STABILITY ANALYSIS OF DROOP-CONTROLLED INVERTER-BASED POWER SYSTEMS

Abstract

Future power systems are expected to have a high penetration of inverter-based generation, storage, and load, clustered into microgrids for reliable operation. Within each microgrid, inverters must operate in the grid-forming mode to regulate voltage and absorb load disturbances. The small-signal stability of such microgrids is of vital concern due to low system inertia, and is primarily influenced by the power sharing strategy adopted. In this thesis, we consider droop control, and develop techniques to preserve the system stability irrespective of the network topology, number of inverters, and controller parameters. At the same time, strategies are presented to recover the damping in real time during possible contingencies. This thesis provides a microgrid operator with both offline and online control design tools. The former maximize the stability region of control parameters, whereas the latter allow the operator to maximize the dynamic performance by maintaining the system close to the stability boundary.