Vrenga Power Plant was commissioned in 1958, While Hølseter was commissioned in 1980. To secure operations for the decades to come, the following work must be carried out:
 
  • The control system of the power plants must be replaced 
  • The high-voltage system must be upgraded
  • Barriers against oil emission must be further reinforced.

Securing supply

The power plants are significant in securing supply for the area. The time and order of completion are chosen in cooperation with Flesberg Elektrisitetsverk and are intended to minimise the possibility of facing a shortage situation in the local electricity grid. 
 
For the same reason, the works will be carried out at Hølseter first, then at Vrenga, so that at least one of the power plants is available for production during the period.

 

Regulation

The projects will be carried out in accordance with the stipulated operating rules for the reservoirs, but will entail a low water level for regulated lakes during some periods. 
 

Schedule

  • 17 September to 23 November: Vrenga Power Plant out of operation 
  • The lakes Kjørkjevatn and Hånavatn will be regulated to their minimum regulated water level (LRV*) before the refurbishment work begins at Vrenga in 2018. After this, they will be refilled by natural feeding.
  • Up to 31 July: Hoppestadvatn lake will be approx. 1-1.5 metres below the maximum regulated water level (HRV*)
  • 1 August to 17 September: Hoppestadvatn will be drained down to approx. 10 metres below HRV
  • From 17 September: Hoppestadvatn will be filled to HRV, depending on precipitation and feeding
  • The lakes Kjørkjevatn and Hånavatn will be regulated to their minimum regulated water level (LRV*) before the refurbishment work begins at Hølseter in 2019. After this, they will be refilled by natural feeding
  • August-September 2019: Hølseter Power Plant out of operation


Map (Click in the map for a complete overview map)

*  HRV: Highest regulated water level granted by licencing
*  LRV: Lowest regulated water level granted by licencing