Transient Differentiation Maximum Power Point Tracker (Td-MPPT) for Optimized Tracking under Very Fast-Changing Irradiance: A Theoretical Approach for Mobile PV Applications

Round 1

Reviewer 1 Report

This paper presents a modification of the traditional Perturb and Observe (P&O) Algorithm for Maximum Power Point Tracking (MPPT) by adding a measurement performed close to the maximum overshoot peak after the perturbation stage. By comparing power changes between these 3 points, the proposed algorithm tries to decide whether the perturbation was made in the correct direction or not. An interesting part of the paper is that the MPPT efficiency is analyzed based on the EN50530 Standard, something that is not met very frequently in the relevant technical literature. The topic has been studied widely during the past 15 years, therefore, the contribution of this paper with respect to the art should be clearly highlighted. This is more or less achieved in the introduction of the paper. Some specific comments appear below regarding the introduction. In addition to these comments the reviewer has two major concerns:

1. The authors compare their method to the classical P&O approach of Figure 1. However, in the introduction, they mention in lines 96-98 that “This approach is very close to the idea proposed in [21], except 96 that the supplementary measurement takes place during the transitory state right after …”. Therefore, in addition to the traditional P&O approach the authors should compare their method also with the method presented in [21] to demonstrate the added value of the proposed approach.
2. Equations (3) to (8) are identical!!! This means that the authors have not paid attention into writing properly their manuscript! In addition, the equations seem to be inserted as pictures. The reviewer suggests that the authors review and write carefully the manuscript before resubmitting it!! In its current form, it cannot be reviewed, since the reviewer cannot evaluate the performance based on the proper equations.

Comments regarding the introduction:

1. The authors mention in lines 63-66 that “… Because of this, the use of boundary conditions combined with dynamic perturbation sizes has been proposed to prevent the system from drifting away too far from the MPP by [15,16]. In [17] the author presents a method to detect irradiance changes using fractional short circuit current (FSCC) while reducing the perturbation size.” Which are the disadvantages of the methods presented in [15, 16, 17]??
2. Then, the methods met in [18-21] are described without mentioning any disadvantages these studies might have. This should be corrected.

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Reviewer 2 Report

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Reviewer 3 Report

This manuscript provides modifications to the P&O algorithm for MPPT by using an additional sample between each perturbation. The author needs to address the following points before publishing this manuscript, especially the third point:  

• In line 98, it is not clear to have T MPPT/2!
• It is not clear from where the author got Figure 2. Was it by experiment?
• The paper compared the Td-MPPT to the P&O algorithm. What are the benefits of using Td-MPPT over other algorithms like adaptive control or other types of controllers?
• It will be better to test the Td-MPPT with unsteady irradiance cases.

 

 

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Round 2

Reviewer 1 Report

Generally, the authors have addressed the concerns of this reviewer adequately in a good manner. The reviewer has only two further (minor) comments:

1. Throughout the simulations section it is shown that in most cases the proposed approach leads to higher efficiency, e.g.

1. Lines 333-335: “Due to this, the overall efficiency of the Td-MPPT reaches 99.68%, while the dP-P&O achieves 99.56%, and the classical P&O drops to 97.26%.”
2. Lines 440-442: “The efficiency of the P&O was similar to the standard test (98.05%). The dP-P&O (Figure 14a) displayed a better efficiency with this test than under the standard one (99.39%). And the Td-MPPT (Figure 14b) showed a slightly lower efficiency than the observer under the standard test (99.59%).”

However, for the proposed approach one additional measurement is needed. What is the required infrastructure and the additional implementation cost for including such additional measurement? Moreover, do the authors have an idea on how the additional measurement cost could be compensated by increasing the efficiency of the MPP control? This question aims to gain a better understanding on why to choose this approach instead of other approaches if the increase in the efficiency is marginal?

2. In lines 277-282 the authors have identified a small drawback of the proposed approach: “it is unable to guarantee tracking of the global maximum power point (GMPP) under non-uniform irradiance. A hybrid algorithm between a GMPP search technique and the proposed algorithm could be implemented to solve this shortcoming.” Could the authors comment on the involved computational burden if an additional hybrid algorithm is simultaneously solved? What would the additional implementation cost of this approach?

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Reviewer 2 Report

Although the authors modified the manuscript as the reviewer commented, there are two previous comments that have not been taken into consideration in addition new minor comment (no.3).

1- The comparisons between the theoretical and measured (simulated) results should be introduced.

2-The Power-Voltage curves for all irradiances values applied in this study should be plotted. Also, it is better to plot duty ratio-Voltage curves for all irradiances values applied in this study.

3- The electrical parameters/characteristics of the PV model should be provided.

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Reviewer 3 Report

The authors covered all of my previous points correctly and clearly 

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