Stability margin monitoring for DC distributed power systems via current/voltage perturbation

The small-signal stability issues in multi-module power electronics systems, especially DC distributed power systems, are often dealt with by employing the impedance criterion. However, for online system stability monitoring, directly measuring impedance of the source and load subsystems then making comparisons is too complicated and difficult. This paper proposes practical and simple methods, which involve applying current or voltage perturbation to the DC side of distributed power systems then only measuring the amplitude of two currents or voltages in order to monitor the stability margin. For both methods (current perturbation and voltage perturbation), an implementation approach that does not employ external voltage perturbation source is also presented. A comparative evaluation of each method and its corresponding implementation approach is provided.