Method to Mitigate the Harmonic Content of Photovoltaic Systems

SANCHEZ REINOSO, C.R.; DE PAULA, M.

Congreso; 14th Conference on Sustainable Development of Energy, Water and Environment Systems; 2019

University of Zagreb

When tackling the design of a photovoltaic system, some papers try to optimize it using estimation methods for the inverterarraysizing. There are also works that adopt other approaches, but all of them focus on the key role of the inverter to improvethe system. Multilevel inverters are widely used in photovoltaic applications due to the fact that they present less harmonicdistortion than mono-level inverters and can utilize several photovoltaic modules as inputs. However, it would also bedesirable to reduce the harmonic content in the multilevel inverters output. There are methods used to eliminate the harmonicdistortion that allow the characterization of the harmonic content; then, the problem can be converted into polynomialequations to be solved analytically. The polynomial degree increases with the number of direct current sources and thenumber of harmonics to be eliminated. Therefore, as the problem size increases, more complex expressions are obtained andthe calculation time of the optimal switching angles also increases. To decrease the computational cost some methods wereproposed but the solutions they yield are discontinuous at some points, thus creating problems to find the possible switchingangles at said points. In addition to that, it is required a great number of switching to eliminate high order harmonics, causinghigh switching losses.This paper proposes a methodology to minimize the harmonic content in a multilevel inverter output. A swarm particle basedoptimization algorithm is proposed to reduce the total harmonic distortion, subject to restrictions over the allowed harmoniccontent. This approach could be useful to obtain the most convenient angles for different modulation indexes and couldprevent discontinuity issues in the solution of the non-linear functions.For different modulation indexes the results obtained show that the proposed methodology reduces the harmonic distortion