Optimum enhancement of voltage profile of the droop controlled islanded microgrid by incorporating shunt capacitors and active power DGs using PSO and SPBO algorithm

This paper investigates the enhancement of the voltage profile of a 33-bus islanded droop-controlled microgrid through the coordinated incorporation of shunt capacitors and active power distributed generators (DGs). The voltage deviation index (VDI) is considered as the objective function. Two allocation strategies are examined. In the first, a 2-step method is employed: candidate locations are identified using sequential load sensitivity analysis, and DG sizes are optimized using student psychology-based optimization (SPBO) and particle swarm optimization (PSO). In the second approach, locations and sizes are determined simultaneously through the mixed discrete versions of SPBO (MDSPBO) and PSO (MDPSO). Simulation results reveal that VDI decreases significantly with the integration of shunt capacitors and/or DGs, with combined placement providing the greatest improvement compared to individual use. The MDSPBO algorithm achieves a minimum VDI of 0.0166 p.u., nearly 1/3 of that obtained by the 2-step method with 4 DGs and 4 shunt capacitors. Furthermore, a 97.8% VDI reduction is achieved with the simultaneous incorporation of 4 unity power factor (UPF) DGs and 4 shunt capacitors using MDSPBO. The analysis also highlights that the coordinated integration of PV-based DGs (UPF DGs) and shunt capacitors yields considerable economic and environmental benefits, including increased annual profit and reduced emissions. Hence, optimum placement of UPF DG and shunt capacitor is found to be technically as well as economically and environmentally beneficial for the droop-controlled microgrid. The study also reveals that simultaneous optimization of sizes and location using MDSPBO yields better results compared to the 2-step method. • A novel approach for optimum enhancement of voltage profile has been proposed. • Simultaneous placement of DGs and shunt capacitors enhances voltage profile. • The study has been carried out using PSO and SPBO optimization algorithms. • Two-step and mixed discrete optimization methods are comparatively analyzed. • Voltage profile becomes nearly flat with MDSPBO optimization strategy.