Switching Ripple Harmonics Attenuation in DFIG and Matrix Converter-Based WECS
Round 1
Reviewer 1 Report
The design of the paper should be improved. Follow other published papers for the sections.
The main weakness of this paper is the authors need better justify its origin and value.
The discussion is not in depth. The whole manuscript is more like a project summary rather than a formal journal paper.
Author Response
Dear reviewer, we have corrected the manuscript according to your comments.
Reviewer's note 1. The design of the paper should be improved. Follow other published papers
for the sections.
Response to the note 1. Dear reviewer. We improved the design of the paper according to
another example of papers.
Reviewer's note 2. The main weakness of this paper is the authors need better justify its origin
and value.
Response to the note 2. Dear reviewer. To better justify the origin and value of this study, I
supplemented the manuscript with an explanation in the introduction section. In this explanation, I
further explained the bidirectional power flow and the converter in the wind turbines equipped with
doubly-fed induction generators and hybrid transformers for the distributed renewable energy sources
microgrids.
Reviewer's note 3. The discussion is not in depth. The whole manuscript is more like a project
summary rather than a formal journal paper.
Response to the note 3. Dear reviewer. I expanded the discussion by forming a separate section at the end of the manuscript.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This paper presents an analysis on the harmonics distortion damping in case of bi-directional power-flow of matrix converter. This analysis is based on the observation that matrix converter generates sinusoidal voltage with some amount of harmonic distortion and worsens in the quality of power in the utility grid. The authors use MATLAB Simulink experiments to validate the analysis. In general, the observation and analysis are interesting. Please see the following comments.
- The Introduction part is too short. The observation of matrix converter should be explained clearly using real data presented in table/figures. And why this observation has not been reported in prior studies.
- Is it possible to merge Figures 3 to 6 into one figure (in different sub-figures) and explain the differences?
- In Section 5, please explain the MATLAB version and directly use the Simulink graph so that the readers can repeat the experiments.
- Please use the figures in vector format, instead of images like in Fig. 22.
Author Response
Dear reviewer, we have corrected the manuscript according to your comments.
Reviewer's note 1. The Introduction part is too short. The observation of matrix converter should be explained clearly using real data presented in table/figures. And why this observation has not been reported in prior studies.
Response to the note 1. Dear reviewer. Dear reviewer. I supplemented the introduction section with a detailed explanation of the operation of the matrix converter in Figures 1, 2, 3, Equations 1, 2 and Table 1. Also I further explained the bidirectional power flow and the converter in the wind turbines equipped with doubly-fed induction generators and hybrid transformers for the distributed renewable energy sources microgrids. Because Back-to-back converters were used in most devices with bidirectional power flow, harmonic suppression in matrix converters has not been sufficiently studied.
Reviewer's note 2. Is it possible to merge Figures 3 to 6 into one figure (in different sub-figures) and explain the differences?
Response to the note 2. Dear reviewer. I merged Figures 3 to 6 into one figure and explained the differences.
Reviewer's note 3. In Section 5, please explain the MATLAB version and directly use the Simulink graph so that the readers can repeat the experiments.
Response to the note 3. Dear reviewer. I supplemented the section 5 with Matlab / Simulink graphs. I also provided a more detailed description of the blocks used for the simulation.
Reviewer's note 4. Please use the figures in vector format, instead of images like in Fig. 22.
Response to the note 4. Dear reviewer. I increased the resolution of most of the figures. I don't have a tool to convert pictures to vector format at the moment.
Author Response File: Author Response.pdf
Reviewer 3 Report
The paper analyzes an interesting subject - harmonics distortion damping in case of bidirectional power flow of the electronics device - matrix converter as an interface between power sources.
The subject is and will be even more, of high interest, since many homes are becoming autonomous from the energy consumption point of view, and they can be have both as consumers and as producers (if they have solar panels for example). In Europe more and more homes use solar panels and energy storage system to help lower power consumption from the grid, but this has many implications, including the harmonics, that is becoming a vert interesting topic.
The paper is well presented, the context is is relevant, the calculus and presentation of the data are well done.
Firstly, I would remark that in Figure 20, the "Filter" (from Two branch filter) is half-cut and not shown. This issue should be addressed.
Secondly, in Figure 22, the images should be a little bigger and of higher resolution/vector images(or of better quality). On zoom in, it is hard to see the text.
Last but not least, although the context and time is right, as we are facing an increase of harmonics on the power grid, it would be a nice touch for the paper to add a short use case/relevant scenario where the work applies.
Author Response
Dear reviewer, we have corrected the manuscript according to your comments.
Reviewer's note 1. Firstly, I would remark that in Figure 20, the "Filter" (from Two branch filter) is half-cut and not shown. This issue should be addressed.
Response to the note 1. Dear reviewer, I have fixed this issue.
Reviewer's note 2. Secondly, in Figure 22, the images should be a little bigger and of higher resolution/vector images(or of better quality). On zoom in, it is hard to see the text.
Response to the note 2. Dear reviewer. I increased the resolution of these figures by changing their type from gif to tif. I also changed their layout in the text, which allowed them to be enlarged. I cannot form a vector type with the tools I have at the moment.
Reviewer's note 3. Last but not least, although the context and time is right, as we are facing an increase of harmonics on the power grid, it would be a nice touch for the paper to add a short use case/relevant scenario where the work applies.
Response to the note 3. Dear reviewer. To indicate the case / relevant scenario in which the work applies, I supplemented the manuscript with an explanation in the introduction section. In this explanation, I introduced the bidirectional power flow and the matrix converter in the wind turbines equipped with doubly-fed induction generators. Also I presented the application of matrix converter in the hybrid transformers for the distributed renewable energy sources microgrids.
Author Response File: Author Response.pdf
Reviewer 4 Report
Review Report on electronics-1380610
The MS entitled ”Switching ripple harmonics damping in bidirectionally operating matrix converter for renewable energy application” by G. Svinkunas and G. Petrauskas presents a an study on the harmonics distortion damping on the directional power-flow in the matrix converters used in renewable energy applications.
The paper is well organized, and its English is satisfactory enough.
Results in the paper are sound and, certainly, they are of interest for researchers working in the field.
My only question is about the modelling. Authors performed a MATLAB/Simulink analysis. Could authors give more details about the model used for components:
- Where all of them assumed to be ideal? For instance, were inductors assumed to be ideal or parasitics were taken into account?
- Circuits were simulated or was MATLAB just used to calculate the transfer functions that are (analytically) given in the paper?
- If circuits were numerically solved using MATLAB, why MATLAB was chosen instead SPICE simulators?
Finally, I would like to express some concerns about temperature: Please, could authors verify – may be performing additional simulations - if temperature is having or not a significant impact on the response?
Author Response
Dear reviewer, we have corrected the manuscript according to your comments.
Reviewer's note 1. My only question is about the modelling. Authors performed a MATLAB/Simulink analysis. Could authors give more details about the model used for components:
Where all of them assumed to be ideal? For instance, were inductors assumed to be ideal or parasitics were taken into account?
Response to the note 1. Dear reviewer. I supplemented section 5 with detailed information on the components of the Matlab / Simulink library that I used in the research model. I also came up with direct graphs for this model as well. The inductor and must of other Matlab/Simulink model components were taken from standard Simulink library and were ideal, no parasitics were taken in to account.
Reviewer's note 2. Circuits were simulated or was MATLAB just used to calculate the transfer functions that are (analytically) given in the paper?
Response to the note 2. Matlab simulation was used to create the transfer function given in the paper.
Reviewer's note 3. If circuits were numerically solved using MATLAB, why MATLAB was chosen instead SPICE simulators?
Response to the note 3. Dear reviewer. The institution hosting this research project has acquired the Matlab / Simulink software. Therefore, I used this software in my research. SPICE group software is not purchased by this institution.
Reviewer's note 4. Finally, I would like to express some concerns about temperature: Please, could authors verify – may be performing additional simulations - if temperature is having or not a significant impact on the response?
Response to the note 4. Dear reviewer. Dear reviewer. In Matlab / Simulink I used components that do not model the influence of temperature on their parameters. It is a subject of further study.
Reviewer 5 Report
The manuscript deals with an interesting research topic, having a robust methodological background, an interesting simulation analysis, and insightful findings of scientific significance in the field of switching ripple harmonics of matrix converter. However, there is still room for organizational and argumentative improvements prior it to be accepted for publication at the Electronics journal. To this end the following review comments can be considered.
1) The Abstract section can conclude with one or more sentences stating the technological advancements and the future applications that are related to the specific research outcomes in real world manufacturing or industrial situations.
2) The term of “renewable energy application” in the manuscript title has to be determined into a more specific notation, since it is vaguely expressed as it is now.
3) Since authors are referring to “application”, they can determine the place, the type of energy application, the type(s) of renewable energy source(s) (RES) referred to/or potentially fitting: wind, solar, hydro,….. and the year of its foundation, in either the manuscript or at the Abstract section.
4) The following text extracts can be checked and cross-cited, enabling a verification and consistency of the conducted analysis with relevant published papers:
a) The narrative flow from section 3 up to the end (in those text extracts that are not cross-cited)
b) All Figures included in the analysis, where they are partially or overly recalled/retrieved from other published media. In such cases the source citations are recommended.
c) All equations can be also cross-cited, enabling the validity of the modeling and the repetitiveness of the conducted analysis from similar research settings worldwide.
5) In the narrative flow a distinct subsection devoted to the introduction of the “renewable energy application” has to be deployed. Besides to the physical description, energy quantity yielded, space and technical characteristics, the synergy potentials towards larger units of: a) the same RES, or b) combination of different RES-infrastructure, they can be succinctly denoted.
6) A synthesis section between the sections 5 and 6 it has to be formed under the heading of “5. Discussion”. In this new section of Discussion authors are recommended to integrate the key-aspects of their analysis, constraints, drivers, barriers, as well as future prospects, in terms of:
a) technological synergies to be developed in a technological or modeling scale of applicability,
b) materials accessibility to assemble the machinery,
c) economies of scale achievement,
d) scalability easiness of the theoretical “Matlab/Simulink model of the bidirectionally operating MC” into practical manufacturing or industrial applications.
7) The referring/recalling of Figures 4 and 5, as well as that of equations of 8 up to 11, in the Conclusions section has to be transferred into the relevant sections of insertion, no in the Conclusions section. Actually the concluding remarks of this last section of research cannot summarize the preceding analysis and outcomes but, based on them, authors can creatively and consistently denote those limitations, constraints, enablers, challenges and future prospects offered, in alignment to reality: benchmarking, commercial market and trading, manufacturing and industrial sectors. To this end one or two no numerical, no cross cited, coherent text by authors it is adequate.
8) At the nomenclature Table 1 a right-side column has to be added, being titled as “Values”, in which each measurable term (no the dimensionless term) has to be accompanied by the value range-taken and units’ measured, where applicable.
9) Research check and update with more and relevant to the topic published papers it is recommended. To this end the following list of papers can be indicatively considered and cited.
Scopus
EXPORT DATE:01 Oct 2021
Choi, D., Bak, Y., Lee, K.-B.
57212882390;56452694700;8215459200;
(2019) Journal of Power Electronics, 19 (5), pp. 1142-1152.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073800590&doi=10.6113%2fJPE.2019.19.5.1142&partnerID=40&md5=8cf322fd905fa09fb5f5e2335df9f4ea
DOI: 10.6113/JPE.2019.19.5.1142
ABSTRACT: This paper presents a control method for reducing the current distortion in an indirect matrix converter (IMC) operating in boost mode under unbalanced input conditions. IMCs operating in boost mode are useful in distributed generation (DG) systems. They are connected with renewable energy systems (RESs) and the grid to transmit the power generated by the RES. However, under unbalanced voltage conditions of the RES, which is connected with the input stage of the IMC operating in boost mode, the input-output currents are distorted. In particular, the output current distortions cause a ripple of the power, which is transferred to the grid. This aggravates the reliability and stability of the DG system. Therefore, in this paper, a control method using positive/negative sequence voltages and currents is proposed for reducing the current distortion of both side in IMCs operating in boost mode. Simulation and experimental results have been presented to validate effectiveness of the proposed control method. © 2019 KIPE.
AUTHOR KEYWORDS: Boost mode; Current distortion; Indirect matrix converter; Positive/negative sequence voltages and currents; Unbalanced input conditions
INDEX KEYWORDS: Electric distortion; Electric power transmission networks; Renewable energy resources, Boost mode; Current distortion; Indirect matrix converter; Sequence voltages and currents; Unbalanced input conditions, Matrix converters
DOCUMENT TYPE: Article
PUBLICATION STAGE: Final
SOURCE: Scopus
Diaz, M., Cardenas, R., Espinoza, M., Hackl, C.M., Rojas, F., Clare, J.C., Wheeler, P.
55788130700;35608353200;56963644500;8919155500;56443662200;7006621743;7101693838;
(2019) IEEE Transactions on Industrial Electronics, 66 (7), art. no. 8469159, pp. 5102-5114. Cited 22 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054269624&doi=10.1109%2fTIE.2018.2870367&partnerID=40&md5=33a17944cc0d0471da4eb8895f9017e4
DOI: 10.1109/TIE.2018.2870367
ABSTRACT: The modular multilevel matrix converter (M 3 C) is an ac-to-ac converter topology suitable for the control of high-power variable-speed drives. The control of this converter is complex, particularly when the two ac system frequencies are similar or identical because large voltage oscillations can be produced in the floating capacitors within the M 3 C. This paper proposes a new vector control system based on nested controllers to regulate the M 3 C over the full range of frequencies. The proposed control scheme is especially useful to mitigate or eliminate the oscillations that arise when the frequencies are similar. An extensive discussion of the model and control of the M 3 C is presented in this work. The effectiveness of the proposed vector control system is demonstrated through simulation studies and experimental validation tests conducted with a 27-cell-5kW M 3 C prototype. © 1982-2012 IEEE.
AUTHOR KEYWORDS: AC-to-ac power conversion; equal frequencies operation; modular multilevel matrix converter (M 3 C)
INDEX KEYWORDS: Capacitors; Control systems; Electric frequency control; Matrix algebra; Matrix converters; Oscillators (electronic); Topology; Vector control (Electric machinery); Voltage control, Ac power; Ac-to-ac converter; Equal Frequencies Operation; Experimental validations; Floating capacitor; Modeling and control; Multilevel matrix converter; Voltage oscillation, Variable speed drives
DOCUMENT TYPE: Article
PUBLICATION STAGE: Final
OPEN ACCESS: All Open Access, Green
SOURCE: Scopus
Diaz, M., Rojas, F., Espinoza, M., Mora, A., Wheeler, P., Cardenas, R.
55788130700;56443662200;56963644500;56893222400;7101693838;35608353200;
(2018) Proceedings - 2017 IEEE Southern Power Electronics Conference, SPEC 2017, 2018-January, pp. 1-6. Cited 4 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85049217969&doi=10.1109%2fSPEC.2017.8333629&partnerID=40&md5=57d64f026d612bb140860d7b1d2641db
DOI: 10.1109/SPEC.2017.8333629
ABSTRACT: The Modular Multilevel Matrix Converter (M3 C) is an AC-to-AC Modular Multilevel Converter composed of H-Bridge Power Cells connected to flying capacitors. This converter has been proposed as a solution to high-power drive applications due to its characteristics such as high power quality, medium or high voltage operation and control flexibility. However, the energy balancing of this converter is complex when the Input Port has a frequency close to the Output Port frequency because large voltage fluctuations can appear in the flying capacitors. Consequently, this paper proposes a novel Closed-Loop Vector Control Strategy, which is implemented in dq synchronous frames, to allow the operation of the converter in a broad range of operating frequencies. Extensive discussion of the model and control of the M3C is presented. The effectiveness of the proposed Control Strategy is validated through simulations and experimental results obtained with a 27 power-cells prototype. © 2017 IEEE.
INDEX KEYWORDS: Bridge circuits; Closed loop control systems; Matrix converters; Power electronics; Vector control (Electric machinery), High power quality; High-voltage operation; Modeling and control; Modular multilevel converters; Multilevel matrix converter; Operating frequency; Vector control strategies; Voltage fluctuations, Quality control
DOCUMENT TYPE: Conference Paper
PUBLICATION STAGE: Final
SOURCE: Scopus
Fan, B., Wang, K., Wheeler, P., Gu, C., Li, Y.
56516104600;55501485400;7101693838;35304827600;7502099056;
(2018) IEEE Transactions on Power Electronics, 33 (2), art. no. 7883960, pp. 1105-1117. Cited 26 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034089652&doi=10.1109%2fTPEL.2017.2685431&partnerID=40&md5=3ccb57ebe717539f18ec88c622bc1a53
DOI: 10.1109/TPEL.2017.2685431
ABSTRACT: The modular multilevel matrix converter (M3C) is a promising topology for medium-voltage, high-power applications. Due to the modular structure, it is scalable and capable to produce high quality output waveforms and can be fault tolerant. However, the M3C suffers from low frequency capacitor voltage fluctuation if the output frequency is close to the input voltage frequency, which limits its application in adjustable speed drive fields. This paper presents a theoretical analysis in the phasor domain to find the branch-energy equilibrium point of the M3C when operating with equal input and output frequency first. Then, a branch energy balancing control method based on branch current reallocation is proposed to equalize the energy stored in the nine converter branches. With the proposed method, the M3C can effectively suppress the capacitor voltage fluctuation without injecting common-mode voltage or applying reactive power to the input side. Experimental results are presented to validate the proposed method. © 2017 IEEE.
AUTHOR KEYWORDS: Energy and balancing control; equal frequency; medium-voltage high-power ASD; modular multilevel matrix converter (M3C); triple-star bridge cells (TSBC) converter
INDEX KEYWORDS: Energy balance; Matrix converters; Power converters; Variable speed drives, Balancing controls; equal frequency; High power; Multilevel matrix converter; triple-star bridge cells (TSBC) converter, Frequency domain analysis
DOCUMENT TYPE: Conference Paper
PUBLICATION STAGE: Final
OPEN ACCESS: All Open Access, Green
SOURCE: Scopus
Ammar, A., Kanaan, H.Y., Moubayed, N., Hamouda, M., Rahmani, S., Ounejjar, Y., Al-Haddad, K.
57198277865;7003890479;24768266500;57207968088;6701331026;25226880300;55667551800;
(2017) Proceedings of the IEEE International Conference on Industrial Technology, art. no. 7915588, pp. 1498-1503. Cited 19 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019641691&doi=10.1109%2fICIT.2017.7915588&partnerID=40&md5=4df8065f134d86422be279ec525c43f5
DOI: 10.1109/ICIT.2017.7915588
ABSTRACT: This paper discusses the design and topology of the indirect matrix converter. The double space vector modulation technique (DSVPWM) is applied on the system and a unity power factor was accomplished along with desired sinusoidal input and output waveforms. The whole system is simulated using Matlab/Simulink, and the results prove to comply with the existing power quality standards. © 2017 IEEE.
AUTHOR KEYWORDS: AC-AC conversion; Matrix converter; Space vector modulation; Unity power factor
INDEX KEYWORDS: AC-AC power converters; Electric power factor; Matrix converters; Modulation; Power converters, Ac-ac conversion; Double space vector modulations; Indirect matrix converter; MATLAB /simulink; Power quality standards; Sinusoidal input; Space Vector Modulation; Unity power factor, Vector spaces
DOCUMENT TYPE: Conference Paper
PUBLICATION STAGE: Final
SOURCE: Scopus
Fan, B., Wang, K., Gu, C., Wheeler, P., Li, Y.
56516104600;55501485400;35304827600;7101693838;7502099056;
(2016) IECON Proceedings (Industrial Electronics Conference), art. no. 7792966, pp. 3111-3116. Cited 4 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010065691&doi=10.1109%2fIECON.2016.7792966&partnerID=40&md5=d218575ce277f56c45244388c95b69db
DOI: 10.1109/IECON.2016.7792966
ABSTRACT: The Modular multilevel matrix converter (M3C) is a promising topology for medium-voltage, high-power applications. Due to the modular structure, it is scalable, produces high quality output waveforms and can be fault tolerant. However, the M3C suffers from capacitor-voltage fluctuation if the output frequency is similar to the input frequency. This problem could limit the circuit's application in the adjustable speed drives (ASD). This paper introduces a theoretical analysis in the phasor-domain to find the branch energy equilibrium point of the M3C when operating with equal input and output frequencies. On the basis of this equilibrium point, a branch current reallocation based energy balancing control method is proposed to equalize the energy stored in the nine converter branches. With this novel control method, the M3C can effectively overcome the capacitor voltage fluctuation without using balancing techniques based on common mode voltage or applying reactive power at the input side. © 2016 IEEE.
AUTHOR KEYWORDS: Energy and balancing control; Equal frequency; Modular multilevel matrix converter (M3C)
DOCUMENT TYPE: Conference Paper
PUBLICATION STAGE: Final
SOURCE: Scopus
Kammerer, F., Brackle, D., Gommeringer, M., Schnarrenberger, M., Braun, M.
54946523900;57192081820;56333487500;56333279900;57158541300;
(2015) PCIM Europe 2015; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management; Proceedings of, art. no. 7149076, . Cited 19 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-84997228971&partnerID=40&md5=abfb0f59b5c8e75442c2e2941b17df62
ABSTRACT: The Modular Multilevel Matrix Converter (M3C) is an emerging topology, especially suitable for high torque low speed drive applications in the medium voltage range. One special benefit is the overload capability of the output currents. Up to 200% of the nominal values can be reached near standstill to overcome breakaway torques without additional efforts. This contribution gives an experimental verification of the operating performance by using a low voltage laboratory prototype with 5 cells per arm. In addition, different energy balancing methods, depending on the operating point are presented. Finally, possible applications for the M3C are discussed. © VDE VERLAG GMBH Berlin Offenbach.
INDEX KEYWORDS: Energy management; Intelligent robots; Power converters; Power electronics, Breakaway torque; Emerging topologies; Experimental verification; Low speed drives; Multilevel matrix converter; Operating performance; Operating points; Overload capability, Matrix converters
DOCUMENT TYPE: Conference Paper
PUBLICATION STAGE: Final
SOURCE: Scopus
Nateghi, A., Kazemi Karegar, H., Hazrati Sagharchi, R.
55607901300;8524583100;56685600800;
(2015) 6th Annual International Power Electronics, Drive Systems, and Technologies Conference, PEDSTC 2015, art. no. 7093348, pp. 633-638. Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-84931030392&doi=10.1109%2fPEDSTC.2015.7093348&partnerID=40&md5=6e6f54901d044bd0b5028d060b7b1e7b
DOI: 10.1109/PEDSTC.2015.7093348
ABSTRACT: The purpose of this paper is investigating the operation of a permanent magnetic wind turbine equipped with matrix converter under the grid's fault. In this regard, when a fault occurs in the grid, the amplitude and the phase of output's voltages of converter controls in such a way that limits the fault's current and turbine remains in power generation mode. This process is implementing by using a simple algorithm without concepts like vector control, and with designing a matrix converter power circuit and controlling that based on VENTURNI method, then the results of simulation are going to be analyzed in MATLAB programming environment. © 2015 IEEE.
AUTHOR KEYWORDS: Current limit; direct matrix converter; grid's fault; permanent magnetic wind turbines
INDEX KEYWORDS: Electric network analysis; Electric power transmission networks; MATLAB; Matrix converters; Permanent magnets; Power converters; Power electronics; Vector control (Electric machinery); Wind turbines, Converter controls; Current limits; Grid fault; Matlab programming; Permanent magnetics; Power circuit; SIMPLE algorithm, Electric power system control
DOCUMENT TYPE: Conference Paper
PUBLICATION STAGE: Final
SOURCE: Scopus
Author Response
Dear reviewer, we have corrected the manuscript according to your comments.
Reviewer's note 1. The Abstract section can conclude with one or more sentences stating the technological advancements and the future applications that are related to the specific research outcomes in real world manufacturing or industrial situations.
Response to the note 1. Dear reviewer. I supplemented the abstract with information on the equipment in which it would be appropriate to use these filters.
Reviewer's note 2. The term of “renewable energy application” in the manuscript title has to be determined into a more specific notation, since it is vaguely expressed as it is now.
Response to the note 2. Dear reviewer. To define the term “application of renewable energy” more precisely, I changed the title of the manuscript.
Reviewer's note 3. Since authors are referring to “application”, they can determine the place, the type of energy application, the type(s) of renewable energy source(s) (RES) referred to/or potentially fitting: wind, solar, hydro,….. and the year of its foundation, in either the manuscript or at the Abstract section.
Response to the note 3. Dear reviewer. To determine the place, the type of energy application, I supplemented the manuscript with an explanation in the introduction section. In this explanation, I further explained the bidirectional power flow and the converter in the wind turbines equipped with doubly-fed induction generators and hybrid transformers for the distributed renewable energy sources microgrids.
Reviewer's note 4. The following text extracts can be checked and cross-cited, enabling a verification and consistency of the conducted analysis with relevant published papers:
Reviewer's note 4.a. The narrative flow from section 3 up to the end (in those text extracts that are not cross-cited)
Response to the note 4.a. Dear reviewer. I put cross-citing for figures, equations, tables, and references in the manuscript.
Reviewer's note 4.b. All Figures included in the analysis, where they are partially or overly recalled/retrieved from other published media. In such cases the source citations are recommended.
Response to the note 4.b. Dear reviewer. There are no figures in our manuscript that would be recalled / retrieved from other published media.
Reviewer's note 4.c. All equations can be also cross-cited, enabling the validity of the modeling and the repetitiveness of the conducted analysis from similar research settings worldwide.
Response to the note 4.c. Dear reviewer. I put cross-citing for figures, equations, tables, and references in the manuscript.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The revision has addressed the concerns from the reviewers. Recommend accept as it is.
Reviewer 4 Report
Authors have satisfactorily responded to the questions and introduced the changes in the MS that I suggested in my first report.
