| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 9.39 MB | Adobe PDF |
Authors
Abstract(s)
A eficiência energética e a gestão da solicitação da energia são factores fundamentais para a
competitividade da indústria. O crescente interesse pela eficiência global do sistema elétrico tem
provocado um crescimento na utilização de equipamentos mais eficientes que, embora permitam
reduzir as perdas, têm levado ao aumento da distorção harmónica. Estudos revelam que os custos
directos relacionados com perda de Qualidade da Energia Eléctrica (QEE) podem representar cerca
de 1,5 % do PIB nacional. Os monitorizadores de QEE vêm ao encontro desta situação detetando
problemas tanto no consumo como no fornecimento/distribuição de energia. O relatório do
Inquérito Europeu sobre a QEE mostrou que os problemas de qualidade de energia são
responsáveis por metade do tempo de inatividade na maioria das instalações. Em termos
financeiros esta situação representa uma perda financeira de mais de 150 mil milhões de euros por
ano nos países da UE-25.
Dando um exemplo mais recente, as luminárias baseadas em LEDs são de facto muito eficientes
mas são cargas não-lineares. Numa linha de iluminação pública é essencial haver monitorização
para a detecção e é essencial correção dos problemas associados à QEE para não comprometer nem
a qualidade do serviço nem a produtividade da EDP. Com efeito, os LEDs apresentam vantagens
bem documentadas mas, por serem cargas não lineares, têm impacto negativo na QEE da rede de
distribuição, principalmente na rede de baixa tensão onde é feita a ligação com a maior parte dos
clientes. É também aí e onde se encontram a ligação às fontes de energia descentralizadas que
incluem conversores de potência que produzem energia com forma de onda com um determinado
grau de distorção. Estes dois factores contribuem para o aumento da distorção da forma de onda de
tensão e tem como consequência o aumento das perdas. Com o presente trabalho centramos esforços no desenvolvimento do sistema de iluminação pública.
Pretende-se analisar o impacto provocado pela migração da iluminação pública tradicional para
luminárias a LED e avaliar da possibilidade de integrar o banco de condensadores ou filtros. Estes
poderiam ser instalados em subestações de distribuição, indústrias e prédios comerciais a fim de
resolver os problemas relacionados com o conteúdo harmónico, com o desequilíbrio de cargas e
com a compensação do factor de potência.
É feito um caso de estudo num sistema de Iluminação Pública (IP) na Avenida João Paulo II, em
Braga. Os resultados mostram um nível elevado de distorção harmónica, no Ponto de Acoplamento
Comum (PCC), no sistema de distribuição e que se torna ainda mais grave para níveis de carga
elevados.
Energy efficiency, effective management of energy demand and its conservation are key factors for the competitiveness of industry today. The growing interest on overall power system efficiency caused an increasing utilization of more efficient equipment that, in spite of reducing losses, increased the harmonic distortion. Studies reveal that the direct costs related to loss of power quality can represent approximately 1.5% of the national GDP. According with this situation, Power Quality Analyzers are used to detect problems related with energy sourcing and energy consumption. The European Power Quality survey report declared that Power Quality problems are responsible for half of equipment downtime in most installations. In other words, PQ problems cause a financial loss of more than 150 billion Euros per year in the EU-25 countries. For example, in the case of street lighting line with non-linear loads (LEDs lamps), it is crucial to have an equipment to monitor continuously the PQ of the grid. If the poor Power Quality causes a problem in the manufacturing process, the product quality can be compromised, along with productivity. Although non-linear loads bring well known advantages, they also have a negative effect on the grid’s power quality, in particular, the low voltage grid where the connection with most non-linear loads and with the decentralized energy sources. It is due to the use of control equipment (power converters) which produce distorted energy and increase losses. This research study makes an efforts on developing a street lighting system, on evaluating the harmonic distortion caused by LEDs. It is intended show the possibility to integrate active filters which can be used in distribution substations, commercial and industrial buildings, to solve problems related to harmonics, load unbalance and power factor compensation. Simulations to obtain the voltage and current waveforms were carried out to a case study on a street lighting system in Braga at João Paulo II Avenue. The results show high level of harmonic distortion, at the Point of Common Coupling (PCC), in the distribution system which becomes even more aggravated when a higher loading level, of the distribution transformer, is considered.
Energy efficiency, effective management of energy demand and its conservation are key factors for the competitiveness of industry today. The growing interest on overall power system efficiency caused an increasing utilization of more efficient equipment that, in spite of reducing losses, increased the harmonic distortion. Studies reveal that the direct costs related to loss of power quality can represent approximately 1.5% of the national GDP. According with this situation, Power Quality Analyzers are used to detect problems related with energy sourcing and energy consumption. The European Power Quality survey report declared that Power Quality problems are responsible for half of equipment downtime in most installations. In other words, PQ problems cause a financial loss of more than 150 billion Euros per year in the EU-25 countries. For example, in the case of street lighting line with non-linear loads (LEDs lamps), it is crucial to have an equipment to monitor continuously the PQ of the grid. If the poor Power Quality causes a problem in the manufacturing process, the product quality can be compromised, along with productivity. Although non-linear loads bring well known advantages, they also have a negative effect on the grid’s power quality, in particular, the low voltage grid where the connection with most non-linear loads and with the decentralized energy sources. It is due to the use of control equipment (power converters) which produce distorted energy and increase losses. This research study makes an efforts on developing a street lighting system, on evaluating the harmonic distortion caused by LEDs. It is intended show the possibility to integrate active filters which can be used in distribution substations, commercial and industrial buildings, to solve problems related to harmonics, load unbalance and power factor compensation. Simulations to obtain the voltage and current waveforms were carried out to a case study on a street lighting system in Braga at João Paulo II Avenue. The results show high level of harmonic distortion, at the Point of Common Coupling (PCC), in the distribution system which becomes even more aggravated when a higher loading level, of the distribution transformer, is considered.
Description
Keywords
Cargas não-lineares Poupança energética Compensação do factor de potência Qualidade de energia THD LED Non-linear loads Power savings Power factor correction Power quality Total Harmonic Distortion THD Light Emitter Diode LED