Method and controller for protecting a voltage source converter

Patent metadata

Field	Value
Publication number	US-9337645-B2
Application number	US-201314142224-A
Country	US
Kind code	B2
Filing date	Dec 27, 2013
Priority date	Jun 29, 2011
Publication date	May 10, 2016
Grant date	May 10, 2016

Abstract

A method in a controller for protection of a voltage source converter including one or more phases, each phase including one or more series-connected converter cells. Each converter cell has a by-pass switch for enabling by-pass thereof. The method includes the steps of detecting an over-voltage condition, and controlling simultaneously the by-pass switches of each converter cell, so as to bypass the converter cells upon detection of such over-voltage condition. The invention also encompasses a controller, computer programs and computer program products.

First claim

What is claimed is:

1. A method in a controller for protection of a voltage source converter comprising three phases connected in delta connection, each phase comprising two or more series-connected converter cells and a respective phase reactor, each converter cell comprising a half-bridge converter cell or a full converter cell, further each converter cell having a by-pass switch connected in parallel with the respective converter cell for enabling by-pass thereof, the method comprising the steps of:
detecting an over-voltage condition, wherein the step of detecting the over-voltage condition comprises measuring an AC voltage of a power grid to which the voltage source converter is connected and determining this AC voltage to exceed a maximum operation voltage of the voltage source converter, and/or measuring a DC voltage of the one or more converter cells and determining this DC voltage to exceed a preset value, and/or measuring a current in the one or more phases and determining this current to exceed a preset value, and
controlling simultaneously the by-pass switches of each converter cell to be configured in closed position so as to short-circuit the converter cells and by-pass the converter cells upon detection of the over-voltage condition, wherein the voltage source converter enters a passive mode upon the converter cells being by-passed, in which in the passive mode the respective phase reactor of each of the three phases absorbs inductive overcurrent caused by the detected overvoltage condition.

2. The method as claimed in claim 1 , comprising the further step of controlling a current in the delta connected voltage source converter prior to the step of controlling simultaneously the by-pass switches.

3. The method as claimed in claim 1 , wherein the step of controlling the by-pass switches comprises sending control signals for closing the by-pass switches.

4. The method as claimed in claim 1 , comprising the further step of re-opening the by-pass switches when the detected overvoltage condition has passed.

5. The method as claimed in claim 1 , wherein the by-pass switches comprises thyristor based by-pass switches, insulated gate bipolar transistor based by-pass switches, or mechanical by-pass switches.

6. A controller for controlling a voltage source converter comprising three phases connected in delta connection, each phase comprising two or more series-connected converter cells and a respective phase reactor, each converter cell comprising a half-bridge converter cell or a full converter cell, further each converter cell having a by-pass switch connected in parallel with the respective converter cell for enabling by-pass thereof, the controller comprising a processor arranged to:
detect an over-voltage condition, wherein detecting the over-voltage condition comprises measuring an AC voltage of a power grid to which the voltage source converter is connected and determining this AC voltage to exceed a maximum operation voltage of the voltage source converter, and/or measuring a DC voltage of the one or more converter cells and determining this DC voltage to exceed a preset value, and/or measuring a current in the one or more phases and determining this current to exceed a preset value, and to
control simultaneously the by-pass switches of each converter cell to be configured in closed position so as to short-circuit the converter cells and by-pass the converter cells upon detection of the over-voltage condition, wherein the voltage source converter enters a passive mode upon the converter cells being by-passed, in which in the passive mode the respective phase reactor of each of the three phases absorbs inductive overcurrent caused by the detected overvoltage condition.

7. A computer program for a controller controlling a voltage source converter comprising three phases connected in delta connection, each phase comprising two or more series-connected converter cells and a respective phase reactor, each converter cell comprising a half-bridge converter cell or a full converter cell, further each converter cell having a by-pass switch connected in parallel with the respective converter cell for enabling by-pass thereof, the computer program comprising computer program code, which, when run on the controller, causes the controller to perform the steps of:
detecting an over-voltage condition, wherein the step of detecting the over-voltage condition comprises measuring an AC voltage of a power grid to which the voltage source converter is connected and determining this AC voltage to exceed a maximum operation voltage of the voltage source converter, and/or measuring a DC voltage of the one or more converter cells and determining this DC voltage to exceed a preset value, and/or measuring a current in the one or more phases and determining this current to exceed a preset value, and
controlling simultaneously the by-pass switches of each converter cell to be configured in closed position so as to short-circuit the converter cells and by-pass the converter cells upon detection of the over-voltage condition, wherein the voltage source converter enters a passive mode upon the converter cells being by-passed, in which in the passive mode the respective phase reactor of each of the three phases absorbs inductive overcurrent caused by the detected overvoltage condition.

8. A computer program product comprising a non-transitory computer readable medium storing the computer program of claim 7 .

Assignees

• Abb Technology Ag

Inventors

• Hasler Jean-Philippe
• Monge Mauro
• De Oliveira Marcio

Classifications

• H02M2001/325

  Electricity · mapped topic

• H02M7/53871

  with automatic control of output voltage or current · CPC title

• H02H3/20 Primary

  responsive to excess voltage · CPC title

• H02M1/32

  Means for protecting converters other than automatic disconnection · CPC title

• H02M2007/4835

  Electricity · mapped topic