfigured in order to restore the supply of some loads situated on non-faulty paths. This paper presents an algorithm developed in Python for optimize the automatic reconfiguration and restoration of radial power distribution systems after the occurrence of a permanent fault. It uses the Multi-objective Evolutionary Algorithm technique and the Step Method in order to optimize all objectives of a given problem, thus providing a greater number of possible solutions. The goals set to the multi-objective function are the maximization of restored customers, minimization of Joule losses and the number of switching maneuvers in the network for the restoration, which are subject to operational constraints. The software features a set of non-dominated solutions, providing the operator with the option to choose from several effective configurations. The grid is modeled by using the node-depth representation (NDR), and the operating constraints evaluated by the forward / backward sweep load flow method. The 16-bus IEEE test system and a proposed 41-bus test system are used to analyze the response of the developed application, which presents good performance and can be safely used by radial distribution system operators.

Desenvolvimento de um laboratório virtual para capacitação tecnológica a distância em proteção de sistemas elétricos

A necessidade por profissionais cada vez mais qualificados, bem como o custo associado a liberacao de funcionarios para participar destes cursos, forcaram a pesquisa de novas formas de treinamento que possibilitassem um bom resultado profissional e racionalizassem a disposicao de recursos humanos. Para atender essa demanda, foi desenvolvido um Laboratorio Virtual para Capacitacao Tecnologica presencial e a Distância em Protecao de Sistemas Eletricos. O laboratorio virtual, denominado Sistema Simulador para Treinamento Presencial e a Distância da Protecao de Sistemas Eletricos (STOP), pode ser aplicado em treinamento presencial e a distância e esta integrado ao Moodle, enriquecendo o ambiente com uma ferramenta capaz de simular situacoes reais que pode proporcionar um ensino-aprendizado mais eficaz.

Power quality assessment and the application of protective digital relays

Along with the restructuring of the power sector and the dissemination of the system automation and the information and communication technology, the power utilities have been encouraged to deliver more and more information to their consumers, grid operators and regulation agencies concerning the performance of the power system. This paper presents the application of protective digital relays to assist the power quality evaluation of a power system. Recommended power quality indices are used to measure the severity of short-duration voltage variation. The indices are calculated based on the registers of digital relays of different characteristics and compared to the indices calculated from a disturbance analyzer. Although the sample rate of the relays is smaller than that of the disturbance analyzer, the numeric relays can be used to assess the power quality of electric power systems.

Multi-agent systems applied for restoration of power networks supported by micro grids

This paper presents a multi-agent-based system for the automatic restoration of power distribution networks supported by micro grids. The multi-agent automatic restoration system (MARS) is composed of eight types of agents: switch agents (AC), feeder agents (AL), tie switch agents (AE), connection point agent (APC), generation agent (AG), demand agent (AD), storage agent (AA), and dispatch generation agent (AGC). The agents work together in order to restore costumers load after a fault occurs in the utility power grid. The MARS was developed in JADE (Java Agent Development Framework), which is written in Java. Case studies are supposed to demonstrate the performance of the proposed MARS when applied to a medium-voltage power distribution network and a microgrid. The distribution network and the micro grid are modeled in Matlab-Simulink environment, while the communication tools between JADE and Simulink are also developed. Simulation results demonstrate that MARS presents a suitable performance, providing fast and reliable recovery of the power distribution network. It also evidences the capability of multi-agent system techniques in the automation and decision support of smart grids.

Design of LCL filter using feedforward controller for grid-connected inverter

This article presents a new approach that provides scaling the LCL-filter inductances based on the harmonic analysis of the filter output current. The approach considers the filter design together with the inverter control, both together, improving the system stability and the dynamic response. The model and general guidelines for selecting the filter parameters, taking into account the variation of the grid equivalent inductor, are presented. The proposed control system makes use of a simple PI since the feed-forward controller removes from the feedback controller the control on the grid current and eliminates the need of synchronization procedure. Simulation tests with a 15 kW three-phase VSI in series with an LCL filter have proved the effectiveness of the proposed approach.

New control strategy for grid-connected inverter using LCL filter

This paper presents a new approach that provides scaling the LCL-filter inductances based on the harmonic analysis of the filter output current. The approach considers the filter design together with the inverter control, both together, improving the system stability and the dynamic response. The model and general guidelines for selecting the filter parameters, taking into account the variation of the grid equivalent inductor and the use of non-linear inductances, are presented. The proposed control system makes use of feed-forward control in order to increase performances of the feedback control and eliminates the need of synchronization procedure. Simulation tests with a 15 kW three-phase VSI with a LCL filter have proved the effectiveness of the proposed approach.