HV DC transmission system control appts. - has regulating circuit for protecting inverter values in cases of disturbance e.g. violation of correct firing sequence

摘要

The high-voltage direct current transmission system with a rectifier (6) and an inverter (12) of the controlled valve type, is controlled so that the reference value of the current supplied from the rectifier (6) to the inverter (12) is in a direct relationship to the value of the difference between a predetermined value and the smallest of the margin angles of the inverter valves when the smallest of the margin angles of the inverter valves falls below the predetermined value, the current reference value being set above or equal to the minimum permissible valve. The regulating device for controlling the high-voltage direct current transmission system comprises a measuring circuit (26) for developing a signal corresponding to the smallest of the margin angles of the inverter valves and a reference current signal generating circuit (20) including a subtraction circuit (35) having inputs (39,40) connected to the output of the measuring circuit (26) and to a reference signal source (53). A limiter (36) has its input connected to the output of the subtraction circuit (35). A second subtraction circuit (37) is provided having its inputs (41,42) connected to the output of the limiter (36) and to a second reference signal source (54). A minimum signal limiter (38) has its input connected to the output of the second subtraction circuit. The output signal of the minimum signal limiter (38) is supplied to a control device (16) for adjustably controlling the firing angles of the rectifier valves. The appts. is used for protecting the valves in the converters of the high-voltage direct current transmission system in cases of disturbance.