Dynamic Voltage Stability Analysis in Multi-machine Power Systems

This paper presents a novel approach for power system dynamic voltage stability analysis based on the multi-input multi-output (MIMO) transfer function. The MIMO system is defined taking into account the critical nodal voltages as outputs and possible control variables as the input. Based on the modal analysis and singular value analysis, the dynamic voltage stability analysis is carried out. The proposed approach takes the advantages of the classical static voltage stability analysis and the modern multi-variable feedback control theory. The singular values and singular vectors are calculated for frequencies corresponding to the critical system modes. The output singular vectors provide an overview as to which outputs and thus which nodes are most affected by the voltage instability. Using the magnitudes of the input singular vectors the most suitable inputs for countermeasures can be selected. The proposed method is also applicable to very large systems.