Voltage source converter

Patent metadata

Field	Value
Publication number	US-2016241127-A1
Application number	US-201415027669-A
Country	US
Kind code	A1
Filing date	Oct 6, 2014
Priority date	Oct 7, 2013
Publication date	Aug 18, 2016
Grant date	—

Abstract

A voltage source converter includes at least one limb connected between DC terminals, the or each limb including: a phase element including switching elements to interconnect a DC electrical network and an AC electrical network; an auxiliary sub-converter configured to be controllable to act as a waveform synthesizer to modify a first DC voltage presented to the DC electrical network; and a tertiary sub-converter connected in parallel with the electrical block and controllable to act as a waveform synthesizer to modify a second DC voltage presented to a DC side of the phase element, the tertiary sub-converter ( 39 ) including at least one energy storage device. The voltage source converter includes a controller configured to selectively control the or each tertiary sub-converter to synthesize at least one tertiary voltage component so as to transfer energy to or from that tertiary sub-converter and thereby regulate an energy level of that tertiary sub-converter.

First claim

1 . A voltage source converter comprising first and second DC terminals for connection to a DC electrical network, the voltage source converter further including at least one limb connected between the first and second DC terminals, the or each limb including:
a phase element including a plurality of switching elements to interconnect the DC electrical network and an AC electrical network; an auxiliary sub-converter configured to be controllable to act as a waveform synthesizer to modify a first DC voltage presented to the DC electrical network; and a tertiary sub-converter connected with the phase element in an electrical block, the auxiliary sub-converter being connected in parallel with the electrical block, the tertiary sub-converter being configured to be controllable to act as a waveform synthesizer to modify a second DC voltage presented to a DC side of the phase element, the tertiary sub-converter including at least one energy storage device; wherein the voltage source converter further includes a controller configured to selectively control the or each tertiary sub-converter to synthesize at least one tertiary voltage component so as to transfer energy to or from that tertiary sub-converter and thereby regulate an energy level of that tertiary sub-converter.

2 . A voltage source converter according to claim 1 wherein the controller is configured to selectively control the or each tertiary sub-converter to synthesize at least one tertiary voltage component so as to transfer energy to or from that tertiary sub-converter and thereby minimise a net change in energy level of that tertiary sub-converter.

3 . A voltage source converter according to claim 1 wherein the controller is configured to selectively control the or each auxiliary sub-converter to synthesize an auxiliary voltage component that is in anti-phase with the respective tertiary voltage component.

4 . A voltage source converter according to claim 1 wherein the or each tertiary voltage component is a 2 nd harmonic voltage component, a 4 th harmonic component, an 8 th harmonic component or a 10 th harmonic component.

5 . A voltage source converter according to claim 1 wherein the or each tertiary voltage component is a (3(2n−1)±1) th harmonic voltage component, whereby n is a positive integer multiple.

6 . A voltage source converter according to claim 1 wherein the or each tertiary voltage component has the same frequency as a current component of a current flowing through the corresponding tertiary sub-converter.

7 . A voltage source converter according to claim 1 wherein the controller is configured to selectively control the or each tertiary sub-converter to modify a phase angle of the or each tertiary voltage component relative to a phase angle of a current flowing through the or each tertiary sub-converter.

8 . A voltage source converter according to claim 1 wherein the controller is configured to selectively control the or each tertiary sub-converter to synthesize the or each tertiary voltage component to be in phase with a current component of a current flowing through that tertiary sub-converter.

9 . A voltage source converter comprising first and second DC terminals for connection to a DC electrical network, the voltage source converter further including a plurality of limbs connected between the first and second DC terminals, each limb including:
a phase element including a plurality of switching elements to interconnect the DC electrical network and an AC electrical network; and an auxiliary sub-converter configured to be controllable to act as a waveform synthesizer to modify a first DC voltage presented by the limb to the DC electrical network, wherein the voltage source converter further includes a controller configured to selectively control each auxiliary sub-converter to modify the respective first DC voltage to include at least two auxiliary harmonic components, each auxiliary harmonic component being a positive integer multiple of a 2 nd harmonic component.

10 . A voltage source converter according to claim 9 wherein each auxiliary harmonic component is a 2 nd harmonic component, a 4 th harmonic component, an 8 th harmonic component or a 10 th harmonic component.

11 . A voltage source converter according to claim 9 wherein each limb further includes a tertiary sub-converter configured to be controllable to act as a waveform synthesizer to modify a respective second DC voltage presented to a DC side of the respective phase element, and the controller is configured to selectively control each tertiary sub-converter to synthesize a voltage waveform that includes at least one tertiary harmonic component, the or each tertiary harmonic component being a positive integer multiple of a 6 th harmonic component.

12 . A voltage source converter according to claim 9 wherein each limb further includes a tertiary sub-converter configured to be controllable to act as a waveform synthesizer to modify a second DC voltage presented to a DC side of the corresponding phase element, and the controller is configured to selectively control each tertiary sub-converter to modify the respective second DC voltage into a near-approximation of an offset rectified sinusoidal waveform for presentation to the DC side of the respective phase element when the respective auxiliary sub-converter is controlled to modify the respective first DC voltage to include the auxiliary harmonic components.

13 . A voltage source converter comprising first and second DC terminals for connection to a DC electrical network, the voltage source converter further including at least one limb connected between the first and second DC terminals, the or each limb including:
a phase element including a plurality of switching elements to interconnect the DC electrical network and an AC electrical network; an auxiliary sub-converter configured to be controllable to act as a waveform synthesizer to modify a first DC voltage presented to the DC electrical network; and a tertiary sub-converter connected with the phase element in an electrical block, the auxiliary sub-converter being connected in parallel with the electrical block, the tertiary sub-converter being configured to be controllable to act as a waveform synthesizer to modify a second DC voltage presented to a DC side of the phase element, wherein the voltage source converter further includes a controller configured to selectively control the or each tertiary sub-converter to generate a compensatory DC voltage component for presentation to the DC side of the or the respective phase element so as to compensate for a change in real power and/or reactive power generated or absorbed at an AC side of the or the respective phase element.

14 . A voltage source converter according to claim 13 wherein the controller is configured to selectively control the or each tertiary sub-converter to generate a compensatory DC voltage component for presentation to the DC side of the or the respective phase element so as to compensate for a change in the or the respective second DC voltage caused by the change in real power and/or reactive power generated or absorbed at an AC side of the or the respective phase element.

15 . A voltage source converter according to claim 14 wherein the controller is configured to selectively control the or each tertiary sub-converter to generate a compensatory DC voltage component for presentation to the DC side of the or the respective phase element so as to compensate for a change in the or the respective second DC voltage caused by the change in real power and/or reactive power generated or a

Assignees

• General Electric Technology Gmbh

Inventors

• Jasim Omar Fadhel
• Trainer David Reginald

Classifications

• H02M1/14

  Arrangements for reducing ripples from DC input or output · CPC title

• H02M7/04

  by static converters · CPC title

• H02M1/12 Primary

  Arrangements for reducing harmonics from AC input or output · CPC title

• H02M7/483 Primary

  Converters with outputs that each can have more than two voltages levels · CPC title

• H02M7/4835

  comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage · CPC title