Ramping restrictions include information about flow in the last hour from the previous day in the calculation.

In the day-ahead and intraday markets, all trading across HVDC (high-voltage direct current) cables is subject to a ramping restriction of 600 MW. The restrictions imply that trade plans on all HVDC connections cannot be changed by more than 600 MW from one hour to the next. This restriction can be put on each of the cables individually or on a set of cables.

Handling of ramping restrictions in day-ahead price calculation

HVDC connections listed below are all subject to specific ramping restrictions. The restrictions have been imposed by the national transmission system operators Svenska Kraftnät, Energinet and Statnett.

Ramping restriction between the Nordic system and the Continent is imposed separately on the links below.

In addition, there is also a joint restriction for KontiSkan and Skagerrak. The ramping restriction sets a limit on the total change of flow on the two connections combined.

Name	Connection points
Konti-Skan	SE3 <-> DK1
Skagerrak	NO2 <-> DK1
COBRAcable	NL <-> DK1
NorNed	NO2 <-> NL
NordLink	NO2 <-> GER
Kontek	GER <-> DK2
SwePol	SE4 <-> PL
Baltic Cable	SE4 <-> GER
Estlink	FI <-> EE
Storebelt	DK1 <-> DK2
NordBalt	LT <-> SE4
LitPol	PL <-> LT

Reasons for ramping restrictions

When imposing ramping restrictions, the Nordic transmission system operators have stated that frequent large changes in production and flow in the grid make it more difficult to control the frequency. The transmission system operators are therefore imposing ramping restrictions on HVDC connections in order to reduce risks that might threaten security of supply.

Without restricting the maximum change of flow per hour (ramping) on interconnectors, very large ancillary services and operational reserves would be needed to handle imbalances within operative hours.