A Gray-Box Parameters Identification Method of Voltage Source Converter Using Vector Fitting Algorithm

This paper presents a vector fitting (VF)algorithm-based gray-box structure and parameters identification method for voltage source converter(VSC). Terminal impedance frequency responses of VSC is first measured by frequency scanning method. Then, these impedance frequency responses are fitted by a polynomial transfer function using VF algorithm. Finally, the theoretical terminal impedance formulas of possible control structures are compared with the fitted transfer function. The actual control structure can be selected, and the actual internal parameters can be identified. Simulation results are given to validate effectiveness of the proposed method. The proposed gray-box method can identify both the circuit and controller information even if no internal information of the VSC is provided by vendors due to industrial confidence. In addition, the effect of measurement noise on parameters identification accuracy can be mitigated by increasing the order of the fitted transfer function.