Multi-time Scale Optimal Scheduling Method For Building Energy System Considering Time-Varying Virtual Energy Storage Of Building Envelope

With the continuous improvement of people’s pursuit of life quality,building energy consumption is increasing year by year.Electric energy and thermal energy account for a large proportion in building energy consumption.How to exploit the complementary characteristics between the two energy sources,optimize the building energy supply and the energy use to reduce building energy consumption and promote the development of renewable energy on the user side is an important research direction in the field of building energy use.The use of distributed rooftop photovoltaic to power the building is an important technical mean in this field.It can provide a clean electricity supply for the building and reduce the the electricity purchase cost of building users to a certain extent.However,distributed photovoltaic power generation is random,which makes it difficult to match the peak-valley time of photovoltaic power generation and the peakvalley time of building’s power consumption,and then lead to difficulties in photovoltaic consumption.Using battery energy storage to absorb photovoltaic is a common method,but the current cost is relatively high and there may be potential safety hazards.Taking advantage of the larger time constant of the thermal energy tranfer,the building thermal energy use is equivalent to a kind of virtual energy storage through regulation and control technology.The development and utilization of the virtual energy storage can effectively increase the sceduling flexibility of building energy system(BES).Utilizing increased scheduling flexibility can not only reduce building energy cost,but also promote building renewable energy consumption.Based on previous work,this paper investigates a multi-time scale optimal scheduling method for BES considering time-varying virtual energy storage of building envelope,including the theory of virtual energy storage modeling considering the thermal inertia of building envelope,the optimal scheduling method for BES with virtual energy storage,etc.The main contributions are as follows:1)A time-varying virtual energy storage(TVES)model of building envelope is constructed considering the influence of time-varying environmental parameters such as indoor temperature,outdoor temperature,and light irradiance.Meanwhile,three time-varying parameters of virtual charge and discharge power,capacity and state of charge are defined to quantify the time-varying electricity storage scheduling potential provided by the building envelope for BES,which is used to provide constraint boundary information for the operation scheduling of BES.2)A day-ahead optimal scheduling method for BES is proposed based on the TVES model.The time-varying adjustable range of three time-varying parameters in the TVES model is integrated into the day-ahead optimal scheduling model for BES as constraints.By optimizing and controlling of the charge and discharge power of the TVES,the electricity purchase cost of building users is reduced and the local consumption rate of photovoltaic is improved.3)An intra-day rolling optimal scheduling method considering the TVES is further proposed based on the day-ahead optimal scheduling model in this paper.The intra-day rolling optimal scheduling method can fully consider the influence of the intra-day random variations of environmental time-varying parameters such as outdoor temperature on the charge and discharge power and electricity capacity of the TVES.According to the variations of intra-day building environmental parameters,this method carries out rolling correction for the three time-varying parameters of the TVES model at an interval of 30 min.The rolling correction for the three time-varying parameters can effectively improve the accuracy of TVES parameters and the matching degree between optimal scheduling scheme and the operation state of BES,which can avoid the problems of poor thermal comfort or high electricity purchase cost caused by the inaccurate TVES parameters.Finally,a numerical example is used to systematically verify the correctness and effectiveness of the proposed method.