No abstract

No abstract

Abstrak Makalah ini menyajikan analisa karakteristik-karakteristik kecepatan angin di Keywords: weibull distribution function, wind power generation, wind speed IntroductionRenewable energy has an increasing role in achieving the goals of sustainable development, energy security and environmental protection. Nowadays, it has been recognized as one of the most promising clean energy over the world because of its falling cost, while other renewable energy technologies are becoming more expensiveWind energy is one of renewable energy which produced by continuously blowing wind and can be captured using wind turbines that convert kinetic energy from wind into mechanical energy and then into electrical energy [3]. Today, wind energy is widely used to produce electricity in many countries such as Denmark, Spain, Germany, United States, and India [4].A lot of researchers have been studying the wind speed characteristics and its potential as a wind power generation in many countries worlwide. Six kinds of numerical methods for estimating Weibull parameters were reviewed by [5]; i.e. the moment, empirical, graphical, maximum likelihood, modified maximum likelihood, and energy pattern factor method. The result showed that the maximum likelihood modified maximum likelihood and moment methods present relatively more excellent ability throughout the simulation test. From analysis of actual data, it is found that if wind speed distribution matches well with Weibull function, the six methods are applicable, but if not, the maximum likelihood method performs best followed by the modified maximum likelihood and moment methods, based on double checks including

This paper provides detailed information on the developed hardware and software for sun tracking mechanism and shows the effectiveness of utilizing time and date-based sun positioning solar collector system in tropical climate. The sun positioning system is based on the calculated azimuth and altitude at location E100°11′, N6°26′ in Northern Peninsular Malaysia where the climate is categorized as tropical climate. The system has two axes tracking with accuracy of 1° controlled by a programmable logic controller (PLC). The field test has been done during a sunny and clear day, cloudy day and, heavy overcast and rainy day in which the results show that the improvement in the generated power of 91.97%, 122.71% and 90.42%, respectively, as compared with the fixed horizontal system.

The conventional grid-connected inverters require a sophisticated digital signal processor to generate the demanded reference signal as a feedforward signal for the sinusoidal pulse width modulation (SPWM) control. However, the reference signal needs to be re-calculated to maintain the demanded power control as the ac mains varies. It increases the computation burden of the controller and has become a major obstacle of the grid connected energy storage system with demanded power flow control. Therefore, a simplified approach to reduce the computation burden of the controller is proposed in this paper. With the proposed simplified equation for the power flow control, the usage of a low cost microcontroller unit becomes possible. In additional, no additional sensors or circuitries are needed. Meanwhile, the performance of desired power flow control by using the simplified control is almost unaffected. The proposed simplified algorithm is validated via mathematical calculations, computer simulation and experimental results. By using the proposed simplified control, 52.3% of the computational clock cycles can be reduced. Different operation scenarios were tested to validate the performance of the proposed simplified control via the MATLAB/Simulink simulations and the 1kVA prototype experiments.