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Articles by Ken Nagasaka
Total Records ( 8 ) for Ken Nagasaka
  Zulati Litifu , Noel Estoperez , Ken Nagasaka , Yasuyuki Nemoto and Izumi Ushiyama
  Granted by research project of Japan Society for the Promotion of Science (JSPS), this research provides planning of installing Wind Power Turbine (WPT) in an existing Local Weak Power System (LWPS). Wind power generation is expected to be used as a power reserve to improve the reliability degree and reduce line loss of LWPS, that suffers from critical load in each summer. Installation buses are selected based on the existing reliability degree derived from system condition in energy service and load demand, two reliability indices namely Weakness Degree in Energy Supply (WDES) that represents bus energy supply ability in a short critical time and Reliability Index in Energy Supply (RIES) that represents bus average energy supply ability during annual time are applied. Appropriate type of WPT is selected according to Percentage Rate of Availability Index (PRAI) and Percentage Rate of Utilization Index (PRUI) derived from Monthly Average Wind Speed (MAWS) through the target region. Operational reliability and stability are analyzed based on formed system characteristics after introducing WPT.
  Zulati Litifu , Yasuyuki Nemoto , Izumi Ushiyama and Ken Nagasaka
  This study presents a realization process of a hybrid system consisting of biomass and wind as well as solar power generation on the ground of Ashikaga Intitute of Technology located in Ashikaga City of Tochiki Prefecture. The installation principle and procedure are introduced based on the conditions of natural energy such as wind speed and solar rediation degree. The output characteristics from 20 kW biomass generator is explained and analyzed in according to cooperational possibility with the wind power and solar power system. The operation characteristics of 40 kW wind power turbine is provided based on the practical operation data collected within three years and the simulated results obtained from the software calculation. The operation conditions of 20.6kW solar power system is also anaylzed based on the solar irrediance desity in the located site. The general efficiency of this triple hybrid power system in ecomomic and environment aspects is also studied by using and comparing the simulation methodology and the data in practical operation.
  Zulati Litifu , Ken Nagasaka , Yasuyuki Nemoto and Izumi Ushiyama
  This study provides an applicable process for introducing wind power generaton into a weak power system regarding the fluctuation of electric parameters so as to determine the installable limitation. The static and dynamic operational situation of a Wind Power Turbine (WPT) that relates to terminal output and connection system are detailly explained. Characters of inductive generator under sudden variation of wind speed and short circiut has been introduced. Wind and generation matrixes are applied for regional wind condition. The methods to determine optimal bus are considered by regarding sytem load particularity. The electric fluctuation of system parameters is analyzed in each bus of substation system. installable limitation is tested regarding fluctuation range of target parameters.
  Suyouli , Zulati Litifu and Ken Nagasaka
  By considering characteristics of rural power system, this study presents an optimal method to estimate wind speed and install Wind Power Turbine (WPT). Entire installation procedure is composed by selecting appropriate buses and verifying the power system after installing WPT. Two innovative indices such as the Power Index in Crisis Time (PICT) and the Endurance Index of Crisis Hours (EICH)) are developed and applied for determining the reliability level of target buses for installing WPT. The stability and reliability of formed hybrid power system are verified by the references of frequency and voltage. Result from this study was applied for a rural power system containing hydro power generation.
  Irina Falconett and Ken Nagasaka
  Introduction of competition in the electricity supply industry has required several adjustments or in some cases significant improvements, depending on the original design and its implementation. This study analyzes the impact of private ownerships on the spot prices and market power in a system dominated by hydroelectric capacity based on the Panamanian electricity market data. Besides, we apply the Cournot-Nash equilibrium model to evaluate the generating company’s profit in an electricity market with cost-based dispatch. Despite the premise that competition in the wholesale market will lead to lower prices, it has been shown that the retail prices for residential consumers have gradually increased after the restructuring process.
  YanBin Xu and Ken Nagasaka
  In the deregulated power markets, the electricity market price forecasting is very important for the market participants, managers GenCo, DisCo, retailers, etc. Although, most of researches has achieved good results on the electricity market price forecasting, however, these techniques mostly focus on normal price forecasting and not considering price spikes in the electricity market. In this study, we propose a price interval identification model using neural network, which can generate forecasted price interval, level of spike and associated forecast confidence. The model is tested with the Queensland electricity market data of Australia and promising results are been obtained.
  Su Youli , Zulati Litifu and Ken Nagasaka
  In this study, the Micro Grid (MG) formed from the renewable energy resources and the storage battery was analyzed and verified by multi-factors. The target MG power system was planned and installed in Kochi prefecture, Japan and it consisits of wind power turbine and solar power plant as well as micro hydro power generator. The efficiency of a stand alone Micro Grid in reliability and economy as well as environment was assessed. The system reliability is verified by the indices of Loss of Load Probability (LOLP) and Expected Energy Not Supplied (EENS). And the economic efficiency was given appraisal by Yardstick indices of the Net Present Value (NPV) and the Benefit-Cost Ratio (BCR) as well as the Payback Period (PBP). The environment efficiency was evaluated considering the amount of CO2 discharge that was reduced by using installed MG power system renewable energy.
  Meita Rumbayan and Ken Nagasaka
  The wind characteristic information will be useful in identifying prospective areas for wind-energy applications. The purposes of this study are to analyze the wind characteristic for selected locations in Indonesia based on available data. The wind characteristic for Bali, Balikpapan, Surabaya and Jayapura were analyzed based on the daily average wind speed which is available in National Oceanic and Atmospheric Administration (NOAA) website. The wind characteristics were analyzed using statistical analysis and the Weibull parameter as the Weibull distribution generally accepted methodology used to estimate the wind speed frequency distribution. Even though, wind characteristic analysis indicates low potential of wind energy in Indonesia, the result of this study can be useful information about wind research in Indonesia. Evaluation of the potential of wind energy resources in Indonesia need to be conducted as there is very limited research on the assessment of wind energy potential in Indonesia.
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