Modeling of a PV system with grid code compatibility

•Transient model of a two-stage grid-connected PV system with LVRT capability introduced in the paper. Modeled system satisfies present day grid code requirements.•Enhanced DC/DC converter controller, which reconfigures the operating point of the PV generator during faults.•“Transient-type” model (EMF behind impedance) is derived for the PV system, based on time-averaged converter models and a simplified, series inductance representation of the LCL output filter.•Simplified model accurate enough and suitable for transient stability studies in large networks.

Increasing penetration of Renewable Energy Sources (RES) to the power systems leads to the continuous evolution of grid interconnection requirements, which now include Low Voltage Ride Through (LVRT) practically for all types of generating units connected to the MV or HV networks, including photovoltaics (PV). It is essential that the Distributed Generation (DG) models used in power system studies properly represent the enhanced response characteristics of the stations. In this paper, a model is presented for a PV system with grid-code compatibility, which is suitable for power system dynamic and transient analysis studies. For this purpose, an overall control strategy is introduced to achieve LVRT capability, while elements essential for the correct representation of the dynamic performance of the system, such as the Phase Locked Loop (PLL) and the output LCL filters, are properly accounted for. Time domain simulations are provided for balanced and unbalanced voltage dips, in order to demonstrate the performance of the PV system and evaluate the accuracy of the proposed simplified model. The response of the detailed switching model is also included in the simulation results.