Current collector optimizer topology to improve maximum power from PV array under partial shading conditions (original) (raw)

The power generated from photovoltaic (PV) series-parallel (SP) array topology is greatly harmed by partial shading phenomenon. Power losses due to shadow may reach up to 30% of total power expected, depending on PV array topology and climate conditions. This paper presents a current collector optimizer (CCO) topology to enhance the power harvest from the PV array under partial shading conditions. A comparative study is carried out using MATLAB/Simulink in order to illustrate the effectiveness of the proposed topology. According to results, the global maximum power generated by CCO topology is substantially increased compared to traditional SP array topology, while the mismatch power losses are significantly reduced during different shading patterns. 1. Introduction Over recent decades, the problems of energy shortage and environmental contamination have become critical research issues worldwide. Thus, the trends of employing distributed generation systems (DGSs) based on renewable energy are drawing more and more attention to reduce energy crisis and carbon emission. Among all various DGSs, solar photovoltaic (PV) systems are rapidly growing in electricity markets and are expected to continue this trend throughout the near future. Nevertheless, the unit cost of energy obtained from PV systems is still high; accordingly, this paper focuses on decreasing the costs by increasing the energy efficiency of the PV system [1-4]. Central inverter technology is one of the most common topologies of the PV installation, which interfaces a large number of panels that configured in series-parallel (SP) combination to the grid. However, the SP array topology suffers from partial shading effects. Due to the presence of bypass diodes, the PV array characteristics are deformed and exhibit multiple peaks, one of which is global. The power losses due to shadow may reach up to 30% of total power expected, that forces researchers to look for different technologies for the interconnection of the PV modules [5,6]. One of the solutions to partial shading effects is AC-module inverters, where the individual control for each module improves the energy efficiency of PV system. The prime downsides of AC-module inverters are high expenditure and increased system complexity since the number of micro-converters is proportional to that of PV modules [7-9]. Other solutions to eliminate local maximum power points (MPPs) and increase maximum power are using differential power processing (DPP) converters and voltage or current equalizers. A portion of the produced power of unshaded modules is transmitted to shaded ones so that all the modules operate close to each individual MPP. Several types of DPP converters and equalizers have been created and presented in literature [7,10-16]. In fact, the number