Bi-Directional Four Quadrant DC/AC Droop-Controlled Inverter Model that Accounts for DC Side Dynamics

The current revisions of IEEE 1547 standard, California rule 21 and Hawaii rule 14H, if ratified, would allow 4 quadrant operation of distributed energy resources DERs. That means that a DER could produce and/or consume real and reactive powers (P and Q) to support the grid. Many DERs utilize dc/ac droop-controlled inverters and thus these inverters need to be bi-directional to produce or consume P and Q. Hence, dc side circuitry could be included to allow a bi-directional inverter to absorb P and/or Q. In this paper, a new model of a bi-directional dc/ac droop-controller voltage source inverter is proposed that includes the dc side dynamics. The inverters model consists of proportional-integral voltage and current controllers, droop controllers and a pulse width modulation (PWM) circuit. Simulation results show the four quadrant operational capability of the proposed inverter model. The model could serve as a basis for future IEEE 1547 compliant inverters.