On Sunday, 05/21/2023, an unprecedented thing happened: from 11:00 to 17:00 in Germany, Austria, France, Norway, Sweden, Finland and the Baltic States for six hours, the price of one megawatt-hour was minus 41 cents. What happened, at first glance, is beautiful and reflects the progress towards a bright, carbon-free future. The cost of electricity has collapsed below zero due to overproduction from alternative sources, namely wind turbines and solar power plants.
Electricity cannot be stacked, pumped into underground storage, or poured into a metal tank. There are pumped storage stations for energy storage and smoothing out load surges on networks, but their number is very small. An alternative is the use of electric vehicle batteries, including those that have exhausted their resource, to smooth out the peaks of electricity overproduction.
Taking advantage of a fortunate combination of weather conditions, private owners of renewable energy stations turned on the switch to the fullest, joyfully reporting on record output. The problem is that traditional stations also want to make a profit. Therefore, on Sunday there was an excess capacity in the power grids of the European Union, which had to be urgently put somewhere. Even if at a loss, otherwise mass failure of distribution networks cannot be avoided.
The described case shows the need for centralized regulation of power networks, not only in cases of network overload during peak hours, but also in case of overproduction of electricity. In a network where any number of private generating companies exist, this is especially true. Otherwise, the generated surplus electricity result in direct losses. At first, they will be borne by electricity producers, and then by end consumers. As the old saying goes, if you are offered something for free, then you have already been robbed.
Ideal consumer for hydro-thermal and nuclear power plants
The average peak is a factor for a residential consumer from 5 to 10. To obtain the minimum crest factor, and hence the maximum possible return of the generated power and minimum losses in the networks, a network inverter with a battery is used in the current (power) consumption control mode from the network. When the load consumes less than the specified level, the difference goes to charge the battery, when the load consumes more than the specified level, the difference is mixed into the load from the battery. So from the network side, your load looks constant.
The figure above shows an example for a 24 hour consumption profile. The average consumption from the network is 2 units, the minimum load consumption is 1 unit, the maximum load consumption is 6 units.
For networks that use generation from wind and solar panels, the consumption profile is more complex and must be set by the network operator based on the weather forecast for wind and solar generation.
The Demand Response energy management system, also known as Ripple Control, is suitable for this task (see the presentation for more details). When the network is overloaded, it turns off the secondary (less relevant) load. But more efficient is the Demand Response -2 Energy Management System, also known as Ripple Control -2, which, when generation exceeds demand, turns on the charge of centralized and local batteries at a minimum cost of electricity, and when demand exceeds generation, it switches the batteries to mixing their energy into the power grid .