An Approach to improve the Performance of Total Cross-tied connected PV array in Partial shading condition

Due to the partial shading condition (PSC) in solar PV systems, performance degrades to a large extent. To overcome from this problem bypass diode is used which creates the problem of multiple local maxima. Therefore, total cross-tied (TCT) connection is introduced in the literature, which improves the performance of PV systems in PSC without using bypass diode. But the performance improvement in TCT connection is also limited. Because for some particular shading pattern the efficiency cannot be improved beyond a certain limit. In line with this, an algorithm is proposed in this paper through which the performance of a PV array can be improved. Here, the performance of a PV array is improved by distributing the shading effect on the entire PV array, which reduces the mismatch losses and to enhance the power output of the PV array

Review of mismatch mitigation techniques for PV modules

The installation of photovoltaic (PV) systems is continuously increasing in both standalone and grid-connected applications. The energy conversion from solar PV modules is not very efficient, but it is clean and green, which makes it valuable. The energy output from the PV modules is highly affected by the operating conditions. Varying operating conditions may lead to faults in PV modules, e.g. the mismatch faults, which may occur due to shadows over the modules. Consequently, the entire PV system performance in terms of energy production and lifetime is degraded. To address this issue, mismatch mitigation techniques have been developed in the literature. In this context, this study provides a review of the state-of-the-art mismatch mitigation techniques, and operational principles of both passive and active techniques are briefed for better understanding. A comparison is presented among all the techniques in terms of component count, complexity, efficiency, cost, control, functional reliability, and appearance of local maximums. Selected techniques are also benchmarked through simulations. This review serves as a guide to select suitable techniques according to the corresponding requirements and applications. More importantly, it is expected to spark new ideas to develop advanced mismatch mitigation techniques.</p

A Simple Mismatch Mitigating Partial Power Processing Converter for Solar PV Modules

Partial shading affects the energy harvested from photovoltaic (PV) modules, leading to a mismatch in PV systems and causing energy losses. For this purpose, differential power processing (DPP) converters are the emerging power electronic-based topologies used to address the mismatch issues. Normally, PV modules are connected in series and DPP converters are used to extract the power from these PV modules by only processing the fraction of power called mismatched power. In this work, a switched-capacitor-inductor (SCL)-based DPP converter is presented, which mitigates the non-ideal conditions in solar PV systems. A proposed SCL-based DPP technique utilizes a simple control strategy to extract the maximum power from the partially shaded PV modules by only processing a fraction of the power. Furthermore, an operational principle and loss analysis for the proposed converter is presented. The proposed topology is examined and compared with the traditional bypass diode technique through simulations and experimental tests. The efficiency of the proposed DPP is validated by the experiment and simulation. The results demonstrate the performance in terms of higher energy yield without bypassing the low-producing PV module by using a simple control. The results indicate that achieved efficiency is higher than 98% under severe mismatch (higher than 50%)

Intrinsic-Capacitance-based Differential Power Processing for Photovoltaic Modules

Partial shading reduces energy production and affects the lifetime of the overall PV system. To mitigate the mismatch effects caused by partial shading, several PV cell- or sub-panel-level techniques employing power electronics have been proposed in the literature, where discrete passive components, e.g., inductors and capacitors, are also used. In this paper, a differential power processing (DPP) technique, which utilizes only the intrinsic capacitance of solar cells, is introduced for small-scale PV applications. The developed DPP topology mitigates the mismatch effects by operating all PV cells at or near to their corresponding maximum power points (MPPs) even under mismatch conditions. The analysis of the topology and its comparison with the frequently used series- and series-parallel (SP)-connected techniques, are presented to validate its efficacy and operational capabilities, through simulation results. Moreover, a prototype is built to verify the topology. The experimental results confirm the elimination of multiple power peaks under mismatch along with maintaining the same voltages across the PV panels.</p

Micro-inverter with Fuzzy logic based MPPT of Partially shaded PV modules and energy recovery scheme

When there is occurrence of partial shading on PV modules there are two to three bypass diodes connected in junction box for 200W rated PV module. Due to this configuration the power-voltage characteristics of the PV module will have many peaks. So to extract maximum power even during the partial shading condition this paper proposes the use of micro-inverter based on flyback configuration with Fuzzy logic based maximum power point tracking technique. This can be achieved by implementing an equalization circuit across the PV module. This equalization circuit consists of series connection of diode and secondary winding of the flyback transformer of the micro-inverter. This equalization circuit is capable of energy recovery from the leakage inductance of the converter when the main switch is turned off. This proposed topology have the following features: fuzzy logic based mppt to extract maximum available power, energy recovery capability and conversion of dc to ac. The proposed technology’s effectiveness is analyzed by comparing it with PV module having bypass diode configuration. The simulation results, control strategies and modes of operation and analysis of the proposed topology are presented in this paper

Hardware Approach To Mitigate The Effects Of Module Mismatch In A Grid-Connected Photovoltaic System: A Review

This study reviews the hardware approach to mitigate the effects of module mismatch in a grid-connected photovoltaic (PV) system. Unlike software solutions, i.e. the maximum power tracking algorithm, hardware techniques are well suited to enhance energy yield because of their inherent ability to extract energy from the mismatched module. Despite the extra cost of the additional circuitry, hardware techniques have recently gained popularity because of their long-term financial benefits. Notwithstanding the growing interest in this topic, review papers that provide updates on the technological developments of the three main hardware solutions, namely micro inverter,DC power optimizer, and energy recovery circuits, are lacking. This is in contrast to software solutions, which have had a considerable number of reputable reviews. Thus, a comprehensive review paper is appropriate at this juncture to provide up-to-date information on the latest topologies, highlight their merits/drawbacks, and evaluate their comparative performance

A review of grid-tied converter topologies used in photovoltaic systems

This study provides review of grid-tied architectures used in photovoltaic power systems, classified by the granularity level at which maximum power point tracking (MPPT) is applied. Grid-tied PV power systems can be divided into two main groups, namely centralized MPPT (CMPPT) and distributed MPPT (DMPPT). The DMPPT systems are further classified according to the levels at which MPPT can be applied, i.e. string, module, submodule, and cell level. Typical topologies for each category are also introduced, explained and analyzed. The classification is intended to help readers understand the latest developments of grid-tied PV power systems and inform research directions