A Robust Circuit and Controller Parameters' Identification Method of Grid-Connected Voltage-Source Converters Using Vector Fitting Algorithm

This article presents a vector fitting (VF) algorithmbased robust circuit and controller parameters identification
method for grid-connected voltage source converters (VSCs).
The dq-domain impedance frequency responses (IFRs) of the
VSCs are first measured using frequency scanning method, based
on which the corresponding measured phasor-domain IFRs are
calculated. Then, polynomial transfer functions are generated by
applying the VF algorithm on the measured phasor-domain IFRs,
from which the circuit and controller parameters, i.e., LCL filter
parameters, digital sampling time, current controller parameters,
and phase-locked loop parameters, are identified. Influence of
measurement noise on parameters identification accuracy and
corresponding countermeasure to mitigate the adverse influence
are also theoretically investigated. The proposed method is able
to identify the circuit and controller parameters, when detailed
parameters are missing due to industrial secrecy or parameters
variation caused by operating condition change, temperature
fluctuation, or aging. Effectiveness of the proposed circuit and
controller parameters identification method is validated by theoretical demonstration, OPAL-RT-based real-time simulation, and
experimental validation.
Index Terms—Impedance frequency responses, parameters
identification, polynomial transfer function, vector fitting algorithm, voltage source converter.