312 PRZEGLĄD ELEKTROTECHNICZNY (Electrical Review), ISSN 0033-2097, R. 88 NR 11a/2012 Alexandru LAVRIC, Valentin POPA, Ilie FINIS, Daniel SIMION Stefan cel Mare University of Suceava The design and implementation of an energy efficient street lighting monitoring and control system Abstract..The reduction of electrical energy consumption has been a highly debated issue on a European level and represents an important topic. This paper presents the design and implementation of a street lighting monitoring and control system using a WSN (Wireless Sensor Network) communication protocol, which has the ability to incorporate a high number of nodes. The main advantages of this system consist in the reduction of the costs related to energy consumption and maintenance by integrating a vehicle detection algorithm. Streszczenie. W artykule zaprezentowano system monitoringu oświetlenia ulicznego wykorzystujący sieć czujników bezprzewodowych o możliwości podłączenia wielu węzłów. System pozwala na redukcję kosztów utrzymania i zużycia energii poprzez wykorzystanie algorytmu detekcji nadjeżdżających pojazdów. (Oszczędzający energię system zarządzania i monitoringu oświetlenia ulicznego – projektowanie i wdrożenie) Keywords: street lighting – WSN – energy saving – monitoring and control system. Słowa kluczowe: Oświetlenie uliczne, WSN, oszczędzanie energii, system zarządzania i monitoringu. Introduction The reduction of electrical energy consumption has been a highly debated issue on a European level, since street lighting accounts for 20% of the worldwide electricity usage [1]. Street lighting meets the needs of local communities, ensuring: increased comfort and quality of life, increased security and safer pedestrian and road traffic. The classical street lighting control systems employ photocells. Dust or dirt build-up, improper installation or calibration may cause them to malfunction and thus compromise the entire control system. Moreover, it is difficult to measure the energy consumption of each lamp [2]. Street lighting administrators rely on the citizens’ willingness to report malfunctions, since there is often no automatic lamp control and monitoring system. Another growing concern is also related to the ability of dimming the luminosity level depending on the changes in the external environment. The concept of Intelligent Street Lighting has been advanced in recent years, prompting the employment of cost-effective schemes in street lighting systems that would primarily reduce the electrical power and maintenance costs and thus ensure the maximum safety of road traffic [3]. Such a state-of-the-art scheme entails the use of Solid State Lighting (SSL) that has certain advantages as opposed to the traditional lighting systems, such as fluorescent, incandescent or HID (High Intensity Discharge) lamps. Moreover, the high efficiency of SSL provides a series of other additional benefits in terms of energy consumption, total carbon footprint and cost-to-lifespan ratio [4]. In light of the above considerations, this paper will focus on analyzing and comparing the state-of-the-art systems presented in the scientific literature and the communication protocols that can be implemented in a street lighting monitoring and control system. The paper first introduces the proposed architecture and will continue with the detailed development of the software and hardware structure of the system. The conclusions will be presented in the final part of the paper. The state-of-the art systems Fig. 1 details the general structure of a street lighting control system. The studies published in the scientific literature follow this centralized structure that includes a command center, concentrator nodes and a number of actuator nodes that are fitted on each lamp. When the remote terminal unit of the command center sends a command to the actuators, the message first reaches the concentrator which forwards it to the nodes that control each lamp. The central control unit is often located in the offices of local authorities. The unit communicates with the concentrators which, in turn, communicate with each command terminal and thus ensure the monitoring of a high number of lamps. At the same time, it collects information about the status of each node and forwards it to the command center. The feedback on lamp status and any possible malfunctions is collected by the concentrator and is then forwarded to the command center [1]. One possible method to implement an automatic street lighting control system would be to integrate an IEEE 802.15.4 standard compliant transceiver in the lamp control relay, each device being thus turned into a node within a wireless network that covers the entire city. The system entails the use of numerous devices installed across a large geographical area. The communication facilities added to these devices require the development of intricate network topologies. Since the LOS (Line-of-Sight) can be limited by obstacles, the network can be implemented in a mesh topology [5]. Gustavo et al. [6] advocated the improvement of street lighting control systems. Thus, they opted for the integration of a transceiver in the photoelectric relay used for the on/off control of HPS (High Pressure Sodium) lamps. The IEEE 802.15.4 standard defines the MAC and PHY layers of the OSI (Open Systems Interconnections) model and is used for low rate wireless personal area networks (LR-WPAN), while the network and application layers are not defined [7]. Fig. 1. Communication technologies used in street lighting control In light of the above, the application should be developed based on an already defined standard, such as DALI (Digital Addressable Lighting Interface), ZigBee or 6LoWPAN (IPv6 over Low power Wireless Personal Area Networks).