In accordance with § 15 of the German Ordinance on Power System Access (StromNZV) and pursuant to Regulation (EU) 2019/943 on the internal market for electricity, in case of congestion transmission system operators are obliged to allocate the available line capacities through market-oriented and transparent procedures without discrimination provided that such congestion cannot be prevented by means of grid- and market-related measures within economically reasonable boundaries. Moreover, the regulatory framework given by Regulation (EU) 2019/943 provides for creation of harmonised network codes and guidelines which amongst others also shall cover rules for congestion management.
With the entry into force of Regulation (EU) 2015/1222 of 24 July 2015 establishing a Guideline on Capacity Allocation and Congestion Management (CACM) on 14 August 2015 harmonised minimum requirements are defined for a uniform capacity allocation in the day-ahead and intraday timeframes as well as framework conditions and processes for further development of an efficient system for capacity calculation and allocation as well as congestion management (e.g. redispatch). Regulation (EU) 2016/1719 of 26 September 2016 establishing a Guideline on Forward Capacity Allocation (FCA) entered into force on 17 October 2016 supplementing Guideline CACM with regulations covering the long-term timeframes. The provisions of these two EU regulations are to be implemented according to the respective Deadlines.
Redispatch is defined as an adjustment of electricity production (feed-in of active power) of specific power plants by the transmission system operator in order to avoid or remedy any occurring congestions in the short term. This measure can be implemented within the grid area, between grid areas or across borders and is always in coordination between the competent transmission system operators. It involves the decrease of electricity production (feed-in of active power) at one or several power plants at one end of the congestion (an overloaded line) and a simultaneous increase at the other end of the congestion. As a result, the total quantity of electricity generated remains almost the same while congestion is solved.