System frequency control by Heat Pump Water Heaters (HPWHs) on customer side based on statistical HPWH model in power system with a large penetration of renewable energy sources

It is expected to install a large amount of generation from renewable energy sources such as wind power generation and photovoltaic generation into power systems. However, a large penetration of such renewable energy sources causes some problems in power systems, e.g. frequency fluctuation. In this paper, a number of Heat Pump Water Heaters (HPWHs), one of the energy efficient-use customers´ appliances and Battery Energy Storage System (BESS) are considered as controllable equipment for frequency control. An HPWH is considered as a controllable load because the power consumption can be changed during water heating as long as the heating is finished when the customer would like to use. This paper proposes an effective control of HPWHs installed in the power system with a large penetration of renewable energy sources on the assumption of a two-way communication network. The control period is determined based on the statistical information of the HPWHs.