Evidently interruption's easier with AC because of the zero-crossings of current every half-cycle.
Three alternate solutions to HVDC circuit interruption are described in this article. Two are electronically integrated with the output circuitry of the bidirectional AC-DC converters (bidirectional energy flow AC-DC converters being an interesting, but off-topic subject in their own right).
I find it an ingenious use of an IGBT bridge surrounding a capacitor to throw the cap's charge into reversed polarity so as to stop the current flow -- effectively opening the circuit. This tells me the cap would seem to be in series with the DC side somehow. Were it in parallel, well, it wouldn't make much sense to reverse the cap's polarity as you'd only get to do it once.
I also find it fascinating that the mathematics it takes to describe AC circuits is far more complex than for DC -- one has to accept that there genuinely exists a square root of negative one, "imaginary" though we may call it.
As in programming, good nomenclature is often late to the table. I wouldn't try (and I'm certainly not qualified) to "refactor" centuries, maybe millennia [1] of mathematical terminology.
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>I also find it fascinating that the mathematics it takes to describe AC circuits is far more complex than for DC
Why? The math is exactly the same as for DC once you substitute complex numbers for current, voltage and impedances.
Things get more complicated in the time domain, which becomes relevant once you want to look into problems like switching HVDC on and OFF. The nonlinearities of the switching devices lead to differential equations that can only be solved numerically.
I don't know the physics modelling switching devices or arcs, but I do recall reading long ago that once an arc starts, its resistance drops dramatically, continuing to drop as more current flows through it (within limits).
So an arc becomes a runaway situation if current flow isn't ballasted or elsewhere interrupted. But if current flow is controlled, an arc has practical application in fluorescent lighting and arc welding.
If centralised generation is replaced with distributed generation there will be the need to route energy between arbitrary sources and sinks, located at any point in the network. One can envisage a network analogous to a packet based data network, where "routing algorithms" are used to direct fixed amounts of energy (a packet) from "A" to "B". A process analogous to flow control is used to govern the number of packets, and so the average power, being transferred between a source and sink. A device analogous to a buffer (capacitor?) could be used to average the power at the entrance and exit to the packet network when smooth power is required, just like running a "smooth" audio stream over a packet data network.
Yes. Originally, the social-democrat/green government of 1998-2005 planned to shut down all nuke plants until 2020 or so, but the conservative/liberal democrats government that took over in 2009 stopped that, mostly against the will of the public. After Fukushima, there was such a huge backslash that our dear chancellor decided it might help her popularity more if she changed her mind.
And while tsunamis are rather rare in Stuttgart, the upper rhine rift is an active earthquake zone, and since we unfortunately are not allowed to just sell the waste to Russia to dump in Siberia, we also have to dispose of it somewhere in Germany. If you look at a population-density map, you will find few places with few enough people to accept highly radioactive nuclear waste.
You are right, however, that it is economically somewhat senseless to shut down the nuke plants basically shortly after the subsidies/initial costs paid off, but, well.
The Biblis power plant (http://en.wikipedia.org/wiki/Biblis_Nuclear_Power_Plant) is located directly at the core of this region, is one of the oldest reactor in Germany and one of the most powerful. It was built in the early 70s, so there is no protection against plane crashes, no secondary remote control room. If it was destroyed, roughly a million people would have to be evacuated immediately and because it is situated right at the Rhine river, major cities like Cologne and Dusseldorf downriver would have to deal with radioactive water flowing by.
Just a worst-case scenario, but people just felt uncomfortable with risks like that.
They're fueled by babies--fission is the act of separating a baby into two or more pieces, and using the released energy (screams) to fuel your city.
No civilized nation would continue to use such an awful and dirty power source.
