A Model of a DC/AC Droop Controlled Inverter that includes DC Side Dynamics
Authors: Mahmoud Kabalan, Dr. Pritpal Singh, Dr. Dagmar Niebur
Abstract: DC/AC droop controlled inverters are used in a wide range of applications to convert dc energy into ac energy. However, most inverter models neglect an important feature of these inverters which is the dc side dynamics. The dc source could be a solar photovoltaic system, a battery bank or a fuel cell. Thus, it is important to account for the dc side dynamics since the dc source could be variable, intermittent or stochastic. In this paper, a new mathematical model of a dc/ac droop controller-voltage source inverter is proposed that includes the dc side dynamics. The inverter’s model consists of proportional-integral voltage and current controllers, droop controllers and a pulse width modulation (PWM) circuit. Simulations were carried out to test the model with a variety of load types such as an infinite bus, constant impedance load and constant power load. The simulation results show the four quadrant operational capability of the proposed mathematical model. The model would be useful for future studies of inverter-based microgrids and shipboard electric systems.