3 ms·

Synchronising isn't really an issue. You need to do a dc-ac conversion in any case, so you take the incoming mains feed and make that the reference for the ac m

Synchronising isn't really an issue. You need to do a dc-ac conversion in any case, so you take the incoming mains feed and make that the reference for the ac modulator.

pdonis 13y ago
I don't think it's the synchronizing that's an issue; it's the fact that power is now flowing from your house into the grid, instead of the other way around. Since there is no storage in the grid, power in has to balance power out at every point in the grid, which means the grid has to be able to manage its own power generation, in real time, to adjust it according to how much is being put back in by homeowners. The grid as it currently exists is not really designed to do that.
- timthorn 13y ago
  It's true that the grid has to balance its own generation, but that happens today - the frequency of the mains changes constantly, and it's the grid controllers' job to bring on supply as required. There are some storage options - pumped hydro for example - but I absolutely take your point that the grid is designed for a classically understood demand/supply environment. Certainly there is a risk that all these intermittent renewables will end up causing the most dirty of generators to be spun up more often, in the least efficient usage pattern. The dream has to be a proper demand response system, with electric cars being a key sink for excess generation. The work of David MacKay at Cambridge University is excellent on this topic: http://www.withouthotair.com/ http://www.withouthotair.com/
  - pdonis 13y ago
    the grid has to balance its own generation, but that happens today Yes, but today (i.e., without individual homeowners putting power back into the grid) the grid's control system can assume that the load is always positive except at a finite and fairly small number of known points, the grid's generators, which are controlled by the grid itself. When individual users can put power back into the grid, the load can become negative at any arbitrary location in the grid, without warning. That greatly complicates the control problem. The dream has to be a proper demand response system, with electric cars being a key sink for excess generation. Yes, and who's going to pay for that? (Not the electric cars, but the improvements in the grid that allow it to make use of them as storage.) An obvious solution is to charge the people who are creating the problem by making their connection with the grid two-way instead of one-way.

Synchronising isn't really an issue. You need to do a dc-ac conversion in any case, so you take the incoming mains feed and make that the reference for the ac modulator.

pdonis 13y ago

I don't think it's the synchronizing that's an issue; it's the fact that power is now flowing from your house into the grid, instead of the other way around. Since there is no storage in the grid, power in has to balance power out at every point in the grid, which means the grid has to be able to manage its own power generation, in real time, to adjust it according to how much is being put back in by homeowners. The grid as it currently exists is not really designed to do that.

timthorn 13y ago
It's true that the grid has to balance its own generation, but that happens today - the frequency of the mains changes constantly, and it's the grid controllers' job to bring on supply as required. There are some storage options - pumped hydro for example - but I absolutely take your point that the grid is designed for a classically understood demand/supply environment. Certainly there is a risk that all these intermittent renewables will end up causing the most dirty of generators to be spun up more often, in the least efficient usage pattern. The dream has to be a proper demand response system, with electric cars being a key sink for excess generation. The work of David MacKay at Cambridge University is excellent on this topic: http://www.withouthotair.com/ http://www.withouthotair.com/
- pdonis 13y ago
  the grid has to balance its own generation, but that happens today Yes, but today (i.e., without individual homeowners putting power back into the grid) the grid's control system can assume that the load is always positive except at a finite and fairly small number of known points, the grid's generators, which are controlled by the grid itself. When individual users can put power back into the grid, the load can become negative at any arbitrary location in the grid, without warning. That greatly complicates the control problem. The dream has to be a proper demand response system, with electric cars being a key sink for excess generation. Yes, and who's going to pay for that? (Not the electric cars, but the improvements in the grid that allow it to make use of them as storage.) An obvious solution is to charge the people who are creating the problem by making their connection with the grid two-way instead of one-way.