A limited volume of electricity conforming to the system security criteria can be transmitted in a power grid. This is referred to as the transmission capacity of the grid. Congestion management ensures that the transmission flows remain within the transmission capacity.
Grid operation is planned in advance over various periods of time. Maintenance work affecting the transmission capacities is scheduled to take place during times which impose a minimum of negative impact on the electricity market, considering technical factors. The transmission situation is monitored in real time, and action is taken whenever necessary to avoid situations where the transmission capacity might be exceeded and to guarantee confirmed transmission capacities for the market. This is primarily done by altering the running order and production volumes of the power plants.
The Finnish transmission grid is connected to Sweden, Norway, Estonia and Russia. The operating procedures of the electricity market in these countries differ from one another, which is why there are also different modes of operation in cross-border transmission management.
Fingrid makes an agreement with its customers on transmission rights through bilateral main grid contracts and cross-border transmission contracts.
There is an agreement with the transmission system operators in Sweden, Norway and Denmark on shared grid operation rules, which ensure the security of the Nordic power system. The operation rules also specify a shared framework for congestion management.
EU legislation provides the guidelines for congestion management, highlighting the importance of market information and market-focused solutions, which give a financial signal to the market.
Fingrid’s congestion management is guided by systematic planning and predictability. The objectives of transmission management are:
Fingrid makes an agreement with a customer connected to the transmission grid. The agreement defines the customer’s right to transmit electricity through its connection point and the potential restriction of the transmission right.
The grid is dimensioned so that the customers can normally transmit a volume of electricity which conforms to their needs through their connection points. Electricity-producing companies report their daily production plans to Fingrid on the preceding day for the grid operation planning.
Fingrid has a right to interrupt or restrict transmissions because of a fault, service, repairs etc. in the grid. The timing and volumes of known restrictions are negotiated with the customers in advance.
The transmission capacity on the cross-border connections is made available fully to the electricity market through Elspot and Elbas i.e. the market places of the Nordic electricity exchange Nord Pool Spot. The Elspot market follows the principle of implicit auctioning, where the energy and transmission capacity between various bidding areas is allocated in a single process to the parties of electricity trading. Capacity which may not have been used on the Elspot market is offered to the Elbas market, where trading finishes no later than one hour before the hour of operation. The Elspot capacities for the next day are announced before noon, and the Elbas capacities in the afternoon.
The market has access to all cross-border lines to Sweden (normal transmission capacity from 1500 to 2100 MW). Elspot price area Finland has a commercial connection to price area Sweden alone, while the connection to Norway (normal transmission capacity from 50 to 100 MW) is used for securing local electricity transmission in Northern Norway.
The issues considered in specifying the available transmission capacity include the operation situation of the grid, such as planned maintenance work as well as production and consumption situations. Changes in the transmission capacity are reported well in advance to the market. 100 MW of the transmission capacity is reserved as a system security margin to cater for instantaneous fluctuations in electricity production and consumption. In potential grid disturbances, Fingrid guarantees the cross-border transmissions it has confirmed by means of counter trading
1 by the end of the day of operation.
A forecast error of the market parties can result in exceeding of the transmission capacity during the hour of operation. The exceeding is adjusted away by using the balancing power market.
Fingrid makes 1,300 MW of transmission capacity available to the electricity market on its 400 kV connections from Russia. Fingrid has reserved a volume of 100 MW to be used as a power system reserve.
Electricity can be imported from Russia by customers who have made an agreement on a fixed transmission right with Fingrid and an agreement on energy purchases with a Russian organisation responsible for electricity sales.
The customers report their transmission programme weekly, and any changes to it on the morning preceding the day of operation.
Fingrid has a right to restrict imports in the event of faults in the grid in Russia or Finland and during other outages or for some other reason occurring in Russia. The restrictions are reported to the importing customers no later than 100 minutes before the beginning of the hour of operation subject to the restriction.
The two 110 kV lines connected to Fingrid’s grid from Russia are not owned by Fingrid, and the owners of the said connections are responsible for electricity transmission on them.
The Estlink sea cable between Finland and Estonia became operative at the beginning of 2007. Up to 365 megawatts of power can be transmitted over the link in both directions. The cable is owned by a Finnish-Baltic energy consortium.
Fingrid confirms daily how much electricity can be imported into Finland or exported from Finland on the connection. Normally, this value does not differ from the maximum transmission capacity of the connection. Within the limits of confirmed capacity, the owner of the cable reports the daily transaction volume to Fingrid.
1 Counter trading is used for changing the geographical distribution of production of power plants determined on a market basis. As an example, if electricity transmissions from Northern Finland to Southern Finland are too high, production is increased in the south of Finland and decreased in the north at Fingrid’s request and expense. This brings the transmission flows within the limits, and the total power balance in Finland still remains the same.