| 摘要 |
A method of operating a converter circuit is disclosed, wherein the converter circuit has a converter unit with a multiplicity of controllable power semiconductor switches and the converter unit is connected at the AC voltage end to an electrical AC voltage network. According to the method, the controllable power semiconductor switches are controlled by means of a control signal. To protect the converter circuit in the event of asymmetrical phase voltages occurring in an AC voltage network connected to the converter circuit, the phase voltages (U<SUB>Na</SUB>, U<SUB>Nb</SUB>, U<SUB>Nc</SUB>) in the AC voltage network are determined, the negative sequence amplitude of the phase voltages (U<SUB>Nn,A</SUB>) is calculated, the Park-Clarke transformation amplitude of the phase voltages (U<SUB>Ndq,A</SUB>) is calculated, the negative sequence amplitude of the phase voltages (U<SUB>Nn,A</SUB>) is monitored at a settable value, the Park-Clarke transformation amplitude of the phase voltages (U<SUB>Ndq,A</SUB>) is monitored at a settable value and the controllable power semiconductor switches are locked by means of the control signal if the negative sequence amplitude of the phase voltages (U<SUB>Nn,A</SUB>) exceeds the settable value or if the Park-Clarke transformation amplitude of the phase voltages (U<SUB>Ndq,A</SUB>) falls short of the settable value.
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