Alstom Grid achieves best performance in High Voltage Direct Current (HVDC) circuit breaker

Alstom Grid has achieved the best performance ever seen in a High Voltage Direct Current (HVDC) circuit breaker while testing a prototype at Alstom’s testing facility in Villeurbanne, France, in presence of an independent expert. In less than 2.5 milliseconds(Comparable to the speed of the nerve impulse between the eye and the brain), the HVDC circuit breaker interrupted currents exceeding 3,000 amperes. These tests were conducted as part of RTE’s demonstration activities on the architecture and technologies for DC power grids, within the large scale demonstration project TWENTIES supported by the FP7 programme of the European Commission. In the context of the energy turnaround, these tests, led by RTE, contribute to the development and implementation of new technologies which facilitate the integration of renewable energy sources into the European electrical grid.

“European electricity transmission operators are faced with the challenge of integrating renewable energy sources. We are proud to be one of the pioneers in this sector”, asserts RTE Chairman Dominique Maillard.

“This technological achievement is excellent news for the entire electrical engineering community, and a considerable advance in our industry,” says Alstom Grid President Grégoire Poux-Guillaume. “The direct current circuit breaker is a key element in building Supergrids, both onshore and offshore. It will help to increase the share of renewable energy on the grid.”

These results validate Alstom Grid’s major technological breakthrough. The circuit breaker is a key element of power network protection in the event of a short circuit. Well-known for alternative current connections, the technology is required to perform 10 to 20 times faster to be used for direct current.

Operators increasingly use direct current to guarantee that power is carried efficiently over long distances or to stabilise the grid as it is confronted with a growing supply of power from variable sources. Circuit breakers are not necessary for direct current transmission line connections between two points. However, having a circuit breaker is vital for protecting complex so-called ‘meshed’ grids that will, in the near future, require the interconnection of several points. The challenge is to avoid failures and blackouts, by cutting the current in the malfunctioning element as fast as possible, isolating the fault from the rest of the grid. Alstom Grid’s new circuit breaker paves the way to multiple possibilities for future direct current grids.

Alstom’s achievement is even more valuable as it was conducted as part of the TWENTIES European project, which aims to foster the integration of renewable energy, especially wind energy, within Europe’s power grid by 2020. To meet this challenge, 26 partners in the energy sector coming from 10 member States are “pooling their expertise”. RTE, the French electricity transmission system operator, has mobilised its R&D resources to lead these demonstration activities on the future direct current offshore grid, one of the six demonstrators within the TWENTIES project.

The partners involved in the RTE lead demonstrator have identified an integrated set of components to protect the grid in case of default and have quantified expected performances in different network architectures. Alstom Grid’s results already met some of these expectations, overcoming one of the major technical obstacles for the development of large scale high voltage direct current networks.

Tests will continue until the summer of 2013 as part of the TWENTIES project. The Alstom Grid teams are then planning on pursuing the qualification of this technology through a new milestone: interrupting a 7,500-ampere current at 180 kV.