Small signal analysis of microgrid with multiple micro sources based on reduced order model in islanding operation

Different from traditional power system, many kinds of micro sources are widely used in microgrid. These micro sources are often called DG (Distributed Generation), such as synchronous generator, induction generator and the voltage source converter. As a result of multiple micro sources existing in a microgrid, the transient model of the microgrid used in small signal analysis is very complex. This paper presents the modeling and analysis methods of an autonomous operation microgrid with three typical kinds of micro sources, i.e. synchronous generator, asynchronous generator and voltage source converter. A reduced order small signal model for electro-mechanical analysis was proposed. Each micro source is modeled in its local state-space form and then combined in a common reference frame. The microgrid model is linearized around an operating point and the system matrix is used to derive the eigenvalues. The eigenvalue analysis is presented to identify the stability and dynamic effect when the controller parameters and power rating of DG changes. The results are verified by the comparison with those obtained from time-domain simulation in the PSCAD/EMTDC which proves the correctness of the proposed method.