Filtro ativo paralelo com controle digital de baixo custo

Este artigo descreve o desenvolvimento de um filtro ativo paralelo de baixo custo utilizado para a melhoria da qualidade de energia elétrica. O filtro permite a correção dinâmica do fator de potência e a compensação dinâmica dos harmônicos e da componente de sequência zero de corrente. O sistema de controle do filtro ativo é baseado na teoria p-q (teoria da potência instantânea), e foi implementado com um microcontrolador standard de 16 bits. Neste artigo a teoria p-q é apresentada de forma sucinta, o filtro ativo paralelo desenvolvido é descrito e são apresentados alguns resultados experimentais

Shunt active filter for power quality improvement

This paper describes the development of a low cost shunt active power filter with digital control, which allows dynamic power factor correction and both harmonics and zero-sequence current compensation. The active filter controller is based on the instantaneous power theory (p-q theory) and was implemented using a standard 16 bits microcontroller. The p-q theory is introduced followed by the presentation of some active power filters topologies. Then a brief description of the implemented solution is made, including references to software tools used for simulation and system development. Experimental results are also presented, showing the good performance of the developed active filter

Comparison of fundamental positive-sequence detectors for highly distorted and unbalanced systems

This paper presents a performance comparison between a PLL and an Adaptive Filter for detecting the positive sequence at the fundamental frequency of any given voltage or current signals of a three-phase system. The comparative analysis was based on the evaluation of a series of steady state performance parameters (phase and amplitude errors, THD and unbalance) and on the response time. The tests were made to study the behaviour of both approaches when working with highly distorted and unbalanced signals. This work was carried out using the computer simulation tool PSCAD/EMTDC.The authors are grateful to FCT (Fundação para a Ciência e a Tecnologia), project funding POCTI/ESE/41170/2001

Algumas contribuições para o controle de filtros ativos

In this work, control strategies for active filters are presented. They are based on the set of active and non-active power definitions proposed by Fryze in the 30’s of the last century and extended to power electronics applications in the 80’s. Basically three control algorithms are described, which are the Sinusoidal Fryze Currents, the Sinusoidal Fryze Voltages, and a Damping Controller. By using these control algorithms it is possible to verify that, in a three-phase three-wire system, the source currents, drained from the network, and the load voltages, delivered to the load, are pure sinusoidal waveforms, in phase with the fundamental positive sequence component of the system voltage. Simulation results of the UPQC conditioner (Unified Power Quality Conditioner) are shown in order to validate the proposed control strategies.Neste trabalho, são apresentadas estratégias de controle para filtros ativos. Estas estratégias estão baseadas no conjunto de definições para as potências ativa e não ativa, em condições não senoidais, propostas por Fryze nos anos 30 do século passado e estendida a aplicações em eletrônica de potência no final dos anos 80. Basicamente são três algoritmos apresentados para aplicações em filtros ativos, sendo eles Correntes Senoidais de Fryze, Tensões Senoidais de Fryze, e um Controle de Amortecimento. Por meio destas estratégias de controle é possível verificar que, em sistemas trifásicos a três fios, as correntes drenadas da fonte e as tensões entregues à carga serão senóides puras, em fase com a componente fundamental de seqüência positiva. Para validar estas estratégias de controle propostas, resultados de simulação do condicionador UPQC (Unified Power Quality Conditioner) são mostrados.Fundação para a Ciência e a Tecnologia (FCT) - POCTI/ESE/41170/2001

Experimental evaluation of a control system based on a dual-DSP architecture for a unified power quality conditioner

An experimental evaluation of a digital control system based on a dual Digital Signal Processor (DSP) architecture is proposed for a three phase Unified Power Quality Conditioner (UPQC). A classical UQPC is constituted by two power conditioners, connected in series and shunted with the power grid, and sharing a common DC-link. In a smart grid scenario of operation, a UPQC will be fundamental for compensating power quality problems, also contributing to improving the efficiency of the electrical grids from a global perspective. The UPQC operation requires a bidirectional energy transfer between the two power conditioners, however, respecting some constraints, they can be controlled independently. In order to take advantage of this characteristic, the control algorithms can be executed on two independent DSPs, without any communication between them and maintaining the operational characteristics of the UPQC. Comparing with the classical control architecture based on a single DSP, with the proposed dual DSP architecture, the computational effort of each DSP is decreased of about 35%, allowing to increase the sampling rate. Therefore, the main advantages of the proposed approach are the minimization of delays caused by the processing time, which are very common in digital control systems, as well as the increment of the UPQC performance. Along the paper, detailed analysis of the processing speed and memory requirements to implement the UPQC control algorithms in both DSPs is presented. The paper also presents a set of detailed experimental results, obtained with a developed 5 kVA laboratory prototype of UPQC, which was used to evaluate the performance of the proposed dual DSP architecture.This work has been supported by FCT — Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2019. This work has been supported by the FCT Projects: Quality4Power — POCI-010145-FEDER-028813 and newERA4GRIDs — POCI-01-0145-FEDER-030283.info:eu-repo/semantics/publishedVersio

A control strategy for a three-level unified power quality conditioner

Comunicação apresentada no 8th COBEP - Congresso Brasileiro de Eletrônica de Potência, Recife, PE, Brasil, 14-17 Julho 2005.In this work a control strategy for a three-level Unified Power Quality Conditioner (UPQC) is introduced. Basically, this control strategy is based on the set of active and non-active (reactive) power definitions in the time domain, which have been proposed by Fryze in the 30´s of the last century. The goal of this work consists in expand this control strategy to deal with three-level converters. The use of three-level converters allows a better performance of the equipment, by reducing harmonics and the ripple of the generated voltages and currents. Simulation results on PSCAD/EMTDC will be illustrated in order to verify the accuracy of the expanded control strategy.Fundação para a Ciência e Tecnologia - POCTI/ESE/41170/2001; POCTI/ESE/48242/2002

Condicionador unificado para a compensação simultânea de problemas de tensão e corrente

Neste trabalho é feita uma análise do condicionador unificado denominado como UPQC (Unified Power Quality Conditioner). Este equipamento tem como objectivo melhorar a qualidade da energia do sistema de potência, minimizando simultaneamente os problemas observados nas tensões e nas correntes. Resultados de simulação obtidos com o programa de transitórios electromagnéticos PSCAD®/EMTDC™ são apresentados com o objectivo de analisar o desempenho do UPQC. Por fim são apresentados resultados de simulações do UPQC com conversores de três níveis, optimizando o seu desempenho.Fundação para a Ciência e a Tecnologia (FCT) - POCTI/ESE/48242/2002.Program de Incentivos de Modernização da Economia (PRIME) - Projecto SINUS.Programa Alban - Bolsa n.º E06D103177BR

Custom power interfaces for renewable energy sources

Interface converters for renewable energy sources can be regarded as custom power devices. Thus they can be designed and operated so as to improve power quality at their connecting locations. This paper presents examples of converter designs based on p-q theory for different applications. Modeling, simulations and experimental results are given for converter prototypes operating either as active power filter (APF) or static compensator (STATCOM), while transferring real power to the utility grid. Compensation of harmonic distortions, power factor control, reactive support and voltage control are achieved with the proposed circuits