Improved droop control method in microgrid and its small signal stability analysis

The P/f and Q/V droop control is a promising load share strategy among distributed generation (DG) units in microgrid. Based on the conventional droop control, an improved droop control with voltage amplitude feedback PI control is proposed in this paper to achieving more controllable output voltage amplitude and more reasonable loading rate between DGs. Moreover, with the improved droop control, the microgrid operating stability is also enhanced effectively under the large droop coefficient for the outer active power allocation loop. A small-signal state-space model of the microgrid containing two DG units with and without the proposed improved droop control is developed for eigenvalue analysis. The effectiveness of this improved control strategy is further validated by he time domain simulation.