Emulation-Aimed Design of Model Fitting Methods for Grid-Connected Inverters

Model identification is necessary for system emulation in hardware-in-loop simulation. This paper design the implementation for complex curve fitting and vector fitting method on discrete domain. Differences between transfer function fitting methods are discussed about their based forms, convergence and accuracy. A LCL-type grid-connected inverter model is taken as an example for the tested transfer functions. The rationality and stability of the result transfer function is achieved by modifying the methods. Accuracy and stability of the proposed method is verified by simulation and experiments.