A co-frequency dynamic equivalence method for power-frequency dynamics simulation in multi-machine power systems

The calculation of power frequency dynamics in the case of sudden supply deficiency in multi-machine power systems always requires a lot of CPU time. To reduce the computation burden of this process, a co-frequency dynamic equivalence approach is proposed in which the root mean square values of generator speeds are used to form the co-frequency criterion, then the generators with the same frequency dynamics are identified by the criterion and aggregated. The co-frequency equivalence approach is compared in detail with some other different coherency methods, and its superiority over others in the calculation of frequency dynamics is proved