Vertical load

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

Voltage stability

Voltage stability is one of the system services for which the network operator is responsible and acts to maintain an acceptable voltage level across the entire grid. This is achieved with a stable balance of reactive power, dependent on the respective reactive power demands of the network and its customers.

Voltage support

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

VSC (voltage source converter)

VSC (voltage source converter) technology is a transmission procedure used for high voltage direct current (HVDC) transmission. It is a 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 current. 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 for example be adjusted independently of each other. The currently installed capacities of VSC are below those of line-commutated HVDC transmission already in operation, however the further development of the VSC technology is foreseeable in order to increase system performance. A detailed description of this topic can be found in Chapter 5, page 94, of the GDP 2012: