Skyddssystem i elkraftsystem

Significance of Protection for power systems (at all levels).

• In the event of a fault, protection systems can protect equipment from destruction, preserve system operation, and protect people from the dangers of shock, burns and explosion.
• On the other hand, many famous blackouts have been partly due to protection functions operating during critical system conditions (e.g. voltage decline in a stressed system) when there is not directly a fault.

Modern changes in power systems make it all the more important to have well designed, high performance protection systems, with a skilled workforce for their design and maintenance.
For example:

• Long-distance exchanges of power with variable generation resources lead to higher stress on the transmission system.
• Distribution systems contain increasing levels of generation: this leads to power flows in either direction ("up" or "down"), more incentive to "mesh" the system to control voltage and reduce losses, and more need of quick fault-clearing to limit disturbance to synchronism of generators and inverters. All of these things imply a usefulness of new or improved protection.
• More combination of ac and dc systems, with HVDC used for subsea or other long cable connections, and possibly for overlay grids in the future. Protection in dc grids is a topic of current interest.