Effects of DQ Droop Settings on Energy Storage Systems of Inverter-Based Microgrids

Abstract

The distributed nature of micro-sources with intermittent behavior requires development of appropriate microgrid integration schemes. In a system comprising of solely renewable sources that have no inertia, the operation at a fixed frequency with effective power sharing capability is a viable solution. This paper presents the effects of dc droop settings on the energy storage systems of three-phase microgrids that utilize a dq droop control for power sharing at a fixed frequency. The microgrid control is modeled according to the Hamiltonian Surface Shaping and Power Flow Control (HSSPFC) scheme. The energy storage control law is developed so that the required storage is in a minimal form however, the choice of grid-side local droop control settings may impose significant burden on source-side dc energy storage systems. Two simulation examples of energy storage requirements versus the dq droop settings are presented in this paper.