I've seen a lot of discussion on fossil and nuclear plants, but as of yet, I've seen nothing about the vulnerability of hydro-electric plants. It seems that they have a much better chance of pulling through, as they are not dependent on fuel supplies or the NRC's rubber stamp of approval.

Is the embedded systems risk lower for a hydro-electric facility? In certain parts of the country a very large percentage of the electricity is generated by hydro plants (thanks to FDR and the TVA).

It would be useful if some of the experts on this forum could develop a risk assessment matrix for various types of generation plants.

Ken Griffith

-- Anonymous, December 24, 1997

Answers

You'll notice on my website that hydro doesn't get a lot of airtime. Two reasons: I don't know a lot about the subject (although technically, it's not a lot different than nuclear or fossil - turn a turbine hooked to a generator and make juice). You still have to have controls on the generation side and pumps and valves and safety features...so I don't think the embedded risk is necessarily lower except by volume - hydro plants aren't typically scaled as large as a big nuke or coal facility.

Also - as an aggregate, hydro makes up a relatively small contribution to the overall national energy mix, but certainly not to those folks in regions dependant on it.

-- Anonymous, December 28, 1997

I live in an area served by TVA. We receive our power from the final dam just north of the Tennessee/Kentucky line before it empties into the Ohio River. There is a steam plant between there and the next dam. Our utility is a county co-operative. Would we more likely not have as much outages as other systems or are they all interconnected.

-- Anonymous, January 01, 1998

The main importance of HYDRO

I am a lowly union SCADA Technician (By Choice) at a large utility in California. I worked as an Automation Engineer for a time automating the E-Grid with PLC's RTU's and now they latest trend utilizing the logic capability to have the Master EMS System run with Artificial Intelligence for what is called a "SMART GRID" What is Most Important about a Hydro station is they can perform what is called a "Black Start" meaning if the E-GRID goes completely in the black a Hydro station can generate its own start-up power with out having energy supplied from the E-Grid Via Auxiliary Transformers like most other Power Plants require.

The first thing Grid Dispatchers will do is order every Transmission Bank Breaker opened to isolate the Grid That is if the Underfrequency relays tied to them didn't beat the operators to it!. Then they will get the hydro up and running (This is on the assumption that they tripped off on sync or underfreq. and not embedded Y2k problems) Then per System Operating Bulletins and Emergency Orders Dispatchers will start powering up the Grid feeding power first into where Steam Plants tie into the Grid. At some point they will start bringing up Load until the job is done and every one in their Jurisdiction has power.

At that point or depending on legal agreements Prior to that point Dispatchers will start to close in the Interties to neighboring utilities. Much like during the August 10, 1998 outage when PG&E and most of the Municipal utilities needed help for days until they got back on their feet.

-- Anonymous, June 07, 1998

That's one of the problems, Joe - they're all interconnected. The electrical outlets in your home don't distinguish *where* the power was made. :) TVA's plants (nuke, hydro, and fossil gen) all dump their power into the regional electrical grid. From the grid, the power is distributed to your house.

The interconnections are the tough part of this whole thing - it doesn't take very many breaks in the chain to cause whole parts of the system to come crashing down.

You might want to check out the North American Electrical Reliability Council's (NERC) website at www.nerc.org.

-- Anonymous, January 01, 1998

I think hydro facilities will suffer less, because they're actually less complex than thermal plants and do not use as much modern computer control. I'm presently manning my plant on Jan. 1st, called out due to computer problems at System Control Center, but the plant has no problems. Many hydro plants are OLD. My station was initially built in the 20's.

Examples: I have no computer controlled valves in my plant -- I take that back -- brand new computer driven governors on two units do open motor operated cooling valves on their respective machines -- but in general all valves are controlled either by hand or by simple trip and lockout protective systems. Woodward tells me our new Summit 517 governors are Y2K compliant, but I place more faith in the simple fact a governor doesn't care what time it is. In general, most automated systems i a hydro plant can be bypassed and the station operated manually. Most hydroelectric utilities do have plans for "islanding." Ours does, though I won't guarantee it's a great one.

I fully expect inter-utility exchanges, metering and billing to be a nightmare. Likewise, if Y2K causes severe civil disturbances, distribution and repair could become extremely difficult. Here in "Hydro Country," I feel we'll keep at least some of the lights on, but as for me, I'll continue to live on a generation site far from the big city. Good Luck to us all.

-- Anonymous, January 01, 1998

A poster, Allan Comstock, on y2k-homestead list, asks these questions (he wanted me to post it here)-- I think they are good questions.

Thanks -- Roleigh http://ourworld.compuserve.com/homepages/roleigh_martin

Speaking of hydro electric power, I wonder if you have any idea on what the default position is for dams when their computers fail: spillway open, spillway closed or spillway no change. If I was an engineer designing a dam I think I would build a system that would tend to relieve the stresses on the dam in the event of unanticipated electronic shutdowns. This logic is the same as that which unlocks buildings as the default positon when security systems fail so people are able to escape the building.

Y2k could be devastating for people living downstream from major dams. Have you come across anything like this in your research? Do you know anyone you could contact who knows hydro power well enough to have a useful opinion on the default position of the spillways? I'm sure there must be a manual intervention process but when would an operator know what was happening was an error and when would he take it upon himself to close an open spillway in the middle of a serious event and in the absense of information? In really big dams, how much control is possible without computers and electronics? Where does electrical power come from to operate the dam machinery when the generators are tripped off line? How does a hydro dam come back on line if the electrical grid is down and if the demand is larger than the capacity of the generation equipment?

Allen Comstock

-- Anonymous, March 23, 1998