A Coherency Identification Approach for Low-Inertia Power Systems

This paper presents a new approach for identifying coherent groups in synchronous generators for frequency stability assessment. A combined Calinski-Harabasz criterion and
$k$
-means clustering algorithm is developed for the determination of the cluster groups in power system. The electrical distances between different generators in the system are considered for partitioning the clusters into frequency control areas. A progressive decommissioning of generation units with rotating masses and their replacement by large-scale integration of inverter-based renewable generation influences the current and future power system dynamic behavior due to the decrease of system inertia. Also, low-inertia power system impacts the system frequency, operation of protection systems and shedding of loads/generators for System Protection Schemes. The proposed approach is successfully implemented and validated on New England IEEE 39-bus test system for evaluating power system frequency stability robustness.