Operation Method of Autonomous Demand Area Power System to Utilize Surplus Power of PV Systems by using Heat Pump Hot Water Heaters and Electric Energy Storage Systems

Abstract

Large penetration of photovoltaic (PV) generation systems into power system will cause surplus power of whole power system, which will be caused by that the sum of the generated power of PVs and minimal output power of generators operating in power system exceed the total electricity demand of whole power system. One of the measures for suppressing the surplus power is using electric energy storage system. However, when the surplus energy exceeds the storage capacity of electric energy storage system, it would be necessary to suppress the output power of PV by setting the output power limit on PV. In order to utilize the surplus power, authors have proposed the daytime operation of heat pump hot water heaters (HPWHs). By considering the customer's convenience, the operation schedules of each customer are varied because of the difference of hot water demand of each customer, and there is possibility to utilize the surplus power more effectively by considering operation schedules of all customers and setting output power limit to appropriate level. This paper proposes the method to determine the appropriate level of the output power limit of PV based on operation patterns of HPWHs of each customer. The proposed method considers the operation of electric energy storage system installed in power system by keeping the integral of the sum of the reverse power flow from each customer in daytime to be constant. The simulation results shows that proposed method reduce the suppressed output power energy of PV effectively compared with the case that determined the output power limit of PV without considering the operation schedule of HPWHs of all customers.