No. You need to do the math. Any cable that carries power "stores" that power times the transmission line delay, which works out to hundreds of joules for a 1000km line. It's not a battery but plenty enough to damage switches etc.
Aren't you simply verifying Gnobuddy's statement that the cable will store a microscopic amount of energy in comparison to what it transmits?
According to my maths, one of your "hundreds of joules" would only keep a 100W lamp lit for 1second!
Galu's exactly right (thank you!)
Think about it for a second - a cable carrying, say, 1 megawatt is transporting one million joules per second. The amount of energy stored in the cable - a hundred joules by your account - is FOUR ORDERS OF MAGNITUDE smaller.
That's one ten-thousandth as big; so microscopic as to only have an effect on the fourth decimal point downstream, i.e. the difference between 1.0000 MW and 1.0001 MW, and that too only for one second.
This doesn't contradict your statement about energy being stored in the cable being sufficient to damage switching equipment. If you discharge a 100 joules in, say, a millisecond, you have 100,000 watts for that one millisecond, enough to do some damage to switch contacts. But that is a transient phenomenon, not part of useful power transmission. And even for that one millisecond, this is still only one-hundredth of the 1MW that the line is carrying. Still negligible.
The misconception I was attempting to address is the belief that the cable itself stores sufficient energy to stabilize a network against the time-varying power output of solar and wind power stations. This simply isn't true.
Solar farms only generate useful amounts of power for maybe six to eight hours a day, and any meaningful stored energy system would therefore need to be able to store enough energy to supply power for 16 to 18 hours at a time.
Our hypothetical 100 J of energy stored in the cable can provide 1MW for 1/10000 of a second, or ten microseconds - instead of the 16 to 18 hours we need.
16 hours is 57600 seconds. Ten microseconds is 0.00001 seconds. The ratio of those two numbers is 5.76 million; the stored energy in the cable is about one six-millionth of the amount of stored energy we actually need. Utterly irrelevant, and so small that calling it "microscopic" may be too generous!
-Gnobuddy
Why don't you explain what it is that you think I don't understand, and then we can have a discussion to resolve the issue.
Simply saying "You don't understand" is combative and doesn't help anybody learn anything.
-Gnobuddy
In the early days of power generation many voltages and frequencies were used, but it was found that the early induction motors worked best with 50 or 60Hz alternating current.
Once these ac motors had become common, generators were standardised to work with them, so 50 or 60Hz generation became the norm.
One frequency has no advantage over the other, 50 or 60Hz was simply adopted depending on where in the world the electricity was generated.
The power line (or mains) frequency is 50Hz in large parts of the world, but in the Americas and Asia it is typically 60Hz. Places that now use the 50 Hz frequency tend to use 220–240V, and those that now use 60 Hz tend to use 100–127 V.
My qualifications? I can look up Wikipedia!
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Apparently Japan actually has both frequencies, in different parts of the country. What fun that must be for all involved!
More on this bizarrely absurd situation, and its sometimes tragic consequences, here: Japan's incompatible power grids | The Japan Times
And there is a second interesting thing about AC power in Japan. They have their own unique line voltage, different from every other country: Electricity in Japan 1
-Gnobuddy
Simple misunderstanding, by grid tie I mean the average home that wants to tie solar panels to their local power connection usually 2 phases of 120 here not tied to the major distribution grid.
the mains in japan
The frequency difference between east and west has no problem now, though my first electric clock had to be trashed when I moved from east to west since it didn't have adjustment switch(20% error !!). The advantages of a Japanese system for audio use are low voltage and no earth ground terminal. If your power is SMPS, it directly switches the mains voltage. Unwanted switching noise from SMPS is almost proportion to switching voltage. The lower, the smaller. The datasheet of ROHM has a comparison between 240V and 100V. 100V is generally superior to 240V in noise voltage.
No earth terminal can have better common noise attenuation from SMPS, though you need some technic to utilize the situation. If the mains has three terminals, you are forced to connect your signal ground to the earth ground. As long as my experience and others, no connection has better measurement data. Two terminals one means you have a chance to connect or not in a particular circumstance. You don't need to worry about the possibility of electrical shock because a Japanese house is made of paper, soil, and wood. I have several experiences of electrical shock in the office but never at my home. Only the washing machine has the earth terminal because it usually locates at the bathroom(toilet is separated) .
The frequency difference between east and west has no problem now, though my first electric clock had to be trashed when I moved from east to west since it didn't have adjustment switch(20% error !!). The advantages of a Japanese system for audio use are low voltage and no earth ground terminal. If your power is SMPS, it directly switches the mains voltage. Unwanted switching noise from SMPS is almost proportion to switching voltage. The lower, the smaller. The datasheet of ROHM has a comparison between 240V and 100V. 100V is generally superior to 240V in noise voltage.
No earth terminal can have better common noise attenuation from SMPS, though you need some technic to utilize the situation. If the mains has three terminals, you are forced to connect your signal ground to the earth ground. As long as my experience and others, no connection has better measurement data. Two terminals one means you have a chance to connect or not in a particular circumstance. You don't need to worry about the possibility of electrical shock because a Japanese house is made of paper, soil, and wood. I have several experiences of electrical shock in the office but never at my home. Only the washing machine has the earth terminal because it usually locates at the bathroom(toilet is separated) .
No. Early projects used *large* motors and they like low frequency.
50/60Hz is all about lighting flicker. 25Hz lights are very unsettling. (Especially arc-lights which go out each half-cycle; incandescents retain some glow in the zero-crossings.)
(Incidentally, the shift from one motor per factory to individual motors on each machine favored small motors that do work OK at 60Hz, and are lighter/cheaper).
Long lines have large capacitance.
Long high-voltage lines therefore take a charging current.
On AC lines, this current must flow twice per cycle. And it can be many Amps, even if all loads are disconnected. The current to the capacitance at the far end flows in the whole line. Lines always have resistance too. This charging current makes a Power loss. It will typically be designed "small" compared to the billable loads on the line. But it flows all the time the line is energized, and is a real "cost" to the power company.
On a DC line, this current flows once when turned-on and once when turned-off. It is not a steady drain on the system.
Very high voltage (above utilization voltage) was "useless" before huge Mercury (later solid-state) inverters and rectifiers. Nobody can eat a million Volts DC. Transformers can't eat DC. But active AC/DC/AC conversion allows transformation at both ends of a DC line. Yes, they use *stacks* of SCRs etc to stand a million Volts.
https://s3.amazonaws.com/dsg.files....ria-converter-station-Brazil_copyright-GE.jpg
https://resources.news.e.abb.com/at..._in_a_HVDC_converter_station_-_the_valves.jpg
https://electrical-engineering-port...s/2014/03/hvdc-800-kv-transformer-siemens.jpg
Charging Current in Long Lines and High-Voltage Cables
Long high-voltage lines therefore take a charging current.
On AC lines, this current must flow twice per cycle. And it can be many Amps, even if all loads are disconnected. The current to the capacitance at the far end flows in the whole line. Lines always have resistance too. This charging current makes a Power loss. It will typically be designed "small" compared to the billable loads on the line. But it flows all the time the line is energized, and is a real "cost" to the power company.
On a DC line, this current flows once when turned-on and once when turned-off. It is not a steady drain on the system.
Very high voltage (above utilization voltage) was "useless" before huge Mercury (later solid-state) inverters and rectifiers. Nobody can eat a million Volts DC. Transformers can't eat DC. But active AC/DC/AC conversion allows transformation at both ends of a DC line. Yes, they use *stacks* of SCRs etc to stand a million Volts.
https://s3.amazonaws.com/dsg.files....ria-converter-station-Brazil_copyright-GE.jpg
https://resources.news.e.abb.com/at..._in_a_HVDC_converter_station_-_the_valves.jpg
https://electrical-engineering-port...s/2014/03/hvdc-800-kv-transformer-siemens.jpg
Charging Current in Long Lines and High-Voltage Cables
The article I linked to earlier pointed out that during natural disasters, when power generation is reduced on one coast, it is impossible to borrow power from the other coast. This can have terrible consequences - people can die if hospitals have no power, for example.
All three of those materials conduct electricity when damp or wet...and soil conducts quite well even when dry.
Soil conducts so well, in fact, that there were electrical systems that used the earth (soil) itself as one of the "wires" - Single Wire Earth Return systems. ( Single-wire earth return - Wikipedia )
-Gnobuddy
Tha main light source in arc lights are the hot tips of the carbon electrodes with considerable thermal capacitances. Hence flickering wasn't that of an issue.
55 V is the voltage of a burning arc. Hence most grid voltages roughly are multiples of 55 V.
Yes, here in Germany and some other countries the electric rail power means 15 kV/16,7 Hz (so called transformable DC).
Best regards!
The history of utility frequencies is fascinating and I recommend this Wikipedia article: Utility frequency - Wikipedia
Very early isolated AC generating schemes used arbitrary frequencies based on convenience for steam engine, water turbine and electrical generator design. Frequencies between 16⅔ Hz and 133⅓ Hz were used on different systems.
London in 1918 had ten different frequencies even although a standard frequency of 50Hz was declared in the UK in 1904. It was only after World War II that this standard was completely established.
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Mains frequency can be difficult to control.
If there’s more demand for electricity than there is supply, frequency will fall. If there is too much supply, frequency will rise.
There is a very slim margin of error. In the UK, anything just 1% above or below the standard 50Hz risks damaging equipment and infrastructure.
Thermal power stations allow automatic response to changes in frequency. If the frequency rises, the turbine reduces its steam flow. If the frequency falls the turbine increases the steam flow. Moreover, this frequency response can, and must, happen in seconds.
Intermittent or weather-dependent power generation technologies such as wind and solar are not as easy to control.
P.S. I found this cool graphic showing the National Grid status. Hover over the instrument dials to discover some interesting information! G. B. National Grid status
If there’s more demand for electricity than there is supply, frequency will fall. If there is too much supply, frequency will rise.
There is a very slim margin of error. In the UK, anything just 1% above or below the standard 50Hz risks damaging equipment and infrastructure.
Thermal power stations allow automatic response to changes in frequency. If the frequency rises, the turbine reduces its steam flow. If the frequency falls the turbine increases the steam flow. Moreover, this frequency response can, and must, happen in seconds.
Intermittent or weather-dependent power generation technologies such as wind and solar are not as easy to control.
P.S. I found this cool graphic showing the National Grid status. Hover over the instrument dials to discover some interesting information! G. B. National Grid status
How is frequency control related to coal fired generation?
Wind to grid is typically via a converter system, either or without storage ability. The converter just autonsynchronises to the grid frequency it sees. Same for all generators, whether diesel low speed, GTA or STA.
In fact, it is the traditional generation schemes which are inflexible to changing system load (you can't shut off a nuclear plant just like that)
The very reason the world at large is exploring alternative energies and storage, after seeming to forget about it, is cost. Also, it is the fact these techs can be used more effectively to stabilise the grid, and minimise the need to 'adjust' baseline supply generation, such as nuclear.
But we still need more storage. Some isnt enough. We have quite a huge wind generation capacity, which broke records recently, but need more storage.
New annual wind energy record shows wind power taking central role in UK’s modern energy system - RenewableUK
And then theyres grid stabilizers, synchronous condensers, to correct power factor, but also transient loads.
They're back in vogue as well.
Wind to grid is typically via a converter system, either or without storage ability. The converter just autonsynchronises to the grid frequency it sees. Same for all generators, whether diesel low speed, GTA or STA.
In fact, it is the traditional generation schemes which are inflexible to changing system load (you can't shut off a nuclear plant just like that)
The very reason the world at large is exploring alternative energies and storage, after seeming to forget about it, is cost. Also, it is the fact these techs can be used more effectively to stabilise the grid, and minimise the need to 'adjust' baseline supply generation, such as nuclear.
But we still need more storage. Some isnt enough. We have quite a huge wind generation capacity, which broke records recently, but need more storage.
New annual wind energy record shows wind power taking central role in UK’s modern energy system - RenewableUK
And then theyres grid stabilizers, synchronous condensers, to correct power factor, but also transient loads.
They're back in vogue as well.
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The way to adjust grid frequency is to control power into the grid. That means controlling electrical power from the generator (or throwing some away). That means controlling non-electrical power to the generator. Coal and oil fired stations were designed to do this, and do it reasonably quickly. Nuclear cannot do it, because you cannot vary reactor power up and down too quickly. Wind and Sun are not in our control, so any use of them requires significant amounts of controllable power to have available on stand-by or alternatively have lots of load you can quickly shed. Hence Wind and Sun are not as 'green' as some people think they are.
Note that you cannot control grid frequency by trying to inject a different frequency. Every source of power must synchronise to what the grid is now, not what you might like it to be. You control frequency by controlling power.
Note that you cannot control grid frequency by trying to inject a different frequency. Every source of power must synchronise to what the grid is now, not what you might like it to be. You control frequency by controlling power.
Or, in the case of the UK, converting them to burn America's trees!
To be accurate, when I say trees, I mean sawmill waste and logging leftovers converted into wood pellets (biomass fuel).
Under EU law, biomass is classified as a source of carbon neutral energy
and Drax power station in England burns more wood pellets than any other plant in the world.20 massive train loads of pellets arrive to be burned at Drax every day, and they come mostly from the USA.
The UK’s move away from coal means they’re burning wood from the US | Public Radio International
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