3 ms·

For anyone else in my position, who thought that AC won because it was inherently more efficient for transmission, the Wikipedia page [1] has a nice overview of

For anyone else in my position, who thought that AC won because it was inherently more efficient for transmission, the Wikipedia page [1] has a nice overview of HVDC. There's also this PDF from Siemens[2] with some data. Interesting points: the voltage being discussed is in the hundreds of thousands of volts (800,000 for the line in the PDF), and the transmission losses are apparently 30-50% lower for HVDC. 1. https://en.wikipedia.org/wiki/High-voltage_direct_current https://en.wikipedia.org/wiki/High-voltage_direct_current 2. https://www.siemens.com/press/pool/de/events/2012/energy/2012-07-wismar/factsheet-hvdc-e.pdf https://www.siemens.com/press/pool/de/events/2012/energy/201...

eigenvector 9y ago
A simplistic explanation of the tradeoff between HVAC and HVDC transmission with modern technology is that HVDC has lower losses, but the converter and switching stations are more expensive. So HVDC can make sense for an application that needs to transmit a very large amount of power over a huge distance with no need for switching stations midway. A classic example would be linking a very large offshore wind farm to the onshore transmission system. But for "normal" transmission applications, where there are many stations connecting different HV circuits to each other as well as to lower voltage distribution circuits, it is less economical.
thescriptkiddie 9y ago
The "DC can't be transmitted long distances" myth seems to date back to a time when solid-state (read: efficient) DC-DC converters didn't exist. In Edison's time, the entire DC grid had to operate at the same voltage, whereas an AC grid could utilize transformers to step the voltage up for transmission. But if a DC "transformer" had existed at the time, DC grids would not have had that limitation. The physics (capacitance, inductance, skin effect) dictate that for a given voltage and distance, DC is always more efficient than AC transmission.

eigenvector 9y ago

A simplistic explanation of the tradeoff between HVAC and HVDC transmission with modern technology is that HVDC has lower losses, but the converter and switching stations are more expensive. So HVDC can make sense for an application that needs to transmit a very large amount of power over a huge distance with no need for switching stations midway. A classic example would be linking a very large offshore wind farm to the onshore transmission system. But for "normal" transmission applications, where there are many stations connecting different HV circuits to each other as well as to lower voltage distribution circuits, it is less economical.

thescriptkiddie 9y ago

The "DC can't be transmitted long distances" myth seems to date back to a time when solid-state (read: efficient) DC-DC converters didn't exist. In Edison's time, the entire DC grid had to operate at the same voltage, whereas an AC grid could utilize transformers to step the voltage up for transmission. But if a DC "transformer" had existed at the time, DC grids would not have had that limitation. The physics (capacitance, inductance, skin effect) dictate that for a given voltage and distance, DC is always more efficient than AC transmission.