Ancillary services - electricity
Last updated on 30. January 2014
Ancillary services - electricity buys ancillary services to provide access to the resources necessary to ensure secure and reliable operation of the power system.

 In a power system, electricity generation and electricity consumption must always balance. Changes in consumption and disturbances at production facilities impact the system balance and cause frequency deviations in the grid.

The need for ancillary services (including regulating power reserves) is dynamic throughout the year, both in terms of volume and the nature of the ancillary services, just as there are regional differences between Eastern and Western Denmark. Consequently, the volumes and services on offer are adapted to requirements for specific periods of the year in Eastern and Western Denmark.

The ancillary services, which are bought from electricity producers and electricity consumers in Denmark and its neighbouring countries, are used for different purposes, and therefore the requirements for how the services are to be supplied differ as well. These requirements are regulated in the ENTSO-E CE Operation Handbook - Policy 1, the Nordic System Operation Agreement and's regulations for grid connection. 

Generally, buys the following ancillary services in Western Denmark:

  • Primary reserves
  • Secondary reserves, LFC (Load Frequency Control)
  • Black-start capability
  • Manual reserves
  • Short-circuit power, reactive reserves and voltage control.

Generally, buys the following ancillary services in Eastern Denmark:

  • Frequency-controlled disturbance reserve (purchased in collaboration with Svenska Kraftnät) 
  • Frequency-controlled normal operation reserve (purchased in collaboration with Svenska Kraftnät)
  • Manual reserves
  • Short-circuit power, reactive reserves and voltage control.

The individual ancillary services are described in the document 'Ancillary services to be delivered in Denmark'.

In order to sell ancillary services to, the supplier must have concluded a main agreement with

Main agreements are made only with balance responsible parties for production or consumption in Eastern or Western Denmark. Also, the plants which are to supply the ancillary services must be approved by

Requests for a main agreement should be sent to, Market Development (Mr Henning Parbo - - tel. +45 7622 4432) or RE - Balance and Market Systems (Mr Kaj Christensen - - tel. +45 7622 4203). Requests for the approval of plants should be sent to, RE - Balance and Market Systems.'s ancillary services strategy has drawn up an ancillary services strategy for the period 2011-2015. The strategy should ensure effective procurement of ancillary services and provide open and equal access for the players to the ancillary services markets. The strategy has been submitted to the Danish Energy Regulatory Authority. The strategy can be seen in the right-hand menu under 'Read more'.

In 2013, has reviewed the status of the strategy and adjusted the initiatives in areas where essential preconditions for the strategy have not been met. The conclusions have been summarised in an amendment to the strategy, which is also available in the right-hand menu under 'Read more'.




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