Output voltage sensor based DMPPT with parallel configuration for PV systems under partial shading conditions

Energy assessment of enhanced fixed low concentration photovoltaic systems

This paper presents IC design of Distributed Maximum Power Point Tracking (DMPPT) controller for Cascade and Mismatched Current Compensation Unit (MCCU) for photovoltaic systems. The Cascade part can handle the conventional DMPPT algorithm and the MCCU part can handle the differential power processing algorithm. This solution can mitigate mismatches in photovoltaic(PV) power system, while introducing no insertion loss and reducing the system cost compared to a microprocessor-based solution. A 0.18um 1-poly 4-metal 5V process was selected for the IC development. MPPT peak efficiency of over 99% is achieved.

Synchronous buck converter based low-cost and high-efficiency sub-module DMPPT PV system under partial shading conditions

Operating photovoltaic (PV) systems under partial shading conditions results in significant power losses. To mitigate partial shading effects, distributed maximum power point tracking (DMPPT) architectures have been proposed. An emerging DMPPT technique represented by PV module cascaded converters (MCCs) has been widely reported in the literature. In this architecture, a DC converter is allocated for each PV module to process and maximise its power. In this sense, mismatch effects are mitigated between PV modules. While MCC architecture has prominent advantages and value‐added features, its challenges and limitations cannot be ignored. This study presents a comprehensive review of the state of the art of PV MCC architecture to help readers realise the progress of this DMPPT technique. Several points are extensively discussed and analysed including concept realisation and analysis, DC converter topologies and design optimisation, DMPPT performance limitations, DMPPT control, and protection. The main concepts are reemphasised through a set of simulations. Finally, a list of potential research areas in this field is introduced.

Fault-tolerant strategy without redundant switches for PV systems based on differential power processing converters

Distributed Maximum Power Point Tracking (DMPPT) has been revealed to be a technique increasing the efficiency and reliability of Photovoltaic (PV) systems in mismatch conditions. To further recover mismatch power loss inside PV panels, subpanel realization of DMPPT solution is developed as an improved penetration of DMPPT concept. This paper proposes a double loop control based subpanel level DMPPT system with a self-adjusted time-sharing Maximum Current Tracking (MCT) algorithm which detects the output current of series connected DC-DC converters. The proposal can always guarantee that all PV units output its individual maximum power regardless of irradiance cases with a greatly reduction of components such as control IC and sensors. Comparing with current commercial panel level solutions, common subpanel level mismatch power loss inside a PV panel can be totally recovered with single current sensor and control IC. The proposal of this paper can be utilized for further integration of PV optimizer.

The building integrated photovoltaic (PV) central inverter architecture comprises various PV module configurations. The PV module configurations are vulnerable to shading effects and cause mismatching power losses. To reduce the detrimental impact of shading and mismatching on energy production, the PV distributed-maximum power point tracking (D-MPPT) architecture has been proposed. In this architecture, an individual dc–dc converter with an MPPT controller is integrated to each PV module for extracting the maximum power. This topology is referred to as module-integrated-converter (M-I-C). In the conventional PV D-MPPT architecture, the output terminals of M-I-Cs are connected either in series or parallel configuration only. The conventional configurations of M-I-Cs have the drawbacks of cross-coupling effects, lower conversion efficiency, two-stage voltage conversion, etc. This paper proposes the total-cross-tied (T-C-T) configuration of string-integrated-converters (S-I-Cs) to overcome the drawbacks of M-I-C configurations. The detailed mathematical analysis of the proposed T-C-T configuration of S-I-Cs is also presented in this paper. The perturb and observe MPPT technique is used for extracting the maximum power. The performance of the proposed T-C-T configuration of S-I-Cs is analyzed under various partial shading conditions and also compared with the PV central inverter architecture as well as with conventional M-I-C configurations.

Energy crises and the growth of the energy demand have increased the interest in utilizing unconventional power sources. Thus, renewable energy sources have become a topic of interest to mitigate rising energy concerns and cope with increased electricity demand. With remarkable merits including cleanness and abundance, photovoltaic (PV) solar energy systems are a key to solving these issues. The employed inverters should effectively utilize the maximum available power from the PV solar system and transfer this power to the utility grid without posing any further limitations. However, the unequal power generation of different PV systems caused by partial shading (PS) and other PV panel degradation factors leads to a reduction in generation capacity. One of the relatively new solutions to mitigate the mismatch concerns between the PV modules and sub-modules is to extract the maximum power of each sub-module individually. The main objective of this paper is to present a comprehensive review of such PV grid-connected inverters topologies associated with sub-module connection and control. It will classify the PV grid-tied inverters in accordance with the level where the maximum power point tracking (MPPT) system is implemented. A special focus has been placed on sub-module microinverters (MI) in terms of circuit topologies, conversion efficiency, and controller design. This paper provides a comprehensive analysis of employing the distributed MPPT (DMPPT) approach to maximize the power generation of PV systems by mitigating the mismatch issues inside the PV module. The circuit topology, PV system configuration, and MPPT algorithms used for applying DMPPT solutions in PV SMs are discussed in detail in this study.

An isolated modular boost converter (IMBC) consisting of plural phase-shifted full bridge converters is proposed as a solution for an automotive photovoltaic system. The IMBC not only controls multiple photovoltaic (PV) modules around their maximum power points individually, but also supplies distributed power from each PV module to the high voltage battery used for propelling the vehicle through boosting by the cascaded structure. This paper shows that 4M-IMBC prototype consisting of four boost modules can operate with distributed maximum power point tracking control under both a solar irradiance imbalance and partial shade transitions. In addition, 12M-IMBC prototype consisting of twelve boost modules charged power by actual photovoltaic modules to the high voltage battery. The average measured power conversion efficiency during sunny weather was 84.8%, which is similar to the efficiency of a single boost module.

For maximum utilization of solar energy, photovoltaic (PV) power systems should be operated at the maximum power point (MPP) which can be achieved using maximum power point tracking (MPPT) methods. However, the occurrence of multi-peak on P-V curve of a PV array due to the changing environmental conditions such as being partially shaded increases the complexity of the tracking process. The global MPP cannot always be achieved by the conventional MPPT methods. Therefore a novel MPPT method for PV systems using flower pollination (FP) algorithm is proposed in this paper and the Levy flight is used to improve the convergence of FP algorithm. MPPT model of the PV system is established in MATLAB to verify the effectiveness of the proposed method, and the proposed method is compared with two well established MPPT methods. The simulation results indicate that the proposed MPPT method can quickly track the changes in external environment and effectively handle the partially shaded condition.

Under partial shading condition or imbalanced temperature distribution, the power-voltage characteristic curve of photovoltaic (PV) array exhibits complicated multiple peaks. Traditional maximum power point tracking (MPPT) method is usually easy to trap into local extreme power point. To solve this issue, this paper proposes a novel MPPT method using quantum-behaved particle swarm optimization (QPSO) algorithm. This algorithm adopts detect-search strategy based on voltage closed-loop control, making voltage particles search photovoltaic characteristic curves in quantum-behaved paths. By setting a modulation strategy of reunion and separation factor and stopping criterion, the proposed QPSO algorithm improves the precision of stable state, and eliminates power oscillation under stability condition. Experimental results show that QPSO algorithm has good performance with less parameters, superior global optimization ability, favorable stability and better adaptability compared with traditional particle swarm optimization (PSO) algorithm in PV MPPT.

Submodule mismatch has become the major cause of losses in the photovoltaic (PV) power generation system, which has been an important factor restricting the development of PV technology. Differential power processing (DPP) architecture is increasingly employed in PV distributed MPPT (DMPPT) due to its low processed power. In order to improve the PV utilization efficiency, minimize the power loss and reduce the system cost, a novel scheme based on DPP is introduced in this article. The proposed DPP converter is composed of multiple buck-boost choppers, and a multidimensional perturb and observe (MPO) algorithm is proposed to achieve true DMPPT through correcting the voltage of each submodule to its voltage at the maximum power point by using a single current sensor. A prototype with multiple buck-boost choppers for 36 V/200 W PV module is designed and built to verify the operating principle and evaluate the performance of the proposed DPP converter and DMPPT strategy, and the experimental results show that the prototype is low-cost and effectively improves system efficiency.

A hybrid global maximum power point tracking method for photovoltaic arrays under partial shading conditions

This paper presents an improved reinitialisation condition for time invariant maximum power point tracking (MPPT) methods used in photovoltaic (PV) systems experiencing partial shading conditions (PSC). Time invariant (MPPT) methods, such as Particle Swarm Optimisation (PSO), overcome the limitations of existing MPPT by tracking the global maximum power point (GMPP) of a PV system operating under PSC. However, due to the time invariant structure of these MPPT methods, they also require a reinitialisation condition to be defined for when a change in irradiance or temperature occurs. Testing was performed using simulations of a model built in Matlab/ Simulink, where the performance of existing and developed conditions was evaluated using test cases with changes in solar irradiance. Limitations of existing conditions were identified and a more robust reinitialisation condition developed. The developed reinitialisation condition used sentry particles to monitor the PV voltage range for changes in the measured power of any sentry. The developed condition had a 96 % rate of successful detection, as compared to as low as 68 % successful detection for existing methods, demonstrating improved performance and robustness.

INTRODUCTION: Significant advances have been made in photovoltaic (PV) systems, resulting in the development of new Maximum Power Point Tracking (MPPT) methods. The output of PV systems is heavily influenced by the varying performance of solar-facing PV panels under different weather conditions. Partial shading (PS) conditions pose additional challenges, leading to multiple peaks in the power-voltage (P-V) curve and reduced output power. Therefore, controlling MPPT under partial shading conditions is a complex task. OBJECTIVES: This study aims to introduce a novel MMPT algorithm based on the ant colony incorporated bald eagle search optimization (AC-BESO) method to enhance the efficiency of PV systems. METHODS: The effectiveness of the proposed MPPT algorithm was established through a series of experiments using MATLAB software, tested under various levels of solar irradiance. RESULTS: Compared to existing methods, the proposed AC-BESO algorithm stands out for its simplicity in implementation and reduced computational complexity. Furthermore, its tracking performance surpasses that of conventional methods, as validated through comparative analyses. CONCLUSION: This study confirms the efficacy of the AC-BESO method over traditional strategies. It serves as a framework for selecting an MPPT approach when designing PV systems.