Microgrid stability enhancement by incorporating BESS droop gain tuning

The distributed generator (DG) droop gains in a microgrid are mainly determined by load sharing purposes and may not be beneficial to system stability. In this paper, for enhancing the microgrid stability under small disturbance, a BESS droop tuning scheme in an inverter-based microgrid is established. Firstly, instead of treating BESS as adjustable power injections, we introduce droop control scheme into BESS so that BESS can provide both power injection support under steady-state condition and dynamical support under disturbances. Then, by applying the linear power flow model, we propose a small signal stability constrained optimal power flow (SSSC-OPF) problem to tune BESS droop gains for minimizing the system generation cost while ensuring the system stability. Further, the Benders decomposition-based method with sensitivity analysis is applied to solve the optimization model, where the problem for each iteration is a Quadratic Programming (QP). Finally, the proposed approach is adopted in a modified IEEE-14 system, simulation results demonstrate that the stability performance will be significantly improved with rather small impact on generation cost and short CPU time.