Category Archives: Fără categorie

The Load Influence on the Diagnosis of the Three-Phase Rectifier by Using the Analytical Model Method

Fără categorie

Abstract 

For the operation of the static power converters, the experience of an expert is absolutely necessary for competitive operation. Minor faults or defects of the elements of the static power converters can lead to ravaging effects both for the other components as well as other equipment from their operating system. The paper proposes a diagnosis method based on the analytic model which investigates the output waveforms of a three-phase rectifier supplying two types of loads: a passive RLC load and a variable DC drive.  Two types of possible faults of the switches are considered: interrupted and short circuit. For identifying the defective components, the waveforms corresponding for different faults are stored in an information database in order to be compared with the ones corresponding to normal operation.. Another solved problem in this article refers to the influence’s analysis of the defect propagation in the driving system. There are analyzed the waveforms corresponding of the different faults for different types of loads including a passive RLC load and a variable DC drive. For the both types of faults, important oscillations of the output voltage of the static power converter are noticed which can damage the load, but also, determine the additional stress to other healthy switches. images

Smart Home Energy Management System for Peak Average Ratio Reduction

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Abstract 

High quality demand-side management has become indispensable in the smart grid infrastructure for enhanced energy reduction and system control. Most of the demand-side management systems that existed were focusing on the interaction between utility company and its customers. Naturally, each home would be interested in minimizing the utility bill. Given price information, an automated DR controller would manage those devices which are flexible to be controlled, to opportunistically take advantage of the times with lower prices. This may cause a “rebound” peak, due to appliances loads flooding to the times with low prices, a reason very different from the one for the day time peak typically caused by the devices which have to run at that time. Consequently, the Home Energy Management (HEM) systems plays a crucial role in realizing residential Demand Response (DR) programs in the smart environment. It provides a homeowner the ability to automatically perform smart load controls based on utility programs, customer’s preference and load priority. This paper presents the hardware demonstration of the proposed HEM system for managing the end-use appliances. The proposed algorithm manages the household loads according to their preset priority and fixed the total household power consumption under certain limit. This work achieves the purpose of reducing electricity expense and clipping the peak-to-average ratio (PAR).

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Design of Separately Windings Control System of Series/Compound DC Traction Motors

Fără categorie

Abstract 

This paper focuses on the problem of the control system of Series/Compound DC motor in both areas of speed adjustment. Traditional field weakening is achieved by means of resistances  and contactors wich  inserting  and/or shunting in  field circuits. It is characterized by shock currents, torque and speed as well as by increased energy consumption. To eliminate these disavantages  paper proposes separate control of  armature,  series and shunt windings  of Series/Compound DC motor and supply their own power converters. Keeping hyperbolic mechanical characteristic of these motors requires setting the series field  current equal to or less than armature current. Developed control system is equipped with a single loop for series field and two loops for armature with a  current and speed controllers. Imposing series excitation current required is achieved through a special computer based on actual values ​​of current and rotor speed. Control system design was made based on a mathematical model and   use  of default instrument of Matlab-Simulink for tuning of PID controllers. Simulation results demonstrate the system’s ability to control separate windings for continuous speed adjustment in both areas, strictly limiting the rotor current, reducing energy consumption and ensuring the imposed  performance indicators. The proposed control method is recommended for use in electric images

Transmission and Processing of the Measurement Signals Generated by a Transformer for the Current Measurement in Medium Voltage Networks

Fără categorie

Abstract 

The trends to improve the performances of the classic instrument transformers was oriented to introducing new materials, components and methods in its design, manufacturing and operation. This paper presents the technical solutions adopted to implement the measuring system at medium voltage based on this current instrument transformer. The transformer uses a fiber optic link to send the measuring signal from the medium voltage point to the monitoring point. The structural block diagram of this transformer is presented and the operation of the main blocks is described. On the monitoring side, the measuring signal is converted from the voltage signal at the current signal which flows through a current loop for remote control and telemetry. Also, analog to digital conversion and the sending of the result of measurement at master monitoring system is possible. A simple algorithm for remote control of the operation of  transformer is presented. If the transformer is integrated into a digital measurement system then it operates as a slave unit under the control of the master unit. The samples taken from the measurement signal are used for digital processing. It is analysed the possibility to realize a network of transformers using the communication bus RS 485 . Finally, the waveforms, recorded during the performed tests, are presented. images

Design and Analysis of Low-Cost Ferrite Permanent Magnet Assisted Synchronous Reluctance Rotor and Permanent Magnet Synchronous Rotor with Flux Concentrator

Fără categorie

Abstract 

Rare-earth magnets which are the best solutions for PMSM rotors are expensive which makes that other types of motors are used in the applications. The solution of the replacement of these motors with PMSynRM that use low-cost type of ferrite magnets becomes more tempting lately. This paper proposes two different types of low-cost ferrite solutions: first a V permanent magnet assisted synchronous reluctance rotor (VPMSynRM) and the second a permanent magnet synchronous rotor with flux concentrator (PMSM-FC) as an alternative solution to the rare earth inserted tangential permanent magnet synchronous motor (PMSM). For the first situation, this paper proposes two topologies of PMSynRM: with one row and respective two rows of flow barriers, equipped with ferrite magnets Finite element (FEM) approach has been utilized to show the performance of the proposed rotors. The purpose of the proposed solution is to replace only the rotor of such a PMSM that is already in production, so the size of the stator and the number of windings will remain unchanged. Finally, for the PMSM-FC, the experimental results have been shown. This one is considered competitive, taking into account the resources required for a limited-series manufacturing. The motivation of this study is to reduce the cost of the rotor by changing the type of PM and by the choice of suitable rotor geometry. images

A New Approach on The Diagnosis of Automatic Block Signaling Installations

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Abstract 

This work presents a new vision on the diagnosis of railroad Automatic Block Signal Installations (ABS), using the current modern technologies that involve mobile devices or personal computers. The ABS installation is the system of signals between two consecutive railroad stations, stations centralized either electrodynamically (with electromagnetic relays) or electronically (using computers). The system of signals ensure the command and control of traffic train. Currently, failure diagnosis of such installations is done by the staff working in the Signals, Centralizations, Block (SCB) department of the railroad company. The diagnosis time depends on the professional qualifications of the staff (detailed knowledge of the installation’s functioning principles, of the electrical diagrams and related installations), on the practical diagnosis and recovery competencies. A long diagnosis time causes train traffic delays which, in turn, cause passenger discomfort and losses for the transporter companies. In this work we present diagnosis charts for two types of failures of the ABS installation: Failures of the 220 V power circuits in the ABS boxes, and failures of the Transmitting Relays (TR or T) power circuits. The diagnosis charts and their software implementation assist the maintenance staff in quick detection the failure causes for these types of ABS installations. This solution leads to shorter train delays, higher rail traffic security, and to the optimization of the transport services. images

Embedded System for Controlling the Temperature Inside of an Electric Furnace

Fără categorie

Abstract 

We have been listening for a long time to the wide functionality that industrial automation technologies can offer for improving the processes and adding security to the plants and the parts of them. However the price and an unstable market have restricted the deployment of such systems. Nowadays, companies offer too technology-dependent solutions which do not cover user demands completely. Meanwhile, papers from the literature focus on small innovations on specific parts of the industrial automation systems, which do not consider integration and deployment issues, in order to present practical designs [1]. The system presented in this work considers user requirements, including novel advances, all in an integral automation solution suitable for thermal treatments. The modular nature of the architecture allows direct adaptation to specific cases using standard technologies, and a proposal of an IP-based network for connecting the main automation module with the rest of plant. The main purpose of the entire plant is to monitor and control in real-time the temperature of the parts inserted into a resistive furnace. The software is based on m-files that contain the source code that calculates the control coefficients for the next step for ventilation and heating, it verifies the failures that could occur and creates a matrix of the coefficients, in order to make graphics. images

Pulse and Transition Measurements in Dynamic Regimes of Electrical Motors

Fără categorie

Abstract 

The paper deals with a modern solution to measure and analyses selected parameters of any electric motor. A virtual instrument with multiple options for selecting the analyzed parameters is described. The values of motor measurement voltages, currents and speed are read from a specified folder. With the virtual instrument presented in this paper it can be see the motor currents, voltages and speed waveforms and from the acquired data and recorded a set of parameters are computed. Boolean selector determine which signals are selected from the original seven signals (three current, three voltages and speed). It can be extract portions of data from the input signals. The extract portion is defined by begin of the offset (point of start) and the length (end the extraction). This instrument allow timing and transition measurements such as: pulse duration (pulse width), duty cycle (duty factor), preshoot (%), overshoot (%), slew rate. Also this virtual instrument allow to find the first highest (maximum) and the lowest (minimum) point in a set of values in signals of currents, voltages or motor’ speed and find the time of the maximum and minimum values so determined. Knowing these values can be determined the range from the lowest point to the highest point in a set of motor’s start current and voltage. images

Influence of the Environmental Aspects on the Quality of the Activity of the Wastewater Treatment Plant from the Repairs Locomotives Industry

Fără categorie

Abstract 

The aim of this paper is to identify an engineering method to study and to optimize the process of treating the wastewaters from the repairs locomotives industry in terms of quality, cost and environmental impact. The main purpose of this paper is to show how the control systems allowed us to investigate the environmental aspects of a wastewater treatment plant. The final issue is to optimize the process in terms of quality which means to decrease the cost and environmental impact. There are few steps to obtain the final issue. The first step is to establish the flux diagram of the wastewater treatment plant activity in the context of repairing locomotives process. The second step is to define this activity as a sum of processes according with ISO 14001 Standard, aimed to identify the interaction between this processes. To do this must be described the control system of a wastewater treatment method based on Dissolved Air Flocculation (DAF), used to treat the waste waters results from the locomotive repairs activity. A case study was made on a pumping station to illustrate the influence of the control system on this activity. All these sentences were made with environmental tools like: ad-hoc methods and control list methods, Environmental Systems Analysis (ESA) tools, critical synthesis of the processes and theirs modeling, observation and the experiment and statistic calculus. The result of this work is a work procedure in the activity of control quality of the repairs activity, being a practical implementation. The theme is completely original and responds to an actual practice of Environmental Management System. images

Analyzing of the Air Preheater Operation of the Steam Generators in Power Plants

Fără categorie

Abstract 

The paper presents, in the firs part, the importance of the steam generator in the operation of power plants, especially, the importance of the air preheater, the last heat exchange surface on the route of the flue gas, with all physical phenomena produced, which lead to the shaping of the physical model. Then is presented the model in relative units imposed by the literature. The paper proposes the development of a mathematical model in absolute units and the simulation the operation of the air preheater of the steam generator. The theoretical model proposed is implemented in Matlab-Simulink obtained simulations in dynamic regime. In order to validate de model, the simulation results were compared with the parameters measured values of the installations during the real time function. The model wants eliminating the major recalculation sequence of parameters at each step – the patterns in relative units the entire set of coefficients are determined and entered into the model according to the parameters achieved in the previous reference system and meet operating values taken as the basis in developing the work. The approach of such a study is justifies by the development and use of computer technology and digital media communication in dynamic analysis of energy processes. images