Thermography-Based Virtual MPPT Scheme for Improving PV Energy Efficiency Under Partial Shading Conditions

Abstract

Abstract -This paper proposes a new thermography-based maximum power point tracking (MPPT) scheme to address photovoltaic (PV) partial shading faults. Solar power generation utilizes a large number of PV cells connected in series and in parallel in an array, and which are physically distributed across a large field. When a PV module is faulted or partial shading occurs, the PV system sees a non-uniform distribution of generated electrical power and thermal profile, and the generation of multiple maximum power points (MPPs). If left untreated, this reduces the overall power generation and severe faults may propagate resulting in damage to the system. In this paper, a thermal camera is employed for fault detection and a new MPPT scheme is developed to alter the operating point to match an optimized MPP. Extensive data mining is conducted on the images from the thermal camera in order to locate global MPPs. Based on this, a virtual MPPT is set out to find the global MPP. This can reduce MPPT time and be used to calculate the MPP reference voltage. Finally, the proposed methodology is experimentally implemented and validated by tests on a 600W PV array.

Online model-based fault detection for grid connected PV systems monitoring

“…Other methods use sophisticated tools, such as time domain reflectometry (TDR) [11] and thermo-reflectance imaging (TR) [12] based methods have been used in several research studies due to their independency to weather conditions. Specifically, TDR has been used to detect both system degradation and PV string disconnection failures.…”

Combining Model-based and Heuristic Techniques for Fast Tracking the Global Maximum Power Point of a Photovoltaic String

“…As a result, it would undoubtedly require a high-performance DSP to support such huge calculations. The authors of [31] proposed a thermography-based MPPT scheme to address PV partial shading faults. It shows a novel idea for the MPPT idea but the thermography camera is costly.…”

Voltage Equalizing of Solar Modules for Shadowing Compensation

“…However, conventional MPPT methods have difficulty in finding the global maximum power point [7]- [10] when part of the solar cell array is shaded. Many advanced MPPT methods [11]- [14] have been proposed to find the global maximum power point on a P-V curve with multiple peaks. Given that the shaded solar cells are bypassed or the output current of the solar cell array is limited by the shaded solar cells, the solar cell array does not output the true maximum output power generated by all solar modules in the solar cell array even when the global peak is tracked.…”

“…Many power technologies have been established for grid-connected photovoltaic generation systems. MPPT methods for grid-connected photovoltaic generation systems can be classified as follows depending on the topology of the power circuit: central MPPT [14], [15], distributed MPPT [15], [17], or central MPPT with power-electronic compensators [3], [18]- [21]. This paper discusses the central MPPT with a power-electronic compensator to solve the shadowing problems of solar cell arrays.…”