Glossary

The vertical load at the withdrawal points between the transmission grid and the downstream distribution grids arises as the result of the balance between the end customer loads and the simultaneous decentralised generation in the distribution grids. If the decentralised input is greater than the end customer load in the distribution grids, then energy is fed back into the transmission grid.

Voltage source converter (VSC) technology is a transmission method used for high voltage direct current (HVDC) transmission. It is self-commutated HVDC transmission based on a power semiconductor element with a turn-on and turn-off capability (IGBT – insulated-gate bipolar transistor) and an intermediate voltage circuit. It is characterised by a considerable increase in control and regulation possibilities in contrast to line-commutated HVDC transmission. When using VSC technology, active and reactive power can be adjusted independently of each other, for example. The currently installed VSC capacities are considerably below those of line-commutated HVDC transmission already in operation; however, further development of VSC technology is foreseeable in order to increase system performance. 

Voltage stability serves to maintain an acceptable voltage level across the entire grid. This is achieved with a stable balance of reactive power, in dependence on the respective reactive power demands of the grid and its customers.

Localised support of the voltage in the event of a fault by means of feeding in reactive power.