David Bidstrup: More silly solar stuff

An article in the Oz prompted me to write the following.

The article referred to “solar saturation” of the power grid where excess solar generation is causing instability, primarily with over-voltage issues. Voltage needs to be kept within limits otherwise things like refrigerator motors fry.

In the article Energy Networks Australia are quoted as saying;

While it is not impossible for electricity to flow backwards, it is tricky for networks to manage the grid…especially where there is a lot of distributed electricity feeding back into the grid in the same area.

Domestic roof-top solar is touted as the answer to all our “bill problems”, and as the owner of a small system I can vouch for the effect on power bills, but I have a feed-in tariff of 56 cents/kWh and as long as this lasts I am doing OK. I recognise that non-solar households are subsidising me but that is due to political stupidity.

When the power system was designed,( by people who actually knew what they were doing), the model was to have large, centralised, reliable and economic power stations as close to the load centres as possible. Electricity was reticulated in a one-way system using various voltages which were progressively stepped down for ultimate consumption. Our houses use 240V. Main transmission lines run at 132, 256 or 500 thousand volts to reduce power losses due to line resistance, (Volts = I,(current) squared X R, (resistance)) so higher voltage give  lower losses.

When it gets to our homes we want 240 volts so the local system draws from a High Voltage feeder, (usually 11,000 volts), through a transformer to get 240. In SA if folk look at the power poles in their street they will see 3 wires on top of the poles, (usually 11,000 volts), and 4 underneath – this is 415V 3 phase distribution system and the 240 volt supplies are taken off this. Every now and then there is a transformer between the 2.

Each transformer serves a “local” area containing a number of homes. Domestic solar systems can “share” their excess within the local area but nowhere else because the transformer will not permit a reverse flow when there is a higher voltage on the supply side. Electrical purists do not like water analogies but the best way to view the transformer is as a one-way valve.

If there is a power failure then solar systems will shut down as there is a need to ensure that there is no extraneous power supply that could endanger those who work to fix the problem. This is done by the solar inverter and it is a legal requirement that this happens. Once the inverter is off line a person’s solar system is no use to them and they will be in the dark until power is restored. A battery would be no use unless the system had the means to disconnect from the grid completely.

The article also states that the Clean Energy Council says 21% of the overall “power mix” is supplied by renewables. Each year the Department of Environment and Energy release statistics on generation and consumption. These are around a year late when released so the following comes from the 2016/17 release. The chart below shows the percentages of generation for all “fuel types”. I have lumped hydro in with “fossil” fuels because it is a mature method of generation and does not have the intermittency of solar and wind. As long as there is some water there is some reliable power.

There is a view that as long as there is daylight the solar system works. Earlier this year I submitted a post showing the vagaries of solar systems but it missed the cut. I will put a couple of charts below to illustrate. These were done in response to a request to see whether a 200 MW solar plant could power a remote mine-site. The load shown in the charts is the 200 MW that the mine needs constantly. Daily and hourly consumption is in MWh.  I picked the “best” day and the “worst” day as well as the “best” month and the “worst” month.

Best day, hours 1 to 24:

Worst day:

Best month, days 1 to 31:

Worst month:

These charts come from an analysis using data for Kalgoorlie but anywhere is the same – perhaps a little better as you go North but not by much. The system used here had 2 axis tracking that gets the capacity factor up to about 25% but it needs power to operate. Most solar systems with fixed panels manage around 17% tops.

The charts show the variation in output over the year where the sun angle changes from summer to winter and also shows variations day to day usually caused by clouds. Every time the system is in deficit some other system has to step in to keep supply equal to demand. As the charts show, this is a frequent occurrence.

Domestic solar suffers the same vagaries of seasons and cloudy days.

In short, the idea of having “virtual” power stations using lots of rooftop solar systems is bullshit.

Electricity suppliers hate solar because they miss out on charging for the “free” power distributed by the rooftop solar systems but have to be ready to pick up the shortfalls and of course the 12 hours of the day when the sun does not shine. To counter this they raise their prices so more “renewables” leads to higher prices. It is a vicious circle that will not be broken until sanity prevails again and we get back to the dreaded coal for our power.

Getting power to “run backwards” is like squirting a syringe full of water into the end of a running hose and expecting it to get back to the reservoir, it is just bullshit.

 

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42 Responses to David Bidstrup: More silly solar stuff

  1. Speedbox

    So, how ‘big’ is a 200Mw system in terms of m2 size/number of panels? My understanding is that no wind/solar renewable system lives up to its ‘plated’ ability. In other words, to actually supply 200Mw, something plated at a higher capacity would be required.

    I’m no fan of the renewable scam but to conceptualize this, I would appreciate some words on how ‘big’ a 200Mw system would be and, to achieve the Kalgoorlie mines requirements, how much bigger would the system have to be to provide 200Mw during the primary daylight hours (say, 7am to 4pm) and what would such an installation cost?

  2. Dr Faustus

    The Energy Networks Australia paper is worth a read.

    Aside from the self-inflicted network costs, the critical issue faced by rooftop solar PV owners (and the government agencies who encouraged them) will be how to divvy up the subsidy market when the local networks downstream of the supply transformers become saturated with rooftop power exported back into the grid.

    Australia faces a community of rooftop solar owners who will be unexpectedly restricted (or curtailed) from pigging in to the subsidised feed-in tariff. With two million paid-up installations, the whinging will be heard in space. And the political response will be truly silly…

    Incidentally:

    (Volts = I,(current) squared X R, (resistance))

    Ohm’s Law
    V = I x R

  3. Dr Fred Lenin

    Dr Faustus I would hate to be one of the poor heroic engineers trying to maintain the semblance of an efficient power grid ,must be a headache, stupid career pollies scrounging for preference votes ,whngeing consumers when you have to black out areas because the stupid pl]ollies wont encourage building more t-reliable clean coal ststions the the Japanese burn our coal in .
    I wouldnt be looking forward to shortens EV fiasco ,imagine when its raining fir four days with no wind and everyone blaming me .

  4. Sidney Cotton

    I get where you are going with this, but firstly
    Power = Isquared * R
    And transformers are not one way valves.
    If you are going to talk tech, at least know the tech.

  5. Woolfe

    We get $0.07 /kWh in WA.

  6. Peter Greagg

    Dr Faustus
    #2991174, posted on April 18, 2019 at 2:15 pm
    The Energy Networks Australia paper is worth a read.

    Aside from the self-inflicted network costs, the critical issue faced by rooftop solar PV owners (and the government agencies who encouraged them) will be how to divvy up the subsidy market when the local networks downstream of the supply transformers become saturated with rooftop power exported back into the grid.

    Australia faces a community of rooftop solar owners who will be unexpectedly restricted (or curtailed) from pigging in to the subsidised feed-in tariff. With two million paid-up installations, the whinging will be heard in space. And the political response will be truly silly…

    Incidentally:

    (Volts = I,(current) squared X R, (resistance))

    Ohm’s Law
    V = I x R

    Well, yes Ohm’s Law is V=I*R, but David was pointing to the power loss of transmission, which is V*I, which, via Ohm’s Law, becomes I^2*R. And this is the reason you use high voltage transmission lines, and then drop the voltage down when you want to use the power.

  7. duncanm

    Getting power to “run backwards” is like squirting a syringe full of water into the end of a running hose and expecting it to get back to the reservoir, it is just bullshit.

    yeh, nah.

    We could certainly design and implement a distributed power system that did just that.. but it would involve a complete reworking of the electricity network. The statement is true for the network as it stands.

    There are some ‘smart’ load balancing transformers coming out, which try to address power factor, over-voltage and other issues at the local level.. it’ll be interesting to see if they work &/or are rolled out.

  8. David Bidstrup

    Dr Faustus: The I squared R relates to losses in transmission.

    Speedbox: To get the 200 MW plant to produce the total annual load requires it to be about 3 to 4 times larger. Still no electricity at night and still no good in winter. Note that the issue will be overproduction on “good” days. If there is only one load to serve then excess is wasted.
    A 280 MW proposal in SA has 925,000 panels over 784 Hectares and has a “budget” cost of $350 million.

  9. Dr Faustus

    Dr Faustus: The I squared R relates to losses in transmission.

    Correct. W = I^ R
    But not: V = I^ R, because V ≠ W

  10. Cynic of Ayr

    Coupla things:
    V = I^2 x R is valid. It’s Ohm’s Law cross multiplied. Cross multiplying does not make it not Ohm’s law. I don’t see what the nit-picking is about.

    I’m ignorant here, and I’d like a pointer to more info on “reverse” transforming. At first glance I can see some problems ! First, it’s a three phase transformer, with three phases in and three phases out, with a neutral extra on the outer. I assume the primary winding is connected in Delta, as there are only three wires. I assume the secondary is connected in Star, with the centre of the Star connected to the neutral.
    The Star is 415 volts from Star Point to Star Point, and 240 volts from each and any Start Point to the Neutral.
    Each 240 volt circuit (one of the phases) is distributed as evenly as possible to the homes in the local transformers little balliwig.
    So, how the hell can, say, one or two of the 240 volt circuits transform back to three phase, and the other 240 volt circuit contributes nothing?
    In the mix, is Rooftop Panels on some of the houses, producing one minute, and not producing the next.
    This seems fraught with danger. When the power from the transformer is zero, because the neighbor’s Solar Panel is supplying all the power, who or what decides is the synchronised frequency?
    (There’s nothing wrong with the idea of simple single winding in and single winding out trannies working both ways. But three phase transformers with different winding configurations?)
    I battle with the idea of current flowing thither and yon too, because for current to flow, there must be a voltage difference. So, for the supplying neighbor to supply his dependent neighbor, the panel must be a higher voltage than the transformer.
    But the Govt says it “buys” power from Rooftop Solar to feed into the grid. Therefore, the Govt says that power is transformed back into 3 phase hi voltage. Or, more likely, they’re lying, and power is not fed back into the grid, but merely to neighbors. IF the darn neighbors want it! They might be away on holidays. In that case, does the Govt pay for power from a panel that goes nowhere! If it ainlt going to the neighbors because there aren’t any, and it can’t go back through the transformer, where does it go? There must be a nice heatsink hidden away somewhere!
    David Bidstrup says backwards through the transformer won’t work. It cannot work. The transformers don’t work backwards.
    I dunno. We’re getting screwed here, and I don’t think it’s all the Pollies doing. They’re just too stupid and lazy to work it out for themselves. I think they are getting some dubious or outright lying information from some dudes who either have an ego in this, or there’s a lot of money going their way.
    And Tits Shorten has been told that doubling or tripling the problems with electric cars, will fix the problems! Really?
    The US isn’t the only country with a lying, snouts-in-trough bureaucracy, or Deep State.
    Peter Ridd has proved that beyond doubt.

  11. Peter Greagg

    Dr Faustus
    #2991241, posted on April 18, 2019 at 3:23 pm
    Dr Faustus: The I squared R relates to losses in transmission.

    Correct. W = I^ R
    But not: V = I^ R, because V ≠ W

    Not sure what you are saying here?

  12. Speedbox

    A 280 MW proposal in SA has 925,000 panels over 784 Hectares and has a “budget” cost of $350 million.

    Jeezus on a bike. I’m conceptualizing all right. And that’s just to install the thing – I know they need ongoing maintenance/care (plus useless at night, inefficient on cloudy winter days, any overproduction wasted). As I understand it these panels also have a ‘life’ namely, that their efficiency diminishes over time.

    FMD.

  13. Tezza

    Thanks David – useful work, and helpful comments/debate by others.
    Wouldn’t it be better to call the black bars ‘deficit’ rather than ‘surplus’? If I understand the diagrams, there is never a surplus of the 200 MW solar plant’s output over the 200 MW steady load of the mining operation.

    As you say, “Every time the system is in deficit some other system has to step in to keep supply equal to demand. As the charts show, this is a frequent occurrence.” Indeed, it is a practically ubiquitous occurrence.

  14. Karabar

    Relative to the current mud-slinging in progress regarding the COST of “tackling climate change”, I think it much more appropriate to focus on the benefit.
    The cost can be expressed (but not accurately calculated) in AUD but the benefit can only be stated in degrees C. What change in the weather will be the resulting benefit of this expenditure?
    There is a huge focus on “emissions” (without defining what these emissions are) but what evidence do these perpetrators of economic vandalism have that CO2 has ANY effect whatever on the weather? For that matter, what evidence exists that human activities have ANY affect on the ratio of CO2 to the other constituents of the atmosphere?

    The only sensible answer is that the cost will be enormous and the benefit non-existent. Why is it so difficult to get this across?

    At the Paul Murray Live inquest in Launceston Tuesday night I asked a panel of candidates, but of course got no answer whatsoever other than waffle.

  15. RobK

    I’ve linked this before. If you have to build a renewables grid this is how you do it. State-of-the-art of hosting capacity in modern power systems with distributed generation.
    Suburban distribution is 3phase with most houses only connected to one. (Country supply is often Single Wire Earth Return.) Transformers do feed backwards, thats only part of the problem (to be solved with expensive On-Load-Tap-Changing (OLTC) transformers. When transformers are out of balance it has the effect of changing the neutral point of the transformer causing changes in the other phases and neutral/earth. All these things are addressable at a cost. Batteries at houses help. Batteries at substations help. Synchronous condensors help. Heavier conductors help. Remote control of distributed PVs helps. It is an insideous creeping, exponentially increasing cost of hosting renewables. To my knowledge no one has a fix on the cost. Finkle was very vague. He said it can be done…which is true, but the cost will be high as is the risk of it being able to support our economy.

  16. DrBeauGan

    Peter Greagg
    #2991259, posted on April 18, 2019 at 3:37 pm
    Dr Faustus
    #2991241, posted on April 18, 2019 at 3:23 pm
    Dr Faustus: The I squared R relates to losses in transmission.

    Correct. W = I^ R
    But not: V = I^ R, because V ≠ W

    Not sure what you are saying here?

    He meant W = I^2 R but left out the 2.

    I’m glad you guys aren’t designing my power distribution system.

  17. Ben

    1. Power = voltage x current.
    2. Voltage = resistance x current.

    Transplant 1 into 2 and you get:
    3. Power = resistance x current squared

    In terms of losses, power is heat generated in the conductors that costs money to generate but is wasted as heat. Also as conductor temperature increases the resistance increases.

    Resistance is inversely proportional to the cross-sectional area of the conductor.
    To transmit power you need conductors, expensive conductors.
    So to reduce the losses you have three variables to play with.
    Losses are also described in terms of voltage drop.

    Increase voltage you need less current for the same power, so less losses.
    Increase area you decrease heat, so less losses.

    It is not true that a transformer is a “one way valve”. Transformers are basically just windings on laminated iron cores.

    Rooftop PV increases local voltage in the day because lots of the current is not coming down the wires, so losses are less. Voltage reduces at night because there is no local generation and all the current comes down the wires.

    I needed to get that out of my system, thanks for listening.

  18. 2dogs

    the 12 hours of the day when the sun does not shine

    This has been proposed as an answer to that issue.

    Is anyone aware of any analysis on it?

  19. RobK

    2dogs,
    Yeah, nah.
    Sparks fly over ultra-high voltage power lines

    Celebrated as the answer to long-distance electricity transmission, China’s enthusiasm for UHV lines is weakening, writes Edmund Downie
    China is the global test bed for ultra-high voltage (UHV) transmission lines, a technology that can carry electricity across vast distances with much greater efficiency than the high voltage lines that you’re probably used to seeing.

    Since 2006, it’s built 19 of these multi-billion-dollar lines, stretching almost 30,000 kilometres and supplying 4% of national electricity demand. For comparison, no other country has a single UHV line in full commercial operation.

    But China’s enthusiasm for UHV is waning. The technology is beset by conflicts of interest between grid companies and central and local governments. The lines themselves are underperforming, and more recent projects are coming online amid a period of electricity generation overcapacity.

    This means that approvals for new lines have slowed, and grid companies are unlikely to meet their targets for new ones.

    As with so much of this stuff: improving all tbe time, an experiment. Not Ready For Primetime……yet.

  20. RobK

    A further lift from the above link. This is the kind of dreaming our planners have too. It is the same problems we will have too relating to long distance UHV. We have coal, gas and nukes . This stuff is insane.

    What’s more, the impact of UHV on renewable energy “curtailment” in inland China has also been disappointing, undermining the case for investment. Curtailment refers to energy that never reaches the grid and is wasted, for reasons including a lack of transmission capacity or quotas for coal-power consumption.

    China’s UHV lines transmit wind and solar power in combination with coal power, which remains the major electricity source. Nonetheless, even a minority share of UHV transmission capacity can still take sizeable loads of renewables from China’s interior to coastal markets. Backers of UHV lines have jumped on this point when championing the technology.

    Yet after a decade of UHV development, renewable curtailment levels remain high, especially in north-western regions. National curtailment rates in 2017 were 12% for wind and 6% for solar, several percentage points below their 2016 peaks. Still, China has room for improvement; in Europe, curtailment rates in countries with high levels of wind-power production have been consistently below 5%.

    Analysis by environmental researcher Darrin Magee and geographer Thomas Hennig suggests that in 2015, curtailment in Yunnan reached 95 terawatt hours (TWh) – more than six times the reported rate, and enough to power Portugal and Singapore combined for one year.

    Lagging wind and solar

    UHV lines successfully transported 172.5 TWh of renewable energy in 2016, or 3.2% of national power consumption. However, 93% of that power came from five lines used for hydropower only.

    Some of China’s non-hydro lines have relied less on renewables than supporters had hoped. Caixin Energyreports that, according to experts at State Grid, renewable shares in lines planned to take a coal-renewable mix should target 30%. Three such lines were in operation for at least part of 2016. Their performance was uneven. Ningdong-Zhejiang carried 29% renewables, and the Southern Hami-Zhengzhou line’s share was at 23%, but Ximeng-Jinan took none at all.

    The Zhebei-Fuzhou line was framed initially as a vehicle for nuclear and wind consumption but did not take any wind in 2016. Reports are unclear on whether it has since added wind to its power mix – though it has added coal.

    It is hoped that these shortfalls will be temporary. One non-hydro UHV line that launched in 2017 has been relying on coal because the renewable projects planned to accompany it faced construction delays. Overall transmission volumes increased significantly for China’s first UHV lines in their initial five years. Several new UHV lines that take renewables have also come online since mid-2016.

    But the shrinking space for new UHVDC projects is a persistent concern for Western provinces, where rapid capacity additions in renewable energy has left long-distance transmission infrastructure struggling to keep pace.

    Power sector reforms

    UHV is certainly not solely to blame for renewable curtailment problems in the interior. They point to a wider set of challenges facing China’s power sector, which are the focus of reform initiatives launched in 2015. These reforms have included some UHV-specific measures. But many hindrances to the development of UHV lines are best addressed through more comprehensive power sector reforms.

    These include power trade markets to make it easier for coastal provinces to buy power from the interior (and locally) at short-notice; measures to strengthen the competitive position of long-distance clean energy against local coal plants; and reforms to reduce disputes around grid planning between central government and provinces.

    These reforms are at an early stage. But while enthusiasm for UHV in China is fizzling, the technology will still have a role in the country’s renewable transition. How successful the reforms are will determine what kind of a role that is.

  21. Tel

    Each transformer serves a “local” area containing a number of homes. Domestic solar systems can “share” their excess within the local area but nowhere else because the transformer will not permit a reverse flow when there is a higher voltage on the supply side. Electrical purists do not like water analogies but the best way to view the transformer is as a one-way valve.

    You can count me as an electrical purist then, because transformers are every bit two-way devices.

    There’s some tricks though. A normal electric circuit requires two wires: an active to carry the power out, and a neutral (or “return”) to loop it around and carry it back again. That means you need two pieces of copper for every circuit, thus if you want three circuits you would need six wires. But wait! you could combine all the returns onto one piece of wire and save a buck, then you get three circuits on four wires.
    But wait again! You can do even better by stacking the phase angles on the active lines at exactly 120 degrees around the circle to ensure all the active circuits perfectly cancel and then you throw away the return wire completely … you get three active circuits on only three wires … big infrastructure saving!

    Now the problem: what if the load doesn’t balance? That’s OK within reason because you can do your best to put equal number of houses on each phase then tweak the transformer a little here or there to make up the difference, put in local Earth lines to soak up anything left over. Good enough.

    What you see is that for the very long transmission legs they run three high voltage wires, and save a buck running no return line whatsoever. If these get out of balance they are forced to use the ground (i.e. the soil under our feet) to clean up the difference, but that’s horribly inefficient. There’s an additional problem with harmonics (the equipment only works efficiently running on pure sine waves). The local area 204V grid runs four wires but often one of those is a bit thin (save a buck, use the minimal “return” line).

    Now try to push backwards up the line and you put one phase out of whack with the others. Sure the transformer will do it, but it’s been tuned to work efficiently in one particular mode and you are pushing it to operate in a different mode. Your three phase is out of balance now, and probably the voltages are different too. That’s where this whole business of the “smart” transformer comes into play, to redistribute the energy onto the most efficient path, keep the Earth line near zero, get rid of harmonics. It’s not a new idea, I’ve seen it probably 15 or 20 years ago … bit of a holy grail if anyone can reliably make it work. The theory is sound: you are not creating something out of nothing, you are merely rebalancing what you already have so it doesn’t get out of whack. The practice for these things tends to be much, much harder than the theory. You need short term, fast energy storage somewhere near the transformer to yank power out and then stick it back in again. You need very smart software to do this consistently, regardless of what gets thrown at it.

    The whole lot can turn unstable. Suppose you have two of these a few blocks down the road from each other, and for whatever reason they get at odds with each other over what the “correct” balancing point is. One pulls energy out and throws it at the other … they get into a bun fight. Suppose you have a whole city full of them and you might as well be running a multi-faith Middle Eastern peace outreach center.

  22. 2dogs

    I’ve have heard suggestions that the Bering Straight link in the IEEE plan was undoable.

    Given China’s problem over land that you point to, doing under the sea would be nigh on impossible.

  23. Tel

    Analysis by environmental researcher Darrin Magee and geographer Thomas Hennig suggests that in 2015, curtailment in Yunnan reached 95 terawatt hours (TWh) – more than six times the reported rate, and enough to power Portugal and Singapore combined for one year.

    I wonder how much of that is an intrinsic problem, and how much is a lack of free market price signals causing poor coordination?

  24. hzhousewife

    Suppose you have a whole city full of them and you might as well be running a multi-faith Middle Eastern peace outreach center.

    They say nerds are boring unimaginative blokes, but really, you guys crack me up. Delightful turn of phrase !

  25. RobK

    I wonder how much of that is an intrinsic problem, and how much is a lack of free market price signals causing poor coordination?
    I wonder too, Tel. That said we dont have a free market either. We dont have the market China has but we do bave have the distances. The thinking here is to break the grid up into geographic renewables zones etc, etc it’s a massive operation.

  26. RobK

    An other problem (amongst many), is fault-current discrimination. Basically, circuit breakers (keeping it simple) protect the wires, but when there is fluctuations in distributed feed and load, and issues with ground currents (from earth returns, out of balance phases), it gets much harder to control what happens when there is some kind of excursion. A complex, expensive grid with many potential points of failure.

  27. richardf

    Lost me at 240V. 230v optimal most of Oz for sometime. BTW grid overloaded, renewables a disaster.

  28. Empire 5:5

    Great post, David.

    Tel
    #2991475, posted on April 18, 2019 at 6:48 pm

    Saved.

  29. Tel

    An other problem (amongst many), is fault-current discrimination.

    Yes that too.

    Could be worse again with smart transformer if it squirts a bit of power here or there, gets the timing wrong and triggers the breaker, only to create a cascade where the next guy tries to compensate. Not saying it’s necessarily gonna happen that way … it’s all down to the control system to get it right … every single time.

    Sometimes taking an unstable physical system and then compensating that with a software add-on can produce surprising results … ask Boeing if you don’t believe me.

  30. RobK

    From wiki:

    The nominal voltage in most areas of Australia has since 2000 been 230 V,[3][4][5] with the exception of Western Australia and Queensland,[6] which chose to remain at 240 V, though Queensland is transitioning to 230 V. 

    From memory, I think the window is +10%,-6%.

  31. Dr Fred Lenin

    Dont know what the fuss is about. If the shorten gang abolish coal power we will still have 11 per cent of the power we have now ,when the wind blows (not to hard though)_and the sun shines .
    And remember early to bed early to rise , might as well be in bed there wonrt be any lights .
    Venezuela might be an attractive option ,got more oil . When the last person leaves Australia they wont need to switch off the light .

  32. yarpos

    We are pushing toward the +10%, its routinely 248V in my little village and sunny day.

    Never thought so much could be said about Ohm’s Law. Rivetting stuff.

  33. Jim Hutchison

    Much useful discussion on this topic.

    Concerning a global network, just a couple of thoughts:

    > readers will be familiar with the current international networks in the Northern Hemisphere. So the UK is able to import power from Europe via interconnection if required. And Denmark can sell surplus power into the European grid when the wind is blowing hard. But it would be a huge task to create a global power network. The technical issues are numerous as well as the whole fantasy being very expensive.

    > In Australia we have relied since 2009 on an underwater HVDC cable, Basslink, to transfer power between Tasmania and Victoria. This link permits Tasmania to be a member of the eastern grid managed by AEMO. Western Australia and the Northern Territory stand alone electrically speaking. There are swings and roundabouts including:

    — The Basslink cable ruptured in Dec 2009 probably because the amount of power being transferred from Tasmania to the Mainland exceeded the design capacity of the electrical cable. The cable was out of commission until June 2010.

    — Most power in Tasmania is generated by hydro plants. Australia has been in drought for many months (approaching 3 years in most districts). The large hydro plants in Tasmania are in the east of the state where the drought has been most severe. So the mainland generators have been supplying electricity to Tasmania. Today (18.04.19 at 20.25 AEMO time [=Eastern Standard Time in Queensland]) the AEMO data board tells me that the mainland is supplying power to Tasmania. Not surprisingly the price of Tasmanian power exceeds the price from all of the other states which supply the eastern network.

    The discussion of a ‘global network’ reminds me of the establishment of the global telegraph network. The first internal Australian telegraph line was established in 1854. By 1864 a telegraph line from Europe to India, Ceylon, Malaya and the East Indies was operational.

    A submarine cable from Java to Port Darwin was laid by 1871. The final link between Australia and the mother country Britain – the Overland Telegraph Line – was completed in 1872. The most important commodity to be carried on the cable was news.

    So long as Australia has plenty of coal and uranium and becomes committed to using those plentiful minerals
    to generate electricity there will not be any need to pay the immense cost of membership of a global electricity network.

  34. RobK

    A Carrington type Event most affects long conductors. We have a warning system thanks to NASA but the remedial action is to de-activate lines. All those extra complexities due to renewables wont make the task easier.
    From Wikipedia: Carrington Event 1859 .

    A solar storm of this magnitude occurring today would cause widespread electrical disruptions, blackouts and damage due to extended outages of the electrical grid.[2][3] 
    The solar storm of 2012 was of similar magnitude, but it passed Earth’s orbit without striking the planet, missing by nine days.[4]Less severe storms have occurred in 1921 and 1960, when widespread radio disruption was reported. The March 1989 geomagnetic storm knocked out power across large sections of Quebec. 

    Always something to bear in mind when stringing up or burying conductors. The main cost to the grid is replacing transformers( and the like) if/when such a thing happens. Long lead times, as they are custom built.

  35. Eyrie

    Rather than a few guys at NASA, I think Carrington event warnings are a proper function of the DoD. They do a great job on GPS.

  36. Rabid Koala

    Or we could move to a distributed energy networks with most people living off the grid while the grid remains only for heavy industry and big buildings.

  37. Cynic of Ayr

    I was wrong.
    It is indeed W = I2R, not V = I2R as I said.
    In this case, the demonstration is that the the Power (W) lost is more due to current (I) than due to voltage (V). Or, current has a greater contribution to the loss, than voltage.
    Therefor, minimise current I at the expense of maximising voltage V, to reduce power loss over a transmission line R.
    I dunno why I made this mistake. I’ve used the Law in hobby for most of my life.
    Dopiness, I suspect.

  38. Karabar

    “— The Basslink cable ruptured in Dec 2009 probably because the amount of power being transferred from Tasmania to the Mainland exceeded the design capacity of the electrical cable. The cable was out of commission until June 2010.”
    On this planet, it was December 2015 and June 2016.

    The root cause of the failure was never determined, but suspected to be a manufacturing defect. The nonsense about cable overload is pure speculation drawn from no evidence whatsoever.

  39. Karabar

    “The large hydro plants in Tasmania are in the east of the state where the drought has been most severe.”
    On this planet, the large hydro machines are in the WEST of Tasmania, where there has been no drought. Only a few run-of river installations are in the EAST part of the State. Your planet must be a mirror image. At 18.04.19 20:25 the combined cycle Mitsubishi M701 TVCC201 was producing nearly a quarter of the demand at an output of 208 MW. The simple cycle Siemens Trent 60 TVPP104 was putting out an additional 58 MW.
    “Not surprisingly the price of Tasmanian power exceeds the price from all of the other states which supply the eastern network.”
    An anomaly which has been rather unusual for most of the year so far.

  40. RobK

    Managing a High Penetration of Renewables– A Tasmanian Case Study

    1. Background The Tasmanian power system has been rapidly evolving over the past 15 years with increasing levels of renewables penetration in conjunction with the commissioning of the Basslink High Voltage Direct Current (HVDC) interconnector that connects Tasmania to the National Electricity Market (NEM). During these advances, Hydro Tasmania, TasNetworks (formerly Transend) and the Australia Energy Market Operator (AEMO) have worked collaboratively to identify key emerging issues and develop innovative and cost effective solutions to allow a largely unconstrained but secure network. While Tasmania is not the region with the greatest deployment of wind and solar energy, the technical and market challenges tend to demonstrate themselves earlier due to its size and electrical isolation. Tasmanian hydro generation is on one hand the most flexible of all energy sources, but conversely, is subject to seasonal fluctuations, ‘must-run’ requirements and limitations on its ability to run at low output on a continuous basis. The Basslink HVDC interconnector adds significant additional flexibility to the system but some operational complexities exist which have driven a number of the technical solutions outlined in this paper. A key aspect of this is catering for the instantaneous loss of this interconnector being up to 50% of the total demand in Tasmania at a given time being a credible contingency. The challenges experienced in Tasmania are now emerging in South Australia (SA) and are attracting NEM wide attention. The key reasons for Tasmania to have proactively managed emerging issues associated with renewables include, but are not limited to:
     The Basslink HVDC interconnector does not transfer the electrical properties of the Alternating Current (AC) system from Victoria, including inertia and fault level, although it does deliver synthetic inertia 1and Frequency Control Ancillary Services (FCAS) when not operating at its limits;
     The Tasmanian transmission network is not as heavily meshed as many parts of the mainland;
     Tasmania has disproportionally large credible contingencies relative to the size of the power system:
     Loss of Basslink, which can export 630 MW (from Tasmania) and import 478 MW.
     Loss of the largest generator, being the Combined Cycle Gas Turbine (CCGT) at George Town rated at 208 MW.  Loss of the largest single load block, currently up to 230 MW.
     Hydro generators supply relatively limited quantities of fast FCAS (raise and lower); and
     Half of Tasmanian wind is currently non-scheduled (140 MW). A portion of the hydro generation fleet is also operated as non-scheduled in the market and not subject to dispatch constraints.

    Things are rarely as simple as they seem. At high power ratings it is easy to break things. RTWT.

  41. Karabar

    “Things are rarely as simple as they seem. At high power ratings it is easy to break things. “
    ” the largest generator, being the Combined Cycle Gas Turbine (CCGT) at George Town rated at 208 MW.  Loss of the largest single load block, currently up to 230 MW.”
    Some things are quite complex indeed.
    When TVCC was but a gleam in Alinta’s eye, there were many possible approaches considered. One was to convert the old Bell Bay power station into a combined cycle arrangement similar to the project at Huntly power station in New Zealand, making use of the two Parsons turbine generator sets. Another was to use two GE LMS 100. The decision to use the M701 GT in CC configuration was considered by the project to conform to the requirement that no single generator could be more than 150 MW. (The GT being 140 MW and the steam set 68 MW). However, since a shutdown of the GT necessarily means a shutdown of the steamer, the project was forced to introduce a crafty scheme. When the machine is online, one or more large customers must be designated as “interruptible”. A rather high tech arrangement enables an inadvertent opening of the generator breaker at TVCC to (within a few milliseconds) open a breaker at an interruptible customer whose load is similar to the GT’s output. Otherwise the unplanned shutdown of TVCC201 could cause an unacceptable frequency excursion.

    Such would not have been the case if one of the other solutions had been chosen. On the other hand, the duration of the project would have been longer, which was at the time also considered unacceptable. The LMS100 option had a thermal efficiency similar to that of the Mitsubishi M701 and double drum double reheat boiler that was chosen. However, the intervening tenor twelve years has demonstrated that the LMS100 option would have likely been much less reliable.

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