Unified SISO Loop Gain Modeling, Measurement, and Stability Analysis of Three-Phase Voltage Source Converters-0811.pdf (2.22 MB)
Download fileUnified SISO Loop Gain Modeling, Measurement, and Stability Analysis of Three-Phase Voltage Source Converters
Frequency-domain modeling
is an effective technique in the dynamic analysis of power electronic
converters-based power systems. In this paper, a unified single-input
single-output (SISO) loop gain modeling for the three-phase grid-tied VSCs
under both symmetric and asymmetric ac grids is presented, which facilitates the
physical measurement and stability analysis. Based on the linear-time-periodic (LTP)
modeling technique, the harmonic admittance model of the three-phase grid-tied
VSC is developed in the stationary (αβ)-frame. Instead of the transfer
function matrix, the frequency-coupling effects are modeled by the transfer
function vector, which simplifies the modeling process. According to the idea
of mathematical induction, a two-by-two recursive admittance matrix (RAM) model
that can accurately capture the coupling dynamics introduced by the power grid is derived. The RAM
has an analytical form and is easy to include harmonic coupling components of
arbitrary order. Furthermore, the RAM is converted to its equivalent SISO
models following the concept of loop gain. The system stability is
thus assessed by the SISO stability criteria (e.g.,
Nyquist stability criterion). In addition,
the loop gain allows the traditional SISO perturbation
and measurement scheme to be used for detecting the stability margin
information. Finally, simulation results verify the feasibility and correctness
of the theoretical analysis presented above.
History
Email Address of Submitting Author
mltortoise@163.comSubmitting Author's Institution
Schoolo of Automation, Central South UniversitySubmitting Author's Country
- China