Balancing energy is used by transmission system operators to balance unplanned fluctuations in the production of electricity or the energy load.
In order to have enough capacity available at all times, balancing energy is tendered via a procurement platform and provided by qualified suppliers. If necessary, the reserved control energy is activated.
In order to minimise the use of balancing energy, the imbalances between production and consumption are first compensated between the transmission system operators (TSOs). This is known as imbalance netting. The total remaining deviation has to be balanced by means of balancing energy.
It is difficult to store large amounts of electrical energy. Consequently, the consumption of electrical energy should be equal to the production at any time. This requires an accurate forecast of the consumption so that the planned production corresponds to the actual subsequent consumption as much as possible. That is why every producer and every consumer have to be part of a balancing group. The Balance Responsible Party (BRP) is required to ensure that there is no gap between production and consumption in its balancing group. Otherwise, frequency deviations will emerge and may decrease system stability.
Imbalances between production and consumption of electricity can, for instance, result from forecast errors, deviations between planned and actual electricity import/export or unexpected power plant outages.
The balancing (offsetting) of imbalances between production and consumption is performed at multiple levels:
The remaining imbalance is then compensated by using balancing energy.
In individual balancing groups, deviations can arise between forecasts/schedules and actual electricity consumption as well as actual production. The deviations of different balancing groups are balanced among the remaining groups with the remaining deviations being balanced by the TSOs.To this end, the so-called grid area balance is calculated which is the sum of all deviations. A positive grid area balance signifies an energy balance deficit in the grid area (deficient cover). A negative grid area balance represents an energy balance surplus in the grid area (excess cover).Only this remaining imbalance, i.e. the total of all balancing group deviations, requires the use of control energy. The costs for its provision are refinanced through the grid fees and the costs for the use of balancing energy are redistributed through balancing group settlement. Balancing group customers can find more detailed information on balancing group management and the balancing group settlement here.
Germany has four transmission system operators (TSOs) which are responsible for the balance between production and consumption of electricity. Since 1 May 2010, these four transmission system operators work together in the context of the Grid Control Cooperation (GCC). Whereas in the past situations occurred in which a power surplus in a grid area and a power deficit in another area were balanced independently of one another, imbalances are now levelled out in the grid areas themselves and only the total deviations are balanced if the necessary transmission capacity is available. This balancing within the GCC saves control energy and therefore overall costs.
In the past few years, the GCC was continuously expanded beyond the borders of Germany. Now Denmark, the Netherlands, Switzerland, the Czech Republic, Belgium, Austria and France are also members of the IGCC. To exchange energy across borders, there is no small transmission capacity kept in reserve at the borders. Instead, free capacities that are still available after intraday trading are used and as a result of the IGCC, less control energy is used without reducing the provision of control reserves. Nevertheless, this additional netting saves tens of millions of euros each year.
In order to use as little balancing energy as possible, the system balances of the four German grid areas (GCC) are first netted as described above and then minimised within the IGCC. 50Hertz balances the resulting differences through the use of balancing energy.This balancing energy must be immediately available immediately. For this reason, their provision is put out to tender and contractually bound with balancing energy suppliers who are licensed (pre-qualified) for this purpose (control reserve = provision of balancing energy). The reserved capacity is only activated when it is actually required, resulting in an electricity flow (balancing = use of balancing energy).
The costs for the capacity provision as well as our data on the use of balancing energy are published here.
In order to have enough capacity available at all times, control reserve is tendered via a procurement platform. 50Hertz operates this procurement platform together with the three other German transmission system operators (TSOs) and in this regard performs its market role as marketplace operator.
To ensure the highest level of system security, transparency and quality, we only work with qualified control reserve suppliers. A prerequisite for participation in the tenders for balancing energy is a successful pre-qualification.
More information on the tenders for balancing energy and the pre-qualification procedure can be found on the procurement platform regelleistung.net.
In order to maintain system balance at all times, the German transmission system operators have defined the different qualities that control reserve has to meet:
Primary control reserve (PCR) is the product that can be activated fastest. Activation is automatic, decentralised and frequency-controlled. Measurement and settlement of primary balancing energy provided is not arranged. In case of a power plant outage, all suppliers of PCR within the European synchronous area activate PCR without an intervention of the TSOs. The grid area with the outage receives the lacking energy from the other grid areas. This results in an import/export balance (system balance).
In case of system balance deviations, the secondary control reserve (SCR) is used. This is a central and automated process (load-frequency controller) controlled by the German transmission system operators. The use of secondary balancing energy should not only result from the complete failure of installations. Continuously occurring deviations between forecasted and actual consumption are also covered with secondary balancing energy.If the demand for secondary control reserve is too great or if it does not decrease, tertiary control reserve (TCR) is activated. SCR is then available again.
The interaction between the different types of control reserve is described in detail on regelleistung.net