Photovoltaic Energy Conversion System Integrated Into Unbalanced Distribution Electrical Networks Through Hardware in the Loop

Abstract

In this article, a real-time, hardware in the loop (HIL) and experimental photovoltaic energy conversion system (PVECS) integrated into unbalanced distribution electrical networks is presented. Commonly, the three-phase voltages are not balanced, because the input–output of single-phase loads in low and medium voltage networks. In this context, the photovoltaic (PV) systems integration under the dq0-Frame control operation scheme, tend to generate current deformations. In contrast, a new control technique for PVECS interconnection is validated in a HIL scheme, even in the presence of unbalanced voltage. This new technique is considered simple and easy to implement, since it consists of a single PI control loop, guaranteeing reliable operation under unbalances voltage events. Thus, preserving favorable characteristics, such as: 1) always balanced currents; 2) low harmonic distortion; 3) unit power factor; and 4) Compliance with the rules of the network code. The PVECS effectiveness is assessed by complete mathematical model, the simulation results are evaluated using MATLAB-Simulink (MATLAB r2018, Mathworks, Natick, MA, USA), and the experimental results are validated with a small-scale prototype operating in a HIL environment and the real-time simulator Opal-RT Technologies (Montreal, QC, Canada); integrating a power capacity of 15 kW in distribution networks.