Comparison of two black-box model identification methods applied on a VSC with LCL filter

Abstract

This work proposes and compares two multivariable identification methods that obtain the discrete state-space model of a grid-connected Voltage Source Converter with LCL filter. The two methods are based on two of the so-called subspace identification methods: the Multivariable Output Error State sPace (MOESP) and the Numerical algorithm for Subspace State Space System Identification (N4SID) methods. That kind of methods is based on the QR decomposition and the singular value decomposition (SVD) and works with black-box model structures, which are particularly flexible in the choice of the model representation. The so-obtained discrete state-space model of the converter could be used to design directly a controller for the system using advanced control techniques as optimal control, robust control, etc.