There is still an under-Channel DC link between Britain and France, to our mutual benefit. I believe that DC was chosen originally simply to avoid the problems of trying to synchronize the AC grids of our two countries.
Re: DC Line#13404 09/03/0209:12 AM09/03/0209:12 AM
The same in Austria. We get power from the Czech Republic, but our PoCos didn't trust the frequency of the czech power. Now power is created as Ac, rectified, goes througha 500V DC line to Austria and is there converted back to AC
Re: DC Line#13406 09/03/0207:46 PM09/03/0207:46 PM
About AC>>DC>>AC, it’s interesting to see postings from different parts of the world. E-C.net has a lot of readers! In the US and Canada there are a number around the continent, and typically the use of earlier installations were for cost-effective power transfer of bulk power over long lines. One form of economy can be a north<>south system, where the north end uses more power during the winter, and the south region needs more power in the summer. It’s all pure economics. If it weren’t cost effective for both ends, it would be a poor investment.
More recently, there are a few back-to-back stations where there in no DC line, just a comparatively short + and – bus between two converters in one building. The idea is that, given increasing price savings with advancing electronics, is that the two AC sides of the station do not have to be synchronized, and can be large, independent systems. In some areas, the two AC systems are even at different frequencies. Also, power can be “sent” either direction with a minor change in electrical-operating characteristics.
Typically the stations are rated at hundreds or thousands of megawatts, and hundreds of kV, but experiments are underway with HVDC “Lite” where the voltage may be 25kV, and at tens to a few megawatts capacity.
Re: DC Line#13408 09/04/0202:54 PM09/04/0202:54 PM
The latest and greatest railroad locomotives do the same thing. Generate ac, with 6000 hp diesesels, turn it to dc, then turn it back into ac again. the exception is that when they turn it back into ac again, they vary both the voltage and the frequency to the motors, for speed control and wheel slip control. They can now for intence, hold a train on a hill with just the motors, and no brakes, without the motors burning up. plc's are a wonderful thing.