Minimizing of energy consumption of public lighting systems

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Dr. Dán András
Department of Electric Power Engineering

Firstly the current lighting network is described, its attributes and specialities are discussed. These include the following topics:

• Network topology

• Luminaries

• Switching methods

• Regulation practices

• Payment options

After this, a few sample networks are proposed, along with its attributes. These represent well the Hungarian lighting networks. The parameters came from field experts and from my own measurements. The following aspects are discussed in details:

• Wires

• Luminaries

• Traffic

Following these sections the luminaries currently in use with induction type ballasts are compared with electronic ballasts and LED luminaries, by yearly energy consumption of the sample networks. An algorithm is made for carrying out these calculations. It is capable of giving a load flow solution, harmonic contents and losses and yearly energy consumption. In the latter the traffic circumstances and the public lighting calendar, which describes the daily on-off periods of the network, are handled, along with a traffic dependent regulation method.

From the results it can be observed that every examined scenario yielded energy savings. In the case of compact fluorescent luminaries, the electronic ballast makes significant savings. The LED luminaries give also a significant drop in energy usage on top of the electronic ballasts. However in the case of high pressure sodium lamps the savings of electronic ballasts are nearly negligible, especially at greater wattage. LED luminaries bring some notable improvements, although not as much as fluorescent luminaries. The effects of regulation possibilities were also examined. In the case of electronic and induction type ballasts, the only possibility is a reduced power for a period in the night, thus the savings are always at the same magnitude, compared to the base cases respectively. With LED lighting fast switching and flexible dimming are possible, so the traffic dependent regulation can be used. It is observed that the savings and the average traffic density are related by a logarithmic manner.


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