Method and a device for control of a capacitor device for a shunt-connected compensator unit

A device for control of a capacitor device (TSCab, TSCbc, TSCca) for a shunt-connected static compensator unit (COM1, COM2, COM3) for compensation of reactive power in an electric power network (NW), the capacitor device comprising a capacitor (C) and a semiconductor valve (TS), connected in series with said capacitor, with a first semiconductor (TYp), corresponding to a first conduction direction (CTYp) for current through the capacitor, and a second semiconductor (TYn), corresponding to a second conduction direction (CTYn) for current through the capacitor, the device comprising members (VN, FSD, CU) which sense a voltage (Uab, Ubc, Uca) at the compensator, which forms a value of the time rate of change of a value of the fundamental component of this voltage, which value is derived from said sensed voltage, and which, in dependence on the sign of this time rate of change, generates a first firing order order (S6p) for the first semiconductor and a second firing order (S6n) for the second semiconductor,

• characterized in that the device, in addition thereto, comprises members (UMp, UMn, CM, 1P, 1P', 2N, 2P, 1N, 1N', 5P, 5N) which, for each of the first and second conduction directions (CTYp, CTYn), form a deblocking signal (S4p, S4n), indicating that the conduction direction associated with the respective firing order does not carry current, and which generate a firing order for the second (CTYn, CTYp) of the first and second conduction directions with an optional delay (T1*f*360.degree.) after the occurrence of said deblocking signal.