Aylton J. Alves

Electromagnetic Problems Solving by Conformal Mapping: A Mathematical Operator for Optimization

Having the property to modify only the geometry of a polygonal structure, preserving its physical magnitudes, the Conformal Mapping is an exceptional tool to solve electromagnetism problems with known boundary conditions. This work aims to introduce a new developed mathematical operator, based on polynomial extrapolation. This operator has the capacity to accelerate an optimization method applied in conformal mappings, to determinate the equipotential lines, the field lines, the capacitance, and the permeance of some polygonal geometry electrical devices with an inner dielectric of permittivity . The results obtained in this work are compared with other simulations performed by the software of finite elements method, Flux .

Firing angles optimization for Switched Reluctance Generator using Genetic Algorithms

This paper reports on a Switched Reluctance Machine (SRM) operating as generator excited through external power source. This device provides DC voltage output through its power converter. Parameters such as rotor speed, excitation voltage and firing angles interferes directly on the output voltage. Thus, many strategies have been studied and developed by scientific community in order to control the output voltage or achieve its maximization. This work proposes a driving strategy applied to the SRM that consists in obtaining the optimal firing angles in order to maximize the output voltage for given rotor speed and excitation. Simulations are presented for results analysis.

Eletricity generation using thermoelectric generator - TEG

Generating machines of electricity, using combustion engines and generate a great amount of residual thermal energy from the exhaust gases. This residual thermal energy can be converted into usable electricity using thermoelectric generator (TEG), which are manufactured cells with semiconductor materials employing the Seebeck effect. When recovering the waste heat in the exhaust ducts using TEG, increases the efficiency of electrical machines, because the same amount of fuel input generates more power or less intake of fuel, has the same amount the generated electric energy and thus less air pollution (as there will be less burning of fossil fuels) makes the system more sustainable. The purpose of this paper is present an electric generation plant using thermoelectric generator (TEG), which recover the thermal energy dissipated by combustion gases of an electric generator. The temperatures values are obtained through thermal imager and laser thermocouples type K. To improve the efficiency of generation is carried out the control and supervision of the temperature on the cold side of the TEG. The Supervisory System is responsible for data acquisition and generation of graphs and reports.

Heuristic and deterministic strategies applied on a PID controller tuning for speed control of a DC motor

This paper reports on a PID controller for speed control of a DC motor. The controller parameters were obtained through optimization methods employing heuristic and deterministic strategies. This methods were applied on a simulation model in order to verify which one provides better control results.

Electrical performance evaluation of PV panel through water cooling technique

This paper presents the development of a cooling apparatus using water in a commercial photovoltaic panel in order to analyze the increased efficiency through decreased operating temperature. The system enables the application of reuse water flow, at ambient temperature, over the front surface of PV panel and is composed of an inclined plane support, a perforated aluminum profile and a water gutter. A luminaire was specially developed to simulate the solar radiation over the module under test in a closed room, free from the influence of external climatic conditions, to carry out the repetition of the experiment in controlled situations. In the test conditions without cooling apparatus, the panel reached about 70°C and produced approximately 62Wh. With the cooling apparatus, the module reached about 50°C and produced approximately 77Wh. Through use of this cooling system the photovoltaic module showed a net enhancement in the power conversion efficiency of 16.66%.

Thermal simulation and validation of 5W high power LED luminaire

This paper presents initial studies on thermal heat dissipation in a high-power 5W LED (Light Emitting Diode) luminaire. Two types of heat sinks are proposed, and three thermal simulations are presented through an analysis by finite element methods (FEM). The first simulation considers a luminaire consisting of a confinement, a LED, and a star shaped heat sink base attached. The second simulation proposes an external heat sink. The third simulation proposes a new heat sink model. From the results, it was possible to design and build a prototype and test different cooling structures and heat dissipation issued by the LED. The results of experimental tests that were held with and without external heat sink are matched with simulation results. The major goal of this study is to know the thermal management of LED luminaires by simulation, in order to optimize geometry, material, and LED layout in a luminaire.

Methodology of Investment Risk Analysis for Wind Power Plants in the Brazilian Free Market

Abstract Despite the strong growth of wind power in the world, it is considered a high risk investment due to variability and unpredictability of wind speed. If the energy trade occurs in the free market, there is another risk factor that is the short-term price. This study proposes a methodology of investment risk analysis for wind power plants using innovative stochastic models to generate synthetic time series of wind speed and short-term price. The simulation is implemented using the Monte Carlo method associated with a Cholesky decomposition. The cashflows gross revenue is obtained through an energy trading model for the Free Contracting Environment (FCE) in Brazil. The investment analysis is based on probability distribution of Net Present Value (NPV) of the power plants cash flow, as well as the Value at Risk (VaR) and the Conditional Value at Risk (CVaR). A case study was performed for Natal city of Rio Grande do Norte (RN) state in Brazil, and the results indicated the economic viability of the power plant. A sensitivity analysis is developed considering important parameters of the modeling, and its results provide information to the decision-making process.

Parametric regression in synchronous and induction generators

The purpose of this work is to find the values of the electric parameters of synchronous and induction machines in order to validate the electrical interactions between an induction generator and a synchronous generator. The two generators will be connected in two ways: i) isolated to the common bus and ii) jointly connected to the common bus in permanent regime, subject to non-linear load. The results obtained from the comparison of the computational simulation and the experimental tests show that the model represents the real system. It is concluded that with the validation of the model it is possible to predict the behavior of the real system with the insertion of new perturbations.

Calculation and analysis of voltage violation problem on electricity distribution networks

The approach of this paper it is about voltage conformity delivered to the final customer, on electricity distribution networks. Have obtained physical and electrical characteristics information from the network coming from the database of the electricity company. The study presents the process of voltages estimation in primary and secondary circuits wich estimation of indicators of voltage violation. The presented cases studies approach a statistical analysis of sampling campaigns of distributor, voltage level analysis of one feeder circuit, the estimative of indicators of voltage violation and simulation validation with field measurements on the circuit. Through the found results it is possible to make better decisions of action to be taken and point out the circuit who needs maintenance.

Studies for the efficiency of a water pumping system for cooling and improving the electrical efficiency of photovoltaic panels

In this work a study is carried out to improve the water pumping system, to be used to improve the electrical efficiency of photovoltaic panels by reducing the operating temperature of the modules. The methodology used modifications in the geometric height of the system and different types of pumping systems, with constant speed and variable speed using a frequency inverter. Through these changes it was verified that there were significant improvements on the cases of the structure elevation and the variation of the speed of the three-phase motor. For the elevation on the structure there was an increase in the flow of 42.9% in the single-phase pump and of 6.53% in the three-phase pump. For adjusted pumping speed, according to the desired flow rate, there was a reduction about 0.12 kW on the power, representing 48% of the rated power of the pump. The best result was obtained with a three-phase pump at reduced speed with an efficiency of 5.16 Watts/liter and 33.1 L/min, sufficient flow to meet the entire system demand.