The development and growth of Wireless Sensor Networks (WSNs) is significantly propelled by advances in Radio Frequency (RF) and Visible Light Communication (VLC) technologies. This paper endeavors to present a comprehensive review of the state-of-the-art in cognitive hybrid RF-VLC systems for WSNs, emphasizing the critical task of seamlessly integrating Cognitive Radio Sensor Networks (CRSNs) and VLC technologies. The central challenge addressed is the intricate landscape of this integration, characterized by notable trade-offs between performance and complexity, which escalate with the addition of more devices and increased data rates. This scenario necessitates the development of advanced cognitive radio strategies, potentially facilitated by Machine Learning (ML) and Deep Learning (DL) approaches, albeit introducing new complexities such as the necessity for pre-training with extensive datasets. The review scrutinizes the fundamental aspects of CRSNs and VLC, spotlighting key areas like Energy Efficient Resource Allocation, Industrial Scenarios, and Energy Harvesting, and explores the synergistic amalgamation of these technologies as a promising pathway for enhanced spectrum utilization and network performance. By delving into the integration of cognitive radio technology with visible light, this study furnishes valuable insights into the potential for innovative applications in wireless communication, presenting a balanced overview of the current advancements and prospective avenues in the field of cognitive hybrid RF/VLC systems.

This paper proposes a control network for a LED street lighting system. The use of LEDs is being considered a promising solution to modern street lighting systems, due to their longer lifetime, higher luminous efficiency and higher CRI. The proposed control network enables disconnection of the street lighting system from the mains during peak load time, reducing its impact in the distributed power system automatically at overload conditions. It also allows to reduce the power consumption, decrease the management cost and monitor the status information of each street lighting unit. In order to meet the system requirements, a wireless sensor network based on IEEE 802.15.4™ standard is employed. Its network layer is implemented using geographic routing strategy, which provides low overhead and high scalability features. However, due to well known drawbacks of the existing techniques, a novel routing algorithm is proposed. Simulations show that this algorithm leads to a significant improvement of routing performance when applied to sparse large scale scenarios, which is the case of a street lighting system. Field tests have been performed on IEEE 802.15.4-compliant wireless control units. The obtained experimental results show that the proposed control network is able to meet the requirements of a LED street lighting system.

The development of platforms and methods for test and calibration of phasor measurement units (PMUs) has drawn attention from the power systems community, especially due to the wide range of specific tests that must be performed. Aiming at reducing labor-intensive processes and the complexity of such tests, this paper presents an automated platform for test, calibration, and performance assessment of PMUs following the IEEE Std C37.118.1. The platform is composed of signal-generation hardware and software running on a personal computer. The test signals are synthesized in software, allowing different waveform configurations for automated testing. Also, the software receives information from the PMU under test and compares it to reference data, displaying results and statistics in real time. Because most of the functions of the system are performed in software, easy inclusion of additional tests or migration to other signal-generation hardware platforms is possible. The resulting test system allows tracing the behavior of the hardware and corresponding embedded software used in the PMU architecture under test through thousands of measurements collected in just a few minutes. The simple and versatile low-cost system presented in this paper enables accurate, flexible, and versatile automated testing of PMU devices with real-time visualization of results.

This paper proposes a dispatchable photovoltaic (PV) hybrid inverter for output power tracking without any dependency on the converter’s efficiency and with no power closed loop. The system uses an extra-low-voltage battery energy storage system (BEES) based on a Li-ion battery pack to be applicable for use inside homes and other installations close to the end-user. A bidirectional isolated current-fed dual-active bridge (CF-DAB) converter associated with the batteries provides a wide conversion voltage ratio and ensures safety for the users. The proposed control system shares the DC bus voltage controller between the ac grid interfacing converter (AC-DC) and CF-DAB (DC-DC), eliminating the converter’s efficiency in the reference equations. When dispatchable power is not required, or according to the user’s request, the battery’s charge/discharge current can be specified. A disturbance rejection technique avoids low-frequency current ripple on the battery side. It contributes to the battery’s lifespan. Experimental results presenting the dc bus voltage control, current disturbance rejection, and power dispatching are included to validate the proposal.

One of the major challenges at the moment is the improvement of the present street lighting system. These systems are considered outdated due the lack of communication capabilities, not allowing system feedback. This work aims to add communication capabilities to the systems already in use, through the integration of an IEEE 802.15.4 compatible transceiver to the photoelectric relay used to turn the HPS lamps on/off. This change will turn each device into a node of a large wireless network across the city.

One of the major challenges at the moment is the improvement of the present street lighting system. These systems are considered outdated due the lack of communication capabilities, not allowing system feedback. This work aims to add communication capabilities to the systems already in use, through the integration of a ZigBeetrade compatible transceiver to the photoelectric relay used to turn the HPS lamps on/off. This change will turn each device into a node of a large wireless network across the city.