In meshed low voltage DC distribution grids, one of the main challenges is achieving controllability of the power flow. The most common approach to achieve the full control over the power flow in the meshed DC grid is to deploy DC-DC converters rated for the full power rating of the grid. The drawbacks of this solution are costs and losses of such DC-DC converters. To reduce the costs and the losses from the system standpoint, we introduce a partially rated power flow control converter. This paper presents the control modes of the partially rated power flow control converter and experimentally demonstrates its functionality. The proposed power flow control converter consists of two cascaded converters. On one side the converter is rated for the maximum grid voltage but only a fraction of the grid current, and on the other side, it is rated for the maximum grid current but only a fraction of the grid voltage. The proposed converter can operate in three modes and demonstrates the power flow control capability.@en

Inside the meshed LVDC distribution grids the power flow is predominantly limited by the line impedances. In order to achieve economical and flexible operation of the meshed LVDC distribution grids, it is required to control the power flow. For that end, the line impedances need to be adjustable. The line impedance can be controlled by a DC-DC transformer, however, it needs to be rated for the full grid power. In order to reduce the installation costs, a partially rated device is desirable. Therefore, a partially rated power flow control converter (PFCC) is proposed. This paper presents the PFCC performance estimate and demonstrates the PFCC functionality. The PFCC is an economical solution for increasing the controllability of the power flow in the meshed LVDC distribution grids. However, due to high step down ratio inside the PFCC achieving efficient performance is challenging. Furthermore, due to unavoidable MOSFET paralleling the part count rises. The proposed PFCC consists of two cascaded converters, therefore the control range and stability depends, besides else, on the impedance interaction between the two stages.

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