Oslo’s existing main grid has insufficient capacity and is nearing the end of its life, which increases the risk of power outages. Outages in the high voltage grid often affect many customers at the same time.
Hafslund Nett is now in the process of completing the expansion and upgrading of Oslo’s main grid, as part of which the grid will be adapted for a voltage level of 132 kV. This is an extensive project which was started in 1990, and then, after a few years’ break, re-initiated in 2005. Work on cable laying and upgrading of the transformer stations to 132 kV is now in full swing. A 132 kV grid will provide a much greater transmission capacity than the current 33 and 47 kV main grid. The upgrading is due to be completed in 2018, when Hafslund Nett will have a robust grid for many years to come.
Digging up Oslo’s streets presents a major challenge. The cable work must be completed with the least possible disruption to traffic and pedestrians. This demands excellent coordination and adept information management for all concerned. Hafslund Nett is striving to use existing cable channels wherever possible, as this allows the old oil-insulated cables to be removed thus eliminating the risk of oil leaks from the cables. It also avoids competition for space in the ground with water, waste and central heating pipes, fibre cables and other infrastructure. In particular in Oslo city centre space is beginning to get very tight.
When the conversion to 132 kV is completed, the higher voltage will reduce power losses in the grid corresponding to the annual power consumption of 3,500 households.
Significant relocation to and development of new areas such as Fjordbyen and Ensjøbyen has resulted in a strong load increase in the grid. The power supply is a key factor in all construction phases, and there is a universal need for more power. In converting to a 132 kV grid Hafslund Nett is choosing a future-proof solution.