Design World

  • Home
  • Technologies
    • ELECTRONICS • ELECTRICAL
    • Fastening • joining
    • FLUID POWER
    • LINEAR MOTION
    • MOTION CONTROL
    • SENSORS
    • TEST & MEASUREMENT
    • Factory automation
    • Warehouse automation
    • DIGITAL TRANSFORMATION
  • Learn
    • Tech Toolboxes
    • Learning center
    • eBooks • Tech Tips
    • Podcasts
    • Videos
    • Webinars • general engineering
    • Webinars • Automated warehousing
    • Voices
  • LEAP Awards
  • 2025 Leadership
    • 2024 Winners
    • 2023 Winners
    • 2022 Winners
    • 2021 Winners
  • Design Guides
  • Resources
    • Subscribe
    • 3D Cad Models
      • PARTsolutions
      • TraceParts
    • Digital Issues
      • Design World
      • EE World
    • Educational Assets
    • Engineering diversity
    • Trends
  • Supplier Listings
  • Advertise
  • Subscribe

DC, Another Option to Improve Electrical Power Transmission

By atesmeh | April 30, 2014

Even though today most of the electricity transmission lines are alternating current ones, in some cases direct current lines are also used.And researchers are becoming aware that in some cases direct current lines are more suitable than alternating current ones.

In this area, the GISEL research group of the Department of Electrical Engineering of the UPV/EHU-University of the Basque Country has been working to improve the technology needed for this conversion.The aim has been that this transmission should be done in a more straightforward, smoother and consequently less expensive way.

Electricity is normally transmitted by means of alternating current, but it is not the only way and not always the best one.In some cases, high voltage direct current (HVDC) is used. In Spain, for example, there is only one direct current line, the one that connects mainland Spain with the Balearic Islands; all the remaining ones transmit electricity by means of alternating current.

In fact, “direct current continues to be highly suitable for underwater and underground lines,” asserted Marene Larruskain, one of the engineers in the UPV/EHU’s GISEL group. Furthermore “less investment is needed to build direct current lines, and there are fewer losses in electricity transmission. “However, as most of the lines in the power grid are alternating current ones, converters are needed to change the type of electricity transmission, and they are very costly.”That is why direct current lines are appropriate beyond a certain length,” specified Larruskain.

And this is in fact the use that is made of high voltage direct current lines, to transmit electricity over very long distances; indeed, the longest lines that exist are direct current ones. “There are facilities worldwide thattransmit direct current electricity.The typical examples are the transmission lines of large hydraulic power stations: the Itaipu power station in South America, the Three Gorges power station in China, etc.

Bearing in mind that right now most of the transmission of electricity is done by means of alternating current lines, “our aim is in no way to replace these lines by direct current ones. Our proposal is based on using direct current as a solution in cases where there are problems with the alternating current lines,” explained Larruskain.

Renewable energies could could an example of this.Renewable energies are produced in a very irregular way; the wind, for example, could blow very strongly at some moments and very lightly in others. And the output may not coincide with moments of peak energy consumption.”One way of solving the problem caused by this situation for the electricity supply could be to connect the farms or parks of various countries where renewables are produced. That way, if at one moment one region has a high consumption of energy but is not producing renewable energy, its demand could be metby using renewable energy which is being produced somewhere else,” explained the researcher. As there is a global grid, the variability in production of renewables could be balanced. The UPV/EHU’s GISEL group is proposing that these global grids should be direct current ones.

The aim, to assist transmission

The GISEL group is working to improve the energy exchange converters between direct current lines and alternating current ones.Specifically, they are working on new technology for converters known as VSCs (Voltage Source Converters).Compared with conventional technology, “the VSC has many advantages; among others, it is easier to control the power that is transmitted, and that is very important on wind farms, for example. At the same time, given the fact that direct current has great economic advantages in underwater lines, it is very appropriate for them.”

However, VSC technology has a number of drawbacks: firstly, its capacity to transmit energy is lower, the energy losses are greater and it does not respond well when problems arise. For example, if there is a short circuit, the system has problems. That is why “we’re working to minimize those problems,” explained the researcher.

Secondly, the researchers want to make use of the advantages of both means of transmitting electricity to be able to address growing power consumption. And it is a fact that “even though more and more energy is being produced to meet the demand, problems may arise when it comes to transmitting that energy. It is not always possible to incorporate the surplus energy produced into the already existing lines owing to their limits. In these cases, the use of direct current could solve the problem of the alternating current lines already installed, because, among other things, the HVDC lines can transmit more electrical power,” explained Larruskain.

The GISEL research group has studied how to make the features of the alternating current and direct current lines compatible. The electricity lines of alternating current are three-phase. For example, the number of conductors are three, or multiples of that number. On the other hand, HVDC lines have two poles: a positive one and a negative one. “How are we going to divide two poles into three conductors?” wondered Larruskain. If we use one pole for each phase, one of the conductors of the original line will remain free and part of the power will be lost. That is why a line and a half of alternating current corresponds to each pole of direct current. Even though it looks impossible, there are various ways of making this distribution.

“In the future HVDC grids are expected to coexist with alternating current grids, which are in the majority nowadays.Transmitting direct current via the currently existing lines could be a first step towards building HVDC grids,” explained the UPV/EHU engineer.

You Might Also Like


Filed Under: Industrial automation

 

LEARNING CENTER

Design World Learning Center
“dw
EXPAND YOUR KNOWLEDGE AND STAY CONNECTED
Get the latest info on technologies, tools and strategies for Design Engineering Professionals.
Motor University

Design World Digital Edition

cover

Browse the most current issue of Design World and back issues in an easy to use high quality format. Clip, share and download with the leading design engineering magazine today.

EDABoard the Forum for Electronics

Top global problem solving EE forum covering Microcontrollers, DSP, Networking, Analog and Digital Design, RF, Power Electronics, PCB Routing and much more

EDABoard: Forum for electronics

Sponsored Content

  • Widening the scope for machine tool designers with FORTiS™ enclosed encoder
  • Sustainability, Innovation and Safety, Central to Our Approach
  • Why off-highway is the sweet spot for AC electrification technology
  • Looking to 2025: Past Success Guides Future Achievements
  • North American Companies Seek Stronger Ties with Italian OEMs
  • Adapt and Evolve
View More >>
Engineering Exchange

The Engineering Exchange is a global educational networking community for engineers.

Connect, share, and learn today »

Design World
  • About us
  • Contact
  • Manage your Design World Subscription
  • Subscribe
  • Design World Digital Network
  • Control Engineering
  • Consulting-Specifying Engineer
  • Plant Engineering
  • Engineering White Papers
  • Leap Awards

Copyright © 2025 WTWH Media LLC. All Rights Reserved. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media
Privacy Policy | Advertising | About Us

Search Design World

  • Home
  • Technologies
    • ELECTRONICS • ELECTRICAL
    • Fastening • joining
    • FLUID POWER
    • LINEAR MOTION
    • MOTION CONTROL
    • SENSORS
    • TEST & MEASUREMENT
    • Factory automation
    • Warehouse automation
    • DIGITAL TRANSFORMATION
  • Learn
    • Tech Toolboxes
    • Learning center
    • eBooks • Tech Tips
    • Podcasts
    • Videos
    • Webinars • general engineering
    • Webinars • Automated warehousing
    • Voices
  • LEAP Awards
  • 2025 Leadership
    • 2024 Winners
    • 2023 Winners
    • 2022 Winners
    • 2021 Winners
  • Design Guides
  • Resources
    • Subscribe
    • 3D Cad Models
      • PARTsolutions
      • TraceParts
    • Digital Issues
      • Design World
      • EE World
    • Educational Assets
    • Engineering diversity
    • Trends
  • Supplier Listings
  • Advertise
  • Subscribe
We use cookies to personalize content and ads, to provide social media features, and to analyze our traffic. We share information about your use of our site with our social media, advertising, and analytics partners who may combine it with other information you’ve provided to them or that they’ve collected from your use of their services. You consent to our cookies if you continue to use this website.