Development and Implementation of Modified Power Loss Detection Algorithm for Partial Shading in Real-time Photovoltaic System

Abstract

The development of maximum power point tracking in solar photovoltaic system is important for obtaining the maximum power, which works satisfactorily when subjected to steady, undisturbed irradiation. Under real-time conditions, the solar panel does not always receive uniform irradiation owing to partial shading, thereby reducing the gross power output from the panel. The presence of partial shading is directly recognized by an occurrence of multiple local peaks in the performance characteristics of the solar panel. During partial shading, conventional maximum power point tracking algorithms fail to detect the global maximum power point, thus operating the panel at a much lower efficiency than desired. This study aimed to accurately detect the occurrence of partial shading condition in the solar Photovoltaic (PV) systems under different irradiation conditions and shading patterns. A partial shading detection mechanism is proposed based on power loss generated from a solar PV array without any sensors incorporated in the real-time platform. The proposed method is cost effective and accurate even under different seasonal and weather conditions, without any empirical constant and sensors. The proposed method is tested experimentally in real-time setup and the results are validated. The method provides a much higher accuracy than the current approximation and power loss method, and it does so by using the minimum number of variables. The proposed detection mechanism is compared with other existing methods in the Maximum Power Point Tracking (MPPT) algorithm, which proves the powerfulness of the algorithm. To test the performance of the proposed method, a real-time PV system with data acquisition using National Instruments LabVIEW is developed. Virtual Bench-8012 is used for data acquisition with a high precision along with intrinsic signal conditioning, and compact RIO-9081with a Field-Programmable Gate Array (FPGA) Virtex-5 LX150 is used for the MPPT algorithm implementation. The experimental results are also verified under different shading patterns and irradiation conditions for detecting the shading of the panel. Hence, it is shown that the detection algorithm has an efficiency of 97% in detecting the shading conditions of the panel.