Three-step impedance criterion for small-signal stability analysis in two-stage DC distributed power systems |
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Authors: | Xiaopeng Wang Ruoping Yao Fangquan Rao |
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Affiliation: | Dept. of Electr. Eng., Shanghai Jiao Tong Univ., China; |
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Abstract: | Small-signal stability analysis methods based on an impedance criterion originate from the minor loop gain method and are gradually utilized in two-stage DC distributed power systems. In this paper, we conclude that the impedance criterion directly dependent on output impedance Z/sub o/(s) of the source subsystem and input impedance Z/sub i/(s) of the load subsystem is possible but gives an incorrect stability analysis for systems with a regulated source subsystem. Through introducing a mapped pure impedance of the load subsystems and the preliminary system, we develop a general three-step impedance criterion, with which a correct small-signal stability analysis can be guaranteed, regardless of the type of source subsystem. Furthermore, we introduce the application of the three-step impedance criterion in two small-signal stability analysis cases and utilize it in an example system to predict the stability shift process arising from the variation on the load resistance and input voltage value. |
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