Abstract
According to different partitioning styles, there exist different
impedance-based stability analysis methods for complex systems such as
voltage source converter (VSC)-based high-voltage direct current (HVDC)
systems. Thus, the determination of the partitioning method is of
importance in impedance-based stability analysis. However, how to
partition a complex system is not paid much attention in the past. In
this paper, the partitioning problems are revisited and a set of
practical partitioning principles are proposed. Based on the principles,
the VSC-HVDC system is partitioned into five parts, satisfying
simplicity and integrity. In addition, the methods to form the
equivalent circuits of the sub-systems are given and the equivalent
circuits of the sub-systems are built, which is helpful to obtain the
input-output models of the sub-systems. Furthermore, a stability
criterion by directly applying argument principle is used instead of the
generalized Nyquist criterion (GNC), which could avoid the calculation
of eigenvalue transfer functions, especially when a large number of
sub-systems are involved. Finally, the correctness of the
impedance-based stability analysis method is verified by control
hardware-in-loop (CHIL) experimental results.