| 摘要 |
1,270,310. Static converter control systems. ALLMANNA SVENSKA ELEKTRISKA A.B. 28 Aug., 1969 [29 Aug., 1968], No. 42789/69. Heading H2F. Relates to a rapid re-starting arrangement for a static converter 1 (Fig. 1) connected between an A.C. system and an HVDC transmission line, after it has been blocked by a blocking device 12 (e.g. part of a protection means for the D.C. line 4), the arrangement ensuring rapid increase in the D.C. voltage without overvoltage and including means whereby after blocking is removed an increased signal is applied temporarily to the input of a control amplifier 5 controlling a pulse delay angle control unit 6 and control pulse generator 7 thereby to reduce the control pulse delay angle. Blocking.-The maximum output voltage from amplifier 5 causes minimum delay angleαand maximum positive direct voltage output from the converter. Minimum output from the amplifier gives maximum control angle i.e. towards 180 degrees. The blocking device 12 thus operates on the input to amplifier 5 through a switching member 14 (e.g. transistor or relay) to apply a positive voltage to the input which predominates over other inputs whereupon the amplifier output decreases toward zero. Control device 6 then increases the delay angle toward 180 degrees so that the rectifier tends toward inverter operation and its D.C. output becomes zero. Alternatively the blocking means may operate to disconnect the pulse generator 7. Rapid starting.-When the temporary blocking is removed the control amplifier output increases. The increase is damped however due to the time required to re-charge capacitor 11. To reduce this time the input to the amplifier is temporarily increased by connecting it to a more -ve point on a desired current order potentiometer 21 by means of a switch 18. (An input representing the actual D.C. line current is derived by a transductor 10). Voltage limiting.-A voltage K 1 U applied at 31 limits the amplifier output to K 1 U and prevents overvoltage from the converter. Further limitation is provided by closing a switch device 17 to apply a voltage K 2 U in opposition to the conducting direction of diode 25. The voltage U is derived from the A.C. network by transformer 30 and rectifier 22. Arrangements are provided (Fig. 2, not shown) to increase the D.C. voltage if the A.C. network voltage decreases temporarily, by permitting the A.C. voltage sensor 30, 22 to influence the same switching members as the unit 12. The line protection unit 12 may be as described in Specification 853,912.
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