DC Bus Signaling for DC Micro Grid System Based on Pulse Frequency Modulation

Abstract

In order to improve the reliability and efficiency of a DC micro grid system, a novel distributed control strategy is proposed by using a dc-bus signaling (DBS) based on pulse frequency modulation (PFM). The dc-bus voltage can be considered as one of system status information in the DBS for power management. This paper suggests switching noise carried on the dc-bus voltage as the system status data. By varying the switching frequency of a grid-connected bi-directional converter according to the load conditions, the frequency of the switching noise will changes. Other components of the DC micro-grid can recognize the status of the grid system by analyzing the frequency variations of the switching noise. Because the switching noise is not relative to the distance of the power flows, the proposed strategy can be an alternative solution of conventional distributed control strategies such as a voltage droop control. Experimental and simulation results will verify the practical feasibility and the effectiveness of the proposed DC-bus signaling strategy.