Tuning of Control Loops for Grid-Connected Modular Multilevel Converters under a Simplified Port Representation for Large System Studies
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One of the present barriers to the widespread use of Modular Multilevel Converters (MMC) is the complexity of its control with respect to its predecessors. This paper presents a simple procedure to tune the current and energy control loops of the MMC, based on standard PI controllers and resembles control tuning approaches commonly used for 2-Level Voltage Source Converters (2L-VSC). The control design is based on a recently proposed simplified model of the MMC which is able to accurately represent the interface variables dynamics on the ac- and dc-side, which are considered as the main variables of concern from a macroscopic point of view. Furthermore, the tuning methodology guarantees the stable behaviour and correct tracking of the states. The paper presents simulation results of a typical case under the proposed tuning procedure.