Impedance Detection Based on Ripple Analysis and Current Sharing Control in DC Microgrid

Abstract

In the operation of DC micro grid, the uniform load distribution is beneficial to the stable operation of the system and prolongs the service life of the system. In order to solve the influence of line impedance on traditional droop control in DC micro-grid, an impedance detection method based on ripple analysis and the structural characteristics of the DC micro-grid system is proposed. The high-frequency harmonic component of microgrid output current and voltage is mainly from the transistor switching frequency. By using the Fourier transform to analyze the high-frequency harmonic component of the voltage and current detected by the converter, the impedance information is obtained, and then the droop control is compensated base on it. In this paper, the compensation method is extended to the application of multiple devices in parallel. This method does not directly operate the system, so it has done no harm to the power quality. Finally, the feasibility of the proposed method in normal working conditions and its effectiveness in the case of communication interruption and load change is verified by RT-LAB hardware in loop experiment.

Keywords

• DC micro grid
• impedance detection
• ripple analysis
• current sharing