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The low power factor in electrical installations results in high power losses and increased installation costs. This comes as a consequence of the high current flowing through the transmission lines due to high reactive power consumption. Most often, before the installation of renewable energy systems involving battery storage, the load demand is not evaluated in terms of the different load power factors. Because of these diversified power factors for different loads, the overall power factor of the installation will witness a decrease which puts the user at a disadvantage as more charges will be incurred. For these reasons, this paper presents the economic benefits of using an automatic power factor correction system in renewable energy installations. The Arduino microcontroller has been used in the proposal as the main automat. The power factor correction is done by installed capacitor banks connected to the loads automatically using MOSFET (Metal Oxide Semiconductor Field Effect Transistor) power electronic switches and relay blocks with control signals from the microcontroller. A small system was analyzed involving a water pump, fan, television, and a fluorescent lamp. A targeted corrected power factor of 0.99 was used and the results showed that 430.18 W of power was saved after power factor correction leading to a reduction of 58% line losses. Also, $1300 could be saved by the user on batteries and photovoltaic modules by incorporation the power factor correction system. The proposed correction algorithm was economically beneficial and is therefore strongly recommended to be employed by renewable energy users in particular and the grid-connected individuals in general.

International audience; This paper proposes a contribution to the development of autonomous wake-up radios from the energy supply perspective. More precisely, a rectifier circuit, designed and manufactured in order to provide the energy needed for a quasi passive wake-up radio receiver (WuRx). The WuRx is intended to operate continuously and to ensure a zero energy consumption in standby mode. After the presentation of the said WuRx, the energy requirement for its power supply is defined. Then, the energy harvesting circuit, able to power up the quasi-passive WuRx, is designed, implemented, and then measured. Compared to the state of the art, the energy harvester that we present here is among the few recent designs that replaced the matching network lumped component by butterfly stubs, which brings compactness to the circuit. The rectifier is built on a high efficiency substrate which increases its performance and reduces its form factor.

Power system operators are in search of proven solutions to improve the penetration levels of distributed generators (DGs) in the grid while minimizing cost. This transition is driven, among others, by global climate concerns, the growing power demand, the need for greater flexibility, the ageing grid infrastructure and the need to diversify sources of energy production. Distributed renewables would not easily substitute the conventional electric grid system, perhaps because the latter is a well-established technology and it would not be prudent to abandon it, while the new distributed renewable energy technologies are generally not adequately developed to support the total load. Thus, it is becoming increasingly necessary to consider sustainable options such as integrating renewable energy sources into the existing power grid. This study is a review that is mainly hinged on distributed generation (DG) classification, the challenges of DG to grid integration, practical options used in DG integration, lessons learned from some countries with successful DG to grid integration, push factors in the growth of DGs and the merits of DG to grid integration. These standpoints of DG to grid interconnection are critical in conducting grid planning and operational studies, which should be conducted in strict observance of aspects such as optimal technology selection, optimal capacity and a suitable connection point of DGs in the network. Therefore, the perspectives highlighted regarding DG can assist power system engineers, developers of DG plants and policymakers in developing a power network that is stable, efficient and reliable.

International audience; The aim of this work is, on one hand, to review the state of the art of the architectures and diodes used in radio-frequency energy harvesting systems, the idea here is to review the most recent works, as well as their characteristics, which include frequency, type of diode used, topology, maximum efficiency and corresponding power, and on the other hand to carry out simulations to determine the most appropriate case for any further work in the field. After having determined the most common topologies, we used the main known radio-frequency diodes to characterize them in a first step, clearly a process of comparing the results of the simulations of the different topologies is done by initially considering an identical frequency. and afterward determine the effect of frequency band on their conversion efficiency.

Sizing of battery storage capacity in solar photovoltaic (PV) systems is based on required autonomy. Most often, batteries used for such energy storage systems after some time come to a state where they can no longer sustain that required autonomy. When this happens, users can only completely replace the old battery set with new ones for a follow up of required system autonomy. That leads to a waste of the remaining active capacity of the batteries in addition to the fact that disposing the old set of battery also leads to environmental challenges. Moreover, charging and using batteries at the same time is not very good for the battery state of health as this stresses up the batteries hence reducing their life span. In this system proposal, in addition to avoiding simultaneous use and charging of battery set, we give possibility of longer use of the old battery set given that it is globally an addition of battery capacity of the two parallel monitored storage sets. The switching between energy storage sources while running each as a supply source at a time was done for different loads. The control of the switches is done using the PIC16F877A microcontroller while the IRF540 MOSFETs have been used as switches. With the static or direct current loads, a switching time of 8.5 ms was obtained while 33.06 ms was obtained for inductive loads; pending on eventual impact investigation of the above switching on AC loads, the switching time of the system is good enough to maintain supply to the loads during the supply sources interchange.

International audience; Water scarcity poses a serious threat to the population in the most areas of developing countries. In addition to that, the traditional manual nearby approach of following up the water distribution network is unable to ensure an effective and equity use of the small water resources available. A dedicated real-time monitoring system based on radio frequency (RF) communication and internet of things (IoT) paradigms is proposed in this paper. This monitoring system is essential and constitutes a proposed solution for the local water management and equity distribution of the available poor water resources. An alert system recalls users to any abnormal water usage to reduce water loss or to check and solve usual leakages. A customer’s water consumption visualization as well as a setting of his desired consumption alert system are performed using a home dashboard; the monitoring of the system by the water utility company is achieved using a web-based system through Thingspeak cloud computing platform. For an immediate and easy local implementation of the prototype, the system technology was chosen in already validated most cases; in other words, Commercial-Off-The-Shelf (COTS) components were used. For better and optimum results, most dedicated similar COTS components will be selected using the already running systems.

This paper presents the design and implementation of an object-oriented platform for the modeling and simulation of hybrid control systems incorporating continuous and sequential sub-systems. The platform is designed based on UML and contains a repository of object classes for modeling continuous components (equations, transfer functions), sequential components (GRAFCETs) and the interactions between these elements. The simulation environment, design in JAVA, incorporates an equation simulator, a Grafcet simulator, and a Graphical User Interface for constructing schematic diagrams, Grafcets, equations and Transfer Functions. Results obtained from the simulation of a Rolling Mill are presented in the paper.

Attendance and punctuality are very critical for a good operation of every organization. This paper proposes a way of taking school attendance using an android device and a web application connected via a Local Area Network (LAN). The student data are stored in an android phone which is to send attendance to the web application when the student comes into the coverage area of the LAN. The web application then displays the attendance data in an interactive interface with attendance grading.

An important tool for the energy management system (EMS) is state estimation. Based on measurements taken throughout the network, state estimation gives an estimation of the state variables of the power system while checking that these estimates are consistent with the measurements. Currently, in the Cameroon power system, state estimates have been provided by ad hoc supervisory control and data acquisition (SCADA) systems. A disadvantage is that the measurements are not synchronised, which means that state estimation is not very precise during dynamic phenomena in the network. In this paper, real-time phasor measurement units (PMUs) that provide synchronised phasor measurements are proposed for integration into the power system. This approach addresses two important issues associated with the power system state estimation, namely, that of measurement accuracy and that of optimization of the number of measurement sites, their location, and the importance given to their measurements on the dynamic state estimation.