Reproducible Method for Modifying a Published Electricity Network Model for Transmission Expansion Planning

Round 1

Reviewer 1 Report (Previous Reviewer 2)

Comments and Suggestions for Authors

Although it has been improved, it still requires further revision before it can be published.

Author Response

Please see the attachment.

 

Author Response File: Author Response.pdf

Reviewer 2 Report (Previous Reviewer 3)

Comments and Suggestions for Authors

The publication presents algorithms and an example of how to extend the existing model structure with new elements and how to make changes to elements.

It should be pointed out why a popular model from the 1980s is used, and not one based on the parameters of real network operators, as is practiced in professional calculations. Perhaps the cost of obtaining data by the researcher is important here?

The work comes down to entering new data into the model and without a thorough analysis of the Swedish operators' data it is difficult to verify.

The given algorithms for introducing changes are very general, they resemble execution instructions more than selection criteria.

The presented summary is very general and concluded to the fact that the introduced changes describe the current state of the network.

The scientific nature of this work is not clearly indicated, however the work is interesting and important from a utilitarian and practical perspective for better analysis of Swedish networks.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

lines 112-114 please give references for the modelling information presented in fig 1 " Visual positioning of this paper’s contribution to academia (top) and to improved trans mission system operator/owner (TSO) and industry processes for transmission expansion planning 113 (TEP) (bottom)."

lines 147 - 151  please give an example from practice about your purpose "When updating a transmission expansion planning model for academic research, the  impact of a new method or technology type or application is being tested to demonstrate  its performance in a simplified controlled environment: simulation results with and with out the novel aspect are used to show its effect on the transmission expansion requirements"

Figure 2 please can you develop with real examples the information "standards System studies: thermal, voltage, stability..." and the influence on your proposed model

lines 285- 289 please show the possible renewable sources implemented in the model ""It is necessary to include this technology change as well as the  additional generation capacity to the generation mix for transmission expansion planning  studies in the Nordic region because the change to the dispatchability and predictability  of the region’s generation on different timescales can be important to identifying trans mission reinforcement requirements."

lines 358-360  please explain how the step "Perform all system studies required" can be acomplished

""3.3. Gathering all the required data ""  - where the technical data information and the equipment real parameters are coming from ? 

"3.6. Identifying performance limit breaches for all secured events" please add explanations about your proposed model in this case , compared with Nordic-32 

lines 460-475 please explain how these methods are selected, which is the criteria? economical purpose is it considered? 

linew 504- 510  which is the economical impact of "Where a single circuit is in place already, there is the option to replace the towers and  create a double circuit route. This can provide more future-proofing than reconductoring  and has less of a problem with permitting than new circuits as the route is existing.  Changes to visual and environmental risk will still need to be considered by the host network and society and may have a delay associated. However, these projects are more  likely to pass through planning regimes smoothly than new lines and can be delivered in  only a few years." 

lines 521 - 525 please give explanation , the information is not clear/correct  "For steady-state voltage performance studies, it is important to choose reactive compensation solutions that are not inappropriately large or flexible; for example, inserting a  few 1 GW synchronous condensers into the base model will likely resolve voltage issues  in a region but might not enable you to identify whether a further increase in flows in that region justifies an additional 225 Mvar shunt capacitor. The"

"3.7.4. Cost estimates for reinforcement options" how this information  influence the model results, taking in account the region /country/ currency ? 

Figure 4." the reinforced model  is  real or only proposed for the reserch purpose ?

""4.4. Reinforcing the Nordic-32 to meet planning standards with 2024 data"" please insert an overview (grafic/ schematic) about the scenarios taken in account - the information is difficult to follow 

"4.4.1. Single pass or incremental increase in demand" how the demand variation influence the results? the prosumators are taken in acount? 

 

 

Comments on the Quality of English Language

english is clear

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report (New Reviewer)

Comments and Suggestions for Authors

This paper presents a reproducible method for modifying existing power system network models, with a focus on transmission network expansion planning. The authors use the well-known Nordic-32 model, based on the Swedish grid from the 1980s, and update it to represent generation and consumption in Sweden for 2024, aligning with the Nordel Grid Code standards. 

The paper primarily examines static and steady-state analyses, without a detailed examination of dynamic, stochastic effects, or market interactions. Therefore, it is essential to discuss the dynamics of the process, including when they may occur and how to manage them. 

The model is versatile and detailed, as illustrated by the Swedish example; however, its application in other countries may require different rules. For example, a parameter such as legal regulation can significantly influence the model's development. The authors should clarify the limitations and the scope of applicability of the general model. 

 Additionally, in Table 1, the unit "Mvar" is incorrectly written and should be "MVAr".

The paper presents a universal model; however, applying it in other countries may face certain technical and regulatory hurdles. Therefore, it is advisable for the authors to suggest specific recommendations and policy measures to overcome these barriers and facilitate the successful replication of the model. Special attention should be given to ensuring that, when used in different national contexts, the model can be effectively adapted and implemented.

Authors are expected to identify relevant technical and regulatory obstacles and propose suitable recommendations and policy measures to promote optimal solutions that overcome these challenges and support the replication of the model in other countries.

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

the paper was improved 

it can be published 

Author Response

Thank you for your time taken to consider the manuscript and its revisions. 

Reviewer 4 Report (New Reviewer)

Comments and Suggestions for Authors

Dear authors,

Thank you for your carefully crafted edits and constructive approach in responding to comments. The discussion is now much more balanced, with a clearer focus on current contributions and work limitations, which is a positive change. Due to limitations in laboratory equipment, research and testing are restricted. They consider the research conducted as the foundation for further development of diagnostic methods.

However, they should specify in the paper the conditions under which they plan to conduct future research to make their claims more credible.

For future work, the existing findings should be expanded with specific criteria and accuracy metrics, including a larger number of transformers and test conditions.

Author Response

Comment 1: 

Thank you for your carefully crafted edits and constructive approach in responding to comments. The discussion is now much more balanced, with a clearer focus on current contributions and work limitations, which is a positive change. Due to limitations in laboratory equipment, research and testing are restricted. They consider the research conducted as the foundation for further development of diagnostic methods.

However, they should specify in the paper the conditions under which they plan to conduct future research to make their claims more credible.

Response 1:

Thank you for your considered comment and suggestion for improvement. 

Already a very long paper, the authors decided that to combine the detail on the model creation method with other research outcomes would result in a lack of sufficient detail to enable the method to be reproduced by other academics. The decision to include detail of the method and an example of implementing it in the paper meant that it became necessary to split this paper away from the subsequent research that it is the foundation for. 

Having said that, the authors agree that there is merit in providing more detail on the future research that is planned to be published using a model created from the method presented in this manuscript.

Edits to achieve this have been made and can be seen by Green highlighting in the text around lines 110--125.

Comment 2:

For future work, the existing findings should be expanded with specific criteria and accuracy metrics, including a larger number of transformers and test conditions.

Response 2:

Thank you again for a specific comment suggesting an improvement to the manuscript. It is indeed one of the challenges of academia to recreate accurate conditions for testing. In transmission expansion planning this is particularly pertinent since models are in many cases, such as Sweden, considered to be secret and security sensitive by the transmission system operators (TSOs). In many ways, this is the purpose and main contribution of this paper: to enable a model to be produced that is realistic enough to be useful for the type of analysis being performed for the case study presented; for example, circuit loading and steady state voltage to enable identification of reinforcement requirements under novel approaches to the transmission expansion planning problem in Sweden. 

Linking the test conditions to external verifiable sources is another challenge faced in this field. Svenska Kraftnät, the Swedish TSO, do not publish a set of conditions against which their network is dimensioned. They consider that to also be secret. However, for a wider audience or when relating to TSOs that do have guidelines, the authors agree that there is merit in bringing the importance of this aspect to the fore in the paper. 

Edits to achieve this have been made and are highlighted in green around lines 73--83.

The number of transformers used in the model is discussed in lines 709--723 and 873--896 where the decision to not include parallel banks of transformers or to consider transformer sizing is justified for the case study example presented. 

Having said that, the authors agree that this, and other limitations of the case study example presented, should be more clearly brought out in the paper and we thank the reviewer for making this suggestion. The limitations in terms of aspects such as transfomers to include lower voltage level representations as well as to enable identification of transmission expansion requirements through provision of grid supply points to distribution networks (through, for example, 400/130kV transformers) is recognised as important to transmission expansion planning and the authors thank the reviewer for bringing to our attention that this is not sufficiently highlighted in the manuscript.

Edits to improve this have been made with green highlight around lines 896--904.

In relation to criteria and accuracy metrics for the model, the authors would like to highlight that the method presented in the paper is not designed to create a model that exactly represents the conditions of a particular network at any specific moment in its operation. Rather, the method enables a model to be produced that complies with the planning standards of a specific TSO. This distinction is important in the case of Sweden where Svenska Kraftnät do not allow accurate data or models to be published. It is in fact a crime in Sweden to attempt to do so. This paper addresses this limitation by enabling a model that is suitable for transmission expansion planning research to be created from published reference models that are not, in their original published form, suitable for such research. The authors have reviewed whether this was brought out sufficiently in the manuscript and draw attention to lines 70--110, 297--306 and to Figure 3, which relate to these aspects.

Specific criteria and accuracy metrics for a model that is aiming to recreate a specific set of network operating conditions from a real network would include cross-boundary flows between regions of the network for given patterns of generation and demand. That would give credibility to the impedances and topological connectivity of the network. It would also depend on what type of study was being performed. For example, when we move away from steady-state and start to consider dynamic voltage stability or rotor angle oscillatory stability then criteria such as time response to a disturbance become important and model aspects such as AVR control structures and power system stabiliser control architectures for generators and dynamic reactive compensation, tap changers and their associated time phases need to be considered. Ths is even more challenging to get accurate data for and so, again, academia is forced to use published reference models. Model preparation for this type of study is outside of the scope of this manuscript but is nonetheless interesting. 

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

MUCH more comprehensive results and evaluations are needed for journal publication.
It would also be necessary that better and clearer graphical presentation should be used in the revised version.

Comments on the Quality of English Language

The authors must check the English mistakes very carefully. 
The authors have to significantly improve the technical writing and graphical presentation of the paper.

Reviewer 2 Report

Comments and Suggestions for Authors

1. Please identify and elaborate on the existing problems in the Introduction section. This will help highlight the paper’s contributions or innovations more effectively. Additionally, please incorporate more recent and relevant references to strengthen the technological foundation of the study.
2. Please revise Figure 1 to present the data flow more clearly and logically. Currently, it is difficult to identify the starting point and the endpoint of the process.
3. It is recommended to present the principles in Section 2 using more technical and concise language, rather than relying on lengthy descriptive paragraphs for each aspect.
4. Please provide a more detailed explanation of the methods used in each step of Section 3. For instance, the key inputs are currently unclear, and the process flowchart in Figure 2 is too general to adequately illustrate the specific processes involved.
5. The case study presented in Section 4 appears to be well-executed and potentially valuable. However, the advantages of the proposed principle or method are not clearly articulated. As it stands, the work reads more like a descriptive report than a research paper with a clear contribution.
6. Please further elaborate on the contributions in the Discussion section, particularly aligning them with the established standards for model expansion. This will help to better highlight the significance and innovative aspects of the proposed method.

Reviewer 3 Report

Comments and Suggestions for Authors

The publication presents algorithms and an example of how to extend the existing model structure with new elements and how to make changes to elements.

It should be pointed out why a popular model from the 1980s is used, and not one based on the parameters of real network operators, as is practiced in professional calculations. Perhaps the cost of obtaining data by the researcher is important here?

The work comes down to entering new data into the model and without a thorough analysis of the Swedish operators' data it is difficult to verify.

The given algorithms for introducing changes are very general, they resemble execution instructions more than selection criteria.

The presented summary is very general and concluded to the fact that the introduced changes describe the current state of the network.

The scientific nature of this work is not clearly indicated, however the work is interesting and important from a utilitarian and practical perspective for better analysis of Swedish networks.