Grid Stability Fundamentals | Watts Up With That?

Visitor put up by Rud Istvan

Charles requested whether or not I’d critique this new nonsense. Positive, why not.

The highlighted ‘sciency’ article purports to create an ‘open supply’ grid knowledge useful resource utilizing 17 ‘synchronous grid’ European areas to design and check how “that can assist develop new energy methods able to assembly altering calls for, such because the transfer in the direction of renewable power sources.” NOPE, this gained’t assist in any respect.

The physique of this foolish paper discovered observationally decrease grid frequency variations in bigger ‘remoted’ European subgrids!  In fact bigger grids have much less frequency variation— one thing trivially true and identified for a lot of many years. The explanations are intuitive and easy. Bigger grids by definition have extra technology feeding the grid, so extra grid inertia, and on the identical time much less ‘instantaneous load variation’ by easy advantage of the statistical legislation of enormous numbers.

Grid inertia is simply the frequency stabilization that comes from the kinetic power of enormous rotating generator lots. As grid load ‘immediately’ will increase, the frequency sags and the generator needs to decelerate. However by slowing, it additionally ‘immediately’ injects a few of its rotational kinetic power till the driving supply (steam, or pure fuel in CCGT) will be turned up a bit to compensate.

CCGT is especially good at this. It runs about 61% environment friendly at full load, 60% environment friendly at 80% load, and nonetheless 59% environment friendly at simply 40% load. The fuel turbine energy response time is actually a couple of second no totally different than a jet engine.

None of this ‘open supply knowledge useful resource’ helps ‘the transfer to renewables’. Fundamental grid electrical engineering (EE) is straightforward and inescapable regarding renewables— they’re uneconomic (funding at all times falls when subsidies dry up), intermittent (requiring underutilized backup technology), and supply no grid inertia (which is automated with massive fossil gasoline fired turbines). ALL BAD.

Irsching Bavaria‘s about 10 12 months outdated CCGT items four (375MW) and 5 (860MW) illustrate the issues that intermittent renewables missing grid inertia create for any grid. The proprietor needs to take them out of service as a result of very unprofitable when run primarily as wind backup relatively than grid load. The German authorities refuses to make up the distinction, but additionally refuses to allow them to shut down.

Within the larger German renewable image, northern Germany exports surplus wind energy to Norway as basically a giveaway. That lets Norway throttle again its hydro. Then, when Germany wants energy as a result of wind is inadequate, Norway spools up its hydropower and sells it to Germany at exorbitant charges. To make issues worse, the German NIMBY crowd gained’t let the utilities set up extra a lot wanted North-South German transmission interconnect ‘eyesores’—regardless of wind generators which can be larger and uglier.

A small quantity of renewables in a big steady grid presents no issues–and no want for this new examine. The backup capability (spinning reserve) and grid inertia are already there. However as renewable penetration grows as a proportion of any steady ‘synchronous’ grid, these points develop and compound. Relying on grid particulars (like how a lot versatile hydro), renewable penetration above about Eight-10% ALWAYS creates further prices and stability issues.  Alternating present grid engineering has been identified now for properly over 100 years, and nothing ‘new’ can change the established maths, physics, and electrical engineering (EE).

There may be additionally some ‘fundamental EE stuff’ this new ‘open supply knowledge useful resource’ ignored.

First, their ‘new’ grid frequency knowledge is nearly at all times accessible from the utilities (grid operators), since required to handle the grid. It’s captured each on the producing crops and on the transmission to distribution substations. Maybe they need to have simply requested for the utility knowledge relatively than gathering their very own.

Second, their tremendous duper ‘proprietary’ grid frequency detectors for capturing their new open supply knowledge will be bought virtually anyplace. Such detectors are a standard electrician’s device. A really high-end multipurpose ‘pocket’ unit is the Extech PQ3450 energy high quality analyzer, pictured.

Third, their discovering that grid frequency sags when demand exceeds provide and rises when provide exceeds demand has been identified since Tesla first envisioned AC technology through the use of complicated numbers (a+bi). The US is designed to be a steady 60 Hertz, EU 50 Hertz. As a result of electrical clocks rely upon grid frequency,  ‘steady’ is about plus/minus zero.2Hz within the US.

Only for enjoyable (as a result of the above is all properly trod floor at WUWT and Local weather And many others), we additionally present a basic math/science enjoyable problem to these at WUWT unfamiliar with AC electrical stuff. (Because of a physics e-book stuffed with lots of of such challenges, sadly in Chicago relatively than Fort Lauderdale, which I half reconstructed from reminiscence and half from Google ‘info’). It’s about proper.

Think about a excessive voltage AC transmission line between Chicago and New York. (Trace: the gap doesn’t matter a lot for this problem, voltage does some, however is at all times ‘excessive’.)  The problem: how far does a single electron cost journey throughout its journey alongside this transmission line? Decisions:

  1. Kilometers
  2. Meters
  3. Centimeters

The velocity of sunshine (aka electromagnetic radiation) is about 299792458 meters/second in a vacuum. However ‘electromagnetic pressure (emf) wave information’ wires are positively not vacuum; their metals have electrical resistance (technically grid AC impedance, a mixture of circuit resistance and reactance). Though electrons pushed alongside by emf have basically no mass, they nonetheless decelerate heaps in metals.

Skipping a little bit of complicated math explaining quite simple physics, the rationale you purchase ‘fats’ DC audio cables with gold terminals is straightforward: DC present flows throughout the whole conductor cross part pretty uniformly. A fatter cable has uniformly much less cross sectional resistance (DC speaker output is analog), and gold terminals decrease connection resistance additional since gold doesn’t corrode. The result’s more true excessive frequency pitch amplitudes. As a aspect factoid, this identical physics is why ‘fats’ excessive voltage DC transmission traces are most well-liked for lengthy grid distances, just like the Germany to Norway undersea interconnects talked about above.

The ‘fats’ AC cable reply is totally different. AC present has a conductor pores and skin impact. In contrast to DC present, AC present travels primarily in an annular ‘pores and skin’ ring whose thickness will depend on frequency (higherèthinner) because of fascinating AC penalties of Maxwell’s equations as defined by Feynman’s ‘Lectures on Physics’ V. 2 chapter 32, ’pores and skin impact’. In a ‘pure’ copper conductor, that annular pores and skin journey (the middle of the conductor basically carries no AC present) is simply about three.2 meters per second. The rather more widespread (cheaper, lighter) aluminum HV transmission conductor is simply about 61% of copper. So in aluminum excessive voltage transmission traces electrons journey at greatest about (three.2m/s*zero.61) ~1.95 m/s ignoring pores and skin oxidation.

 AC is a sine wave various from zero to plus emf to zero to minus emf to zero at x occasions a second, (US 60Hz, EU 50Hz). One cycle is from zero voltage to max emf to zero to reverse polarity max emf again to zero. The emf backwards and forwards is a nominal US 120 peaks/second, 60 occasions in every course. (Aspect be aware: in contrast to most DC circuits, AC emf is said to, however not the identical as, voltage.) For simplicity think about this AC problem as merely digital relatively than sine wave (all on or all off emf relatively than a various emf sine wave), thereby eradicating any want for the proper calculus problem formulation. Then probably the most distance a nearly massless electron might journey in its aluminum excessive voltage pores and skin is about (1.95/60) three.2 cm, backwards and forwards and backwards and forwards. The precise (sine wave emf calculus) US reply is lower than one centimeter backwards and forwards, and EU lower than 2. That’s as a result of there isn’t a number of emf besides close to the height and trough of the sine wave, slowing down intermediate time issues additional. Both reply (over simplified or right) ends in not very a lot electron journey distance (c).

Returning to the principle matter of this visitor put up, regardless of this new European ‘ grid analysis’:

Wherever, anytime, renewable subsidies get diminished, so does funding in them. They’re provably uneconomic, stand alone.

Renewables are intermittent; but don’t cowl the backup prices of intermittency.

Renewables present no grid inertia; but don’t cowl the prices of offering frequency stability utilizing huge synchronous condensers.

Extra analysis and new ‘open supply’ knowledge sources regarding essentially dangerous propositions doesn’t enhance them. NOPE!

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