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Question

Best HVDC tech / HVDC financing?

Hello friends!

We're looking at the newest innovations for building and operating HVDC transmission infrastructure.

  1. In your view, what is the most critical HVDC technology for new projects moving forward?
  2. How are you financing your HVDC transmission projects?

Let us know your thoughts!

If you're a TSO (transmission system operator), we'd especially like to hear from you.

Thank you!

Rex Sayson
 

Answers

This is a very wide topic but I would hightlight the latest innovations in Voltage Source Converter technology, facilitating the integration of HVDC links to the local grids at greater ratings -also providing power controlability, reacting power / voltage support, black start, wide dynamic performance, etc).

From the line transmission side there's a wider availability of XLPE cables with much higher ratings and suppliers -which facilitates underground transmission hence a friendlier permitting process comparing to having to build new overhead lines. 

 

The HVDC question:

Unfortunately, my work so far had been in AC transmission lines (HV, EHV) and I am not knowledgeable about DC lines. Use of XLPE cables as pointed above is a great idea and as far as I know they have been used in U/G and Uder-Water applications. 

I am also a Civil-Structural fella and your best bet for a good answer is any experienced Electrical Engineer specialist.

Financing? As far as AC lines are concerned, if they are in a rural setting, then RUS/USDA finances all rural HV lines. That is, lines built and maintained and operated by Rural Electrical Cooperatives.

Hope this little bit of info helps.

Best Wishes,

Sriram 

(Dr. Sriram Kalaga Ph.D., PE, F.ASCE., SECB) 

I think Orestes Macchione hit all the salient technical merits of HVDC. If one looks at all of the NERC efforts in the area of inertia response and primary frequency response as inverter based renewables become a major resource in the future generation mix, the VSC controls can be set to provide support in this area which will be important reliability contribution.

Financing as well as siting will continue to be a major hurdle to overcome.

In response to your question, I have put several links to resources below.

I worked in another group at Siemens for many years (now retired), but I was occasionally was briefly involved with projects that used HVDC transmission lines as well as a related technology, Flexible AC Transmission Systems (FACTS).  Some additional explanation is below.

With AC transmission on the grid, the power follows the path of least resistance (some say, it goes where it wants to). DC transmission can be dispatched like generation to control the amount of power that goes down an HVDC transmission line. FACTS (really a family of technologies) uses power electronics to dispatch AC transmission.

Also, there really are not any great new developments in either HVDC transmission or FACTS in the last ten years, just incremental improvements. These are described in the two Siemens brochures linked below. Also there have been several major new application for HVDC, mainly connecting offshore wind projects to coastal terminals and ultimately the grid. Also transmission lines that need to cross bodies of water are now much more viable using the technologies described in the first link below.

Financing is provided by the incremental payback a given project provides for the grid (described for one project below), or in the case of linking offshore wind (described below) whether it is the best fit (it generally is).

The link below is a link to a brochure on Siemens Latest HVDC technology “HVDC Plus”.  Further below I link a paper I wrote over a year ago that describes how this technology is used in both of the above applications.

https://assets.new.siemens.com/siemens/assets/api/uuid:3562ce17-8962-4329-b973-5e8cd674c555/version:1557823702/263_160390_ws_hvdcplususlowres.pdf

The link below is to a Siemens Brochure on FACTS:

https://assets.new.siemens.com/siemens/assets/api/uuid:14331eadd9b9b70a911fe4e238c96a5a67041eeb/version:1490615084/263-160391-ws-parallel-compensation-us-o2e-1611.pdf

Siemens is a leader in the above complex technologies because they are a full spectrum provider, providing consulting on how to best utilize these technologies on the grid, and training for utility personnel. There are links to these services below.

https://assets.new.siemens.com/siemens/assets/api/uuid:7fd74bf0-9d91-4242-95b2-066158fcce38/version:1542624222/ccem-170132-bro-pti-overview-psc-en.pdf

https://w3.usa.siemens.com/smartgrid/us/en/transmission-grid/training/training-siemens-power-academy/Documents/PSSC_655_Power%20Electronics%20in%20Transmission%20Systems.pdf

A link to a paper published on Energy Central over a year ago. In section 4.2 it describes how an underwater HVDC Transmission cable now provides 40% of San Francisco’s demand. Section 5 in this paper suggests a new project to link this cable to a huge set of offshore wind farms north of San Francisco. The second link below is to the Transbay Cable site.

 https://www.energycentral.com/c/iu/wind-and-water

http://www.transbaycable.com/

And finally, when I wrote the above paper, I was not aware that the arear I proposed for the windfarm (and the terminal in San Francisco) in the above linked paper had already been  identified by a NREL study.  Since California offshore wind is starting to heat up, I posted a paper last week (linked below) In section 1.2 it identifies the five possible areas for offshore wind development in California, including the one north of San Francisco. By the way, as of this year I started posting papers in PDF format, which means that you will need to go to the site linked below, and then click on the “Publication” button.

https://www.energycentral.com/c/cp/california-offshore-wind

-John

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