Experimental analysis of voltage distortion caused by distributed energy systems in a low-voltage grid node using power-hardware-in-the-loop

The growing penetration of distributed energy resources based on power electronic components, such as photovoltaic inverters and electric vehicle charging infrastructure, is altering the operational behaviour of low-voltage distribution networks. This paper presents a method for analysing voltage quality using a standardized and reproducible Power-Hardware-in-the-Loop test environment. Real hardware operates under defined grid conditions using a low-voltage network model with a standardized source impedance. Voltages and currents are recorded with high temporal resolution and evaluated using established power quality indicators, including total harmonic distortion, individual harmonics, root mean square values, and voltage unbalance. The study examines several operating scenarios, including photovoltaic feed-in, vehicle charging, vehicle-to-grid operation, and combined cases. The setup enables time-resolved analysis of dynamic effects, such as fluctuating PV generation or state-of-charge-dependent behaviour of electric vehicles. As the experiments are conducted in an isolated test environment, external disturbances are eliminated, ensuring repeatable and comparable results across different configurations.