Coordinated Frequency Control Strategy with the Virtual Battery Model of Inverter Air Conditionings

Round 1

Reviewer 1 Report

The paper presents a model for inverter air conditioning system together with the dedicated hierarchical control system. While the idea seems to be interesting, the paper was quite difficult to follow. The main reason was poor language (I was not able to understand several phrases) and lack of compact symbols’ description (table with nomenclature). On top of that, some symbols were not described at all (e.g. R, Tij, f) and in some cases there was the same subscript used for different purposes (e.g. subscript “i” stands for integral in one place and in the other serves as a vertex index).

The Author states in line 103 that the paper presents novel approach for the AC modeling, so in my opinion, the model validation, based on experimental data should conclude section 2.

Simulation tests section is also unclear. At the beginning of the section Author mentions some cases (1-4) which are not clearly described and then are almost not mentioned in the results. Moreover, in line 393 Authors refers to “case A” which was not mentioned before at all. There is also no description of the differences (e.g. disturbance-wise) between simulations presented in Fig.5 and Fig. 6 as well as in Fig. 7 and Fig. 8.

Other minor remarks:

·        Instead of “Reference [n] proposes” in the text you should rather use “Author Name proposes… [n]”, e.g. lines 50-52, 61-64

·        Figures 4 – 20 should indicate the symbol of the simulated signal at y axis (if adequate)

·        A step disturbance in case presented in Fig. 4 seems to be in 810s, so lines 313 and 321 should be corrected.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The research manuscript of Yin and Zhao from North China Electric Power University, Beijing, aims at increasing the energy efficiency of energy conversion process involved in the operation of inverter air conditioning systems.  There have been absolutely no research reports on the subject of “coordinated frequency control strategy” in the operation of “Inverter air conditioners” based on a “virtual battery model”.  A web of science search with key words “Inverter air conditioners” and “Virtual battery” gave “zero” results showing the originality of the research work of Yin and Zhao.   Owing to the originality of the research work and significant advancement of knowledge compared to the state-of-the art literature on “inverter air conditioners” aiming at developing a strategy for the efficient conversion of electrical energy to thermal energy via a series of refrigeration cycles that convert mechanical energy in the compressor into thermal energy, the research manuscript is recommended for publication in the journal of “Applied Sciences” after minor revision.

Reviewing the work of Yin and Zhao, has been a learning experience and the research findings were presented with coherence and in an easily comprehendable manner with much of the data generated being depicted in the form of figures (1-20).  The key contribution of this work comparted to contemporary research findings is highlighted in 3 points in page 3 of the manuscript and are rewritten here below.

1. Derivation of virtual battery model of inverter air conditioner’s (ACs) based on ETP model with practical utility to ancillary services.

2.  A decentralized control strategy is developed to integrate the aggregated ACs into conventional control.  The control strategy proposed deals with an adjustable control error based on unit capacity (UPCE). Such a control strategy was found to improve the control performance with the participation of heterogeneous ACs.

3.  A decentralized/distributed finite time consensus via pinning control algoritham is proposed.  This has resulted in coordination between numerous ACs dynamic performance, namely, convergence of power tracking and state of charge (SOC) balancing of inverter ACs.

Inspite of the merits that necessitate the publication of this work in the journal of “Applied Sciences” there are few minor corrections that can be incorporated in the manuscript for improving the scientific value of the manuscript as stated below:

Minor revisions suggested:

1. What is the energy savings (%) or the enhancement in energy efficiency (%) achievable using the coordinated frequency control strategy the author’s have proposed in this study compared to either control strategy 1 or control strategy 2?  This aspect could be mentioned in either the abstract or conclusion and could enhance the scientific value of the manuscript to the field of energy conversion processes particularly pertaining to virtual battery model inverter air condition systems.

 2. The following corrections can be incorporated in the revised manuscript if the author’s consider the same appropriate as they are more knowledgeable than the present referee.

Comments for author File: Comments.docx

Author Response

Please see the attachment.

Author Response File: Author Response.pdf