Improving Power Transmission Line Design by Injecting Third Harmonic Voltage


In the field of power engineering, any frequency other than the fundamental is generally undesirable and engineers usually try to filter harmonics in effective ways. But what if we could use these harmonics beneficially? Researchers at the University of Alberta have developed a method to use the third harmonic voltage to their advantage in an alternative transmission line design. By injecting third harmonic voltage through a synchronous machine or a single-phase inverter to the line, they can reduce the peak amplitude of the phase voltage, while the fundamental component is left intact. This can reduce the conductor to ground clearance and can ultimately result in shorter tower heights. Similarly, the third harmonic voltage can be used to increase the phase voltage for increasing the line loadability.



  • Reduces the line construction capital investment by using shorter transmission towers.
  • Existing AC lines can be upgraded to increase their ground clearance.
  • Increases the loadability of existing AC lines.

Potential Markets

The invention represents a valuable opportunity in designing new transmission lines and offers improvements to existing lines.

Product Number


Contact Information

Mandira Das
Technology Management Group
TEC Edmonton – University of Alberta
Phone: 780-492-9123