Impact of active resistance on dynamic power responses in a CERTS microgrid

Abstract

Frequency droop algorithms used by CERTS Microgrid inverters adjust power by changing the output frequency. This concept assumes that the interconnecting impedance is primarily inductive, but it can be shown that the reactance-to-resistance (X/R) ratio significantly affects the dynamic response and the rate at which steady-state behavior is restored following transient events. The concept of active resistance is introduced as a means to accelerate the rate of convergence to steady state following a transient without the dissipative losses associated with additional line resistance. With active resistance, the damping of the system is shown to significantly increase and the stable operating region is expanded.

Improved power control bandwidth of grid-forming sources in a CERTS microgrid

“…The block diagram in Figure B1 shows the CERTS frequency droop controller including the power limit feature, used for both dynamic simulation and experimental tests [3] [5]. The total frequency droop gain when operating in the power-limited mode is Mp + KpPmax.…”