| 摘要 |
A control system to control at least one of the thyristor converters (1) or (2) of an ac system (7,8) or (9,10) connected by busbars (5,6) and transformers (3,4) to the converters (1,2) which have their dc sides connected by a dc link, for example inductor (11). Each thyristor converter receives firing pulses from a firing control (12) or (13), including a firing angle control (18) and a summing junction (16) receiving a control current signal input (17) and a current signal (14) which is a function of converter operation. An electrical power measurement is made of one of the ac systems, for example the ac system (7,8,5) and in accordance with that power measurement a signal which is a function thereof is produced as an output (19) from an integral two-axis ac servo control having demodulator, integrator and modulator circuit receiving the power measurement signal as input. Signal (19) is a function of the cross-modulation noise component caused by interaction of electrical noise from the two converters. This signal (19) is input to at least the firing control (12) to vary the firing of thyristor converter (1) so as to remove from at least the ac system (7,8,5) the cross-modulation noise. Signal (19) may also be input to firing control (13).
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