Public Lighting Network Research Articles

Night sky brightness trends above Zagreb, 2012–2022

The night sky brightness at the RGN site (near the centre of Zagreb, Croatia) was monitored from January 2012 to August 2022. The first data set, covering the period 2012 to 2017, has already been analysed and the conclusions were published in Andreić (2018). The main conclusions are repeated here for comparison and completeness. The results of the analysis of the second dataset, covering the period from January 2018 to July 2022, are reported here. The first data analysis showed that the average night sky brightness did not change significantly from 2012 to 2017, excluding differences due to annual variations in meteorological parameters. The second data set (2018 to 2022) showed a slight decrease in night sky brightness compared to the first data set. The difference is small, about 0.2 mag/arcsec2 (mean values). In the second data set, there is a trend toward darker nights in later years that began three or four years ago (around 2019 or 2020). It is attributed to the modernisation of the public lighting network, where old, often very poor lighting fixtures are slowly being replaced by modern LED lighting fixtures, and to the effects of climatic changes leading to warmer winters with more clear nights.

Neutral Currents in Large Public Lighting Networks

The modern large public lighting networks are characterized by two major aspects that rise problems from both power quality and neutral current point of view in low voltage wye-connected three-phase electrical systems: (i) the supply system is unbalanced loaded; (ii) the presence of discharge sources. It is important to underline that nowadays,these aspects are not taken into account in the proper sizing of neutral conductors. The paper presents a simplified but enough accurate methodology to estimate the RMS value of neutral currents in lighting networks. The theoretical relationships are illustrated for a three-phase public lighting network that contains high pressure sodium lamps.

Analysis and Improvement of Machine Learning Models for Detecting Street Lighting Lamps

The Brazilian public lighting network is maintained by city halls. To bill the energy provided to city halls, energy distribution companies should maintain an updated database of network poles, their lamp types, and wattages. However, it is common to encounter issues with misinformation, where the company is not notified about changes in the public lighting network by city halls and cannot update its database appropriately. To mitigate commercial losses, companies have resorted to sending teams for manual infrastructure checks, which is an expensive, time-consuming, and unreliable process. In this regard, this work aims to optimize the models proposed in the literature capable of accurately classifying the type and wattage of lamps on public lighting poles based on data collected from radiometric sensors and a professional camera. Data is processed using traditional machine learning and deep learning algorithms, along with more sophisticated validation techniques such as data transformation and hyperparameter optimization to achieve improved results. Based on this methodology, the results demonstrate that models employing more robust algorithms (Support Vector Machine, XGBoost, Random Forest, and Multilayer Perceptron) can attain a final average accuracy of 80-86%. This confirms the usefulness of this methodology as an alternative solution to address the issue of public lighting billing.

Knowledge-based decision intelligence in street lighting management

As the availability of computational power and communication technologies increases, Humans and systems are able to tackle increasingly challenging decision problems. Taking decisions over incomplete visions of a situation is particularly challenging and calls for a set of intertwined skills that must be put into place under a clear rationale. This work addresses how to deliver autonomous decisions for the management of a public street lighting network, to optimize energy consumption without compromising light quality patterns. Our approach is grounded in an holistic methodology, combining semantic and Artificial Intelligence principles to define methods and artefacts for supporting decisions to be taken in the context of an incomplete domain. That is, a domain with absence of data and of explicit domain assertions.

Sustainable strategy for the implementation of energy efficient smart public lighting in urban areas: case study in San Sebastian

Public lighting connects hundreds of millions of streetlights with access to power across the globe, being responsible for 19% of global electricity usage, 30% - 50% of a typical city's energy bill and the already exceeding levels of CO2 emissions. Consequently, this represents a priority issue for cities in their strategy towards sustainability. In this framework, the momentum for smart public lighting is growing as its implementation represent quick wins (such as increase security and safety, improve mobility, increase the attractiveness of public spaces, or improve quality of life for citizens) with a massive impact on energy savings and maintenance, and can be achieved through low-cost connectivity. This paper discusses the effectiveness, efficiency, and feasibility of any city establishing a smart public lighting infrastructure network. With this aim, a pilot intervention in San Sebastian's public lighting network is presented together with a holistic analysis based on the Value Creation Ecosystem (VCE) and the City Model Canvas (CMC) to visualise how such plans may offer public value with a long-term and sustainable approach. Additionally, relevant, and fundamental patterns and recommendations are provided, which may help other public managers effectively implement this service and scale-up its use and business model.

Design and Modeling of a Flexible Conductive Fabric Antenna Integrated in an OLED Light Source for WIMAX Wireless Communication Systems

This work presents a new bendable antenna for worldwide interoperability for microwave access (WiMAX) wireless communication systems. These antennas, transparent and flexible, will be easily integrated into various mdia and in particular OLED lighting which could be part of the public lighting network of tomorrow as well as on all display media. The integration of these antennas as close as possible to the end-user is a possible solution to reduce the energy consumption which goes hand in hand with the increase in the data rate. This kind of new antenna, designed to be integrated in organic light-emitting diode (OLED), was modeled from a transparent VeilShieldTM conductive fabric and was placed on a 100% polyester substrate with a thickness of 1.5 mm and a loss tangent of 0.02. We have tested and evaluated the characteristic parameters of our antenna, namely the reflection coefficient, the radiation pattern and the gain, to find out the performance of our proposed design. The performance of the transparent conductive fabric integrated in the 100% polyester substrate is tested for the application of flexible antenna operating at 3.5 GHz with a gain value of 5.38 dB. We have integrated this proposed new antenna with the OLED light source containing four layers of different materials and electrical properties: aluminum cathode layer, polymer layer, indium tin oxide (ITO) anode layer and glass substrate layer. After integration, the resonant frequency shifted to 3.52 GHz with a gain value of 4.61 dB. In addition, we also tested the concave bending on the reflection coefficient of the proposed flexible antenna taking into account the different bending angles. This work demonstrates the possibility of integrating these unconventional materials used for the proposed antenna within the OLED despite weak effects on the resonant frequency and the gain of the proposed antenna after integration.

Feasibility Study of Power Line Communications for Backhauling Outdoor Small Cells

Small cells are low-power and low-range radio access nodes that can be used to increase network capacity in reduced areas with high traffic demand and to provide coverage to small isolated zones. As their number is expected to be very high, connecting them to the aggregation point in a cost-efficient manner is a key challenge, and there is consensus that none of the current technologies is valid for all scenarios. Since lamp-posts are one of the most convenient locations for outdoor small cells, this work analyzes the use of power line communications (PLC) over outdoor public lighting networks (OPLN) as a backhaul technology for outdoor small cell deployments. To this end, the characteristics of the PLC channels established in OPLN are firstly assessed. The analysis combines noise measurements performed in existing OPLN and channel responses obtained from a multiconductor transmission line (MTL) model. The attenuation, delay spread and spatial correlation of the multiple-input multiple-output (MIMO) channels are investigated and their influence in the physical layer parameters of PLC systems is discussed. Afterward, the performance achieved by state-of-the-art PLC systems is assessed. To this end, estimations obtained by means of simulations and measurements taken in actual networks are included. Data throughput achieved by PLC systems based on the ITU-T G.hn standard, as well as the expected improvements obtained by $3\times 3$ MIMO systems, are given. Results indicate that PLC can be an interesting technology for coverage-driven small cell deployments with backhaul length shorter than 150 m, offering throughput values similar to existing Sub-6 GHz wireless solutions in non-line-of-sight (NLOS) conditions and wired ones like G.fast.

Visionary Infrastructure: Community Solar Streetlights in Highland Park

This article develops the concept of ‘visionary infrastructure’, defined as infrastructure that provides visions of and begins to build more sustainable futures for local communities, through the case study of a solar-powered street lighting project in Highland Park, Michigan, near Detroit. After the local utility company repossessed most of the city’s streetlights, residents began building their own grassroots public lighting network. This infrastructure is visionary because it allows members of the largely African American community to determine precisely how their city is illuminated, and thus how seeing operates therein. By shifting control over the conditions of urban visuality from state and corporate officials to local residents, the lighting project intervenes in a long history of light on the street as a racialized tool of state surveillance and policing. And it shows how utility infrastructure can become a key site and mode of contemporary political resistance.

Přerušovaná spojení. Budování infrastrukturního zázemí v jedné východoslovenské romské osadě

The article deals with the implementation of the basic infrastructure into the area of an Eastern Slovakian Roma settlement. The infrastructure is conceptualized as an assemblages of material objects, practices and knowledge organizing the existing social relationships, and contributing to the exclusion and marginalization of Roma people. Based on the fieldwork, author discusses the consequences of the infrastructural building (public water supply system, public lighting and electric network) and how do they contribute to the forms of disconnections creating the differences between local majority and people who live in the described Roma settlement.

Streetlight Control System Based on Wireless Communication over DALI Protocol

Public lighting represents a large part of the energy consumption of towns and cities. Efficient management of public lighting can entail significant energy savings. This work presents a smart system for managing public lighting networks based on wireless communication and the DALI protocol. Wireless communication entails significant economic savings, as there is no need to install new wiring and visual impacts and damage to the facades of historical buildings in city centers are avoided. The DALI protocol uses bidirectional communication with the ballast, which allows its status to be controlled and monitored at all times. The novelty of this work is that it tackles all aspects related to the management of public lighting: a standard protocol, DALI, was selected to control the ballast, a wireless node based on the IEEE 802.15.4 standard with a DALI interface was designed, a network layer that considers the topology of the lighting network has been developed, and lastly, some user-friendly applications for the control and maintenance of the system by the technical crews of the different towns and cities have been developed.

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.