Am I correct in assuming that a Polywell would generate high voltage DC (HVDC)? If so, that could actually be an advantage for power transmission.
There is a relatively new methd of high voltage DC transmission that uses three conductors. It shares power on the conductors in order to operate them at their thermal limit without the normal fixed polarity problems caused by HVDC. It's called Tripole HVDC, and was invented by IEEE fellow Lionel Barthold. See http://www.conference-power.com/2006/ppt/PN3-2.pdf and http://www.google.com/search?q=tripole+hvdc .
With the Polywell, depending on the voltages that it generates, you could eliminate the AC to DC conversion on the source end that would be required for a normal steam plant.
HVDC Power Transmission
I don't know if you caught the de-icing bit. With variable voltage constant current operation you can keep the lines warm enough to prevent ice formation. Something you can't do with AC which are constant voltage variable current.
This would reduce line breaks in the winter from ice loading.
This is a +/- 200KV system. However a 2 MV to 200 KV switcher is not too difficult.
This would reduce line breaks in the winter from ice loading.
This is a +/- 200KV system. However a 2 MV to 200 KV switcher is not too difficult.
Engineering is the art of making what you want from what you can get at a profit.
There are two main advantage to HVDC, the first is that there is no phase losses on long line, a problem we have in Québec. It requires the addition of sub-stations midway, for lines in the order of a a1000 Km long.MSimon wrote:I don't know if you caught the de-icing bit. With variable voltage constant current operation you can keep the lines warm enough to prevent ice formation. Something you can't do with AC which are constant voltage variable current.
This is a +/- 200KV system. However a 2 MV to 200 KV switcher is not too difficult.
The other is that the ice buildup is very weak, and falls on its own weight. I do not think heating the line is required for DC lines. It does have to do with the polar electric properties of H2O molecules. The DC field cause the ice buildup to be more like snow in consistency.
I think the reason the AC lines are still in use is that a transformer is cheaper then a HVDC step down transformer. A HVDC polywell power system will have to adapt itself to the grid. I would not think the entire industry will want to change the grid, just because it is easier for us. So, we better have a design compatible with an HVAC inverter.
Once you have a DC source then DC to AC converters will be common and the price will go down. At that point DC transmission will be logical.Jboily wrote:There are two main advantage to HVDC, the first is that there is no phase losses on long line, a problem we have in Québec. It requires the addition of sub-stations midway, for lines in the order of a a1000 Km long.MSimon wrote:I don't know if you caught the de-icing bit. With variable voltage constant current operation you can keep the lines warm enough to prevent ice formation. Something you can't do with AC which are constant voltage variable current.
This is a +/- 200KV system. However a 2 MV to 200 KV switcher is not too difficult.
The other is that the ice buildup is very weak, and falls on its own weight. I do not think heating the line is required for DC lines. It does have to do with the polar electric properties of H2O molecules. The DC field cause the ice buildup to be more like snow in consistency.
I think the reason the AC lines are still in use is that a transformer is cheaper then a HVDC step down transformer. A HVDC polywell power system will have to adapt itself to the grid. I would not think the entire industry will want to change the grid, just because it is easier for us. So, we better have a design compatible with an HVAC inverter.
Re heating the lines. Better that the moisture falls as water than icicles. Also the problem with ice/snow is wind loading.
Changing the grid increases capacity without new rights of way, which are hard to come by.
Long distance transmission DC local transmission AC.
Engineering is the art of making what you want from what you can get at a profit.