14 minutes ago, Sidewinder said:

"There are about 4000 homes in my property"

@Bobster. How big is you property?😁

Where is that "smacks self upside the face" smiley?

4000 homes in my SUBURB

1 hour ago, Pho3niX90 said:

I would have thought, that in instances of cloud coverage etc, the instant power fed back into the grid would increase the Hz

Frequency is controlled by large power plants and grid operators, not small distributed generators.(SSEG)

If too much generation is injected and demand is low, the grid operator (e.g., Eskom) will reduce power from larger sources to maintain 50Hz.

Edited March 6, 20251 yr by TaliaB

6 hours ago, Pho3niX90 said:

Private solar (October 2024) = 8970 Mw

8097MW seems like a more plausible number. Cloud cover events can't affect the whole country to cause rapid changes in frequency. Cloud cover over the whole country in winter (cold front) will cause load shedding.

[deleted by author. Forum needs a delete button]

Edited March 7, 20251 yr by Bobster.

On 2025/03/05 at 10:36 AM, mzezman said:

Which smart breaker do you use and is it on your main incoming Eskom / municipal feed?

I have a single pole breaker like this.

Installed after the main incoming breaker and before the inverter feed.

So the below article touches on what I have been suspecting all along, it doesn't make it true, but one has to wonder.

This has been my first month not neededing the grid, and also not pushing back. So eskom isn't getting free solar from me anymore. To make matters worse for them, they have now started forcing all residents in my area to have the old meters replaced with the new conlog meters, which in turn will give them even less free power. I do suspect the the users that were pushing back will probably also look at expanding their battery pretty soon. It's just a nadty ouroboros at the moment, where eskom is creating more havoc for themselves.

Another observation. Since after the major drive to remove old meters, and replacement with prepaid, load shedding started up again. But, this could also be due to the past cloudy days.

Eskom’s silent saviour – MyBroad...

Eskom’s silent saviour

Continuous cloudy weather conditions played a major role in the need to implement load-shedding in recent months, showing solar power’s contribution to reducing the power cuts at other times should...

I don't see the exact hertz fluctuation - due to loadshedding and power outages in my area....

I hope there is less panic from members when they see a frequency 49.5-50.5Hz as has been explained. This is very normal with no equipment not functioning.

May be it's time for some systems to have high inertia driving some generators purely for the sake of proving a more stable grid. PV by day and battery by night.

This video provided by one of our members does explain the events in Spain and that the grid only had serious problems once 47.5Hz was reached. @zsde

Could it be a good thing for us to lower our min frequency setting on inverters?

Luckily in SA PV does not contribute such a high % of power. Thank Eskom for forming the STABLE grid. 😀😀

Worth a watch. Only 3min long.

On 2025/05/17 at 6:46 AM, Pho3niX90 said:

So the below article touches on what I have been suspecting all along, it doesn't make it true, but one has to wonder.

MBB are late to the party. Eskom have been saying for at least a year that there's a lot of private PV out there. They can see the effect of this vary with the weather. They also believe that most of these systems aren't feeding back into the grid, but the relief for them comes from the reduction in demand.

On 2025/05/17 at 6:46 AM, Pho3niX90 said:

To make matters worse for them, they have now started forcing all residents in my area to have the old meters replaced with the new conlog meters, which in turn will give them even less free power

I think you'll find this is the City, not Eskom. It's also not exclusive to Tshwane, COCT are forcing all domestic consumers onto new meters. I don't KNOW, but I would think that part of this is so they can introduce large scale load reduction programs such as Eskom have trialled. Also they get out of their grid old meters which a PV system could drive backwards (though I wonder how many there are). In Johannesburg they've been rolling out new meters in Alexandra, which is infamous for low payment and illegal connections. It's partly a data gathering exercise, though if they think people are going to start paying because there's a new properly installed meter they should think again. If you bridged the old meter, you'll bridge the new one.

TLDR: It's not Eskom replacing meters, it's municipalities. They have to recover money from us so that they can pay their Eskom bill and these new meters are supposed to reduce unauthorised back-feed and reduce bridging. Maybe they will also allow load reduction as I suggested earlier.

The power market is changing. I see there's been a go ahead given for private transmission lines. The legislation to split Eskom into two is in place. IPPs are being bought on board.

Edited May 21, 20251 yr by Bobster.

Eskom National control center controls the frequency, they can increase/decrease load in some of the power stations, they are able to increase decrease load on the turbines, I know that because I did install, commissioned and tested such a system at Hendrina Power Station units 1 to 5. Some other company installed a similar system on units 5 to 10, tested and worked well

I saw it working, it's effective,

I presume Eskom have similar system in other power Station.

13 minutes ago, Antonio de Sa said:

Eskom National control center controls the frequency, they can increase/decrease load in some of the power stations, they are able to increase decrease load on the turbines, I know that because I did install, commissioned and tested such a system at Hendrina Power Station units 1 to 5. Some other company installed a similar system on units 5 to 10, tested and worked well

How does this work nationally then? EG in COCT they have their own generation at Steenbras. Does that have to sync with the national grid? And if they want to use Steenbras during load shedding then how do they manage what happens when the grid comes back?

Not trying to throw shade, just trying to understand better.

1 hour ago, Bobster. said:

MBB are late to the party. Eskom have been saying for at least a year that there's a lot of private PV out there. They can see the effect of this vary with the weather. They also believe that most of these systems aren't feeding back into the grid, but the relief for them comes from the reduction in demand.

I think you'll find this is the City, not Eskom. It's also not exclusive to Tshwane, COCT are forcing all domestic consumers onto new meters. I don't KNOW, but I would think that part of this is so they can introduce large scale load reduction programs such as Eskom have trialled. Also they get out of their grid old meters which a PV system could drive backwards (though I wonder how many there are). In Johannesburg they've been rolling out new meters in Alexandra, which is infamous for low payment and illegal connections. It's partly a data gathering exercise, though if they think people are going to start paying because there's a new properly installed meter they should think again. If you bridged the old meter, you'll bridge the new one.

TLDR: It's not Eskom replacing meters, it's municipalities. They have to recover money from us so that they can pay their Eskom bill and these new meters are supposed to reduce unauthorised back-feed and reduce bridging. Maybe they will also allow load reduction as I suggested earlier.

The power market is changing. I see there's been a go ahead given for private transmission lines. The legislation to split Eskom into two is in place. IPPs are being bought on board.

I think they are forcing the service fee via the meters. But like you said, this will not stop individuals from bridging the meter, and buying the bare minimum units monthly.

1 hour ago, Bobster. said:

How does this work nationally then? EG in COCT they have their own generation at Steenbras. Does that have to sync with the national grid? And if they want to use Steenbras during load shedding then how do they manage what happens when the grid comes back?

Not trying to throw shade, just trying to understand better.

The way the system works is quite simple.

Every unit will be synchronized to the grid frequency before delivering power to the grid regardless of if they are Eskom, private wind farms, solar etc...

Remember that load shedding is done at local substations, the power is disconnected at local substation level by means of medium voltages circuit breakers, for individual neighborhoods, But the main HV on the power lines are still on.

Eskom will have the majority of the units on what it's called base load, a big % of the demand, usually the bigger power stations are used for that.

A X number of units, depending on the predicted load and time of the day, they will be used to rump load up or down to control the frequency within established parameters.

On 2025/05/17 at 9:25 AM, Marius2001 said:

I don't see the exact hertz fluctuation - due to loadshedding and power outages in my area....

If you set your graph to start just after the power returns and end before the power disappears again, you may get something like...

2 hours ago, Antonio de Sa said:

The way the system works is quite simple.

Every unit will be synchronized to the grid frequency before delivering power to the grid regardless of if they are Eskom, private wind farms, solar etc...

Remember that load shedding is done at local substations, the power is disconnected at local substation level by means of medium voltages circuit breakers, for individual neighborhoods, But the main HV on the power lines are still on.

Eskom will have the majority of the units on what it's called base load, a big % of the demand, usually the bigger power stations are used for that.

A X number of units, depending on the predicted load and time of the day, they will be used to rump load up or down to control the frequency within established parameters.

Just to add to @Antonio de Sa there is 3 methods of coal fire power plants to controll the frequency nation wide(grid).

1. Turbine Governors (Primary FrequencyControl) Mechanical/electronic governor attached to each steam turbine to

   automatically adjusts the steam input to the turbine when a frequency deviation is detected (typically from the standard 50 Hz).

   Immediate correction of small frequency fluctuations (within seconds).

   If grid frequency drops (demand > supply), the governor increases steam flow to boost power output.

   If frequency rises, it reduces steam flow.

2. Automatic Generation Control (AGC) Secondary Control

   Centralized control system operated by Eskom’s System Operator (national grid control centre in Germiston).

   Sends setpoint adjustments to generators across the country based on real-time frequency data to restore frequency to exactly 50 Hz and balance area control error (ACE).

   Uses SCADA and telemetry to monitor load and frequency.

   Adjusts output from multiple plants in real-time, every few seconds to minutes.

3. Governor Droop Control (Part of Primary Control)

   Conceptual Setting: A droop characteristic (e.g., 5%) allows generators to share frequency control effort proportionally.

   Example: If frequency drops, a unit will increase output according to its droop setting — larger power stations contribute more.

Edited May 21, 20251 yr by TaliaB
Spelling

1 hour ago, TaliaB said:

Just to add to @Antonio de Sa there is 3 methods of coal fire power plants to controll the frequency nation wide(grid).

1. Turbine Governors (Primary FrequencyControl) Mechanical/electronic governor attached to each steam turbine to

   automatically adjusts the steam input to the turbine when a frequency deviation is detected (typically from the standard 50 Hz).

   Immediate correction of small frequency fluctuations (within seconds).

   If grid frequency drops (demand > supply), the governor increases steam flow to boost power output.

   If frequency rises, it reduces steam flow.

2. Automatic Generation Control (AGC) Secondary Control

   Centralized control system operated by Eskom’s System Operator (national grid control centre in Germiston).

   Sends setpoint adjustments to generators across the country based on real-time frequency data to restore frequency to exactly 50 Hz and balance area control error (ACE).

   Uses SCADA and telemetry to monitor load and frequency.

   Adjusts output from multiple plants in real-time, every few seconds to minutes.

3. Governor Droop Control (Part of Primary Control)

   Conceptual Setting: A droop characteristic (e.g., 5%) allows generators to share frequency control effort proportionally.

   Example: If frequency drops, a unit will increase output according to its droop setting — larger power stations contribute more.

Great insight into this topic. Just on frequency some industries like steel smelters are very fussy when it comes to frequency. Some of these consumers have under frequency cubicles just for this purpose. They set the frequency at the level that their power lines should be tripped out. This level is much higher than what would be used for the country as a whole.

Years ago with lots of space generation power stations tendered each day to supply power to the transmission business unit. Some of the most expensive stations were only used when the cheaper stations had a problem on a generator. This was the time that Eskom was run as 3 business units. Generation, transmission and then distribution. Even the pool of money for bonuses for good performance against kpi's were measured against how well they performed. This was in the good old days.