Method for operating converter and converter arrangement

A computer program product comprising computer program code embodied on a non-transitory computer readable medium, wherein execution of the program code in a computer controlling a converter comprises:

• convert, by the converter, DC power into AC power supplied to a three-phase AC network connected to a three-phase output of the converter, wherein the three-phase AC network is associated with one or more single-phase tripping devices that performs a single-phase tripping by switching off a single phase of a transmission line in the three-phase AC network connected to the three-phase output of the converter;
• determine, during the converting, that the single-phase tripping has started in the three-phase AC network connected to the three-phase output of the converter, wherein determining the single-phase tripping has started is in response to:
• a) detecting that a voltage unbalance in the three-phase AC network exceeds a predetermined magnitude, and
• b) subsequent to a), detecting that the voltage unbalance in the three-phase AC network decreases back below the predetermined magnitude;
• and
• after determining that the single-phase tripping has started in the three-phase AC network, directly control an active output current in the three-phase output of the converter such that a negative sequence voltage in the three-phase output of the converter remains at or below a predetermined level, wherein the controlling is performed until determining that the single-phase tripping has ended in the three-phase AC network.

An arrangement comprising:

• an electric power converter with a three-phase output;
• and
• a controller configured to:
• control the converter to convert DC power into AC power supplied to a three-phase AC network connected to the three-phase output converter, wherein the three-phase AC network is associated with one or more single-phase tripping devices that performs a single-phase tripping by switching off a single phase of a transmission line in the three-phase AC network connected to the three-phase output of the converter;
• determine, during the converting, that the single-phase tripping has started in the three-phase AC network connected to the three-phase output of the converter, wherein determining the single-phase tripping has started is in response to:
• a) detecting that a voltage unbalance in the three-phase AC network exceeds a predetermined magnitude, and
• b) subsequent to a), detecting that the voltage unbalance in the three-phase AC network decreases back below the predetermined magnitude;
• and
• after determining that the single-phase tripping has started in the three-phase AC network, directly control an active output current in the three-phase output of the converter such that a negative sequence voltage in the three-phase output of the converter remains at or below a predetermined level, wherein the controller is configured to perform the controlling until determining that the single-phase tripping has ended in the three-phase AC network.

A control system for an electric power converter, the control system comprising a processor, and a memory storing instructions that, when executed by the processor, cause the processor to carry out the steps of:

• control the converter to convert DC power into AC power supplied to a three-phase AC network connected to a three-phase output the converter, wherein the three-phase AC network is associated with one or more single-phase tripping devices that performs a single-phase tripping by switching off a single phase of a transmission line in the three-phase AC network connected to the three-phase output of the converter;
• determine, during the converting, that the single-phase tripping has started in the three-phase AC network connected to the three-phase output of the converter, wherein determining the single-phase tripping has started is in response to:
• a) detecting that a voltage unbalance in the three-phase AC network exceeds a predetermined magnitude, and
• b) subsequent to a), detecting that the voltage unbalance in the three-phase AC network decreases back below the predetermined magnitude;
• and
• after concluding after determining that the single-phase tripping has started in the three-phase AC network, directly control an active output current in the three-phase output of the converter such that a negative sequence voltage in the three-phase output of the converter remains at or below a predetermined level, wherein the controlling is performed until determining that the single-phase tripping has ended in the three-phase AC network.