Evaluation of Net Transfer Capacity Reductions in the Nordic Power System

Abstract: The day-ahead dispatch of the Nordic power system is managed by the common electricity market Elspot, operated by Nordpool. Elspot is an area-based market and takes as input the net transfer capacity (NTC) between the price areas. The NTC between the price areas thus have a direct impact on the social welfare obtained from the solution of the market clearing algorithm. This thesis analyses the reasons for reductions in the NTC values using open source data from Nordpool and ENTSOE. For each interconnector, the historical unavailability is analyzed using Nordpool data, by computing measures such as the unavailability factor and the total share of unavailability caused by different reasons. Further, the impact of planned and unplanned outages of transmission system elements such as lines and transformers on NTC reductions is evaluated, using outage data from the ENTSO-E Transparency Platform.   To evaluate the system costs of NTC reductions, two case studies are performed using a dispatch model for the Nordic power system. In order to give more accurate results the model is improved by explicitly modelling the Baltic countries, which were previously treated as external regions in the model. The first case study estimates the cost of NTC reductions due to stability issues in the West Coast Corridor in Sweden. It is seen that these NTC reductions have a big impact on the social welfare. The second case study estimates the cost of NTC reductions due to unavailability of several HVDC connections. The unavailability caused by these NTC reductions is an order of magnitude smaller than for the West Coast Corridor, with the exception of the Skagerrak HVDC connection between Norway and Denmark, which has the highest cost among the HVDC connections analyzed.