Monthly Archives: December 2015

Information and Communication Technology in Urban Electric Transportation

17 December 2015Fără categoriecburada

Abstract

This paper is a first attempt at assessing the impact of information and communication technology in transport, with an accent on electric public transportation. Information and communication technology is present in all spheres of human activity. Transport systems are made of vehicles and infrastructure. Modern vehicles are filled with complex technology, such as electric drives, mechatronics, artificialintelligence and information and communication technology. And the infrastructure currently numbers only the roads and traffic lights, but the evolution of things leads to Intelligent Transport System. A technology that would connect vehicles and infrastructure to make transportation on land safer and more efficient. Electric vehicles require special attention to motor control. Power converters driven by intelligent modules allow an efficient control of the motor. A series of electronic systems for trolleybus and tram control, the SDMC, were made in Chiinău by the Informbusiness Company. The SDMC systems are intelligent system, built on microprocessors and CAN communication protocol. Modern ICT technology allows simultaneously to ensures diagnostics, monitoring and protection of all components; to store the current state of the elements; to provide information means for the driver and passengers and ensure good function of complex control algorithms. Information technology is present also in intelligent transportation systems with smart or even driverless vehicles. Technologies such as GPS and Wireless Networking allow optimizing urban transport, and are basic stones in the future of transport, which includes Intelligent Transport Systems and Driverless vehicles.

Transversal Shape Optimization of a Brushless DC Motor for Electric Vehicles

17 December 2015Fără categoriecburada

Abstract

The opportunity of this research is to emphasize certain approaches related to the design and modeling of low and medium power permanent magnet brushless DC motors for electric vehicles, which are presently poorly treated. The challenge of any manufacturer is to develop electric machines with minimum manufacture and maintenance costs by accomplishing the performance required by the customer. One looks for mathematical models as exact as possible as tools for the design and parameter computation. As a consequence of the progress of control and power electronics, the performances of brushless DC motors have been improved. Therefore, the problems of optimal design and optimal operating mode of such motors are currently reported by the technical literature. By exploiting the available numerical computation tools, we developed the optimized technical design of a brushless DC motor for an electric bicycle. The performed simulations emphasize the technical performances which accomplish the customer requirements as follows: manufacture cost reduction of 27.9%, total cost reduction of 9.11% and a slightly growth of the maintenance cost of 8.01%. It is advisable to do a periodical optimal re-design, which will take into account new performant electrotechnical materials with adequate technologies, in order to decrease the fabrication cost and to increase the energy efficiency of brushless direct current motors. The optimized motor achieves the required overallsize.

Factors Involved in Choosing LEDs for General Lighting Applications: a Critical Review

17 December 2015Fără categoriecburada

Abstract 

 

Electric lighting accounts for 19% of electricity consumption worldwide and generates remarkable concern to get energy savings. As a modern source of light, LEDs open up a multitude of innovative lighting solutions. LEDs lighting is already widely used in many niche areas like traffic lights, car lights, lighting displays, TVs etc. Now, based on lowered manufacturing costs, they penetrate into the general lighting market. But for specialists, LEDs are not yet the end solution in any lighting application. There are a lot of factors that can influence their adoption decision.Among them, the most favorable and promising one is the high efficiency, with values in permanent increasing. The paper discusses various aspects of LEDs efficiency and demonstrates that luminous efficiency is not a relevant criteria for a decision, a better understanding being got with an indicator like the Lighting Power Density, in W/m2. And beyond the efficiency, the paper makes a critical analysis of other parameters that matters in the lighting decisionmaking process, like lifetime, color rendering and chromatic shift, health and environmental impact. Finally, the paper point out that the calculation of cost and return of investment represent a very technical effort, based on accuracy of the entry data, often unknown by the investor itself, like different confidential costs, daily average time of functioning, temperature hazards and lifetime in condition of poor quality of electricity.

Management of Renewable Energy Sources Integrated in a Micro Smart Grid

16 December 2015Fără categoriecburada

Abstract 

 

Future trends in the energy sector are crossing from centralized to distributed electricity production. A national and international organism encourages and informs consumers about the efficient use of energy. Such an approach of an efficient energy consumption lead to use of a certain number of renewable energy sources and a proper management of their. This paper, approach some issues of energy management and the use of unconventional sources of energy under the stochastic conditions. It showed a possibility of interconnection of renewable energy sources in a micro-smart grid. Four energy sources are proposed: the main source – power grid; secondary source 1 – photovoltaic generator; secondary source 2 – wind generator; secondary source backup 3 – diesel generator. The interconnection of these energy sources is achieved by a system of energy management and control based on a microcontroller structure type. Interconnection is based on the availability of energy sources and by energy consumption. The command and control algorithms for energy sources were implemented in Matlab Simulink software using specific functions and blocks. The energy management system ensures directing the flow of energy between sources and consumers. Also it manages the total energy distributed to consumers. The information can be stored and interpreted by a PC.

Lead Acid Battery Pack Charging Optimization

16 December 2015Fără categoriecburada

Abstract 

Still used as a rechargeable power sources, rechargeable batteries pack require attention primarily to ensure higher life operating. One of the factors that influence lifespan is the process of charging and discharging. For batteries is manifested in the so-called memory effect which manifests itself by decreasing the operating voltage, even when was loaded to its maximum capacity. The article presents this issue but also offers a solution direct applicable for lead-acid batteries. The principle has based on reducing the number of charge and discharge processes in a certain time. So the hysteresis characteristic becomes wider and the time between switching from charge mode in the discharge and vice versa is higher. Analysis of three algorithms, step-by-step set of operations, and implementation in an experimental device is the main goals of paper. Optimization technique represents here to maximize battery lifetime. The device developed has a microcontroller and proves useful with minimal changes in any situation, by replacing the existing or interposing circuit between the power source and battery. Designed circuit can have easily adapted to correspond for other types of batteries. It can integrate with minimal changes, additional functions such as current battery measure and temperature.

Aspects Regarding Influences of Voltage and Resistant Torque on Asynchronous Motors Operation

16 December 2015Fără categoriecburada

Abstract 

In this paper there are analyzed a series of dynamic regimes that occur in the case when a phase of an asynchronous motor is accidentally interrupted and in the case when the resistant torque increases by step. For these situations there have been carried out, starting from the motor equations written in the two-axes theory, two Simulink programs (detailed in the paper). With their help, for a motor rated at1,2 kW, there have been obtained relevant simulations together with conclusions emerging from them. Thus, in the case when a phase was interrupted it results that: the interruption of a phase leads to a dynamic regime that is relatively quickly stabilized; this stabilized regime is characterized by high values of currents, slight decrease of the rotor speed, small oscillations of speed, important oscillations of torque. In the case when the resistant torque is modified by step there have been resulted the following conclusions: a reduced torque shock leads to increased values of the currents and to a slight decrease of the speed (after a few oscillations); an increased value of the inertia moment leads to an increased number of current oscillations in dynamic regime but also to the disappearance of the speed and torque oscillations when a torque shock occurs; for very high resistant torques the maximum torque developed by the motor becomes smaller than the resistant one which causes the decrease of the speed towards zero, finally reaching, if the protections do not cut, the shortcircuit regime; the simulation program conceived here can also be used for establishing the value of the motor maximum torque; the simulations have been confirmed, as essential elements, quantitatively and qualitatively, by experiment.

About the Analytical Methods Applying for Fault Diagnosis of the Static Converters from the Electric Locomotive

16 December 2015Fără categoriecburada

Abstract 

 

In this paper, the results of the monitoring and diagnosis system based on the analytical methods of the auxiliary ventilation service of the electric locomotive which is supplied from the static converter are presented. Because of the complexity of the electric locomotive structure and of the big number of components, a large number of the parameters must be monitored and detected the range of variation of their imposed values. Consequently, a large variety of monitoring and diagnosis procedures have been developed. In literature in the field, the many advanced fault diagnosis methods were presented. Using the analytical method, the analytical model of the static converter was developed using the Matlab Simulink. Starting from the model of the static converter, three types of the faults were simulated: losing inverter supply, interrupting of the inverter output phase and biphasic shortcircuit at inverter output. For all three types of mentioned faults, the waveforms of motor speed, electromagnetic torque and electric currents have been registered. These waveforms were compared with those corresponding to the normal operation regime. The impact of the type of fault on the waveforms was pointed out. The results were analyzed based on the evolution of the motor parameters in the normal and abnormal operating regime.

Modern Techniques for Monitoring Circuit Breakers by using Microcontroller System

16 December 2015Fără categoriecburada

Abstract 

The paper deals with experimental monitoring system, developed by the authors, by using a microcontroller within the 8051 family, Dallas DS87C550. This micro-system has two main parts: the acquiring and transfer module and the user interface developed using the facilities specific to Graphic User Interface of Matlab®. The achievement such a way implies designing a hardware structure that meets the proposed functions in a versatile approach and programming of controller using its facilities. The electrical equipments, being characterized by small time constants and high risk, impose major efforts in orderto develop competitive monitoring systems. On the other hand, the costs involved by such systems need to be as low as possible, without cutting the imposed performances. The possible functions of the experimental system are related to the monitoring of IO breaker using modern diagnostic methods: monitoring of the contacts condition, the computation equivalent switching number, the estimation of the insulating oil quality, monitoring the achieved service, the diagnostics of the weaken contact by vibration analysis technique and the dependence of voltage versus temperature on contact. The results are presented as graphical user interfaces developed by using the facilities of the software MATLAB. The interface is versatile and with ease allows the tracking of results after data processing.

Electromagnetic Field Coupling Between Over-Head Power Lines and Nearby Metallic Pipelines in Case of Direct Lightning

16 December 2015Fără categoriecburada

Abstract 

Lightning-induced voltages in power systems are nowadays one of the causes of the main power quality and electromagnetic compatibility issues. In recent years, due to the increasing demand by customers for good quality in the power supply along with the widespread use of sensitive devices connected to distribution lines, the protection against lightning-induced disturbances became of primary importance. Installing pipelines in energy utility corridors containing high-voltage AC transmission lines subjects the pipelines to induced AC voltages which are a real and serious problem which can place both operator safety and pipeline integrity at risk. In case of a lightning strike on power line, the electromagnetic field produce by this pulse induces voltages in the nearby metallic structures. An electromagnetic interference analysis has been performed in case of a metallic gas pipeline that runs nearby a 110 kV/ 50 Hz power line. Different scenarios regarding the lightning strike on HVPL were investigated. Due to high value of the separation distance between HVPL and MP, only the effect of inductive and capacitive coupling is taking into account. Professional software for power system transients (EMTP-RV) is used to create an original transient state equivalent electrical circuit model of the system and to perform simulation of the transient process during lightning strike and compute the induced voltages in the metallic pipeline.

Hybrid Petri Nets in Modeling the Packing Processes: Case Study

16 December 2015Fără categoriecburada

Abstract 

In many cases, the packing processes are considered as hybrid systems, consisting of a set of workstations, where various components must be processed, and at least one flexible transport system used for loading and/or unloading operations. This paper is focused to a Hybrid Petri Nets approach for modeling and simulation the behavior of such systems, considered a hybrid dynamic structure, with both continuous and discrete components interacting. For heuristic representation of the model, several sequences and rules were however followed. For the case study, starting from the structure of the system, in order to achieve a primary topology of the model, a bottomup synthesis technique was used, which allowed us to obtain a basic version, consisting in several sub-models of related physical subsystems of the packing station. Aggregation of these partial models was made in accordance with the interactions of the physical elements of the whole system, laid down in the operation protocol. Hence, into model topology various elements characteristic to generalized Petri Nets were used, with inhibitor arcs and test arcs, mainly aiming to reduce the complexity of the whole model. The validation of the model was done through on-line simulation, in various scenarios, under the Visual Object Net++ tool, which offers multiples facilities for the analysis of behavioral properties in various real operating conditions of the real physical system. Starting on the modular structure of the whole model, consisting in several submodels of the same type, the authors obtained a multilevel architecture, using Object Petri Nets paradigm for representation and exploiting their analysis potential.