Inertia-less power converters are one of the main obstructions to increase the penetration level of distributed energy resources in the utility grid. The stability of the power system mainly depends on the system inertia. Virtual synchronous machine and synchronverter-based grid-tied inverters have been introduced as a solution to this problem. Here, a modified selfsynchronised synchronverter is introduced to enhance the dynamic response of the active power loop and to limit the injected active/reactive power to the grid. Furthermore, the injected current to the grid is limited during faults employing proportionalresonant-based inner current loop. Feed-forward voltage is implemented in the current control loop to achieve seamless transfer between standalone and grid-connection modes of operation. Extensive simulation and experimental results are obtained to verify the proposed enhanced controller.

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Current fed solid-state transformers (CF-SSTs) offer substantial weight and size reduction advantages over 50/60Hz traditional transformers. CF-SSTs have low source current ripple which makes it suitable for the connection of large batteries in the medium voltage grid. However, power losses are high compare to the traditional one due to the high operating frequency range. Therefore, power losses calculations are the main key to select the main design parameters. Unlike most of the published work dealing one aspect of power losses or a specific element and only consider voltage fed Solid State Transformers topology (VF-SSTs), this paper presents a power losses calculation method for CF-SSTs considering all the power losses, the shape of the voltage waveforms, cores dimensions and manufacturer datasheets are main paper pros. ANSYS and Matlab Simulink are employed to validate the analytical equations. Due to simplicity, this method can be used for optimization.

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