EVALUATION OF AGING EFFECT ON DYNAMICS AND PERFORMANCES OF A GRID CONNECTED PV SYSTEM

Malay Bhunia and Bidyadhar Subudhi

Keywords

Small signal modelling, PV system, ESR, power degradation, aging,PV modelling

Abstract

We study the effect of aging associated with photovoltaic power (PV) source and passive components on the electrical performances of three-phase grid-connected PV system (GCPVS). A quadrature axis small signal modelling (QASSM) is developed by considering the nonlinearities present in GCPVS. Due to aging, optical and electrical properties of the PV modules vary. Also, the equivalent series resistance (ESR) of a capacitor increases with time. By pursuing a detailed eigenvalue analysis, it is observed that GCPVS dynamics vary signi´Čücantly with aging. Furthermore, due to variation in dynamics, electrical performances such as maximum power point tracking (MPPT) efficiency, ripple in DC-link voltage, and total harmonic distortion of inverter current deteriorate. The analysis concludes that due to the aging of PV source over the period of 20 years, the PV cell series resistance increases by 4.615%, the ideality factor decreases by 1.538% and the maximum power of PV decreases by 12.153%. Furthermore, due to aging of the capacitor, the MPPT efficiency decreases from 99.96% to 99.5% in only 3.3 years.

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