Research On The Key Technologies For Coordinated Operation Of Ice-storage Air-conditioning And Distributed PV

With the continuous improvement of living standards,the air-conditioning is employed more and more widely.And the increasing air-conditioning load led to higher demand for electricity.In addition,the increasing air-conditioning load gives rise to the further expansion of the peak and valley power grid.Reducing effectively the peak load of power grid is an urgent problem to be solved.Installing the ice-storage air-conditioning and distributed photovoltaic systems in office buildings and shopping malls can both transfer the peak power load,but also effectively alleviate energy and environmental problems.The coordinated operation of ice-storage air-conditioning and distributed PV involves control strategy of them.Considering the current building photovoltaic power generation is relatively small,without problem of consumption,this paper studies the control strategy of the ice-storage air-conditioning in the case of full photovoltaic power generation.This paper introduces the research background and significance in aspects of energy,environmental protection and grid load characteristics,the preface briefly introduces the current research situation of ice-storage air-conditioning and distributed photovoltaic research,and main contents of this paper.In the second chapter,the cooling mode of air-conditioning system,operating conditions,topologies,operation strategies and control strategies and so on are introduced.Then,the main factors affecting the cooling load of the building are analyzed,and the cooling load forecasting model by BP neural network is established with similar daily cooling load,temperature and predicted daily temperature as input neurons.Data of a comprehensive building in Jiangsu is employed to verify the accuracy of the model.The prediction results are consistent with the actual cooling load,similar to the change trend of the cold load,and the relative prediction error is within ±5%.The photovoltaic power generation forecasting model by BP neural network is also established.A network training sample screening algorithm is proposed to screen out the training samples,which are closest in climatic conditions to the day to be forecast.The photovoltaic power generation is predicted by the forecasting model,and the prediction error of sunny and rainy days is within ? 10%and ± 20%respectively,which is because in rainy days,the random of photovoltaic power is large and the volatility is strong.On the whole,the prediction models of cooling load and the photovoltaic power generation are accurate enough to satisfy the practical requirements.This paper analyzes the early investment of ice-storage air-conditioning and calculation methods of economic benefits after operation.The initial investment in ice-storage air-conditioning mainly covers the cooling host,ice-storage equipment and related ancillary equipments.Economic benefits mainly come from the reduced electricity bill which is produced by ice-storage air-conditioning transferring the building load from the high price period to the low price period.According to the initial investment and economic benefit calculation method,to obtain the maximum net benefits of the ice-storage air-conditioning system in the effective use life period,this paper establishes the ice-storage air-conditioning capacity allocation model,and the actual data is taken to test the model.Finally,based on the forecasting model of the cooling load and the photovoltaic power generation,this paper sets the cooling capacity of the system as the objective function,considering the constraints such as the heat balance,the power balance,the cooling/cooling capacity of refrigerators and so on,to establish coordinated operation optimization control model of ice-storage air-conditioning and distributed PV.Actual building data are employed to analyze the system coordination operation control strategy on weekdays and holidays.The results show that when the fraction of the theoretical number of the refrigerators is large,the refrigerators work.under rated operating condition and the remaining cold demand is produced by melting the ice.When the fraction is small,the ice-storage tanks melt ice to cool at the maximum rate,and the remaining part of the cold is distributed evenly to refrigerators.Regardless of the load characteristics,the model can calculate the best coordinated operation control scheme of ice-storage air-conditioning and distributed PV.The control scheme can,under the premise of not affecting the cold demand of the users,transfer the daily period load to the valley period,which can reduce grid peak difference and make operating costs to a minimum.