Applied Mechanics and Materials Vol. 785

Abstract: Solar energy is one of the more attractive renewable energy sources that can be used as an input energy source for heat engines. In fact, any heat energy sources can be used with the Stirling engine. Stirling engines are mechanical devices working theoretically on the Stirling cycle, or its modifications, in which compressible fluids, such as air, hydrogen, helium, nitrogen or even vapors, are used as working fluids. When comparing with the internal combustion engine, the Stirling engine offers possibility for having high efficiency engine with less exhaust emissions. However, this paper analyzes the basic background of Stirling engine and reviews its existing literature pertaining to dynamic model and control system for parabolic dish-stirling (PD) system.

Abstract: Parabolic Dish (PD) system is one of the Concentrating Solar Power (CSP) technologies that converts the thermal energy from solar irradiance into mechanical energy and then to electrical energy. The concentrator in PD system works by focusing the solar radiation onto the receiver located at the focal point. The solar power that produced from the concentration process is intercepted by the receiver and then used for the energy conversion process in PD system. This study is carried out to understand the effect of the intercept factor, reflecting material and the DNI to the solar power intercepted by the receiver in PD 1kW system. Meanwhile, Matlab Simulink was used in this study as the simulation tool. The study shows that the solar power intercepted by the receiver in 1kW PD system are strongly depending on the intercept factor, DNI of the locations and reflecting material used for the concentrator. Whereas, the results from this study are useful for a better understanding especially on the effects of the intercept factor, reflecting material and the DNI to the solar power intercepted by the receiver for 1kW PD system in different locations with different DNI level.

Abstract: During wind farm planning, the farm layout is generally optimized to minimize the wake losses, and thereby maximize the energy production. However, the scope of layout design itself depends on the specified wind farm land-shape. In this paper, a novel framework is developed to explore how the farm land-shape influences the output potential of a site under a given wind farm area directional orientation or for a set of sample land-shapes with the fixed land area. The full free stream wind speed will be utilized by using definite point selection (DPS) criteria. The DPS is then represented as a function of the wind farm area shape and land orientation. Three types of wind farm land with different dimensions and same areas are considered. The effect of the wake on wind farm power production is calculated. The extracted power is measured for all land shapes. It is concluded that the diamond shaped wind farm is the most suitable, irrespective of regular or irregular layouts of the farm following the square shape.

Abstract: Reliable solar energy forecasting enables grid operators to manage the grid better as PV penetration level increases. This research explores the use of support vector regression to forecast hourly power output from a grid-connected PV system in Malaysia. Data is obtained from a grid-connected PV system that is equipped with a weather monitoring station. Three parameters are used as input to the forecast model; global irradiance, tilted irradiance and ambient temperature. Results were compared against a persistence model. The SVR model manages to forecast hourly power production with satisfactory accuracy.

Abstract: This paper presents a comparative study in terms of copper weight required and losses generated in transporting energy harvested in PV plant using different Centralized Inverter (CI) configurations. For the sake of simplicity, the Standard Test Conditions (STC) rated PV power value has been used in this study. The key findings suggest that different Combiner Box (CB) configurations in CI plays an important roles in determining the total conductor weight and losses attributed by each configuration. The outcome of this study will help the PV plant designers and system integrators to estimate the cost of solar cable of implementing different design configuration.

Abstract: This paper presents a methodology for sizing Stand-Alone Photovoltaic (SAPV) system. An iterative-based sizing algorithm, known as ISA, was developed for determining the optimal PV module, battery, charge controller and inverter such that the expected Performance Ratio (PR) of the system could be maximized. The ISA basically evaluates all possible combinations of SAPV system components derived from the respective database of each component. Two sizing scenarios were evaluated based on the types of charge controller that has been used, i.e. the standard charge controller and maximum power point tracker (MPPT)-based charge controller. Results showed that the optimal sizing solution was discovered within 14 to 19 hours based on an evaluation of 46,080 possible combinations of components.

Abstract: Renewable energy invariably foreseen to be fully spurs by 2030-2050 and Malaysia has been seriously intensifies their capabilities on producing solar energy for generating amount of power to be injected into the national grid. The aim of this paper is to investigate the provision of photovoltaic generators quantitatively with respect to future load generation while considering the Loading Margin (LM) capability. Renewable energy resources are known with its ambiguity and commonly for rural electrifications each houses or buildings are installed with battery storage system which allows unused power during daytime to be stored and will be utilized at night. This kind of system would not experience big impact in conjunction of intermittent level of insolation due to its small requirement at receiving end. Conversely, in big cities located in the west region of Malaysia it becomes a big issue to cope with variations of load demand. In an explicit form of voltage deficiency caused by irregular operation on the grid, a fragile electrical nodes most likely vulnerable and PV generators are inevitably have to stay connected to the point of common coupling supporting grid’s voltage. Eventually at this stage, Grid System Operator (GSO) needs to have brisk respond to these online scenarios but in practice it could not be done at ease. Thus, an intelligent model of ANN which incorporated tremendous set of local data is developed in this paper to regulate loading margin (LM) at critical node by taking into account possible wheather condition at any given time and loading increments. This method employed a kind of supervised training and successfully yields smart predictive technique of LM in any certain correspond inputs. By having this, GSO can barely make the arrangement of reactive power injection throughout the network with the central coordination control among PV generators. Simulation results show the effectiveness of the proposed method and have been discussed thoroughly.

Abstract: This paper presents sizing software for the design of a solar farm system. The sizing software provides few guidelines to the designer for the planning procedure before the final of optimum array configuration is decided. Some specifications that the designer may consider are the type of PV module, the type of inverter, the available space for installation, the required energy per year and also the sum of money to be allocated for the instalment. The output result of this software will be the suggestion of possible configuration of the total number of modules in series per string with the total number of strings in parallel. This software also does the prediction of the system performances such as final yield, specific yield and performance ratio. The expected income is provided by the software is based on the Feed-in Tariff rates and the energy generated by the system.

Abstract: Solar energy is considered as one of the solution to the worldwide depletion of fossil fuel resources as well as the economic alternatives in protecting the atmosphere from the adverse consequences of global warming. Nevertheless solar power is often criticized because the output power generated is variable and virtually uncontrollable. Potential analysis on introduction of photovoltaic system at particular site however requires the knowledge of solar irradiance and photovoltaic power distributions. This paper will focus on the possibility in applying statistical moments approach in solar irradiance and photovoltaic power distribution evaluation. Applying the first to forth statistical moments, the density function approximation of the parameters from 5MW grid connected Photovoltaic system were evaluated using the Pearson system. This method is based on the relationship between the first four moments of the distribution where the probability distribution is estimated by equating their theoretical moments with the moments of empirical distributions. Application of various statistical moments has the advantage in estimating the potential of photovoltaic system in view of dynamic changes of skewness and kurtosis coefficients of solar power irradiance distributions.

Abstract: In this study, wind energy potential in three different stations in Malaysia in period of 5 years is analyzed. Base on Weibull distribution parameters, the mean wind speed, wind power density and wind energy density is estimated for each defined location. Although there are many works about wind potential in Malaysia, however a few of them have been provided a comprehensive study about wind power in different places in Malaysia. According to the findings, the annual mean wind speeds indicates that the highest wind speed variation is about 2 m/s and is belonged to the Subang station and the highest wind speed is 3.5 m/s in in Kudat. It is also found that the maximum wind power densities among these three sites are 22 W/m², 24 W/m² and 22 W/m² in Kudat station in January, February and September respectively. The results of the study show that as the second parameter for Weibull model, the highest wind energy density has been 190 kWh/m² per year in Kudat and the lowest one has been about 60 kWh/m² in Kuching.