Residual load

In the context of electrical energy technology, the term residual load (lat. Residuum "rest") denotes the electrical power (load) demanded in a power grid minus the proportion of fluctuating feed-in from supply-dependent producers such as B. wind power or photovoltaic systems . It represents the remaining demand for electrical power, which has to be covered by available and controllable power plants such as storage power plants and caloric power plants such as gas-fired power plants , limited by operation with poorer efficiency, including coal and nuclear power plants . If there is an insufficient supply of controllable power plant output , uncovered residual output leads in extreme cases to load shedding , which becomes noticeable for the electricity consumer in the form of power outages .

The residual load R at a specific point in time is calculated from the total current power N demanded by all consumers and the share of the offered power from fluctuating renewable energies F _EE that cannot be influenced at a time as follows:

{\ displaystyle R = N-F_ {EE}}

Residual load fluctuations

The residual load depends on the spatial area under consideration (e.g. the supply area of a network operator ), as strong regional fluctuations are balanced out over larger areas. If the power is balanced across larger regional areas, the transmission losses in the power grid increase. In addition, seasonal fluctuations - with photovoltaics the summer yields are high, with wind power the winter yields are high - have an effect on the residual load.

The increased volatility naturally leads to fluctuations in the residual load over time. This changes the usual weekly and seasonal courses. Within a day, residual load values, for example for the supply area Germany, can fluctuate by up to 70 GW , with a maximum load in Germany of 85 GW.

Strong fluctuations in residual power over time can be reduced on the consumer side by means of demand side management by adjusting the electricity demand of electricity customers, similar to load shedding customers , to the supply of fluctuating feed-in and further expansion of the grid to balance out regional fluctuations. Further future possibilities are the expansion of storage technologies, central pumped storage power plants , local (decentralized) energy storage or battery-based uninterruptible power supplies (UPS).

Individual evidence

^ ^A ^b Adolf J. Schwab: electrical energy systems . Generation, transport, transmission and distribution of electrical energy. 5th edition. Springer Vieweg, 2017, ISBN 978-3-662-55315-2 , Chapter 2.1.2 Energy transition, p. 21 - 33 .
↑ ^a ^b What is the residual load? Next Kraftwerke, accessed on March 9, 2017 .
↑ Power supply in Germany according to the expansion scenario of the renewable energy sector. (No longer available online.) IWES, December 2009, archived from the original on January 20, 2012 ; Retrieved February 25, 2012 .

[schwab1-1] A ^b Adolf J. Schwab: electrical energy systems . Generation, transport, transmission and distribution of electrical energy. 5th edition. Springer Vieweg, 2017, ISBN 978-3-662-55315-2 , Chapter 2.1.2 Energy transition, p. 21 - 33 .

[next1-2] What is the residual load? Next Kraftwerke, accessed on March 9, 2017 .

[iwes1-3] Power supply in Germany according to the expansion scenario of the renewable energy sector. (No longer available online.) IWES, December 2009, archived from the original on January 20, 2012 ; Retrieved February 25, 2012 .