Power Grid Stability and Renewable Energy

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Does the usage of renewable energy resources have an influence on the grid stability?
You might remember the song Silent Night… all is calm…
For energy providers the lyrics contain essential information for their generating- or purchasing capacities.
a) It’s night, so there is no possibility to use solar power
b) It’s calm, this excludes the power generation from wind farms

Let’s take Germany as an example. The German term Energiewende has already been adopted by the international nomenclature, similar to the term Kindergarten.
Energiewende means the transition of power generation to a low-carbon and nuclear-free supply. When I read the pros and cons of Energiewende, I feel that there is a certain affinity to Kindergarten in argumentations.
True is that the transition to renewable energy comes together with high cost.
Rumour is that Germany is the world leader in terms of energy cost per kWh. The price per unit on the Solomon Islands is higher.

When we look at the diagram we can still see an overproduction. The black line indicates the actual load. The grid control has still potential for optimization.
Wind- and solar power generation are not stable as expected. Fossil- and nuclear resources are necessary to keep a fundamental energy generation.

Net Electricity Generation Germany Oct2020
Source: Fraunhofer-Institute
Data Source: 50 Hertz, Amprion, TenneT, TransnetBW, EEX, ENTSO-E

If we consider only the renewable resources, the diagram looks like this:

Net Electricity Generation Germany Oct2020 Renewable Only
Net Electricity Generation Germany Oct2020 Renewable Only

The white gap between the load curve and the generation by renewable energy sources needs to be filled somehow. Especially calm and silent nights will be a problem. There is a certain need for energy storage.

The main factor to measure the grid stability is the net frequency. If the load is higher than the power generation, the frequency drops. The allowed tolerance is 50 Hz ┬▒0.2 Hz.
When the frequency drops below 49.8 Hz, the power generation companies activating their reserves. Below 49 Hz their start to disconnect regions, while a frequency of 47.5 Hz leads to a complete disconnection of all power plants from the grid. Then we have a Blackout, the grid needs to be reset and build up from scratch.

While TenneT and other large power generation- and transmission companies are claiming that the renewable energy is responsible for instability of the grid, a study done by the Max-Planck-Institute G├Âttingen comes to a different result. The frequency variations are in alignment with the 15 minutes interval for energy trading. Still I’m mentally more with TenneT.

How can we contribute?

Our AMI system delivers excellent results in monitoring. By nature all AMI systems are slow in direct meter control, see the incident in India.

From the meter side there are still options which have never been requested, e.g. a frequency based load limiting or sequential reconnection after a shoot-down. These measures can work instantly without remote control and distress the power supply situation. Contact us if you are interested.

Final Thoughts

With increasing percentage of renewable energy on power generation we will see more disturbances in the grid. Many parties are involved to assure a proper power supply. We in CLOU are contributing with our technology.

Thank you for reading. Unfortunately, this year is no international exhibition. So we can’t have a personal mind exchange. Please drop me a comment with your opinion or experience.

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