EWH: In this paper, the DC bus voltage is controlled by the voltage control of the controllable loads. EWH and
battery are used as controllable load in this research. The decentralized EWH model for each house group in the DC grid
is illustrated in Fig. 5(a). The EWH is modeled as a current source, and each EWH is controlled to consume in rated range.
The temperature of accumulated water of EWH is controlled by feedback control with integral of power consumption.
In the control system, the DC bus voltage fluctuation is suppressed by the droop control. As shown in Fig. 5(a),
the power consumption command IE is decided by droop coefficient RE and controlled variable Ite by PIE controller
of impounded water temperature TE. The design of the droop coefficient RE is explained in the next section.