HVDC > HVDC Classic > HVDC technology > Control system
The control system is the brain in an HVDC transmission system.
One major advantage of a HVDC transmission is its controllability. A modern HVDC station is equipped with a well integrated microprocessor based control and protection system.
The basic power control is achieved through a system where one of the converters controls its DC voltage and the other converter controls the current through the DC circuit. The control system acts through firing angle adjustments of the thyristor valves and through tap changer adjustments on the converter transformers. Each pole in a bipolar ABB HVDC link has its own control system and each control system is duplicated. In the normal mode, the control systems of the two stations of a two-terminal HVDC system communicate with each other through a telecommunication link between the stations. Most of the ABB HVDC transmissions are remotely controlled from a dispatch center for the grid.
The MACH 2™ control and protection system developed by ABB is fully digital. All functions for control, supervision and protection of the stations are implemented in software running in a family of microprocessor circuit boards.