I wrote PIC code for banks of AC inverters. The sine wave generator would add or subtract a few uSec dependant on a sync pulse (every 16.6mSec for 60Hz) at the zero crossing. In extreme mismatch cases it would hold off on the sine wave until the next sync pulse. The code would also generate 50 Hz or 400Hz depending on other inputs. The inverter banks had output inductors to share current and were hot swappable. The power was clean enough for telephone line back up requirements. It would be easy to make a sync pulse from other power lines and sync at start up. ----- Original Message ----- From: "Steve Smith" To: "Microcontroller discussion list - Public." Sent: Tuesday, June 8, 2010 5:58:13 PM GMT -05:00 US/Canada Eastern Subject: RE: [EE] Power grid synchronization The link between England and France is Dc and if I remember it's a cuk converter both ends (it's the only topology that is reversible) It arrives in England at Sellinge converter station at 500Kv DC if my memory is correct... Steve -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of Olin Lathrop Sent: 08 June 2010 22:36 To: Microcontroller discussion list - Public. Subject: Re: [EE] Power grid synchronization Carl Denk wrote: > I thought that way back in the early electricity days, that the issue > with DC was it couldn't be transported very far before the losses left > little power available, and the AC was necessary to get the power some > distance from the generating station. This goes back to Edison's days. There is nothing inherent to DC that prevents pushing power long distances. In fact, DC is more efficient due to no skin effect and no inductive or capacitive or radiation losses. The farmer stealing power with a long fence next to the power line isn't possible with DC, for example. In the early days it was probably difficult to get high voltage DC. That's easier with AC as you can run it thru a transformer. It's pretty much a voltage versus current game. The longer the distance, the more it makes sense to pay for high voltage infrastructure. At higher voltages it takes less current to transfer the same power, and the limitations and losses are related to current (mostly). ******************************************************************** Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products (978) 742-9014. Gold level PIC consultants since 2000. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist