Power system investigation concerning wind power integration
By request of Skellefteå Kraft and Vattenfall Eldistribution Solvina has analyzed the future integration of Uljabuouda wind power farm to the power grid. It was investigated how the wind power farm affected the dynamic behavior of the grid as well as the need for a new or modified control system in the grid and in the neighbouring water power plants.
The task included dynamic modeling of the wind power plants and the subtransmission power grid, dynamic simulations of different scenarios and analysis of the results.
A number of problems were discovered, for example the possibilities for the wind power farm to meet the grid codes concerning fault ride-through capability set by the authorities.
Power system investigation of a paper mill plant
Billerud AB Gruvön Paper Mill is one of the larger energy consumers in Sweden. As the energy system of the mill was upgraded recently Solvina was engaged to analyze the electric power system. The internal grid was about to be upgraded and the main voltage was increased from 30 kV to 130 kV. The upgrade included installation of new transformers and exchange of a number of switchgears. In addition a new back-pressure turbine for electric power generation was installed.
The task contained short circuit calculations which gave selectivity plans and protection settings for the entire mill. Dynamic simulations were also carried out to investigate the island operation possibilities in the new modern power system. During thunderstorms the mill is run in island operation mode to avoid disturbances caused by the external power grid. Disturbances in the mill could lead to a shut down when important process equipment trips The investigation led to guidelines for island operation and functions were added to the turbine to ensure safe island operation.