On 23/08/2019 22:00, tony sayer wrote:
In article , The Natural Philosopher
scribeth thus
On 22/08/2019 22:29, tony sayer wrote:
It does seem that this DC to AC inverter software circuitry needs some
further though it's not that stable seemingly?

No. And there is a fundamenal point you are missing

It CANNOT be solved just with software.

A temeporaty rid overlaod must be covered either by a loss of load -
load shedding or load reduction - or by an incease of power.

In general load reductiuon and slowering freqeuncy go together in
syncrhonrous motors, and lowering volatges will in general lower to load
with resistive lods. Not so with switched mode power supplies.

So what happens with spinnging nennies is that the rotational inertia os
in fact kinetic energu and that is what represents the increase in power
that will be fed into te grid. As the rotors slow, energy is lost, and
that becomes what keeps the grid up. Until somethinmg else can. Like
openeing the throttle on a coal or nuclear plant

Because steam boilers also represent energy storage too.

The point is this: althoiugh software that reads mains frequency and if
it slows advances the phase of the inverters to feed more power in, are
possible, there IS NO MORE POWER to be had!

Well in that case then perhaps they ought to keep a small amount in
reserve say they have around 100 MW available send as it were 90 MW so
they do have a reserve?.

Battery would work better.



Unless you strap lithium bastteries to the DC output of every wind
turbine. Or supercapaciors. Or use a big ****-off rotary inverter. (DC
from wind turbines drives DC motor attached to AC generators attached to
the mains)

Ain't happening is it?..

Course not. Costs money.



More expense. Less profit.


Come to think of it how does the inverter right out in the North see or
know what the grids running at, or does it just ramp up frequency and
see what currents flowing back to blighty?..

Anyone know?..
Phase is the issue.

Before connection the mains frequency and phase is read and the inverter
will connect at slightly leading phase to it. So it draws power. Then
the power in is monitored and the phase adjusted so that full power is
delivered.

How do they determine what the load side is in an inverter system?

So it ramps up phase, not frequency.


How's it do that without altering the frequency??

Cmon Tony.

You know the difference bnetween frequency and phase.

If you like the frequency is incereased by a tiny amount for a
millsecond And then goes back to what it was.



The whole grid is phaselocked. If you want to connect a generator to it
you MUST lock phase and advance it a tad until you are feeding it. At
zero phase you are not delivering or taking pwer.

Indeed thats the way its done with alternators but are inverters exactly
the same?..

Er no, Tony. They dont have big coils and spinning iron and slip rings

They have ferrite chokes Fat transistors and software



The problem is domestic inverters are set to trip out if the frequency
drops too far as well as having no storage.

They are not serious generators. They are bolt on additions







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The New Left are the people they warned you about.