Zero Oscillation and Irradiance Slope Tracking for Photovoltaic MPPT
TL;DR: The proposed zero-oscillation adaptive step P&O strategy combines three techniques to improve steady-state behavior and transient operation and achieves superior overall performance while maintaining simplicity of implementation.
Abstract: Maximum power point tracking (MPPT) strategies in photovoltaic (PV) systems ensure efficient utilization of PV arrays. Among different strategies, the perturb and observe (PO 2) identification of the irradiance change through a natural perturbation; and 3) a simple multilevel adaptive tracking step. Two key elements, which form the foundation of the proposed solution, are investigated: 1) the suppression of the artificial perturb at the MPP; and 2) the indirect identification of irradiance change through a current-monitoring algorithm, which acts as a natural perturbation. The zero-oscillation adaptive step P&O strategy builds on these mechanisms to identify relevant information and to produce efficiency gains. As a result, the combined techniques achieve superior overall performance while maintaining simplicity of implementation. Simulations and experimental results are provided to validate the proposed strategy, and to illustrate its behavior in steady and transient operations.
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TL;DR: Simulation and experimental results showed that the proposed algorithm accurately tracks the maximum power and avoids the drift in fast changing weather conditions.
Abstract: The perturb and observe (P&O) maximum power point tracking (MPPT) algorithm is a simple and efficient tracking technique. However, the P&O tracking method suffers from drift in case of an increase in insolation $(G) $ , and this drift effect is severe in case of a rapid increase in insolation. Drift occurs due to the incorrect decision taken by the conventional P&O algorithm at the first step change in duty cycle during increase in insolation. A modified P&O technique is proposed to avoid the drift problem by incorporating the information of change in current $(\Delta I) $ in the decision process in addition to change in power $(\Delta P)$ and change in voltage $(\Delta V) $ . The drift phenomena and its effects are clearly demonstrated in this paper for conventional P&O algorithm with both fixed and adaptive step size technique. A single-ended primary inductance converter is considered to validate the proposed drift-free P&O MPPT using direct duty ratio control technique. MATLAB/Simulink is used for simulation studies, and for experimental validation, a microcontroller is used as a digital platform to implement the proposed algorithm. The simulation and experimental results showed that the proposed algorithm accurately tracks the maximum power and avoids the drift in fast changing weather conditions.
420 citations
TL;DR: In this article, a modified P&O was proposed to reduce the steady-state oscillation and mitigate the probability of losing the tracking direction of the perturb and observed (P&O)-based maximum power point tracking (MPPT) for PV system.
Abstract: This paper proposes a method to reduce the steady-state oscillation and to mitigate the probability of losing the tracking direction of the perturb and observed (P&O)-based maximum power point tracking (MPPT) for PV system. The modified scheme retains the conventional P&O structure, but with a unique technique to dynamically alter the perturbation size. At the same time, a dynamic boundary condition is introduced to ensure that the algorithm will not diverge from its tracking locus. The modified P&O is simulated in MATLAB Simulink and its performance is benchmarked using the standard MPPT efficiency ${{\boldsymbol{\eta }}_{MPPT}}$ calculation. Furthermore, the proposed concept is validated experimentally using a buck-boost converter, fed by a solar PV array simulator (PVAS). Based on the EN 50530 dynamic irradiance tests, the proposed method achieved an average ${{\boldsymbol{\eta }}_{MPPT}}$ almost 1.1% higher than the conventional P&O when irradiance changes slowly and about 12% higher under fast change of irradiance.
320 citations
Cites background from "Zero Oscillation and Irradiance Slo..."
...Notwithstanding this, authors in [19]–[21], have introduced several solutions to address these two problems....
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...In [19], the authors managed to effectively track the gradient of G using the PI voltage controller, followed by a (inner-loop) current controller....
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TL;DR: The results show that the proposed method tracks the global peak successfully under distinctive patterns of partial shading, when other algorithms fail occasionally, and improves the tracking speed by two to three times, while efficiency is maintained over 99%.
Abstract: This paper proposes an enhanced adaptive perturb and observe (EA-PO second, modified incremental conduction; third, cuckoo search; and fourth, the hybrid ant colony optimization-P&O. The results show that the proposed method tracks the global peak successfully under distinctive patterns of partial shading, when other algorithms fail occasionally. On top of that, it improves the tracking speed by two to three times, while efficiency is maintained over 99%.
271 citations
Cites background from "Zero Oscillation and Irradiance Slo..."
...Consequently, in many recent work, conventional MPPT methods such as perturb and observation (P&O) [11]–[13], hill climbing (HC) [14], [15] and incremental conductance (IC) are re-visited and improved....
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...A number of recent work, notably by [14]–[16] dealt with the divergence along with the oscillation issue....
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TL;DR: In this article, an enhancement is introduced to the Inc.Cond algorithm in order to entirely eliminate the division calculations involved in its structure, thus, algorithm implementation complexity is minimised enabling the utilisation of low-cost microcontrollers to cut down system cost.
Abstract: Variable-step incremental conductance (Inc.Cond.) technique, for photovoltaic (PV) maximum power point tracking, has merits of good tracking accuracy and fast convergence speed. Yet, it lacks simplicity in its implementation due to the mathematical division computations involved in its algorithm structure. Furthermore, the conventional variable step-size, based on the division of the PV module power change by the PV voltage change, encounters steady-state power oscillations and dynamic problems especially under sudden environmental changes. In this study, an enhancement is introduced to Inc.Cond. algorithm in order to entirely eliminate the division calculations involved in its structure. Hence, algorithm implementation complexity is minimised enabling the utilisation of low-cost microcontrollers to cut down system cost. Moreover, the required real processing time is reduced, thus sampling rate can be improved to fasten system response during sudden changes. Regarding the applied step-size, a modified variable-step size, which depends solely on PV power, is proposed. The latter achieves enhanced transient performance with minimal steady-state power oscillations around the MPP even under partial shading. For proposed technique's validation, simulation work is carried out and an experimental set up is implemented in which ARDUINO Uno board, based on low-cost Atmega328 microcontroller, is employed.
175 citations
Additional excerpts
...[35] (2014) 800W Boost ----------Zerooscillation adaptive step P&O Microcontroller TI C2000 20W (2....
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TL;DR: A SOFT-MPPT algorithm is proposed which aims to improve both the steady state as well as the tracking performance of both P&O and InC algorithms, and is able to detect any change in operating conditions while operating in the steadystate, and that too without using any additional sensors.
Abstract: Among the various MPPT algorithms developed until date, Perturb and Observe (P&O) and Incremental conductance (InC) algorithms are most widely used, mainly due to their simplicity and ease of implementation. However, both algorithms suffer from the drawbacks of continuous steady state oscillations, and inefficient tracking in case of rapid changes in irradiation. In this article, a SOFT-MPPT algorithm has been proposed which, in a simple way, aims to improve both the steady state as well as the tracking performance of both P&O and InC algorithms. An adaptive step size is used to track the MPP, which provides a faster tracking performance. The proposed algorithm identifies the attainment of the steady state and then stops the artificial perturbations. This stops the oscillations around the MPP and provides a steady power output from the PV panel at the MPP value. The SOFT-MPPT algorithm is also able to detect any change in operating conditions while operating in the steady state, and that too without using any additional sensors. Accordingly, it restarts the tracking process in order to track the new MPP. The detailed theoretical discussions of the SOFT-MPPT algorithm, is followed by the simulation and experimental results to validate the proposed performance improvements.
125 citations
Cites background or methods from "Zero Oscillation and Irradiance Slo..."
...So, the performance of a VR-P&O based algorithm, the ZA-P&O MPPT algorithm [3] is tested under step changes in irradiance as shown in Fig....
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...as provided in [3] is not quite clear, and necessary modification have been done such that steady state oscillations around the MPP are absent....
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...In [3], the proposed ZA-P&O MPPT algorithm uses a variable Vmid which is eventually be stored as Vmpp....
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...So, the performance of a VR-P&O based algorithm, the ZA-P&O MPPT algorithm [3] is tested under step changes in...
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...3) Comparison With Other MPPT Algorithms: To validate the effectiveness of the proposed algorithm, its performance for a resistive load is compared with the performance of the DDRP&O MPPT algorithm with fixed step size [15] and the ZA-P&O algorithm [3]....
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References
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TL;DR: The many different techniques for maximum power point tracking of photovoltaic (PV) arrays are discussed in this paper, and at least 19 distinct methods have been introduced in the literature, with many variations on implementation.
Abstract: The many different techniques for maximum power point tracking of photovoltaic (PV) arrays are discussed. The techniques are taken from the literature dating back to the earliest methods. It is shown that at least 19 distinct methods have been introduced in the literature, with many variations on implementation. This paper should serve as a convenient reference for future work in PV power generation.
5,022 citations
"Zero Oscillation and Irradiance Slo..." refers methods in this paper
...Complex implementations achieve high performance by using a detailed model of the PV panel and additional measures of the irradiance (G) and temperature (T ) [3], [11], [12]....
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TL;DR: In this paper, a comprehensive review of the MPPT techniques applied to photovoltaic (PV) power system available until January, 2012 is provided, which is intended to serve as a convenient reference for future MPPT users in PV systems. But, confusion lies while selecting a MPPT as every technique has its own merits and demerits.
Abstract: This paper provides a comprehensive review of the maximum power point tracking (MPPT) techniques applied to photovoltaic (PV) power system available until January, 2012. A good number of publications report on different MPPT techniques for a PV system together with implementation. But, confusion lies while selecting a MPPT as every technique has its own merits and demerits. Hence, a proper review of these techniques is essential. Unfortunately, very few attempts have been made in this regard, excepting two latest reviews on MPPT [Salas, 2006], [Esram and Chapman, 2007]. Since, MPPT is an essential part of a PV system, extensive research has been revealed in recent years in this field and many new techniques have been reported to the list since then. In this paper, a detailed description and then classification of the MPPT techniques have made based on features, such as number of control variables involved, types of control strategies employed, types of circuitry used suitably for PV system and practical/commercial applications. This paper is intended to serve as a convenient reference for future MPPT users in PV systems.
1,584 citations
"Zero Oscillation and Irradiance Slo..." refers background or methods in this paper
...Many techniques have been presented to track the maximum power point (MPP) [2]–[8]; some have a very simple implementation but reduced efficiency, such as the constant voltage, fractional open-circuit voltage, and fractional short-circuit current methods, where the relationship between the open-circuit voltage/short-circuit current and the MPP voltage/current is assumed to be constant and independent of the environmental conditions [3]....
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...Complex implementations achieve high performance by using a detailed model of the PV panel and additional measures of the irradiance (G) and temperature (T ) [3], [11], [12]....
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TL;DR: Evaluations among the most usual maximum power point tracking techniques, doing meaningful comparisons with respect to the amount of energy extracted from the photovoltaic (PV) panel [tracking factor) in relation to the available power, PV voltage ripple, dynamic response, and use of sensors.
Abstract: This paper presents evaluations among the most usual maximum power point tracking (MPPT) techniques, doing meaningful comparisons with respect to the amount of energy extracted from the photovoltaic (PV) panel [tracking factor (TF)] in relation to the available power, PV voltage ripple, dynamic response, and use of sensors. Using MatLab/Simulink and dSPACE platforms, a digitally controlled boost dc-dc converter was implemented and connected to an Agilent Solar Array E4350B simulator in order to verify the analytical procedures. The main experimental results are presented for conventional MPPT algorithms and improved MPPT algorithms named IC based on proportional-integral (PI) and perturb and observe based on PI. Moreover, the dynamic response and the TF are also evaluated using a user-friendly interface, which is capable of online program power profiles and computes the TF. Finally, a typical daily insulation is used in order to verify the experimental results for the main PV MPPT methods.
1,205 citations
"Zero Oscillation and Irradiance Slo..." refers background in this paper
...MAXIMUM power point tracking (MPPT) for photovoltaic (PV) panels has seen many contributions in the past years [1], but some issues remain unsolved such as the oscillations in steady state, the tracking of changing environmental conditions, and the global maximum location....
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TL;DR: In this article, a detailed theoretical and experimental comparison of the two perturb and observe (P&O) implementation techniques on the basis of system stability, performance characteristics, and energy utilization for standalone PV pumping systems is presented.
Abstract: The energy utilization efficiency of commercial photovoltaic (PV) pumping systems can be significantly improved by employing simple perturb and observe (P&O) maximum power point tracking algorithms. Two such P&O implementation techniques, reference voltage perturbation and direct duty ratio perturbation, are commonly utilized in the literature but no clear criteria for the suitable choice of method or algorithm parameters have been presented. This paper presents a detailed theoretical and experimental comparison of the two P&O implementation techniques on the basis of system stability, performance characteristics, and energy utilization for standalone PV pumping systems. The influence of algorithm parameters on system behavior is investigated and the various advantages and drawbacks of each technique are identified for different weather conditions. Practical results obtained using a 1080-Wp PV array connected to a 1-kW permanent magnet dc motor-centrifugal pump set show very good agreement with the theoretical analysis and numerical simulations.
646 citations
TL;DR: The goal of this paper is to provide an overview of the open problems related to PV power processing systems and to focus the attention of researchers and industries on present and future challenges in this field.
Abstract: Power processing systems will be a key factor of future photovoltaic (PV) applications. They will play a central role in transferring, to the load and/or to the grid, the electric power produced by the high-efficiency PV cells of the next generation. In order to come up the expectations related to the use of solar energy for producing electrical energy, such systems must ensure high efficiency, modularity, and, particularly, high reliability. The goal of this paper is to provide an overview of the open problems related to PV power processing systems and to focus the attention of researchers and industries on present and future challenges in this field.
559 citations
"Zero Oscillation and Irradiance Slo..." refers methods in this paper
...The hillclimbing techniques, perturb and observe (P&O) and incremental conductance (InCon), are simple algorithms that can obtain high efficiency with a low computational cost and with no information about the particular PV to which they are connected with a sufficient degree of reliability [13], and for this reason, they have gained a predominant position among the MPPT algorithms....
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