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Articles on the cost of upgrading the US T&D network for renewables?


I'm looking for any articles or discussions on the cost of upgrading the US distribution network - or any general discussion on this topic.  I'm doing some research on NWAs and generally looking for some stats that talk to what this may be (or may not be) a big impact to the economy in the future.

Thanks, will keep searching!



I assume you've seen the most recent Wires report, but on the off chance you haven't, here's a link to it. 

Peter Key's picture
Peter Key on Apr 6, 2020 2:56 pm GMT

Oops, that's transmission, not distribution.

Chris Law's picture
Chris Law on Apr 6, 2020 8:51 pm GMT

Thanks for this, was interesting either way so thanks!

I'm not aware of recent private research reports (a lot of the specific D-level details tend to be redacted from utility PUC filings), but this was a US Department of Energy focus a few years ago.  You've probably already stumbled across them, but the EIA and DOE released reports in 2018; it's been years since I've been deep into the files, but I'd imagine that much of the raw data is from FERC Form 1 and EIA 861.  The table at the bottom of the EIA post is particularly interesting for the 20,000 ft evidence of correlation between CapEx and Customer Expentiture with DER resource/penetration maps.   


Chris Law's picture
Chris Law on Apr 6, 2020 8:53 pm GMT

Thanks for this, very useful.  I had not seen that table but yes was useful thanks.

I’m not much of D person, I spent my career on the T side but friends have told me one of the biggest challenges going forward on the D side with the proliferation of VER/DER is protection. Check the NERC, EPRI and ESIG sites, there may be some good insight into issues.

Chris Law's picture
Chris Law on Apr 8, 2020 6:53 pm GMT

Thanks John.  No harm being from the T side of "the force" :). Thanks for those suggestions I have started to check them out.


Dear Chris

The cost of upgrading a T&D network for renewables involve several factors. Some of them are easy to visualize, for example when you insert near a “weak” network a new biomass or wind plant that will increase the local short circuit power in that point. Another may be some extra-costs to avoid voltage fluctuation when a new  wind plants is inserted.

My suggestion to you is that you list the, lets say, four (4)  main aspects that you wish to consider in your study. Having clear which are these aspects maybe some of us can suggest some readings.

Possibly you will not find all these aspects in just one document. Maybe you can find a comprehensive list of the aspects is some academic postgrad thesis. In a competitive market the power utilities will not disclose reference numbers.

Try to search the term “renewables_cost_data”,  previous documents at and the term “ Overview of Renewable Energy Cost Database”   “

In the past, when I developed the software Decidix ( assessment of energy projects ) I learned very much in the excellent documents issued by EPRI like “ Report EPRI Eletric Power Research Institute (EUA) TR-100281 - Vol. 3 - December 1991 ; “. Possibly they have modern versions of that with updated data...

Good Luck **  **

Chris Law's picture
Chris Law on Apr 8, 2020 7:00 pm GMT

Thank you this is excellent.  I do agree my question was a little vague, which was somewhat deliberate to see what opinions where out there.

However with the help so far I have connected with various industry bodies and researchers who have really helped me understand the question and areas in more detail - great stuff Energy Central.

Generally, I'm thinking about Distribution System Planning outcomes, but now realize from discussions this is evolving currently.  What I have seen here in AUS is the need for more granular Hosting Capacity Planning in the D-network i.e. beyond the feeder level to the secondary network - to plan phase loading, balancing and voltage issues.  However, as I understand it now this is all driven by the Utilities Distribution System Plan and investing priorities - which is different for all (which makes sense)

I think the other area that of this is the tension between the current Rate base/model and the impact of new generation technology - which seems from an outsiders point of view to mean a shift to performance-based Rates/KPIs is needed to better balance the future needs.

Still learning, but thank you! 

John Simonelli's picture
John Simonelli on Apr 9, 2020 4:56 pm GMT

Very true Sergio. I've heard from a lot of the D side of the house folks about very low short circuit strength on the system where renewables are going in. In some cases it was low enough that they were forced to install additiobal dynamic reactive devices such as very small synchronous condensers. We all know that comes at a cost.

Chris Law's picture
Chris Law on Apr 9, 2020 7:06 pm GMT

Thanks for pointing this out John,  not being an expert in the area but I get a general concept.  My thinking is how quickly do these issues tend to manifest i.e. would it be possible to manage voltage fluctuations using say data ( minutes to react ) rather than require reactive devices to manage what I assume is an ongoing larger dynamic range of voltage.

John Simonelli's picture
John Simonelli on Apr 14, 2020 5:31 pm GMT

I’m not an expert on inverter technology but I have been told by the solar panel folks that every single one of those has the capability to provide leading and lagging MVAR capability. The problem then becomes how do you control potentially hundreds of these devices out on a distribution feeder. Are they in voltage control, are they in constant power factor, are they in fixed MVAR output? Do all of them regulate, do some of them regulate, and how do you coordinate all that with voltage regulators on the distribution circuit and the step-down tap changing transformers to the T side. It potentially becomes an overwhelming voltage control problem.  Also, I have been told the inverters themselves have problems when they are installed on a system with low short circuit strength. So, if the distribution circuit is weak and you have the right type of fault will any of these inverters be able to help reactively with voltage control assuming they all meet the IEEE 1547 voltage and frequency ride thru requirements? I’m not sure but it in of itself is a huge modeling and PSCAD study effort.

Hi Chris:

There is no accurate estimate that I have seen, but there are processes, and I can provide links to some my earlier papers and point you to some future papers that I will post in the next few weeks that might help you understand these. Note that I tend to focus on my home state (California) with these, but the processes should be similar elsewhere in the U.S.

Let's start with the transmission network. About a year and a half ago, I posted a six part series on the California Independent System Operator (CAISO). Part 2 of this, section 3.1 described the CAISO Planning Process. There is a link below to this part.

However, California coordinates with the Western Electricity Coordinating Council (WECC) and the other states therein in their planning process. Furthermore there is a related process called Reliability Coordination, and the entity responsible for this is the Reliability Coordinator. CAISO recently took over this responsibility for most of WECC. I will need to send you through two links for this. The first is part 6 of the CAISO series, section 4. The transition to CAISO as the Security Coordinator was in process when I wrote this series, so I wrote a later update, which is the second link below (read it after the section 4).

Now distribution: There is also a process that relates to the distribution system, called resource adequacy. There is a link below to a paper on this and other related subjects.

Although the above processes are specific to California, I expect they will be in the future for much of the U.S.

Also there that many choices and many constraints when upgrading distribution systems. PG&E is currently restructuring, and one of the steps they are taking to mitigate the impacts of Public Safety Power Shutoffs is to implement a large number of microgrids in their service area. I'm starting a two-part post next week on their reorganization, and part 1 (to be psted next Tuesday) will cover these microgrids (among other subjects).




Chris Law's picture
Chris Law on Apr 9, 2020 6:52 pm GMT

Great John, very interesting indeed.  As a secondary note I will be interested to read you Microgrid topics - we have a lot of work happening here in Australia on that front - so keen to read about this in the context of say PG&E and particularly what it may mean for Distribution management as a result.

John Benson's picture
John Benson on Apr 13, 2020 4:51 pm GMT

Hi Chris:

When I worked for Landis & Gyr and then Siemens (Siemens acquired my division from L&G and now its the Power TG Division) we had a few customers in Australia, mainly HECT. I believe they originally bought their EMS system around 1990, and when I retired from Siemens (2013) they were talking to them about a major upgrade.

I'll send you through one more link. This is my list of all papers, and I just updated it. One section in this list is Renewables & Microgrids, each paper has a brief description with a link to the paper in Energy Central. Be sure to read the list's Intro - the list is linked from the index.

Also, I'm posting a paper in on PG&E tomorrow morning. I don't know if you have heard about the PG&E Bankruptcy, but they are starting to emerge from this. One of solutions they are implementing to improve their service is a series of more than 20 microgrids. I write on PG&E frequently - look under "Western Grid" in the list. I'm also working on a second paper for early May that drills into these microgrids.


Chris Law's picture
Chris Law on Apr 10, 2020 10:15 pm GMT

Thanks, Charles.  These links are excellent!  Thank-you.

In response to my own question, I have realized that my real questions was related to Distribution System Planning. 

A few good documents exist by this one was the most useful and has a number of references that are also useful incase anyone is intrested.


Matt Chester's picture
Matt Chester on Apr 13, 2020 2:10 pm GMT

Thanks for coming back and providing the insights that you found most useful-- some great resources throughout this Q&A!

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