Advanced Materials Research Vols. 433-440

Abstract: Voltage stability of power grid would be affected greatly by the connection of large-scale wind farms. Conventional continuous power flow method can not accurately simulate the system’s operation when wind farms are connected to power gird. A new continuous power flow method is proposed, considering auto-disconnection of large-scale wind farms. The step-size control segment is improved in this algorithm in order to simulate the operation characteristics of wind farm and determine the precise time when a certain wind farm is cut off.

Abstract: With the rapid development of urbanization and the power system, the damages for the power system and electrical equipments which due to lighting strike are increasing. As the distributions of lighting activity are regional and random, the requirements for electrical and electronic equipment, voltage and insulation level are varied from lighting activity in different regions. This paper adopts the Lightning Location Data on the Pearl River Delta in the last 10 years, and uses the method of probability statistics to analyze the regional ground flash density, the probability of lightning strike accident, the damages of the lightning strikes accidents and other risk factors. It takes the topography, regional features, population density and other factors into account, and uses the weighted scores to establish the risk assessment model for the lightning strikes, programs to achieve the automatic calculation in allusion to the risk of lightning strikes in different types of buildings and insulation levels of the electrical and electronic equipment, and assess the risk of lightning strikes on the electrical and electronic equipment. And based on the risk assessment result, it incorporates the installation location, characteristics, importance and other factors to study the electronic equipment withstand voltage and insulation level.

Abstract: The mathematical model for three-phase four-leg grid-connected inverter is modeled by the simplified p-q-r theory. The control strategy is proposed based on the characteristic of controlled variables. PI algorithm is adopted for variables of p axis and q axis, and PR algorithm is adopted for variable of r axis. The full design and analysis of the proposed control algorithms are given in this paper. Simulation results and experimental result show that quality of four-leg grid-connected inverter output current is higher, and effectiveness of the proposed control strategies is validated by all results.

Abstract: This paper proposes a new method: GRA-SVM model which is composed of GRA and SVM to predict grain production through annual production data. In view of the fact that the complexity and incomplete information of grain production system, the primary factors influencing the grain production is decided on the basis of the grey ralational analysis of the grain producing system, then, the grey ralational analysis and support vector machine model is established by the principle of the support vection machine regression. The application case proved that the proposed method can improve the feasibility of the program in grain production, and it is suitable for on-line grain production control for food system.

Abstract: With the increasing development of sustainable energy, the technology of wind power generation becomes more and more mature. This paper introduces the application of one-cycle control in the converter section of the wind power generation. The performance of the whole system can be improved. A one-cycle control principle of derivation is conducted, A simulation to the one-cycle control by MATLAB software shows high power factor and quick system dynamic response.

Abstract: In this paper a micro grid that consists of micro turbine, fuel cell, wind turbine, electrolyzer, ultra capacitor and battery, is analyzed for frequency control, during several load disturbances. In other word, produced power from all the other distributed generation (DG) sources are regulated by PI controllers. As the balance between the load and generation changes, the power system frequency deviates. In order to reduce these frequency deviations, the PI controllers, used to regulate the power flow from DGs. It is proposed that, proportional and integral gains tuned through trial and error method.

Abstract: The wind energy plays a vital role in the world renewable energy scenario. The modern wind turbine system has a complex and repairable components due to sophistication and centralized control. The failure characteristics of the onshore wind turbines depend on the terrain conditions. In the main mountain pass and hill area, there is a heavy uncertainty in the wind that is due to the frequent change in the direction of wind and the change in the velocity. It causes a rapid failure in the individual sub assemblies. There is a substantial need for improving the reliability in the stages of design, manufacturing, operation and maintenance. Normally the infant mortality failures are more in the onshore wind turbine and the failure rate is constant during normal operating period. It is a surprise that the failure rate has rapidly increased during normal operating period of the wind turbines placed exactly in the mountain pass and hilly area due to the high uncertainty in the wind. This paper deals with reliability analysis of major components of wind turbine system and its sub system such as rotor system, gear box, brake system, generator, hydraulic system and yaw system. This paper also investigates the reliability of wind turbines and its sub assemblies placed at Aramboly pass in India by using Weibull software as reliability tool for a grid connected 250 kW wind turbine. This analysis yields some surprising results about some sub assembly like yaw system, brake system and generator which are most unreliable.

Abstract: This paper presents an electric generating from sea waves in gulf of Thailand. The design procedure and modeling metrology were performed for a rotary permanent magnet generator. A hydraulic system which consists of a floating buoy with vertical movement drives the rotary generation using gear box driving system. The appropriate coupled mechanic models for the proposed generator and the hydraulic system have been developed for maximum power generation. A 1 kW prototype power unit has been performed at the Sirindhorn international environmental park to verify the proposed models.

Abstract: The growing demand for electrical energy is one of the most important subjects today. Renewable energies give a good perspective to be an alternative to fossil and nuclear-fueled power plants, in order to meet growing demand for electrical energy. River current energy conversion systems are electromechanical energy converters that convert kinetic energy of river water into other usable forms of energy. However, the potentials of this technology as an effective and renewable source of alternative energy have not yet been explored to a great extent. In this research investigated the use of computational fluid dynamics in predicting hydrokinetic energy, and effective parameters of river's meander to generated hydro electrical energy. The survey shows that in this case study can generate justifiable energy in meander and it show that can use the meander of rivers are one of the renewable source. This article may serve as a coherent literature survey or technology review that would provide better understanding of the subjacent issues and possibly rejuvenate research interest in this immensely potential field of energy engineering

Abstract: This paper discusses two important issues: one is the Malaysian government decision to go nuclear to meet the future energy demands and the other is Lynas Rare-earth project to boost up the economy of the country. It should be noted that Malaysia is not new to such experiences as the Asian rare-earth project in the 1980s proved very costly causing rash of birth defects, painful miscarriages, and leukemia cases because of radioactive waste. This paper highlights the needs that future energy needs and economic targets can be overcome through other sources probably investing in renewable energy such as solar, wind, and hydropower.