Total Harmonics Distortion (THD) with PV System Integration in Smart Grids: Case Study

The share of renewable energy systems in modern smart grids have increased in many countries, and with that increase the quality of power becomes a major concern for power system operators, especially at the load side. Among the most important power quality challenges, the harmonics comes on top, as they affect the voltage and current quality at the point of common coupling (PCC), and negatively affects the loads. One of the most used renewable generators is the solar photovoltaic (PV) systems, where it is connected into the low voltage distribution grid using power electronics inverters, and with the increased penetration level, massive harmonic current is injected into the network. There is a need to analyse the resulting harmonics distortion and highlight its possible constraints. This paper presents a case study of a radial distribution network with a connected 5 MW Solar PV plant. The system is modelled and simulated using DigSilent software to assess the total harmonics distortion (THD) at the PCC. The simulation is performed with increasing the connected PV modules, and the results are analysed showing high level of THD with the increased PV penetration at the PCC considering a higher loading level of the distribution transformer. The methodology of the introduced analytical study is recommended for distribution system operators in order to develop the appropriate solution to mitigate the harmonics effect.