Fast measurement-based identification of small signal behaviour of commercial single-phase inverters

This paper presents a fast approach for a measurement-based method for the identification of the small signal behaviour of commercially available single-phase inverters. This small signal behaviour is typically represented by a frequency coupling matrix and is used for stability analysis and to derive black-box frequency domain models, e.g. for harmonic power flow studies. Typically, a large amount of measurements is required to identify the frequency coupling matrix of a single device. In case multiple small-signal models are required, i.e. in case of operating point dependency, the amount of measurements increases even further. However, the large number of required measurements is very time and energy consuming. This limits often the level of detail required for developing a comprehensive and accurate model. Therefore, this paper proposes an approach that significantly reduces the required measurements to identify the small signal model in terms of the admittance characteristic of commercially available single-phase inverters with unknown topology and parameters. The improved method is explained and tested for a commercial single-phase photovoltaic inverter in the laboratory.