  Linear Time Periodic (LTP) framework-based analysis of Voltage Source
Converters (VSCs) is becoming popular, a driven factor is that many of the
existing VSC applications inevitably exhibit the periodic steady-state (PSS),
e.g., VSCs with unbalanced grid connections and the operation of a modular
multilevel converter (MMC). In these studies, acquisition of the VSC's PSS
conditions is a necessary precondition for proper linearization and stability
analysis, and the efficiency of this process is particularly important for
parametric studies. To this end, this work develops a computational method for
automating the LTP analyses of VSCs with an integrated PSS solver. The core of
the method lies in a unified frequency-domain iteration process that is
developed by applying the generalized averaging principle. Given this,
modeling, stability analysis, as well as the solution of PSS conditions can be
unified in one process. The algorithmic implementation of the method in MATLAB
is elaborated. Application of the obtained tool in impedance generation and
parametric stability test is presented with an unbalanced grid-tied VSC as the
exemplification. Finally, PSCAD/EMTDC simulations further consolidate the
validity of the results.
