We had recently asked the following questions, which were very kindly answered

"Can anyone (please) explain why NY/NJ/etc had to experience loss of power - when it is a part of the one huge Grid that supposedly shares electricity over the entire Eastern part of the USA? Isn't that the reason for the design? To distribute the excess electricity available... to other areas that need more?"

(answer:) "It might help to think of the electric grid like a drinking water distribution network in a city. In the grid, there are many different pipe size diameters and pipe lengths, locations of water treatment plants, etc. Think of the water plant as a power generation plant. Think of the diameter of pipe sizes as diameters of wire. First of all, you would think that anyone connected to the water grid would have the same amount of water pressure available to them and the same amount of flow (gallons per minute) as well. This is not the case. The pipe sizes will only allow so much water through them and it makes a difference if you live near a big water user or near the water treatment plants. Sometimes, the fire department opens a fire hydrant and causes a pipe near it to start leaking. The electrical grid will protect itself against sudden attemts to get too much out of it at a singular point or region. Hope this helps..."

Thanks James - yes it helps alot, -but- - -

Can anyone please elaborate further???

We just don't understand how the distribution system is supposed to cover these problems. If some extra AC summer draw caused localized outages like that, then what will happen if several (or many) utilities cannot supply come years end? Is the system THAT vulnerable? Don't they maintain ways of re-working extra juice to areas that need it?

-- Anonymous, July 12, 1999

Answers

The confusing part of the problem is that it is really two separate problems. A lack of generation and a lack of transmission.

If the load exceeds the available line capacity (which is related to ambient temperature) then the lines overheat and wind up either shutting themselves down or being manually shut down. In a paradox as the ambient temperature goes up the amperage capacity of the line goes down. So when you need it the most the lines are not always capable of carrying the amperage you need. One of the problems in the New York City area is that most of the power has to be imported from up state and it doesnt always want to flow downstate. Cables also have less capacity then open air transmission lines which leads to special problems in cities like New York where everything is underground.

. There is also the problem that electricity tends to follow the path of least resistance and it doesnt always flow the way you want it too. Under heavily loaded ( and very lightly loaded, a further paradox) situations you can get unwanted loop flows that limit your ability to transfer power. Another component is the reactive (imaginary) power. Reactive power is needed for support and unfortunately doesnt transfer as well as real power. It has to be generated close to the bus its supporting and cant be imported from far away. This last wasnt a cause in the NY blackout but was a cause in the one in the Pacific Northwest.

If its a lack of generation then you go into a situation of brownouts or rolling blackouts. The ability to transfer power from generators very far away is limited by the impedance in the lines and the connections between where its needed and where its generated. One of the (many) misunderstandings on how the grid works and what it does is the idea that you can transfer power from Florida to Maine. The ability to get power into NY is limited by all of the above constraining factors.

These conditions wont exist for the Y2K roll over. The ambient temperature will be low so the capacity of the lines will be high. The generation margin is supposed to be from 25 to 50% over use in most areas. A lot of generation would have to go down to duplicate the situation of this summer. Plus since most business and factories will probably be shut down the need for reactive support will be low. One of the problems may be that people will shut off too much and a very low load can cause almost as many problems as a too heavy load.

-- Anonymous, July 13, 1999

Engineer said: "These conditions wont exist for the Y2K roll over. The ambient temperature will be low so the capacity of the lines will be high."

I understand, due to an extremely cold period XMAS c.1987, that areas of Florida experienced rolling blackouts. Presumably, a Canadian high swept through the country, with areas to the north borrowing from areas to the south. By the time the cold wave reached Florida, at a time of year that should have been relatively low demand (and therefore one or more local generators were off-line for maintenance), there was not enough electricity to service the unexpected load on heating system.

As far as I can see, the prediction of 50% load at rollover assumes average winter conditions. We just had rationing (brownout?) here in New England in June because an extreme heat wave hit at a time that (according to Bonnie) Pilgrim was unexpectedly offline as a result of a transformer blow during y2k remediation during an otherwise scheduled shutdown.

It is comforting to know that extra generating capacity is coming on line and that one of the grid's contingencies is to ensure that all available existing plants are also on line. However, there are some major assumptions here, for instance, that the software/hardware necessary to complete the generator upgrades will arrive on time and that we will experience average or warmer conditions at rollover. Frankly, I do not have unlimited faith that the New England Power Pool can manage its load.

-- Anonymous, July 13, 1999

No, its not extra generating capacity coming on line. Its generators being in a condition called spinning reserve. Ordinarily only a certain percentage of generating capacity is kept in this condition. It varies from pool to pool and due to the time of year but it might be between 10 and 15 % under normal conditions. For Y2K far more will be kept in this condition than is required by the expected loads. The 25 to 50% figure I quoted was for all of North America. It will vary from place to place, again depending on load and what was available in the first place. The New England area is one that has a lack of generation and transmission capacity compared to some other areas. However this shows up mostly in the summer rather then the winter.

You in turn are making the assumption that the generators need hardware\software upgrades. Can you tell me what they are or what you think they are?

I dont think that average or warmer conditions are expected. One shouldnt confuse adverse weather conditions with Y2K. A repeat of an ice storm like two winters ago will result in outages. Being Y2K Ready or Compliant or what ever name you choose doesnt mean no problems, no way, no how, never ever. If a some one skids and runs into the pole that has the transformer that supplies your house you will be out of power. Y2K or no Y2K.

I doubt if the transformer blew due to Y2K since they have no chips in them. Not everything that happens, happens because of or in spite of Y2K. There should be enough redundancy in the system to ameliorate any Y2K related incidents, if any.

-- Anonymous, July 13, 1999

You certainly twist things, Engineer.

Last Feb. I attended a lengthy presentation by the y2k remediator for a nat. gas generator near Springfield, MA. They had replaced a great deal of their equipment due to potential problems with chips. They considered themselves all set except that the replacement software system for the DCS was on backorder. They hoped to have that wrapped up by this summer.

Bonnie reported on this forum last month that the Pilgrim transformer, which was being upgraded for y2k during a scheduled outage, broke down as a result, and put the plant off-line for an additional month.

This forum had various threads a few weeks ago about generators that were being taken out of mothballs this year, and that the result would be increased capacity. (Deregulation was offered as one possible reason why this investment was being made.) Jim Sinclair's (NEPOOL) estimate for New England is that we will be at 50% next winter - I would welcome an explanation as to why that is not based on an assumption of "normal" weather conditions at that time.

-- Anonymous, July 13, 1999

Brooks, I think you might not have read carefully enough, or possibly read more into what I posted than was there. The news release I posted stated that the transformer was damaged by a fire resulting from electrical testing, not Y2K testing. Here is the section from the June 6 post of mine which I believe you are referring to:

6/4/1999 - "Entergy Nuclear is in the process of purchasing Pilgrim Station from Boston Edison. The sale close is expected to take place this summer, after the refueling outage is complete and the unit is returned to service."

"Boston Edison officials have announced the duration of the refueling outage at Pilgrim Station will be extended about 25 days while the utility replaces the main transformer. The transformer was damaged May 18 during a small fire that resulted from electrical testing. Subsequent inspections have shown that the damage to the main transformer is more extensive than originally thought and repairs cannot be completed on-site. Pilgrim was expected to return to full power on June 14th. The transformer replacement will add about 25 days to the original schedule."

The full post can be found at: http://www.greenspun.com/bboard/q-and-a-fetch-msg.tcl?msg_id=000v4J

-- Anonymous, July 14, 1999

Bonnie, I appreciate the clarification. It still was a bloody nuisance here in Greater Boston that the plant was not available, as I'm sure the grid operator had expected it to be by then, and of course the extreme heat wave was not expected so early in the summer.

-- Anonymous, July 14, 1999

Because New England doesn't depend on electricty (much) for heating. Certain other parts of North America do. BC and Alberta Canada as well as the Pacific Northwest. New England depends mostly on oil and gas. So even if it is colder then normal your electicity use should not greatly increase as it would in Alberta say if they had very cold weather.

-- Anonymous, July 14, 1999

Engineer, you're right that most heating systems in New England are gas or oil systems, not electric, which fortunately does create less generation demand. Of concern, however, is that those gas and oil home heating systems usually have electric ignitions and/or electric control/safety systems. My home is heated by a natural gas furnace, but if the electricity is out, I still don't have heat. Conversely, if the power is on and the natural gas supply stops or is decreased, my heat is also impacted. Considering the frequency of winter weather related outages, long-term resident "Yanks" also tend to look askance at anyone who doesn't obtain a back-up heat supply, regardless of any 2000 problems. (Just like those in Kansas or Oklahoma should make sure they have a tornado shelter.)

Whether it's because of the severe ice storm outage, or Y2K, or just a general prudence, for the last year and half the wood stove/fireplace businesses up here have had more business than they can handle, and vent-free propane tank heaters are sold out in our area, too. Personally, if Y2K risks have prompted preparedness, I think it's created a long term benefit even if Y2K does not cause electric failures. Anybody living in the cold northern areas is better off with a back-up heat source, no matter what - as long as they know how to use that source safely.

I've seen several posts predicting a massive supply of generators will be on sale after 2000. I seriously doubt that will be true in the northern states, irrespective of what Y2K brings. People up here will keep them for future emergencies, of that I have no doubt. Only a fool would get rid of something they'll for-sure have a need for eventually - and probably nearly every winter.

-- Anonymous, July 14, 1999