Comparative Eigenvalue Analysis of Synchronous Machine Emulations and Synchronous Machines

This paper presents a comparative eigenvalue analysis
of the stability characteristics and small signal dynamics
of four different control strategies for Synchronous Machine
Emulation (SME) by power electronic converters, considering a
Synchronous Machine (SM) as the benchmark system. The four
SME techniques are selected to represent the most established
general approaches for emulating the inertial characteristics of
SMs in the control of power electronic converters. The smallsignal
stability assessment is based on the analysis of system
eigenvalues, including evaluation of participation factors and
parametric sensitivities. All the investigated techniques can be
tuned to obtain similar inertial dynamics under grid frequency
variations, but exhibit differences in other small-signal characteristics
due to the distinct control system implementations. Among
the analyzed cases, the current-controlled virtual synchronous
machine has the highest damping of the most oscillatory mode.
However, the study shows that the most oscillatory modes of the
other techniques are associated with the LCL impedance, and
could be further attenuated by active damping techniques.