Application of Predictive Control in Scheduling of Domestic Appliances

Round 1

Reviewer 1 Report

In this paper, model predictive control is applied to scheduling of home appliances. Heat pumps, solar water tanks, and non-thermal load appliances are modeled by a discrete-time linear system. The scheduling problem is reduced to a mixed integer linear programming (MILP) problem. Finally, the effectiveness of the proposed method is presented by a numerical simulation.

 

The main result in this paper is interesting as one of control applications. This paper is well written and well organized.

 

I have one minor comment.

The authors should add some comments on the computation time for solving the MILP problem at each discrete time. I want to know if the MILP problem can be solved on-line. This is an important issue. The authors should also add some comments on the computer environment such as CPU and memory.

 

Author Response

The authors should add some comments on the computation time for solving the MILP problem at each discrete time. I want to know if the MILP problem can be solved on-line. This is an important issue. The authors should also add some comments on the computer environment such as CPU and memory.

The authors thank the reviewer for the valuable suggestion. A short section on the computation time of the simulation for entire simulation period has been added to the manuscript [Line - 370]. Since, the non-thermal appliances can start at any time, 10 simulation cases have been run with random starting time for non-thermal appliances and the computation time for each case is provided.

The information about the computation environment has also been added in the manuscript [Line - 371].

Author Response File: Author Response.pdf

Reviewer 2 Report

In this paper, an algorithm for the scheduling of household appliances to reduce the1energy cost and the peak-power consumption is proposed. The system architecture of a home energy management system (HEMS) is presented to operate the appliances.

 

In the present study, an architecture of HEMS is presented for automated scheduling of appliances with an objective of reducing the peak-power consumption and the total electricity cost. The HEMS is designed to operate in two modes of operation (MOO) based upon the load category: thermal or non-thermal.

 

R1. For an easy understanding it would be best if the two modes of operation will be summarized in a Table:

Nr. Crt.	Mode	Optimization	Constrains

  The constrains should be presented as an equation, and not as a reference.

 

MR1. From the two modes of operation, except constraints, (7), (11) and (13), it is not clear how the other constraints are implemented in the proposed algorithm.

 

MR2. The scenario without HEMS and on-off control, in its present form, is very unlikely due to the fact that most of the heat pumps and solar water heater are equipped with at least a thermostat which assures a minimal control strategy. The scenario should be revised under the new terms.

MR3. Table 3, 4 and 5 should be explained better, because now it is not clear what cases are presented, for thermal appliances, non-thermal appliances or both.

 

  The article has the main key elements of a review paper: abstract, introduction, formulation of the method, results and conclusion.

R2. The article has very few languages and style errors.

I would like to suggest to the authors the following reference, which could be of help for them for both current and future research endeavors:

Vatu R., Seritan G., Ceaki O., Mancasi M. - Microgrids Operation Improvement Using Storage Technologies - 10th International Symposium on Advanced Topics in Electrical Engineering (ATEE), March 2017, pp 791-796, WOS:000403399400154

Enescu D., Gianfranco C., Porumb R., Seritan G. - Thermal Energy Storage for Grid Applications: Current Status and Emerging Trends, Energies 2020, 13(2), 340, doi.org/10.3390/en13020340

Figures and Tables are not blurred, with good resolution, clear content, uniformly text included, and all are cited in the text.

R3. There is a lot of empty space at the end of each Table, it should be removed.

All the references are cited in the text.

Author Response

R1. For an easy understanding it would be best if the two modes of operation will be summarized in a Table:

The constraints should be presented as equation, and not as reference.

The authors thank the reviewer for the comment. As per the suggestion, the constraints, mode and optimization program type have been presented in a table [Table - 3].

The authors have removed the references to the constraints and replaced them with constraint equations. [Line – 257 and Line – 262] 

MR1. From the two modes of operation, except constraints, (7), (11) and (13), it is not clear how the other constraints are implemented in the proposed algorithm.

The authors apologize for the confusion and offers the following explanation:

The constraint no. (12) is not implemented in the optimization problem, rather the extension of this constraint which is constraint (13c) is implemented. The constraint (12) explains the constraint on the maximum power consumption capacity. The constraint (13c) relaxes that constraint by introducing slack variable (soft constraint). The authors have added this information to the manuscript [Line – 247].  

In this work, the constraint no. (9) is implemented before the optimization problem is formulated i.e. offline to give the starting time and deadline of non-thermal appliances for entire simulation period (1-week). Therefore, it is not considered in the optimization problem explicitly. However, in the real-life implementation of home energy management system this constraint can be implemented directly in the optimization problem in real-time.

The authors have added this information to the text [Line – 234].

MR2. The scenario without HEMS and on-off control, in its present form, is very unlikely due to the fact that most of the heat pumps and solar water heaters are equipped with at least a thermostat which assures a minimal control strategy. The scenario should be revised under the new terms.

The authors thank the reviewer for the comment.

The authors agree with the reviewer that the on-off control is a basic control strategy. The authors have revised the scenario with an LQR control. In this case, the control action is derived based upon the state feedback-law. The new scenario and results have been added to the manuscript [Line – 317].

MR3. Table 3, 4 and 5 should be explained better, because now it is not clear what cases are presented, for thermal appliances, non-thermal appliances or both.

The authors apologize for the confusion. All the results presented in these tables are for both thermal and non-thermal appliances together. The manuscript has been updated with this information to clear the confusion [Line - 356].

The authors thank the reviewer for the suggested papers for future research. The author believe that the papers would be helpful in their future research undertakings. The present work can be extended with incorporation of thermal and electrical storage systems along-with appliances. 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

I reckon the authors have replied correctly and the updated version of the article is ready to be published.

thanks.