Early prevention of instability-use of self propagating graph for the fast search for optimal grid nodes to apply countermeasures

This paper presents a method for a fast determination of the grid nodes where countermeasures, in the form of changes in nodal admittance, would provide greatest impact on the stability margin for a specific generator that is facing the risk of instability. The sensitivity of the stability criteria for aperiodic small signal angular stability to the change in nodal admittance is used as a factor quantifying impact that the node has on the stability of a critical generator. In order to lower the number of nodes which are processed through sensitivity analysis, a self-propagating graph with discrete steps is applied. The suggested method is tested on the IEEE 30 bus test system and on the 1648 bus US west coast test system where the results show that the number of nodes processed through sensitivity analysis are well reduced compared to the full sensitivity analysis, illustrating the potential of the developed approach for the fast identification of the optimal nodes for countermeasure application.