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This paper proposes a distributed control alternative for modular power converters. The focus is on the use of singlephase power units with embedded control capabilities, namely intelligent Power Electronics Building Block (iPEBB) for power conversion in hybrid DC/AC microgrids. The distributed control is achieved by the use of a versatile controller inside each iPEBB, so that they can operate independently by controlling their own voltage(s)/current(s). For the management of the entire system, a central controller is integrated into the control scheme. The central controller is in charge of the application-level control of the modular power converter, so that it determines the role of each iPEBB and commands the references to achieve the control goals. As a demonstration of the proposed approach, the control of a 4-wire 4-leg STATCOM using 4 independent power units is shown in this paper. For the implementation of the iPEBB control system, two different approaches are evaluated: Proportional-Resonant (PR) and Repetitive Control (RC) alternatives. Analysis is done using direct discrete design. Different simulations as well as experimental results are performed in order to validate the proposed system. The study considers communication delays between the central controller and the iPEBB as well as internal reconstruction of the reference from the central controller command.

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This paper proposes several alternatives for the compensation of power sharing errors in the DC bus of hybrid DC/AC microgrids. The case of study consists in a multi-port converter used for the interconnection of a AC grid-tied converter, a battery, a supercapacitor and a regenerative DC load that has to be supplied. The storage elements and the load are connected by means of DC/DC converters. The power sharing between the battery and the supercapacitor is determined by using an estimation of the load power. However, due to errors in sensors or control actions of the converters, the real load power is not exactly equal to the estimated one and hence a power mismatch is produced. Those mismatches are absorbed by the DC-link voltage, which is controlled by the grid-tied converter. However, considering restrictions in the grid-tied converter, the differences in the power sharing can compromise the operation and the stability of the system. In this paper, three compensation methods are proposed and compared. The proposed methods allow for the stable operation of the system, even with noticeable errors in the power sharing.