Posted on 06/26/2011 11:21:27 AM PDT by matt04
A yearlong experiment with the nation's electric grid could mess up traffic lights, security systems and some computers — and make plug-in clocks and appliances like programmable coffeemakers run up to 20 minutes fast.
"A lot of people are going to have things break and they're not going to know why," said Demetrios Matsakis, head of the time service department at the U.S. Naval Observatory, one of two official timekeeping agencies in the federal government.
Since 1930, electric clocks have kept time based on the rate of the electrical current that powers them. If the current slips off its usual rate, clocks run a little fast or slow. Power companies now take steps to correct it and keep the frequency of the current — and the time — as precise as possible.
The group that oversees the U.S. power grid is proposing an experiment that would allow more frequency variation than it does now without corrections, according to a company presentation obtained by The Associated Press.
...
In the future, more use of renewable energy from the sun and wind will mean more variations in frequency on the grid, McClelland said. Solar and wind power can drop off the grid with momentary changes in weather. Correcting those deviations is expensive and requires instant backup power to be always at the ready, he said.
(Excerpt) Read more at masslive.com ...
An absolutely idiotic idea.
Ping.
ALL heavy industrial electrical equipment that utilizes SCR’s (Silicon Controlled Rectifiers) will be severely affected. These devices are used in controllers that control the speed of DC motors and chopping frequencies of older inverters.
The problem is that they are designed to synchronize at 60HZ and most controllers are not designed to vary from that frequency.
What this article is telling us that solar and wind power is not to the design that it can synchronize with the power grid frequency and rather than design it to do so, they are simply going to ignore the “Massive” problem and hope some day a cure will be found........but first..........they want GREEN energy to take precedence over professional engineering.
Nice to know OUR Fed’l Gummint has run out of other more important issues to tackle...
Sheesh.
Most clocks these days are electronic. In an electronic device, the AC is rectified and filtered into DC to power the electronics, which have their own clock chip that sets the time rates. Line frequency does not affect electronics, unless it is so far away form 60Hz that the filters can’t handle it. Most AC loads in your house (fans, compressors, etc) can handle a 10Hz shift in frequency, but will run faster or slower with the frequency shift.
There may be some old traffic lights that still work off an AC motor-driven timer, but not many.
On the other hand, industrial machinery will be hard hit by this because any motor with an across-the-line starter is a slave to the line frequency. Industrial processes are finely tuned to maximize efficiency and randomly changing line freq will be extremely disruptive, especially in high-speed manufacturing. It will cost a fortune (that most manufacturers can’t afford) but we can put VFD (variable frequency drives) on most industrial motors and set the run frequency at anything we want. However, VFDs for large motors are expensive and inefficient. They will waste energy on an industrial scale.
Well, I guess it’s a good thing (/sarc) that Most industrial manufacturers are leaving or have already left the country.
>>ALL heavy industrial electrical equipment that utilizes SCR’s (Silicon Controlled Rectifiers) will be severely affected.
Just the opposite. They’ll be unaffected because an SCR is a DC device. In an inverter or VFD, they are fired by an electronic timing device (also powered by DC and timed by a clock chip) to create an effective AC waveform. Changes in input frequency (to the degree that these proposed changes will permit) does not affect the operation of any of these components.
I’m hoping one of our resident EE’s will weigh in here. I thought that generators delivered 60HZ power by design. If it generates, it generates 60HZ, not 58HZ and not 62HZ. Output can vary in amplitude due to load and length of wire, but the frequency of produced electricity is designed in.
There’s something wrong about the assumptions in this article - including a reference to a NERC presentation that I can’t find.
If the frequency is so mission critical, why isn’t there a backup? GPS or weather radio or an internal digital clock. Poor engineering if you ask me.
>>Well, I guess it’s a good thing (/sarc) that Most industrial manufacturers are leaving or have already left the country.
I thought the same thing. But, even when they’ve driven out the last manufacturer, you still have industrial processes to deliver electricity and water to your home, and to take away and treat your sewage. And even Obama won’t have us to the point where we lose utilities until his 4th or 5th term as “President-for-Life”.
What’s the bottom line on how this is going to affect us?
Its more than idiotic, there is some degree of false information in the report.
Am no Electical Engineer, but have some experiences around large electrical generators and a supply, such as wind, dropping off the grid is no different that a coal or gas fired plant having an emergency outage and dropping off the grid. It would reduce the current available to the grid, to which until another replacement generator is online, you would have lower voltage and brownouts.
The Hz is a function of the speed of the generators. 60Hz is not designed in to enable the damn clocks to run right! How absurd. In our 60Hz grid, all the generators MUST be running the same speed when they are connected to the grid or you’ve got BIG trouble at the generator trying to Snyc with the grid as it is connected.
Solar would have solid-state inverters to change the DC the panels make into a pre-determined 60Hz AC. Not sure if wind is DC or AC, but if DC it would use same inversion to AC as solar, if AC, there are likely speed governors at the generator to make sure they were all running same speed.
This “floating Hz” thing is probably some diverson by the nobama idiots to get us to not watch something else they are trying to pull.
>>If the frequency is so mission critical, why isn’t there a backup? GPS or weather radio or an internal digital clock. Poor engineering if you ask me
That’s my point. Frequency isn’t as mission-critical as it used to be. In the old days (when I started in the industrial process control business), your processes were controlled by relays, drum sequencers, and mechanical timers. They were designed for 60Hz and 60Hz only.
Today, industrial processes are controlled by PLCs and DCSs and use VFDs to set motor speeds. Even if your process wants the motor to run at 60Hz, you usually put a VFD in the line to allow you to tune the process later, so that if 58Hz or 63Hz becomes the sweet spot, you have the option.
Regardless of line frequency, I can set my process speeds to anything I want (within reason, usually 50-100Hz). I haven’t designed anything in years that would be affected by a frequency deviation of a couple Hertz (as is being proposed).
permitting the power generating frequency to fall below 60 Hertz(cycles), is pure madness....running loaded motors at a lower frequency, will pull more power, or else they will stall and burn out...the lights will flicker....but on the operating side of the equation, allowing the frequency to sag, will save some energy used, at the generators...it costs money(energy) to maintain a 60 Hertz frequency....a good explanation, is that the existing power grid and system, doesn’t have suffice power capacity to generate the electrical power to carry the peak loads...over reliance on wind generation, is a factor, sometimes the wind doesn’t “blow”...
It isn’t called Fedzilla for nothing.
Also, how hard would it be to clean the power at the mains with a frequency converter? The power company does it now on the outbound side; why can’t a large manufacturing concern do it on the inbound? Again, why wouldn’t they already be doing this if it were so important to the synchronization of their fine tuned industrial processes?
>> but the frequency of produced electricity is designed in.
Frequency output is determined by the speed of the prime mover (i.e. the turbine or engine). Actual bus frequency (what arrives at your home or business) is a more-complicated issue involving load-sharing and a variety of things that would take hours to explain.
The bottom line is that allowing the bus freq to vary by a couple Hertz will require some reprogramming of power plant control systems, but it is not that big of a deal. But, I’m really not sure what the advantage would be. We build our systems for 60 Hz and it isn’t that hard to maintain, so why mess with something that works perfectly as-is?
The mechanism that drives the generator (Engine, motor, Turbine) must be governed to a precise speed to achieve the desired output frequency.
The green technology should be responsible for converting whatever frequency they are producing into syncronized 60hz sine wave. Pretty expensive and wasteful unless we are willing to let them put some “Ugly” 60hz power on our grid.
I’m not an engineer.
>>Also, how hard would it be to clean the power at the mains with a frequency converter? The power company does it now on the outbound side; why can’t a large manufacturing concern do it on the inbound? Again, why wouldn’t they already be doing this if it were so important to the synchronization of their fine tuned industrial processes?
The cost of a giant inverter at the front of the plant would be prohibitive. As I said earlier, we can put a VFD on each motor since VFDs have become extremely inexpensive over the last 20 years and run whatever frequency we want.
We already do that in most cases because we want to be able to tune our processes to squeeze out every drop of efficiency we can.
Nothing else in the plant even cares about minor frequency deviations. When I was a submarine electrician (NEC 3364), we routinely varied bus frequency for the entire boat by a lot more than they are proposing and nothing bad ever happened.
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