Hasimah Abdul Rahman

Mathematical model of Compressed Air Energy Storage in smoothing 2MW wind turbine

This paper presents the mathematical modeling of Compressed Air Energy Storage, (CAES) in obtaining mechanical power generated from expander. Mechanical power is injected to a generator to generate electricity that will stabilize 2MW active power fluctuated caused by intermittent behavior of wind speed. The control system in maintaining dc-link voltage at constant value and control system in supplying generated power from CAES is also discussed here. The goals in using CAES are to smooth out the fluctuated power and increased low power integrated into the grid. This system is analyzed using SimPowerSystem of MATLAB/simulink. Results show that the jCAES is able to not only mitigate generated power but it also can promise constant power generated to grid even at low wind speed.

Power optimization for a small-sized stall-regulated variable-speed wind turbine

This paper focuses on power optimization for a small-sized stall-regulated variable-speed (SS-SR-VS) wind turbine system. In this paper, the behavior of the SS-SR-VS wind turbine during power optimization is demonstrated. The Speed Loop Control method with the assistance of classical Proportional Integral (PI) controller is used. Controller parameter is designed based on the linearization process, and the pole-placement procedure has been applied during the controller tuning. Further improvement is then done by using the Good Gain method. The comparison between these two methods is presented. Results show that the turbine speed, generator speed and hence the generated power can be optimized at the optimum values corresponding to the wind speed variations during power optimization.

Short term load forecasting using data mining technique

Accurate load and price forecasting are become very essential in power system planning. This will increase the efficiency of electricity generation and distribution while maintaining sufficient security of operation. This paper proposes method for Short Term Load Forecasting using data mining technique. The data provided by utility of Malaysia were analyzed to see its behavior or load pattern in a day during weekday and weekend in Peninsular Malaysia. By considering day-type in a week, five model of SARIMA (Time Series approach) have been created using Minitab. The forecasting is held based on the similar repeating trend of patterns from historical load data. The half hourly load data for six weeks had been plotted according to day-type to forecast the load demand for a day ahead. The MAPEs (Mean Absolute Percentage Error) obtained were ranging from 1.07% to 3.26%. Hence this modeling had improved the accuracy of forecasting rather than using only one model for all day in a week.

Design and economic analysis in stand alone photovoltaic system

Photovoltaic generating system has a high potential, since it is clean, environmental friendly and secure energy sources. Stand alone photovoltaic system is chosen as an alternative to grid utility where excess to utility is impossible especially in remote area. In stand alone photovoltaic system, the system is designed to fulfill a specific load demand, normally close to its point of utilization. This paper describes the design steps in stand alone photovoltaic system that include sizing of PV modules, battery storages, charge controller and inverter. An economic analysis was performed to identify system practicality based on predefined load. The finding shows that the levelized cost of energy for proposed system is RM 1.76/kWh.

Identification building energy saving using Energy Efficiency Index approach

Energy can be reused or saved instead of simply wasted by implementing strategic planning. In commercial building, energy consumption varies due to various factors such as building design, climate, load usage, type of electrical appliances, and management. Since each room in a building is designed to accommodate certain number of occupant, the room capacity is also considered as one of the factors that affect energy consumption. However, by placing inappropriate number of occupants in a room, the optimum use of energy cannot be achieved. For an example, energy may be wasted if the room that is designed for 200 occupants is only occupied by 98 people. In response to this concern, energy saving can be made by shifting or reconfiguring the number of occupant to make more suitable room. This strategy is called as a class shifting method. It can minimize electricity usage by simply shifting occupants into an appropriate room which is design nearly for that amount of capacity. This paper presents evaluation on class shifting strategy in term of its ability in reducing energy consumption. The study was conducted on selected building in Faculty of Electrical Engineering, Universiti Teknologi Malaysia (UTM) by using Energy Efficiency Index (EEI) reading as a baseline in determining how much energy is being wasted as well as being saved. The result from the application of shifting method showed a significant number of energy saving that can be made.

Climate-based empirical model for PV module temperature estimation in tropical environment

The paper proposes new mathematical models to estimating PV module temperature for poly and mono crystalline technologies in tropical climate such as in Malaysia. The developed models are based on measured hourly global solar radiation, ambient temperature, relative humidity, wind speed and module temperature. All data were collected over the year 2009 at GreenTech 92 kWp installed PV system in Selangor, Malaysia. The models were compared using r, MBE, RMSE, and MPE. The results showed that the proposed models give the highest value of correlation coefficient r, and good result when considering statistical indicators i.e. low RMSE, low MBE, and low MPE values. The results show that the proposed regression models have advantages over the conventional approaches for calculating the hourly and day-average PV module temperature, and give the closest results comparing to the actual measurements. The proposed approaches can be used as effective tools for predicting the PV module temperature, whether a simple PV module, open rack system, BIPV installations, or even PV/Thermal collector, in remote and rural locations with no direct measurement equipment. The proposed models can be very useful in studying PV system performance and estimating its energy output.

Short-Term Forecasting Of Solar Photovoltaic Output Power For Tropical Climate Using Ground-Based Measurement Data

This paper highlights a new approach using high-quality ground measured data to forecast the hourly power output values for grid-connected photovoltaic (PV) systems located in the tropics. A case study using the 1-year database consisting of PV power output, global irradiance, module temperature, and other relevant variables obtained from Universiti Teknikal Malaysia Melaka is used to develop forecast models for three typical weather conditions—clear, cloudy, and overcast sky conditions. A machine learning method (Support Vector Regression—SVR) and an Artificial Neural Network method (nonlinear autoregressive) are used to produce the models and the results are compared with a benchmark model using the persistence method. Comparison with all the variables suggests that tilted global horizontal irradiance (GHItilt) and module temperature (Tmod) are the essential input variables to forecast the PV power output. It has also been observed that SVR performs well across all types of sky conditions, with the fore...

Photovoltaic technology in Malaysia: past, present, and future plan

This article presents solar energy or specifically the solar photovoltaic (PV) development outlook in Malaysia. The paper first introduces the massive potential of solar energy in the country, the key players in the solar energy development and the early solar energy policies, and programmes in the country. The most important to the PV development is the Malaysia Building Integrated Photovoltaic initiative, which is presented in this paper followed by an explanation on the Feed-in Tariff recently introduced in the country to encourage new solar PV projects. The outlook for solar PV in Malaysia is optimistic and as the uptake of solar PV increases, the unit cost is coming down rapidly. Solar PV is expected to be the most competitive Renewable Energy (RE) source, with the potential to achieve grid parity for electrical power in the country in the near future, and surpassing all other REs combined by 2050.

An optimization method for designing stand alone photovoltaic system using iterative method

Worlds fuel sources are decreasing and global warming phenomena cause the urgency to search for alternative energy sources. Photovoltaic system has high potential since it is clean and environmental friendly. Standalone photovoltaic (SAPV) system is usually chosen as an alternative to grid utility, where excess to main grid is impossible. The system is designed to fulfill a specific load demand, close to its point of utilization. This paper presents SAPV system sizing and design that include sizing of PV modules, battery storages, charge controller and inverter using iterative method. Loss of power supply probability analysis is set as a benchmark to determine all possible configurations. Then, the optimum design is chosen based on the lowest levelized cost of energy. A case study on small-scale household load profile and hourly solar irradiance is employed to design this system. The findings indicate that the annual LCC for the proposed system is RM 632.08 with LCOE of RM 0.79/kWh.

Cost comparison between Amorphous Silicon and cadmium telluride for stand-alone photovoltaic system in Malaysia

The paper presents a cost comparison between amorphous silicon (a-Si) and cadmium telluride (CdTe) technology for a stand-alone photovoltaic system by applying life-cycle costing (LCC) method of analysis. A simulation tool; RETScreen is used to perform the financial analysis in setting up the stand-alone photovoltaic system for a typical house with an occupancy of four persons. The analysis consists of the photovoltaic cells cost per watt, efficiency and all factors contributing to the output power generated from these cells include the balance of the system, the battery storage, charge controller and inverter. From this investigation, although stand alone photovoltaic system provides several advantages from the environmental viewpoint, the major drawback is the fact that it costs ten times more than the cost of conservative energy. The price of energy for a standalone photovoltaic system ranges from RM 5.20/kWh for cadmium telluride to RM 5.32/kWh for amorphous silicon with an average of RM 5.26/kWh.