Zero fluctuation: Electric-fluctuation-elimination heat pump system with water storage tank based on time-of-use tax

Abstract

Due to the difference of heating load between day and night, the power load of heat pump heating system varies greatly day and night. Furthermore, the rapid growth of heat pump heating systems for meeting the requirement of low carbon heating will result in more and more serious electricity fluctuation, which will threaten the stability of the power grid. In order to reduce this power fluctuation, a single-heat-pump heating system with water tank thermal storage (SHPHSTS) is constructed. Based on the thermodynamic calculation of the heat pump refrigeration cycle, using step search optimization method, the operation parameters of the constructed heating system are optimized with the goal of constant power consumption from power grid within a day. Then, the corresponding electricity consumption and power fluctuation, after adopting the proposed operation optimization strategy in heating season are analyzed. At last, function of power fluctuation (FL) and degree of fluctuation (DF and DF’) are proposed to quantitatively evaluate the effect of the power fluctuation reduction in heating season, and the correlation between the electricity consumption of the heating system and power grid load is analyzed. The results show that due to the thermal storage of HWST and the optimizing operation strategy, constant power consumption of heating system could be realized within a day. On the typical heating day, the power consumption in traditional peak time reduces by 60.8%, and the electric bill is 22% lower compared with that of the traditional heat pump heating system. Furthermore, the power consumption fluctuation during the whole heating season reduces substantially, the power fluctuation function reduces from 460% to 150% by adopting the proposed operation optimization strategy. The correlation analysis indicates that the busy degree of power grid in peak time could be relieved by thermal storage and the optimizing operation strategy. Consequently, the peak of power consumption of heat pump heating system could be decoupled from the peak of power grid.