Modelling of PV systems as distributed energy resources for steady-state power flow studies

Abstract This paper introduces a PV system model useful for steady-state power flow studies of practical electrical networks. This multi-array PV system model features a comprehensive representation of the three main stages taking part in solar energy conversion systems: (i) PV arrays for the solar-to-electrical energy conversion, (ii) the DC boost converter useful for establishing the MPPT strategy and for stepping up the output voltage of the PV arrays, and (iii) the DC-to-AC power conversion by the voltage source converter (VSC) used to link the PV system with the AC grid. The derived PV system model is flexible and modular as it permits to consider any desired number of PV arrays with different irradiance conditions each. For validation purposes, a 1.5-MW PV system coupled to a 3-bus AC network was simulated. Its steady-state power flow results were compared against those obtained by a highly-detailed switching-based PV model implemented in Simulink©. It is shown that the proposed model retains sufficient accuracy since the computed relative errors were inferior to 2% between both fundamentally different methods. The IEEE 57-bus test grid is also used to incorporate five PV plants, thus showing the practicality of the introduced modeling approach for distributed PV systems.