Monitoring and simulation of power quality of PV inverters

Abstract

People are becoming more concerned about the environment and the concept of renewable energy sources is deeply researched. Malta’s PV Systems uptake has remarkably increased throughout the past four years. Even though it is a greener solution than burning of fossil fuels and usage of steam turbines to produce electrical energy, it might be negatively affecting the electrical grid.

The objectives of this project were to conduct Power Quality data logging of several single- and three- phase PV systems and perform analysis of the data, develop both types of inverters on MATLAB Simulink ® and assess the effect of different PV penetration levels on the grid.

Power Quality data was gathered for 7 different systems, four were three-phase systems and three were single-phase systems. The data logging was repeated for two of the systems in a different season. The harmonic profile of each brand was analysed. The developed models on MATLAB Simulink were tuned to match the performance of commercially available inverters. With these profiles, the effect of different PV Penetration levels of single-phase systems on the low voltage network were simulated and analysed.

From the harmonic results obtained it was concluded that different brands have different architectures and harmonic profiles. During sunrise, sunset and cloud cover, harmonic currents with respect to the fundamental increase in relative harmonic content. The practical results obtained were used to tune the modelled inverters and assess their effect on the network. The harmonics generated during different times were simulated in 4 different scenarios with a typical loading of the network. Harmonic content is prevalent during sunrise and sunset in the network infrastructure but may be affecting more the network operators rather than the end-consumers.