The future of power grids is expected to face a surge in the number of power electronics devices connected to it. This increases the possibility of resonances occurring due to harmonic current injections which is known the harmonic instability. In order to further study this phenomenon, models which are both capable of capturing the harmonic characteristics of the power electronic devices and are computationally inexpensive need to be developed. In this paper a Hammerstein-Wiener identification approach is proposed to develop a black box model for a voltage source converter which is capable of meeting such requirements. The approach is implemented in a simulation environment and then tested on a commercial photo-voltaic inverter for validation.