Improved Energy Management Scheme in Active Distribution Network with Grid-tied Microgrids

Abstract

This paper proposes an improved energy management scheme in an active distribution network with grid-tied microgrids (MGs). The proposed scheme consists of two control layers to enhance energy management performance. An active-reactive optimal power flow model is formulated in the upper layer to coordinate DGs’ curtailment rate and power injection from grid-tied MGs. Moreover, an energy management model is developed in the lower layer, which schedules the power generation in grid-tied MGs. The lower layer model also determines the adjustable range for the power injection from grid-tied MGs. The adjustable range is set as complementary constraints in the upper layer model. Comparative case studies were performed on a modified 11 nodes distribution system to validate the advantages of the proposed scheme. Compared to the traditional energy management scheme in which active and reactive power from DGs and MGs are not fully leveraged, the proposed method improves the distribution network’s power quality. It also significantly reduces the active power loss and renewable generation curtailment cost in the distribution network and the fuel cost in grid-tied MGs.