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

Abstract

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. I. INTRODUCTIONRenewable energy sources, such as wind power and solar power, have been increasingly penetrating into conventional

Insight into Frequency-Domain Extrapolations of Least-Squares-Based Curve Fitting Algorithms

“…It should be noted that (1) and the VF-routine-produced transfer function are in the same form in order to facilitate the subsequent analysis. In practice, the impedance/admittance models of physical devices (e.g., the voltage source converters) can be reformulated into (1) after appropriate linearizations [12]. Fig.…”

“…The vector fitting (VF) was originally proposed in [1] for black-box wideband modeling of transmission lines, transformers, and frequency-dependent network equivalents of complex distribution networks. Due to its high accuracy, robustness, and efficiency, the VF has been widely used and modified in many engineering communities, e.g., power system community [2]- [8], power electronic community [9]- [12], and electromagnetic compatibility community [13]- [16].…”

Application of Extrapolation Capability of Vector Fitting for Out-of-Band Dominant Modal Synthesis of Voltage-Source Converters

“…On its basis, the poorly-damped and unstable eigenvalues can be identified, and their participation factor analysis can further be performed in order to locate the root cause. Although mature and powerful, the state-space method can be hindered by the devices' black/gray-box feature [6], [7]. Since the admittance/impedance model is in essence the transfer function (matrix) reformulation of the SSM with appropriate input and output variables defined, the matrix fitting (MF) and vector fitting (VF) were recently applied as the inverse solving algorithms in order to identify the SSM from the admittance/impedance frequency responses (AFRs/IFRs) of the inverter-based power systems [8]- [11].…”

Extrapolation of Band-Limited Frequency Responses for Out-of-Band Modal Synthesis

“…For a specific fitting order, the VF can achieve the most accurate fitting result, whereas the other two techniques can reach the same accuracy as that of the VF at the cost of higher fitting order [9]. In addition, it has high robustness when fitting noisy or contaminated frequency samples [11]- [14]. Due to its high accuracy and robustness, the VF has been widely utilized in power electronic [11], electromagnetic compatibility [13], microwave [14], and power system [15], [16] communities in the last two decades.…”

“…In addition, it has high robustness when fitting noisy or contaminated frequency samples [11]- [14]. Due to its high accuracy and robustness, the VF has been widely utilized in power electronic [11], electromagnetic compatibility [13], microwave [14], and power system [15], [16] communities in the last two decades.…”