Design of an Innovative Structure for DC Electric Spring Based on Fully Isolated Three-Port Converter

The adjustment of DC bus voltage is one of the most critical challenges in DC microgrids. Any changes in power generation or load leads to voltage fluctuation. Recently, the DC electric spring (DCES) has been suggested for bus voltage adjustment and maintaining the DC network stability. An electric spring is a power electronic converter that adjusts the voltage of critical loads (sensitive loads) by utilizing the variations in the power of non-critical loads (insensitive loads). In this paper, a new structure of DCES, based on a fully isolated three-port converter (TPC), is presented. The proposed structure not only solves the issues associated with conventional structures, but it also provides isolation between critical and non-critical loads, as well as the battery energy storage system. Furthermore, the separate control of each port converter ensures that DCES has the required dynamic performance to keep a stable critical load voltage. Utilizing the suggested DCES structure produces an adequate voltage range for non-critical loads, reducing battery sizing and minimizing converter losses. The performance and feasibility of the three-port DC electric spring (TP-DCES) and its control method are acknowledged by the simulations carried out by the MATLAB/SIMULINK software for various scenarios.