| The carbon peaking and carbon neutral targets are China’s important promise of emission reduction in long term,which guiding and promoting the energy conservation technology and the utilization of renewable energy in buildings.Using free roof and facade space of buildings to develop off-grid photovoltaic system can not only avoid energy waste and high equipment cost caused by long-distance transmission,but also reduce the stability risk of the grid.Which is a new trend of renewable energy development in the future.Energy storage technology is important technical to improve the stability of renewable energy utilization.Using energy storage system can significantly improve the flexibility of the building load demand.Therefore,this paper proposes a set of latent heat storage heating system and operation strategy,analyzes the economy and flexible load transfer capability under different configuration,and optimizes the system from the perspective of equipment capacity and operation strategy,and further explore the potential of the system.In order to verify the operation effect of the multi-energy complementary energy storage and heating system,the experiment system with photovoltaic panels,batteries and latent heat storage electric heater was built,and four different operation strategies were designed.The experiment was carried out in a 10m~2room in Beijing.The experimental results show that one latent heat storage heater with 900Wp photovoltaic panel and 3k Wh lead-acid battery can be used to maintain the indoor temperature above 18℃in the heating season without using peak electricity from the grid.The temperature of phase change material in the heat storage unit is positively correlated with the output power of the heater.When the temperature of the heat storage material is maintained above 100℃,there has high temperature difference between the inlet and outlet of the heater,which is conducive to indoor temperature control.Based on the experiment results,in order to study the effect of the system using in multiple rooms,the mathematical model is built by MATLAB.The indoor dynamic thermal process model is used to calculate the indoor temperature,and the operation strategy of flexible load regulation is designed.This paper using the multi-energy complementary energy storage and heating system in existing building renovation projects as example,the flexible load regulation ability and economy of the system is studied,and the sensitivity of each parameter in the system is analyzed.It is found that the multi-energy complementary phase change storage electric heating system can reduce primary energy consumption by 23.9%and peak electricity consumption by 93.9%in the case building,when the indoor temperature is basically maintained at 18℃.By analyzing the influence of various factors on flexible load,it is found that with the increase of the effective photovoltaic power in the system,the peak electricity consumption will decrease significantly.When the capacity of the battery in the system is higher than 15k Wh,increasing the capacity of the battery has little effect.The improvement of thermal performance of building envelope can greatly reduce the primary energy consumption of the multi-energy complementary latent heat storage heating system,and the total peak electricity consumption can be reduced by 95.8%at most.The payback period of the system is 5.4 years to more than 10 years.The initial investment of the equipment and the photoelectric waste rate in the system are the main factors to affect the economy of system.In order to deeply explore the economy and flexible load potential of the multi-energy complementary energy storage and heating system,the global optimization and operation strategy optimization of the system is studied by using CPLEX solver,and compared with the design scheme.The optimization results show that the battery capacity in the design scheme has great potential to improvement,the effect of 15k Wh battery in the design scheme can be achieved only by 3.69k Wh battery with ideal operation strategy.In addition,the optimization scheme reduces the energy storage in the off-peak grid period of the system,thus improving the renewable energy storage capacity when the photovoltaic power generate.Compare with the same capacity of photovoltaic system,the optimal scheme can reduce the photoelectric waste by 10.93k Wh and reduce the comprehensive cost by 15.6%in one week during the heating season. |
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