At the Turn of the Millennium, Iceland Decided to Capitalise on its Vast Natural Energy sources to increase electricity generation capacity significantly. The country elected to base the industrial production of the new electricity generation on hydropower and geothermal power sources. This decision was attractive from both a financial and an environmental perspective. It would enhance Iceland's lead in the field of green electricity generation, as the country would produce more than 99% of its electrical energy from renewable energy sources.

Iceland's goal was highly feasible given that, with a geographical area of 103,000 sq km (39,768 sq miles) and a population of 320,000, it is the only country in Western Europe that still has great potential to further utilise its large quantities of renewable energy sources in an economical way.

Although feasible, the goal was still going to be a major challenge for Landsnet, the operator of Iceland's transmission system. Comprised of long transmission lines with weak electrical interconnections, Iceland's transmission system suffers from inherent stability issues. Aside from Canada, Iceland has the lowest population density in the world at 3 persons per square kilometer (7.8 persons per square mile). Supplying electricity cost effectively to this sparse population, with somewhat remote energy sources, has led to a transmission system that is relatively weak.

Landsnet was particularly concerned that the introduction of new generation sources on the scale planned for East Iceland would result in severe stability problems. Investment in bulk reinforcement of the network would have required major new transmission lines between regions, which would have incurred large investment costs.

To ensure the transmission system could absorb the large increase in generating capacity and overcome the long-term system-stability problems, Landsnet installed real-time monitoring of power-system dynamics using a wide area monitoring system (WAMS), as well as installing a new system protection scheme to ensure network reliability in case of fault situations.

STABILITY PROBLEMS

For the past decade, Landsnet had experienced problems with low-frequency oscillatory incidents that threatened system stability. These usually occurred on the 132-kV, 1000-km (621-mile) transmission line loop erected along the coastline of Iceland, with the generators in the north oscillating against the generators in the southwest. The 132-kV coastline circuit was electrically weak, and the problem was compounded by the two power plants connected to the circuit at Blanda and Krafla, which are large in relation to the capacity of the transmission system.

Landsnet conducted studies on the deployment of local power system stabiliser (PSS) devices to see if they would improve system stability, and simulations showed good results. However, to tune PSS devices to achieve optimum performance on the live system, and verify the results, is not an easy task. PSS devices that are not tuned properly can make the situation worse. Since Landsnet was never fully confident about the performance of the PSS devices that had been installed on various parts of the Icelandic network, the transmission system operator decommissioned them.

The crunch point came in 2007 when commissioning work started on a new hydropower plant and an aluminium smelter, both remotely sited in East Iceland. The 690-MW Karahnjukar hydropower plant was the biggest construction project Iceland had ever undertaken, designed to increase the installed generating capacity by 40%. With an initial production capacity of 346,000 tons, the new Alcoa Fjarðaál (meaning "aluminium of the fjords") aluminium smelter would take most of Karahnjukar's output.

The connection of the new hydropower plant to the transmission system created additional problems as far as system dynamics. Before the Karahnjukar plant was commissioned, the bulk of the generation and load was in Southwest Iceland, where two-thirds of the 320,000 Icelanders live clustered around the capital city of Reykjavík. The Karahnjukar hydropower plant increased the installed generating capacity in Iceland from 1700 MW to 2400 MW. With the connection of the new hydropower plant and additional load at the aluminium smelter plant, Landsnet was aware that without detailed information about network dynamics, increased system instability could be ungovernable. The increased generation capacity and increased smelter plant load were major concerns as there was a real possibility of damage to equipment or a blackout occurring. This prompted Landsnet to award a contract to Psymetrix (Edinburgh, Scotland), a company with extensive experience in the area of power system dynamics measurement, stabiliser tuning and performance assessment. Psymetrix also had proven experience in deploying the WAMS and providing real-time power-system dynamics information, including oscillatory monitoring and damping determination for transmission systems.