US 12,756,177 B2 · DC fault management in electrical power system

Abstract

Embodiments herein provide a protection method of protecting a Modular Multilevel Converter (MMC) for Direct Current (DC) fault protection in a symmetrical monopole configuration. The MMC for each of at least one phase comprises a leg, which comprises a first branch and a second branch comprising director valves connected in series. Further, legs of the MMC are connected in series between DC poles. The method comprises measuring DC pole voltages relative a common ground and accordingly determining a DC fault identifying a DC pole to ground fault of one of the DC poles. Upon determining the DC fault, the method comprises controlling the director valves of the second branch for each leg to bypass the DC poles through the second branch for protecting a DC pole other than the DC pole identified with the DC fault.

Claims15

Dependent claims

A protection method of protecting a Modular Multilevel Converter (MMC) for Direct Current (DC) fault protection in a symmetrical monopole configuration, wherein the MMC for each of at least one phase comprises:

a leg comprising:
a first branch having an upper arm and a lower arm connected in series, wherein the upper arm and the lower arm each comprises submodules configured to contribute to a waveform of an output voltage of the MMC;
and
a second branch having a first director valve and a second director valve connected in series;
wherein the first branch and the second branch are connected in parallel;
wherein legs of the MMC are connected in series between DC poles of the MMC, the method comprising:
measuring DC pole voltages relative a common ground;
determining based on the measured DC pole voltages, a DC fault identifying a DC pole to ground fault of one of the DC poles;
and
upon determining the DC fault of a DC pole, controlling the director valves of the second branch for each leg to bypass the DC poles through the second branch of the director valves for protecting a DC pole other than the DC pole identified with the DC fault.

7 more elements

A controller for protecting a Modular Multilevel Converter (MMC) for Direct Current (DC) fault protection in a symmetrical monopole configuration, wherein the MMC for each of at least one phase comprises:

a leg comprising:
a first branch having an upper arm and a lower arm connected in series, wherein the upper arm and the lower arm each comprises submodules configured to contribute to a waveform of an output voltage of the MMC;
and
a second branch having a first director valve and a second director valve connected in series;
wherein the first branch and the second branch are connected in parallel;
wherein legs of the MMC are connected in series between DC poles of the MMC, the controller comprises:
a measuring module configured to:
measure DC pole voltages relative the common ground;
a determination module configured to:
determine based on the measured DC pole voltages, a DC fault identifying a DC
pole to ground fault of one of the DC poles;
and
a protection module configured to:
control, upon determining the DC fault of a DC pole, the director valves of the second branch for each leg to bypass the DC poles through the second branch of the director valves for protecting a DC pole other than the DC pole identified with the DC fault.

11 more elements

Dependencies are inferred from the claim text.

DC fault management in electrical power system

Life of this patent

DC fault management in electrical power system

Life of this patent

Abstract

Claims15