Frequency and Time-Domain Comparison between LCL and LLCL Filters for a Grid-Connected Inverter Using Selective Harmonic Modulation

Abstract

This paper shows a comparison between the analytical design of a photovoltaic power station filter and a real-case filter. Indeed, the analytical filter considered in the design phase is an LCL filter, while the real case is an LLCL filter. This difference could impact the current harmonics rejected on the grid and breaks grid codes. The main objective of this study is to maximize the power injected into the network while respecting the harmonic rejection standards in force, namely, G5/4, French decree of 2008, and IEEE 519 standards, by adopting a current control design to improve the performance of a grid-connected three-phase inverter, which is regarded as the central component in a photovoltaic production system. The selective harmonic modulation strategy (SHM) is a common technique to achieve this goal. For that, a frequency and a time-domain comparison for a grid-connected inverter using both filters have been highlighted. Simulation results confirm the excellent transient behavior of both filter topologies and the advantage to consider the flexibility of LLCL filter when combined with SHM strategy. This manuscript is an extension of an earlier version of “Comparison between LCL and LLCL Filters for a Grid Connected Inverter Using Selective Harmonic Modulation.”