Category Archives: Fără categorie

System for Monitoring Asynchronous Motors Powered at Variable Voltage

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Abstract

This paper presents some experimental aspects related to the operation of asynchronous motors powered at variable voltage. A modern system for actuation of low-power asynchronous motors is presented, equipped with a voltage and frequency converter. Also, a data acquisition system is presented, with a sampling frequency of up to 100 kHz, supervised by an acquisition program that allows the visualization of the variations of the main characteristic sizes of the motor. The program contains both graphic interfaces developed by the manufacturer and by the authors of the paper. This program solves, among other things, an electromagnetic compatibility problem. The experimental tests carried out with the help of this system (in permanent non-sinusoidal regime at various power supply frequencies) are detailed. Technical details of the main system components are provided. The tests are accompanied by photos taken during the experiments and many original explanatory graphics. The authors’ contributions are mainly in the software area. Thus, in the original program, a series of windows for harmonic analysis and visualization of the characteristic phasors of the analyzed electrical quantities were implemented. The paper ends with the main conclusions resulting from the completion of the study and with a representative bibliography.

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Small Scale Models of Solar Tracking Systems

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Abstract

Increasing the efficiency of photovoltaic panels using solar tracking systems is a current topic. The use of solar tracking systems is a solution, especially in low power applications. The paper presents two types of solar tracking systems, one based on astronomical data, and the other based on tracking the point of maximum illumination. Both systems are made on small scale for educational purposes. These systems can be used for the analysis of methods, principles and particularities in order to use them in practical applications. For the two experimental models of solar tracking made, the hardware and software structure are presented. To orient the photovoltaic panels in the two directions (East-West, respectively South-North) DC motors or stepper motors are used. One motor is used for each axis of rotation. Both structures have the control part composed of a microcontroller development system. This control method has the advantage that can significantly reduce the number of electronic components as well as the cost of designing and building of equipment. For the solar tracking system based on astronomical data, a remote monitoring and control system has been achieved. It uses a friendly graphic interface made on PC with the help of Visual Basic software. Both models were tested and the experimental results showed correct operation according to the imposed protocol. Finally, an energy efficiency analysis was done and it was found that the PV panel that uses the tracking systems produces 35% more energy compared to a fixed PV panel. images

Configuration of SCADA System Graphical User Interface for Electrical Station

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Abstract

In order to efficiently and practically solve the problem of analyzing the performance of the SCADA (Supervisory Control and Data Acquisition) system of the power grid, this paper proposes to reconfigure the graphical user interface (GUI) in the substation, as well as to remap the signals according to the hardware structure used. After replacing the hardware solution with PLC and software for protocol conversion installed on the local HMI with a specialized remote terminal unit for data storage and protocol conversion in the substations, it is important to adapt the graphical user interface of the SCADA system according to the latest hardware configuration. This is necessary for the stability and reliability of the SCADA system. In the last part of the paper, the configuration of the graphical user interface of a SCADA system and the remapping of the signals in the specialized software in an electrical substation in Romania is presented and highlighted through screenshots. images

The Design of a Location Monitoring System for a Fleet of Electric Scooters

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Abstract

The development of geolocation systems( geostationary satellite networks), as well as devices capable of receiving signals and processing the data coming from them, makes possible the implementation of location monitoring systems for various purposes. Whether it’s about security or optimizing travel times or routes, these systems are based on information in the form of global coordinates (latitude and longitude) from satellite systems or cell towers. The design of such a system is presented in this paper, being a good guide in the design and implementation of such a system, regardless of the application. Both, the hardware part (the designed equipment) and the software part (the backend component running on a virtual private server, as well as a mobile application) are presented in this paper. In the development of the system, was used only location provided by information from satellites, without using GSM cell signals. The entire system has been successfully tested in different GSM signal conditions as well as various locations to see the influence of environmental parameters on performance. The system described in the paper can be the starting point for the development of other systems for a variety of applications that require the management of the location of some devices. images

Data-Driven Control of the Second Order Inertial Systems with Astatism

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Abstract

In order to realize an efficient synthesis of the control algorithm, it is necessary to be known the mathematical model of the control object. This paper deals with the problem of data-driven control of second order astatic inertial systems with, or without time delay, that supposes an experimental identification of the mathematical model in the closed-loop and algorithm for synthesis the PD and PID controllers. The control algorithm was synthesized according to the maximum stability degree method with iterations. The closed-loop identification method and control algorithms of the PD and PID controllers were verified by computer simulation in MATLAB and there are obtained good results in model estimation and in the tuning of the PD and PID controllers. images

Modelling, Simulation and Implementation on dSpace 1103 of the Direct Power Control in a Three-Phase Shunt Active Power Filter System

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Abstract

This article describes a control method called “direct power control” designed specifically for parallel active power filters. The purpose of this method is to attenuate harmonics in the supply current and offset reactive power problems. The main goal is to bring the active power and reactive power back to the reference values through hysteresis control. The output of the hysteresis controller is combined with the switching table to regulate active and reactive power in real time by determining the optimal switching configuration of the inverter. This study proposes a novel switching table design based on analyzing the impact of the inverter switching vector on the instantaneous reactive and active power derivatives. The goal is to reduce the number of commutations by eliminating zero vectors while maintaining the required DC bus voltage using anti-windup techniques based on PI controllers. images

Comparative Performance Analysis of Photovoltaic Power Plants – a Case Study

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Abstract

The aim of this paper is the comparative study of the behavior and performances of two photovoltaic power plants of different installed power, but which uses identical equipment. The difference in size is being given by the number of specific equipment used (the power inverters and solar panels). The plant behavior was investigated, as the injected active power is dependent on the available sunlight to the photovoltaic panels (and a larger plant leads to a larger panel area), as well as the influence of the power plants to the power grid, given the fact that a large power plant will inject more active power, and the grid local power transformer must be able to accept this power. The power plants efficiency was also investigated, as typically, the bigger the plant, the higher the efficiency must be. But, the efficiency depends on the generated active power (which must be high, to have a good efficiency) and in the case of photovoltaic power plants, the produced power depends on the available sunlight, and again, the bigger the plant, the bigger the panel area susceptible to be shaded. This gives the fact that although the injected power is higher for the bigger power plant, if the power of each inverter is below the rated power, the overall efficiency is lower compared to the small power plant which works at the rated power. images

Experimental Study of the Pressure Exerted in the Body of a High-Voltage Fuse and Metal Enclosed Switchgear

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Abstract

This article presents the importance of analyzing the breakdown behaviour of high voltage fuses and highlights the pressure values at the fuse ends.  The theoretical basis, test scheme structure, design and sizing elements of fuse components, and numerical simulations performed in Matlab/Simulink are presented. The extinguishing environment is not modelled as it is considered to be a vacuum Starting with the oldest overcurrent protection device and continuing with the importance of high voltage fuses for operational safety, the study presents the behaviour of high voltage fuses during short-circuit current interruption. The key element is the value of the pressure on the contacts of fuses, which is often ignored in favour of the pressure of the middle element. When fuses change from solid to liquid state the inner parts are hotter than the outer parts and melt first, and the melting zone extends to the periphery. The study found that the pressure is much higher and is an important value for designers. Experiments showed that the maximum pressure is reached during the arcing period, a significant finding for the design process of the contacts of a high-voltage fuse. The research was then extrapolated to check the pressure in metal enclosed switchgear containing fuse combinations. images

Equipment for the Detection of People Falling

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Abstract

There are people whose state of health requires permanent supervision. There are a number of medical or aging-related conditions that can have quite an impact on the daily life of these people, therefore, in order to provide them with proper assistance and care, various health monitoring devices have been developed. This article proposes the use of advanced technologies with the help of which we can observe and record the changes in the position of a person with such problems. The equipment has a sensor that can determine the position of the body by measuring the height from the ground. The device can be integrated into a belt or bracelet to record data in real time. This data is analyzed and interpreted by means of a program. The program can detect changes in posture, providing notifications and alerts when the person has suffered a fall. Greatly simplifying surveillance, the device also provides an objective assessment of a person’s balance ability. Since each person has a specific posture and movement, the developed device must be tested and adapted to adjust the coefficients in the program, to avoid the triggering of false events.

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Integrated System for Remote Health Status Monitoring and Analysis

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Abstract

With the emergence of new types of diseases and viruses that can affect the human immune system, different types of vaccines and treatments have been developed to combat the new threats. Various technical methods have been developed to monitor the health status of a patient suffering from a certain ailment in order to certify the efficacy of a given treatment scheme. A way to monitor the health condition of a patient is proposed, based on the Arduino platform. The prototype can transmit data collected from a sensorial system and store them to a web server. The system is designed to monitor human body temperature with three temperature sensors placed on the head, body and lower limbs to obtain the average body temperature; an oximeter sensor for simultaneously monitoring the heart rate and the blood oxygen level of a patient; and two sensors for measuring indoor air quality, namely a gas sensor and a temperature and humidity sensor. This last sensor determines if a given bacteria or virus can thrive in the environment. A specialized software program was used to create the remote health monitoring prototype, which was subsequently manufactured using a 3D printer. The prototype is resilient and efficient, being appropriate for long-term use. images