DC-Link Capacitor Diagnosis in a Single-Phase Grid-Connected PV System

The DC-link capacitor is one of the components that are more prone to faults in energy-distributed systems based on voltage source inverters. A predictive maintenance approach should allow to foresee the risk of an unexpected system shutdown. In this study, a two-stage diagnostic approach that is ai...

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Bibliographic Details
Published in:Energies (Basel) 2021-10, Vol.14 (20), p.6754
Main Authors: Plazas-Rosas, Ramiro Alejandro, Orozco-Gutierrez, Martha Lucia, Spagnuolo, Giovanni, Franco-Mejía, Édinson, Petrone, Giovanni
Format: Article
Language:English
Subjects:
Algorithms
Capacitance
Capacitors
diagnosis of aging
Electrochemical impedance spectroscopy
Electrochemistry
Electrolytes
frequency analysis
Humidity
Impedance
indicators of degradation
Irradiance
Maximum power
multi-fitting
Photovoltaics
Predictive maintenance
Shutdowns
Spectroscopy
Wavelet transforms
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Summary:The DC-link capacitor is one of the components that are more prone to faults in energy-distributed systems based on voltage source inverters. A predictive maintenance approach should allow to foresee the risk of an unexpected system shutdown. In this study, a two-stage diagnostic approach that is aimed at determining the health status of the DC-link capacitor in a single-phase grid-connected PV system was proposed. The equivalent series resistance (ESR) and the capacitance (C) values were used as indicators in the estimation of the degradation stage. Electrochemical impedance spectroscopy (EIS) was used to estimate the impedance curve of the DC-link capacitor, and a multi-fitting algorithm allowed us to determine the ESR and C parameters. A comparison between the estimated values C and ESR and the nominal values was used to quantify the fault severity. It was demonstrated that the EIS allowed the determination of the capacitor impedance regardless of the actual operating conditions of the photovoltaic generator, such as during irradiance changes and with the maximum power point algorithm turned off. By using the capacitor simplified model and a multi-fitting algorithm, the C and ESR values were estimated with an error that was lower than 1%. An analysis of the hardware required to implement the proposed approach in real applications by achieving the desired accuracy was also proposed.
ISSN:1996-1073
1996-1073
DOI:10.3390/en14206754