A normal form analysis approach to siting power system stabilizers (PSSs) and assessing power system nonlinear behavior

A nonlinear analysis framework based on normal form (NF) theory and center manifold reduction is proposed to determine the most effective selection of generating units to be equipped with power system stabilizers. The proposed method takes into account the nonlinear system structure and provides information on the effect of control action on nonlinear behavior and modal interaction. Based on a second-order NF representation of the system, the effect of control action on nonlinear behavior is approximated via suitable modification of the initial conditions in the nonlinear coordinate transformations which relate the physical system to the NF coordinates. On the basis of this model, nonlinear power system stabilizer (PSS) sensitivity indices are then proposed to determine the optimum sites to allocate PSS, and criteria to assess the effect of control action on linear modal interaction are developed. Examples of application of the developed approaches on a two-area four-machine test system are presented to estimate controllers' effects on system dynamic performance. The efficacy and accuracy of the method is demonstrated by comparisons to conventional analysis techniques.