Decoupled Control to Improve DC-Link Dynamics of Energy-Storage-Equipped STATCOM

Energy-storage-equipped static synchronous compensator (E-STATCOM) plays an important role in a modern power grid. Such a compensator can be efficiently applied to control the active and reactive power thus improving the voltage and frequency stability especially in a power grid that is dominated by renewable energy resources. A challenge using an E-STATCOM is to minimize the adverse effect of the AC components present in the DC-link voltage especially during charging and discharging of an energy-storage system (ESS). This paper proposes a novel application of the dq- decoupled control to minimize the undesired dynamical effect of the ESS on the DC-link voltage of the E-STATCOM. In this method active and reactive power are decoupled by eliminating the dq- frame cross-coupling terms using reference current produced by the power controller instead of the measured inductor current. Experimental measurements are shown to demonstrate the effectiveness of the proposed method.