A Study on Suitable Grid Configuration of a Remote Rural Area Using Hybrid PV-Diesel-ESS System

Abstract

It is undeniable fact that even though fossil fuels are likely more to fulfill the requirements of energy, the rare of natural resources and their harmful contents for the environment have directed people to search for new energy sources. Renewable resources of energy like hydropower, biomass, wind, solar and other types of clean energy are widely integrated into electric power systems around the world as they can decrease the environmental pollution effectively. However, only using the renewable energy systems cannot be reliable in itself without using the back-up system like engine generators or energy storage devices like batteries. Therefore, hybrid energy system that combines more than one renewable energy technology with back-up system may be obtained by combining various kinds of resources, using diesel-, biomass-, wind-, PV-, or small hydro-generators. Relying on the characteristics of a particular use (that is, willingness to pay and load profile), meteorological facts (wind speed, solar radiation, temperature, and hydro) and the local provided options, the solution of least cost for a rural off-grid system may contain any combination mentioned above. The decision as to what types of hybrid system that should be utilized must be made on the basic of economic, social, environmental and safety considerations. Therefore, the intent of this dissertation is to show economical for investment in diesel stand-alone or PV-diesel or PV-diesel-ESS hybrid systems in the proposed area for making the investment decision. To reach this objective, the researcher has developed a techno-economic approach described by two models: the reliability model developed beneath the Total Energy Deficit (TED) concept based on the Loss of Power Supply Probability (LPSP) and the economic model based on the calculation of Total Net Present Cost (TNPC) and Cost of Energy (COE) by using Hybrid Optimization Model for Electric Renewable (HOMER) Tool. By combining these two models, it can be decided to the optimal configuration leading to the total system autonomy in the most cost effective manner. The sizing parameters have been used in the screation, i.e. the PV subsystem capacity. Regarding the diesel generator, it is measured to meet the peak electrical demand (due to to the suggested strategy). Applying the developed methodology, all configurations that rate 0% of TED are retained and at the same time, the optimal configuration is predicted on the basis of the less cost by TNPC concept. In addition, the developed model is used to calculate how much fuel is consumed by diesel generator and the amount of CO2 that can emit. In order to highlight the suggested methodology, three different system configurations have been analyzed, which are diesel standalone, PV-diesel without BESS, and PV-diesel with BESS to supply the Kyit Sone Pwe village which is situated at 20.154N latitude and 94.945E longitude in Magway Township in Myanmar. The yearly average solar radiation of that area is 4.841kWh/m2/day and it is very important to prepare a proper load data to meet the current situation of the target village. The load determination of that village is 1300 household numbers with average of five family members per household and so, the totally population numbers is around 6500. By calculating the total load demand, the peak demand of that proposed village is 563kW. For the first case, diesel standalone system, although it can meet the power demand, both the fuel cost and CO2 emission level are too high to be economically feasible. In order to reduce the system operating cost, PV generation was added to the system, creating a PV-diesel hybrid system. However, due to the intermittent output of PV generator, the PV-diesel system was infeasible to maintain the system security for getting the optimal design. In order to address these issues, the system of battery energy shortage (BESS) was added to the PV-diesel hybrid system to store power during the times of excess generation and generate power during the time of power shortages. This system displays the most excellent characteristic by means of net present cost which involves capital cost, replacement cost, fuel cost, operation and maintenance cost that happen during the project lifespan, levelized energy cost, and operating cost. A simulation time step with one hour is provided in this research work, like in the first step, the system reliability model is improved in terms of the concept of LPSP. For this purpose, considering the different combinations of hybrid systems has made several simulations. The algorithm input data set contains hourly solar radiation on the horizontal flat surface, ambient temperature recorded at Magway for 2016, and the energy requirements expressed by the load throughout the year and specifications of the system devices. All of these three systems are simulated by running the developed computer program and the dealings among system configurations, the amount of excess electricity, the amount of CO2 emitted and system costs are studied. The optimal configurations of the hybrid system are measured in terms of total system reliability (TED = 0%) and system costs. According to the simulation results, the optimal values of TNPC, COE, and the amount of CO2 emitted for the proposed PV/diesel/BESS hybrid system are obtained for configuration with $5,212,293 (TNPC), $0.367/kWh (COE) and 947,218 kg/yr, but these values for PV/Diesel systems are significantly increased with $7,984,073 (TNPC), $0.562/kWh (COE) and 1,585,267kg/yr. The fractions of energy production from PV array and generator of the proposed hybrid system are 44% and 56% to meet the demand. This is mainly due to strong solar potential in the Magway region. Therefore, the proposed hybrid system provides the lowest TNPC, COE and carbon emission among these three systems according to the evaluation results. In contrast, the analysis of evaluation results shows that the PV/diesel/battery choice is more economically possible compared to PV/diesel system or diesel generator only.