Transient droop for improved transient load sharing in microgrids

Abstract

Inverters and synchronous generators in islanded microgrids exhibit poor transient load sharing where the inverter initially picks up the majority of any load step. Transient voltage and frequency droop are proposed to allow the inverter voltage and frequency to dip more during transients to improve the transient load sharing, reduce peak inverter power requirements, and allow the microgrid designer more control over the transient load sharing characteristics. The impact of the transient droop terms on system stability is evaluated using small-signal analysis, and validation of the proposed method is provided by simulation and experimental results.

Overview of Power Management Strategies of Hybrid AC/DC Microgrid

“…In order to improve the transient power sharing, the coordination among DGs and conventional synchronous generators is necessary, and the DGs must allow the voltage and frequency to swing in the expense of increased voltage and frequency dip. For example, in [105] control strategy has been modified for the droop control in order to improve the transient load sharing by changing the droop slope during transient and restoring it to normal in steady state. The synchronverter concept proposed in [106], [107] and synchronous converter concept proposed in [108] are other methods that allow the power electronic interfaced DGs to follow the conventional synchronous generators principles and may help the transient load sharing.…”

Evaluation of control methods to prevent prime-mover stalling in a mixed source microgrid

“…An investigation was carried out in [8] to fmd the cause for poor transient load sharing in an islanded microgrid. In [9] and [10], a modified droop control technique and virtual impedance was proposed to limit the inverter' s current during overloads. In summary, all these papers analyzed the microgrid performance assuming normal operating conditions.…”