Enhancing the maximum or flexible power point tracking control of a photovoltaic array with a non-invasive and computationally robust model-based method for partial shading detection

Abstract

The objective of this paper is to devise an efficient partial shading detection (PSD) scheme so that the PSD may not degrade the speed of power tracking of a photovoltaic array, while retaining the ability of accurately differentiating uniform irradiance from partial shading. A model-based approach is chosen to make PSD very accurate without using any expensive infrastructure. It is also ensured that the proposed PSD does not affect the power tracking dynamics when there is no partial shading, which is not true for some existing PSD schemes. The new PSD scheme is developed by deploying only one pair of irradiance and temperature sensors. In order to make PSD fault-tolerant to a sensor failure, provisions are kept for estimating the relevant irradiance or temperature quantity when the corresponding physical measurement is unavailable. A novel peak-power environmental dependence model is further derived to estimate the cell temperature without any convergence issue. Apart from the irradiance sensor failure, the issue of the irradiance sensor shading is also suitably addressed in the proposed dual-sensor non-invasive fault-tolerant (DSNIFT) PSD. Detailed simulation and experimental studies are performed to verify the improvement of PSD accuracy and power tracking speed by deploying the proposed DSNIFT methodology.