A multi-objective planning approach for optimal DG allocation for droop based microgrids

Abstract

This paper proposes a multi-objective planning approach to determine the optimal DG locations for droop-based microgrids. A secondary control operating region is mathematically formulated and incor-porated in the multi-objective optimization problem to constrain the optimal droop characteristic within the acceptable frequency and voltage thresholds. The proposed planning problem is formulated as a Mixed Integer Non-Linear Programming (MINLP) problem and is tested on a modified version of the IEEE 38 bus system operated as an islanded microgrid. The proposed approach is applied to the three most common microgrid control strategies: P-f/Q-V droop, the P-V/Q-f droop and master/slave. The proposed formulation is compared to existing planning algorithms for droop-based microgrids. The re-sults show that including the secondary control region in the optimization problem achieves lower volt-age deviations and no frequency deviations at all demand levels. The optimal DG allocation solution may vary from the cases where the droop gains or references are fixed.