# Streetlight Control System Based on Wireless Communication over DALI Protocol
## 1 Introduction  
Public lighting installations are important sources of energy consumption that are affected by certain factors, such as regulation and maintenance. This energy consumption can be reduced considerably by applying new communication and control technologies. The International Energy Agency (IEA) has estimated that the potential energy savings due to lighting technology can be approximately 133 to 212 TWh/y on a global level. The corresponding reductions in CO\({}_{2}\) emissions could equal about 86-137 MT/y for IEA countries [1]. The European Commission carried out a recent study [2] proving that between 30% and 50% of the electricity used for lighting could be saved through research into energy-efficient lighting systems. The use of low-consumption lamps, lighting fixtures and other types of outdoor luminance lighting fixtures is advisable, as is the use of cleaner methods of generating electric energy. This is not just a profitable investment but can also improve the quality of the lighting [3]. Two-thirds of the public lighting systems currently in use are still based on obsolete and inefficient technologies, with higher energy consumption than needed; therefore, there is great technological potential to renovate public lighting and reduce energy consumption [4]. According to estimates, around 5% of the energy used in lighting is consumed by public lighting, which is the most important component of a city or town's energy consumption. The minimum acceptable or legal requirements for controlling lighting are different for industry, offices, streets, and public lighting, but the concept is always the same: a fixed lighting intensity mustbe always achieved with energy efficiency and the lowest possible cost for energy consumption to increase the expected lifespan of the lamps. As a result, by using available lamps, ballasts and control systems, as well as techniques to develop an efficient lighting system, it is possible to produce quality energy in a more efficient and profitable way [5]. Traditional energy-saving techniques entail totally or partially turning off streetlights, but this implies a reduction in the uniformity of the lighting, which also has a considerable impact on the lifespan of lamps. Several recommendations exist to reduce the electric energy consumption of public lighting [6]. One of these actions is to control the on-off timespan of the lighting. This period can be controlled using photocell relays or astronomical time relays [7]. The photocells are activated or deactivated depending on the level of environmental light. Their main disadvantage is their low sensitivity to dawn and the presence of clouds, which can cause the relay to be activated too soon. On the other hand, astronomical time relays use a program that contains the sunrise and sunset times in each time zone. A second action is to reduce light output (dimming) during hours with reduced traffic by reducing the voltage applied to each lamp, which reduces electric energy consumption. Lastly, another proposed action is to use high-performance lamps and lighting devices. This consists of installing smart, adjustable electronic ballasts that are able to automatically detect electric failures and lamp problems; measure and send data, such as on the state of the lighting, the lighting level, the energy consumption, voltage, current, and power factor; and receive interruption and lighting control commands. Regarding the need for uniform lighting, the control systems have two possibilities: light posts with two lamps or with only one fully controllable lamp. In the first case, one of the two lamps can be turned off late at night and during the early morning hours. In the second case, the lamp needs to be connected to a regulation system. The last method has two practical options: dimmable ballasts or centralized control systems as line voltage regulators. On the other hand, remote management systems also exist that allow the user to control and monitor each lamp individually.