Advanced Modeling of a Synchronous Generator Under Line-Switching and Load-Rejection Tests for Isolated Grid Applications

This paper deals with an efficient method behind the analysis of a saturated synchronous generator (SG) under line-switching and load-rejection tests for islanded networks. This novel approach is based on a SG and (
P
,
V
,
Q
) load-equivalent combined state-space model. Full and partial load-rejection tests and line-switching tests are explored. The
k
-factor cross-saturation theory of SG is applied to account for the saturation phenomenon in the proposed model. The paper also attempts to point out the duality between line-switching and load-rejection tests. As the best alternative to the load-rejection test, the line-switching test is simple and more suitable, providing easy steady-state conditions (zero armature currents and rotor angle). Consequently, there is no need for rotor angle positioning when performing the test. Comparisons between simulation results and actual data obtained from a four-pole 1.5-kVA, 208-V, 60-Hz laboratory machine show the effectiveness of the proposed SG stator decrement tests analysis framework.