The main design objective of photovoltaic (PV) systems has been, for a long time, to extract the maximum power from the PV array and inject it into the ac grid. Therefore, the maximum power point tracking (MPPT) of a uniformly irradiated PV array and the maximization of the conversion efficiency have been the main design issues. However, when the PV plant is connected to the grid, special attention has to be paid to the reliability of the system, the power quality, and the implementation of protection and grid synchronization functions. Modern power plants are required to maximize their energy production, requiring suitable control strategies to solve the problems related to the partial shading phenomena and different orientation of the PV modules toward the sun. Moreover, the new policy concerning the injection of reactive power into the grid makes the development of suitable topologies and control algorithms mandatory. A general view of actual solutions for applications of the PV energy systems is presented. This article covers several important issues, including the most reliable models used for simulation, which are useful in the design of control systems, and the MPPT function, particularly in distributed applications. The main topologies used in the PV power processing system and, finally, grid connection aspects are discussed, with emphasis on synchronization, protections, and integration.

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Grid-Connected Photovoltaic Generation Plants: Components and Operation

This paper reports the development of a maximum power-point tracking (MPPT) method for photovoltaic (PV) systems under partially shaded conditions using firefly algorithm. The major advantages of the proposed method are simple computational steps, faster convergence, and its implementation on a low-cost microcontroller. The proposed scheme is studied for two different configurations of PV arrays under partial shaded conditions and its tracking performance is compared with traditional perturb and observe (P&O) method and particle swarm optimization (PSO) method under identical conditions. The improved performance of the algorithm in terms of tracking efficiency and tracking speed is validated through simulation and experimental studies.

MPPT of PV Systems Under Partial Shaded Conditions Through a Colony of Flashing Fireflies

For the maximum utilization of solar energy, photovoltaic (PV) power generation systems are operated at the maximum power point (MPP) under varying atmospheric conditions, and MPP tracking (MPPT) is generally achieved using several conventional methods. However, when partial shading occurs in a PV system, the resultant powervoltage (PV) curve exhibits multiple peaks and traditional methods that need not guarantee convergence to true MPP always. This paper proposes an artificial bee colony (ABC) algorithm for global MPP (GMPP) tracking under conditions of in-homogenous insolation. The formulation of the problem, application of the ABC algorithm, and the results are analyzed in this paper. The numerical simulations carried out on two different PV configurations under different shading patterns strongly suggest that the proposed method is far superior to existing MPPT alternatives. Experimental results are also provided to validate the new dispensation.

Enhanced Energy Output From a PV System Under Partial Shaded Conditions Through Artificial Bee Colony

This paper presents a concise and an organized review of various maximum power point tracking (MPPT) algorithms implemented in the photovoltaic (PV) generation system useable under partial shading condition Various algorithms, PV modeling techniques, PV array configurations and controller topologies have been widely explored till date But, every technique always has its advantages as well as disadvantages simultaneously; as a result, a proper literature review is essential while designing a PV generation system (PGS) under partial shading condition In this paper, the detailed review of MPPT algorithms has been done The review on MPPT techniques has been classified into mainly four essential groups The first among them includes all the new MPPT optimization algorithms, the second group includes the hybrid MPPT algorithms, the third category includes new modeling approach, and the fourth category includes the various converter topologies This paper provides an accessible reference to undertake mass research works in PV systems in the near future under partial shading condition

A review on MPPT techniques of PV system under partial shading condition

Modeling, analysis and comparison of solar photovoltaic array configurations under partial shading conditions

Partial shading of a photovoltaic array is the condition under which different modules in the array experience different irradiance levels due to shading. This difference causes mismatch between the modules, leading to undesirable effects such as reduction in generated power and hot spots. The severity of these effects can be considerably reduced by photovoltaic array reconfiguration. This paper proposes a novel mathematical formulation for the optimal reconfiguration of photovoltaic arrays to minimize partial shading losses. The paper formulates the reconfiguration problem as a mixed integer quadratic programming problem and finds the optimal solution using a branch and bound algorithm. The proposed formulation can be used for an equal or nonequal number of modules per row. Moreover, it can be used for fully reconfigurable or partially reconfigurable arrays. The improvement resulting from the reconfiguration with respect to the existing photovoltaic interconnections is demonstrated by extensive simulation results.

Optimal Photovoltaic Array Reconfiguration to Reduce Partial Shading Losses

A mismatch in a photovoltaic array implies differences in the I-V characteristics of the modules forming the array. This can lead to significant energy losses known as mismatch losses. The mismatch and the resulting losses can be reduced by altering the interconnection of the array. This paper proposes an optimal total cross tied interconnection, based on a thorough mathematical formulation that can significantly reduce mismatch losses. The improvement over existing photovoltaic array interconnections has been demonstrated by extensive simulation results.

An Optimal Total Cross Tied Interconnection for Reducing Mismatch Losses in Photovoltaic Arrays

The condition of having different irradiance levels among different photovoltaic modules in a photovoltaic array is called partial shading. Energy losses have been reported to occur due to partial shading. These losses could be reduced by reconnecting the modules of the array in such a way that the overall impact of partial shading on the array is reduced. This paper proposes a novel optimization model for the optimal total cross tied interconnection which significantly reduces partial shading losses. The improvement over ordinary total-cross-tied interconnection has been demonstrated by extensive simulation results. The patent number PCT/CA2011/000556 has been filed based on this work.

M. Z. S. El-Dein

Papers

Optimal Photovoltaic Array Reconfiguration to Reduce Partial Shading Losses

An Optimal Total Cross Tied Interconnection for Reducing Mismatch Losses in Photovoltaic Arrays

Optimal total cross tied interconnection for photovoltaic arrays to reduce partial shading losses