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Re: Double Tracking and Underground Utilities
Author: Dr Zarkoff
Date: 06-04-2014 - 11:00
Having first heard about HV DC transmission about 50 years ago from my father, who was an electrical engineer with the local power company, I looked around on the internet, and found some interesting stuff (from the aritcle on wikipedia): it's not at all "new" nor "recent".
The earliest attempts were in 1882 in Germany and Italy in 1889. It wasn't found found to be practial because mechanical conversion was necessary (M-G sets, etc.), and the equipment was too prone to problems and failures. In 1914, the use of mercury arc rectifiers was suggested but these didn't become practical for another 10-15 years. Mercury arc installations were built in 1932 (NY), Germany (1941), USSR (after WWII using equipment captured from Germany), and Sweden (1954). Since 1972 all mercury arc HV DC lines have been either shut down or converted to solid state (New Zealand, the last mercury arc apparatus in the world was shut down in favor of solid state in 2012).
It's solid state equipment which has finally made HV DC economically practial. I can recall Pop carrying on at great length in the 1960s about the "pinheads in the Federal Government" who were insisting that the US needed to build this type of transmission line because "the USSR is ahead of us". He said that if you are generating power East of the Urals and sending it to Moscow, with very few users in between, then yes it made sense, but the US didn't -and never would- transmit power over such vast distances (the US equivalent would be to generate power in California and transmit it to New York, with no users in between). At the time, the USBR (US Bureau of Reclamation) was planning a 750 kv DC line line from Bonneville power plant in Washington State to Southern California through eastern Oregon and western Nevada and intending to serve serveral communities along the way. His point was that the conversion equipment was so capital intensive (that mercury arc apparatus) that it was cheaper to live with the losses of an AC line, particularly if you were going to serve intermediate customers.
Out of all this came the 1,000 kv DC line (+500 kv and -500kv, with ground -earth- being 0), now called the Pacific DC Intertie, from Celilo OR to Sylmar CA line and the 500 kv 3ph AC lines built and owned by the commercial power companies (there have been a few more DC lines built since).
Having just installed a 1-phase-3-phase inverter for a lathe in my house, this solid state stuff is truly amazing and cost effective nowadays.
The earliest attempts were in 1882 in Germany and Italy in 1889. It wasn't found found to be practial because mechanical conversion was necessary (M-G sets, etc.), and the equipment was too prone to problems and failures. In 1914, the use of mercury arc rectifiers was suggested but these didn't become practical for another 10-15 years. Mercury arc installations were built in 1932 (NY), Germany (1941), USSR (after WWII using equipment captured from Germany), and Sweden (1954). Since 1972 all mercury arc HV DC lines have been either shut down or converted to solid state (New Zealand, the last mercury arc apparatus in the world was shut down in favor of solid state in 2012).
It's solid state equipment which has finally made HV DC economically practial. I can recall Pop carrying on at great length in the 1960s about the "pinheads in the Federal Government" who were insisting that the US needed to build this type of transmission line because "the USSR is ahead of us". He said that if you are generating power East of the Urals and sending it to Moscow, with very few users in between, then yes it made sense, but the US didn't -and never would- transmit power over such vast distances (the US equivalent would be to generate power in California and transmit it to New York, with no users in between). At the time, the USBR (US Bureau of Reclamation) was planning a 750 kv DC line line from Bonneville power plant in Washington State to Southern California through eastern Oregon and western Nevada and intending to serve serveral communities along the way. His point was that the conversion equipment was so capital intensive (that mercury arc apparatus) that it was cheaper to live with the losses of an AC line, particularly if you were going to serve intermediate customers.
Out of all this came the 1,000 kv DC line (+500 kv and -500kv, with ground -earth- being 0), now called the Pacific DC Intertie, from Celilo OR to Sylmar CA line and the 500 kv 3ph AC lines built and owned by the commercial power companies (there have been a few more DC lines built since).
Having just installed a 1-phase-3-phase inverter for a lathe in my house, this solid state stuff is truly amazing and cost effective nowadays.
