| 摘要 |
A series-compensated converter station included in an installation for transmission of high-voltage direct current comprises a converter (SR1, SR2) with at least one 6-pulse bridge (BR). Via series capacitors (SCR, SCS, SCT) the 6-pulse bridge is connected to a three-phase alternating-voltage network (N1, N2) with a fundamental frequency (f01, f02). Control equipment (CE1, CE2) generates an ordered value (AOL) of a control angle ( alpha ) for valves (V1-V6) included in the 6-pulse bridge in dependence on a limiting signal (AMAXL) capable of being influenced. An amplitude signal (AMPL) is formed which corresponds to the amplitude (C1) for a component (C1cos(2 pi f0t + rho 1)) of the fundamental frequency in the direct voltage (Udb) of the 6-pulse bridge and a compensating signal (ACOMP) is continuously calculated in dependence on a sensed voltage (Un1, Un2) at the converter station and on the amplitude signal. The limiting signal is formed in dependence on the compensating signal for the purpose of maintaining the commutating margin ( gamma m) for the valves equal to at least the preselected value ( gamma p) in case of unbalance between the voltages (UCR, UCS, UCT) of the series capacitors.
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