Design of an LLCL type filter for stand-alone PV systems' harmonics

This paper is regarding the design, modeling and simulation for reducing harmonics with passive LLCL filter in off-grid solar system. It is desired that current and voltage waveforms are to be in the sinusoidal form during energy generation from stand-alone solar systems. This condition can be provided by the most important one of the main factors which to determine the quality of electrical energy. Due to the harmonics produced by the non-linear loads, the waveform of the current and voltage is distorted from the sinusoidal form. The passive LLCL filter is designed and analyzed for mitigation of the total harmonic distortion for current (THDI) in the proposed off-grid PV system. The passive LLCL filter is practically installed between solar inverter and non-linear load. Simulation results are in a good compliance with the theoretical analysis. This study describes a design methodology of a LLCL filter for off-grid power system with a comprehensive study of how to mitigate the harmonics in off-grid solar system. The using of a LLCL filter mitigates the THDI that injected by a six pulse rectifier which is used as a non-linear load. The simulation result shows that the reduction of THDI from 89.89% to 3.257%. This paper attempts to show that the using of LLCL filter with a stand-alone solar system can highly improve the power quality of the system. © 2019 Published by peer-reviewed open access scientific journal.