On Sat, 16 Aug 2003 00:25:14 +0200, Iljitsch van Beijnum <iljitsch@muada.com> writes:
On vrijdag, aug 15, 2003, at 23:58 Europe/Amsterdam, alex@yuriev.com wrote:
Amount of energy generated must be balanced with the amount of energy used
at any time. Otherwise Bad Things (tm) will happen. The shutown of the grid is a very good thing compared to what it would have been had it not
shutdown.
It seems to me that the power guys are still living somewhere in the last century. Is it really impossible to absorb power spikes?
I don't know, but at least reading this IEEE Spectrum article: http://www.ece.umr.edu/courses/f02/ee207/spectrum/Grid/ implies that long distance transmission is full of strange and nonlinear effects such as 'reactive power', voltage support, and other technical concepts that made me conclude that there are nasty details that are not widely known. Excerpts follow: Generators at another smallpower plant also tripped. The tripping was due to high reactive power output associated with supporting transmission voltage ** Reactive power sidebar: Reactive power consumption tends to depress transmission voltage, while its production or injection tends to support voltage. Transmission lines both consume it (because of their series inductance) and produce it (from their shunt capacitance). Because transmission line voltage is held relatively constant, the production of reactive power is nearly constant. Its consumption, however, is low at light load and high at heavy load. The variable net reactive-power requirements of a transmission line give rise to a voltage control problem. Generators and reactive-power compensation equipment must absorb reactive power during light load, and produce it during heavy load. In a general emergency, when there are outages and high loading on re-maining transmission lines, those lines consume reactive power that must be supplied by nearby generators and shunt capacitor banks. (Reactive power can be transmitted only over relatively short distances.) If reactive power cannot be supplied promptly enough in an area of decaying voltage, voltage may in effect collapse. Insufficient voltage support may in addition contribute to synchronous instability. --C.W.T. ** Done Later it talks about how ''fast capacitor-bank switching in southern Idaho would have contained the initial 2 July outages.''. It also says something about: ''That August day, though, the power system stabilizers at a large nuclear plant in Southern California were out of service. (Power system stabilization at this location is especially effective because it is near one end of the north-south intertie oscillation mode.)'' I think to really understand the material above one needs to read author's book: _Power System Voltage Stability_ I also think that its hard to appreciate the stability differences between shipping power a few hundred feet and shipping power 1000 miles. It looks like that long-distance shipping is the root cause of the half-dozen major outages over the past 30 years. Why is the northwest getting power 800 miles away in Wyoming instead of putting up their own plant? Also, 'alternative generation' isn't there yet. For instance, from California's wind energy site http://www.energy.ca.gov/wind/overview.html The total output of all 13000 turbines in CA, *together* average only 400MW of unreliable power over the course of a year. Diablo Canyon (nuclear, california) produces five times this so does Jim Bridger (coal, wyoming). After 20 years of effort and subsidies, thats 1% of CA's energy use, and 10% of what was imported today. http://currentenergy.lbl.gov/ca/ Scott