Control of Multilevel Converters for High Penetration of Renewable Energies

Increasing integration of converter-interfaced renewable power generation challenges the stability of the frequency in the modern power systems due to the lack of inertia in this type of generators. In this regard, this paper establishes a control method for controlling multilevel converters as an interface between renewable power generation and the power grid, which enables them to operate as voltage-controlled sources, thus grid-forming capabilities like conventional synchronous generators (SGs). In fact, the proposed control technique mimics the behavior of synchronous generators in the control loop of the neutral point clamped (NPC) converter. Consequently, supportive functionalities for frequency stability i.e., inertia and frequency/power oscillation damping will be provided by the multilevel converter as a virtual synchronous generator (VSG). Simulation results in Matlab/Simulink verifies the well-designed inertia and damping features for the interfaced converter as well as appropriate performance of multilevel converter in reducing total harmonic distortion (THD).