Study on the contribution to Electric Demand-Supply Control by District Heating and Cooling System with Electric Heat Pumps

摘要

At present, much attention to power generations from renewable energy sources such asphotovoltaic (PV) generations and wind power generations has been gained. In Japan a lot ofPV generations are expected to be installed in the future. When a lot of PV generations areinterconnected to power system, however, surplus power issue will occur. Installation ofBattery Energy Storage System (BESS) is an effective solution to surplus power issue. Butbecause BESS is expensive, other solutions are also studied. As one of more economicalsolution to the surplus power issue, an effective use of District Heating and Cooling system(DHC) is proposed in this paper. Recently DHCs have been equipped with Combined Heatand Power (CHP) because of its high total efficiency, and some DHCs will be equipped withelectric heat pump because of its high COP (Coefficient Of Performance). DHC with CHPand electric heat pump buys and sells power from and to power system, and it can contributeto power system by absorbing the surplus power from renewable energy sources. In this paper,the cost increase by the DHC contribution is studied, and it is shown that the cost increase iscalculated by two sorts of the optimal operation of DHC. One is the normal operation underwhich the running cost of DHC is minimized, and the other is an optimal operation underwhich the DHC absorbs the surplus power from power system. The cost increase by the DHCcontribution is given by the difference between the costs of the two optimal operations. Fromthe cost increase calculated by the proposed method, the effectiveness of DHC is discussed.