Decentralized Droop Control in DC Microgrids Based on a Frequency Injection Approach

Power sharing control among grid forming dc sources employing a conventional voltage droop approach meets inaccurate load sharing and unacceptable voltage regulation performance. Thereby, communication-based secondary and supervisory controllers have been presented to overcome the aforementioned issues. Furthermore, with the aim of eliminating communication system, frequency-based droop approaches have been introduced for low-voltage dc grids where the frequency of the superimposed ac signal onto the dc voltage is proportional to the output power. However, in reality, dc grid structures can be applied to medium and high voltage applications with different
X/R
ratios. This paper generalizes the frequency-based droop scheme for dc microgrids with different low, medium, and high
X/R
ratios. Obtained simulation and experiment results demonstrate the effectiveness of the proposed control method.