Would high voltage DC power grids work the same?

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Discussion Overview

The discussion centers on the feasibility and operational characteristics of high voltage DC power grids compared to traditional AC power transmission systems. Participants explore the implications of transforming DC voltage and the role of the Earth as a ground in AC systems, specifically questioning whether it functions more as a capacitor or an ohmic resistor.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants assert that the primary reason for using AC in power transmission is the ease of voltage transformation.
  • There is mention of a conceptual method for transforming DC, although it is not yet practically implemented.
  • One participant argues that three-phase power systems do not require a ground connection for current return, as the phase currents ideally sum to zero.
  • Another participant questions the reliance of AC power transmission on the Earth as a ground functioning as a capacitor, seeking references to support this claim.
  • Participants are directed to investigate the 'single wire Earth return' (SWER) system as a related concept.

Areas of Agreement / Disagreement

Participants express differing views on the role of the Earth in AC power transmission and the practicality of transforming DC. The discussion remains unresolved regarding the extent to which AC systems depend on the Earth as a capacitor versus an ohmic resistor.

Contextual Notes

Some claims about the transformation of DC and the role of grounding in AC systems lack detailed references or empirical support, leaving certain assumptions and definitions open to interpretation.

greypilgrim
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Hi.

As far as I know, the main reason for using AC in electric power transmission is that voltage can easily be transformed.

If there was a similarly easy way for transforming DC, would power grids work basically the same? To be more specific, how much does AC power transmission rely on the Earth as ground working as a capacitor rather than an ohmic resistor?
 
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greypilgrim said:
Hi.

As far as I know, the main reason for using AC in electric power transmission is that voltage can easily be transformed.

If there was a similarly easy way for transforming DC, would power grids work basically the same?

Yes there is a way of transforming DC, but only conceptually so far. See this recent thread.
https://www.physicsforums.com/threads/dc-to-dc-power-transformer.921023/

greypilgrim said:
To be more specific, how much does AC power transmission rely on the Earth as ground working as a capacitor rather than an ohmic resistor?

No. Three phase power systems don't need the ground connection. The currents in the three phases are 120 degrees apart, they add up to zero so ideally there is no need for an Earth return. There are other reasons for neutral to ground earthing, but not to return the power current.
 
greypilgrim said:
To be more specific, how much does AC power transmission rely on the Earth as ground working as a capacitor..

Got a reference for that?
 

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