| The world’s energy demand is mainly dependent on the use of fossil fuel and other non-reversible energy sources.To mitigate the impact of climate change and global warming,the use of renewable energies is significantly increasing.Different sources of renewable energy have been identified,and solar energy has been proven to be a suitable candidate for a sustainable energy source.However,solar power generation is highly dependent on weather conditions,particularly solar resources.Thus,it is crucially important to forecast solar power to mitigate some of the challenges that may arise due to the uniformity of climate and thereby hinder future power output.The present work evaluates firstly solar resource assessment between Rwanda and China based on meteorological radiation data.Furthermore,linear extrapolation and moving average forecasting methods have been adopted to predict solar power output in an ultra-short-term period.This study has tested the hypothesis further and analyzed performance,control strategy of the solar system with a battery energy storage system(BES)-in tracking power generation plan.Control strategy has been studied into two parts,which are expecting output value control strategy and constraint control strategy of the battery.The former part is using a linear extrapolation method and moving average method to forecast and smooth the next moment’s power of the station,then comparing the forecasting power with the generation plan.The expected output of the energy storage system was also calculated with constrain of the output of the rated power and capacity that can keep the battery system running safely in long time.The real-time control strategy was formulated to optimize the charging and discharging characteristics of the energy storage system and improve the effect of tracking power generation plans.This strategy considered linear extrapolation and moving average method of past storage behavior to generate the power status of a storage system in the future and to formulate the output value of the battery based on the original strategy.Finally,simulation and analysis of data have been carried out by Matlab according to the above control strategy.Also,this thesis has studied the impact of solar PV with and without BES system on power system using IEEE-14 bus test system with bus four as a heavy load bus by using PSAT toolbox for power flow simulation and analysis.The results found,showed that when the power is injected on a bus system for PV solar connected with BES system,there is a significant change in real power,reactive power and phase voltage.In addition,the real and reactive powers losses are lower compared to the pv solar system without battery energy storage system.As a result,the qualitative resource assessment that has been done shows that China is more abundant in solar resources,the level of solar resources in China is grade B which indicates more stable and more direct radiation;compare to Rwanda with grade A,whereby solar resources are stable and direct radiation are abundant.Furthermore,it was found that the prediction of solar power is not accurate,which caused by a considerable difference between the actual output and power generation planned by the superior grid.That difference leads to the phenomenon of the solar power plant being discarded.According to simulation results,different gradients of battery’s rated power and capacity are selected to reflect the effect of the scheme for tracking power. |
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