A Hybrid PV-Battery/Supercapacitor System and a Basic Active Power Control Proposal in MATLAB/Simulink

Round 1

Reviewer 1 Report

The abstract focuses on the problem to be solved and clearly summarizes what is described in the work. This section is clear on both the subject and the proposed solution.

The introduction and the general description of the work are comprehensive and clear; problems and possible solution are clearly contextualized taking into account the current state of the art.

The idea and the proposed system appear of great interest in order to contain the oversizing of the energy storage systems necessary to support load peaks; this offers significant positive implications for energy saving and the environment.

Sections 2 and 3 on the state of the art of supercapacitors and storage systems are clear, and the tables also give excellent evidence of the quality of technology available today.

The abstract, introduction and sections 1 and 2 do not clarify to which rated power, sistem dimension and processed energy the work refers.

Request for revision: please clarify in all introductory sections what are the values of energy, power, type of electrical/electronic equipment and components being researched. As a further improvement, some practical examples with the description of some devices and related problems could be added.

Request for revision: In Figure 3, the numerical setspoints and units of measurement on the axes are missing.

Request for revision: both Figure 4 and figure 6 should be readjusted, (a) parts should be enlarged to read the contents better, (b) parts should be compacted to leave more space for (a) parts.

Request for review: for all charts, the thin green line is difficult to see, it would be better to use a darker color, possibly increasing the thickness.

Chapter 6 shows the results of the simulations clearly. In any case, there is no description of how much the overall performance of a generator-user group using the system proposed here improves.

Request for revision: a quantification of the efficiency improvement of the proposed system, also compared to traditional systems, should be added to Chapter 6 and the conclusions.

The conclusions are clear.

The references are abundantly consistent with the topics covered.

Author Response

The responses for reviwers are in attached file. 

Author Response File: Author Response.pdf

Reviewer 2 Report

The presented topic has a great technical potential to the energy storage systems, but the paper did not use it very well. While the main “possibly contributing” core of the paper is relatively weak in content, several passages recapitulate already known facts and the reader feels like it is a filler for the paper “volume”. Moreover, the authors have failed to provide details about the originality of the paper.

Author Response

The responses for reviwers are in attached file 

Author Response File: Author Response.pdf

Reviewer 3 Report

Dear authors,

The paper quite interesting as a whole but need major review. The major points should be addressed:

No reference to the source in Figure 1. Introduction requires a deeper analysis of the current state of knowledge regarding hybrid systems based on the battery and supercapacitor, accordingly. Tables 1 and 2 should be clarified on the basis of a broader literature analysis, among others: what is typical self-discharge, e.g. for a week / month / year, maximum number of cycles throughout the entire life cycle /shelf life, cost per kW, cost per kWh, what materials are used for production of supercapacitor, Li-ion, PbA/LA components? figure 2 should be clarified. Are bidirectional converters considered? What connections are shown in the picture? Please divide figure 2 into diagrams for passive, semi active and active connection respectively. Please characterize the main advantages of these topologies especially with regard to bidirectional DC / DC converters. Table 3 is incomprehensible. What are the lower costs of HESS? Did the authors take into account the self-discharge occurring in the supercapacitor, the battery? For what temperature conditions are the costs presented? It needs to be clarified, in its current form it is too general. all input parameters used, together with the values and units, should be presented in an additional table in section 5. Please use SI units. In section 5 the authors should add a substitute diagram of the adopted models: PV module, supercapacitor and battery, respectively. Do the adopted models include losses? The description of units on axles should be standardized, e.g. Fig. 10 and other drawings. Please delete the chart title and add a legend to the chart. This will increase transparency for the future manuscript reader. How was irradiance determined in Figure 12? Where do these irradiance changes come from? Fixed or variable step used in the simulation configuration? Why is the battery waveform not shown in Figure 14? In the hybrid system, the current flow and voltage drops at BES and SC are of key importance. The supercapacitor effect should be presented on a collective graph, i.e. BES current, SC current and total current. On a separate summary graph please presents PV voltage, HEES voltage, and BES and SC voltage. Define Nomenclature, Greek symbols, subscripts, superscripts, acronyms and abbreviations separately in table form. The summary should also indicate the main advantages of HESS. The main advantage, i.e. voltage stabilization by the supercapacitor and limitation of the battery load, which directly translates into longer battery life was not indicated. The entire text should be checked by performing a professional language correction.

Author Response

The responses for reviwers are in attached file. 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors have made a lot of work on revised paper and changed my previous decision. Now I feel the manuscript could be accepted in present form.