Stability monitoring using voltage perturbation for DC distributed power systems

The stability issues in nonlinear systems such as multi-module power electronics systems, especially DC distributed power systems, are often dealt with by employing the impedance criterion. However, for on-line system stability monitoring, to direct measure the impedance of the source and load subsystems and then making comparisons is complicated and difficult. This paper proposes a practical and simple method, which involves utilizing voltage perturbation, to monitor the stability margin of DC distributed power systems. A voltage perturbation source is applied to the DC side of the system and only the amplitude of two voltages needs to be measured, therefore this method can be easily used for on-line stability monitoring. An implementation approach of this method, which does not employ additional voltage perturbation source but utilizes the front-end subsystem, is also presented. Theoretical analysis and computer simulations are given to verify the effectiveness of both the monitoring method and the implementation approach. A comparative evaluation of the voltage perturbation method versus the current perturbation method for stability monitoring is provided.