Energy Saving of Large-Scale High-Intensity-Discharge Lamp Lighting Networks Using a Central Reactive Power Control System

This paper summarizes the test results on several large-scale lighting systems based on a range of high-intensity-discharge (HID) lamps. The study focuses on the energy-saving, energy-efficiency, and dimming characteristics of magnetic-ballast-driven HID lamp systems that are suitable for public lighting networks. A central energy-saving unit that can change the input mains voltage of 220 V to a variable voltage within the range from 220 to 170 V is used to control a large lighting network. This central dimming unit offers a new freedom for users to use lighting energy when and where it is needed and to an appropriate power level. Lamp characteristics under full and reduced voltage operation for six types of HID lamps have been measured. Six large-scaled networks of ballast-lamp sets have been set up and dimmed with a central energy-saving unit with a rated power of 13.2 kVA per phase. The full load current under test was set at about 40 A per phase. The loss of the energy-saving unit on a per-lamp-set basis was measured at different voltage levels. It is found that the energy-saving unit can reduce overall system power at least 40% without causing lamp flickering. Through the controllable voltage range, there is no obvious change in color temperature. The lamp power and light output decrease almost linearly with input voltage within the range from 170 to 220 V, and the power loss of the energy-saving unit is less than 2.4% of the full power in all tests. For these large-scaled lighting networks, it is envisaged that 25%-35% of energy saving can be achieved in large public lighting applications.