Norway plans to develop over 2000 MW of wind generation in the northern part of the country. Northern Norway has a weak ac system, which would require augmentation for the transport of the wind energy to load areas in the central part of the country.
Statnett retained Teshmont to evaluate the suitability of a multiterminal HVDC link for integration of the planned wind generation into the current ac network. Teshmont's key focus in working with Statnett was to identify significant issues that could be encountered in the planning, operation, and maintenance of a multiterminal HVDC system.
The work included looking at issues related to multiterminal HVDC operation, operation of isolated wind farms connected directly to a conventional HVDC system, and issues associated with connecting the windfarm ac collector system to the local ac network. The performance of the overall system will be influenced not only by the HVDC system, but also by the performance characteristics of the wind generators.
Teshmont developed a high level report covering the following:
- Advantages of a multiterminal HVDC solution
- Impacts of multiterminal HVDC configuration on the availability of the link
- Challenges with a multiterminal solution
- Minimum short circuit ratio for the converter in inverter operation
- Necessary short circuit ratio to ensure fast recovery after commutation failure
- Influence of the available short circuit capacity on the required recovery time after a commutation failure
- Protection of the system against overvoltages caused by sudden disconnection of HVDC link due to failures
- Estimated costs for the HVDC converter stations and transmission lines
- Evaluation of the staging and upgrading of the HVDC system