HVDC series current source converter
View Patent ↗A multilevel current source converter (CSC) for controlling electrical power transmission in a high voltage direct current (HVDC) transmission system includes an alternating current (AC) side for input/output of AC to/from the CSC; a direct current (DC) side for input/output of DC to/from the CSC; and a plurality of modular CSC cells connected in parallel with each other between the AC side and the DC side of the CSC, each modular cell comprising a plurality of switches. The CSC is configured for being connected in series with an HVDC transmission line and for injecting a voltage in series with the HVDC transmission line at the DC side of the CSC.
1. A multilevel current source converter, CSC, for controlling electrical power transmission in a high voltage direct current, HVDC, transmission system, the CSC comprising:
an alternating current, AC, side for input/output of AC to/from the CSC;
a direct current, DC, side for input/output of DC to/from the CSC;
a plurality of modular CSC cells connected in parallel with each other between the AC side and the DC side of the CSC, each modular cell comprising a plurality of switches; and
a thyristor diverter comprising a plurality of thyristors at the DC side of the CSC and connected to the plurality of modular CSC cells,
wherein the CSC is configured for being connected in series with an HVDC transmission line and for injecting a voltage in series with the HVDC transmission line at the DC side of the CSC, and
wherein the thyristor is configured to allow the CSC to inject the voltage in series with the HVDC transmission line regardless of the direction in which a current flows in said HVDC transmission line.
2. The CSC of claim 1 , wherein the thyristor diverter is an H-bridge converter.
3. The CSC of claim 1 , wherein the plurality of switches have bi-directional voltage blocking and unidirectional current conducting properties.
4. The CSC of claim 1 , wherein the plurality of switches each comprises a forced commutated thyristor, an insulated-gate bipolar transistor, IGBT, with series diode, a reverse blocking integrated gate-commutated thyristor, IGCT, or a reverse blocking IGBT, RBIGBT.
5. The CSC of claim 1 , wherein the AC side is configured for input of three phase AC, and wherein each modular CSC cell comprises six switch positions, two per AC phase.
6. The CSC of claim 1 , wherein the AC side is configured for input of single phase AC, and wherein each modular CSC cell comprises four switch positions.
7. The CSC of claim 6 , wherein the CSC comprises three CSC parts configured to be connected in parallel or in series with each other, each of the three CSC parts being configured for single phase AC input, to form a CSC with three single phase CSC parts in parallel or series with each other, one for each phase of a three phase AC supply.
8. The CSC of claim 1 , wherein each modular CSC cell comprises a reactor upstream of the plurality of switches and a reactor downstream of the plurality of switches.
9. The CSC of claim 2 , wherein the plurality of switches have bi-directional voltage blocking and unidirectional current conducting properties.
10. The CSC of claim 2 , wherein the plurality of switches each comprises a forced commutated thyristor, an insulated-gate bipolar transistor, IGBT, with series diode, a reverse blocking integrated gate-commutated thyristor, IGCT, or a reverse blocking IGBT, RBIGBT.
11. The CSC of claim 2 , wherein the AC side is configured for input of three phase AC, and wherein each modular CSC cell comprises six switch positions, two per AC phase.
12. The CSC of claim 2 , wherein the AC side is configured for input of single phase AC, and wherein each modular CSC cell comprises four switch positions.
13. The CSC of claim 2 , wherein each modular CSC cell comprises a reactor upstream of the plurality of switches and a reactor downstream of the plurality of switches.
14. The CSC of claim 3 , wherein the plurality of switches each comprises a forced commutated thyristor, an insulated-gate bipolar transistor, IGBT, with series diode, a reverse blocking integrated gate-commutated thyristor, IGCT, or a reverse blocking IGBT, RBIGBT.
15. The CSC of claim 3 , wherein the AC side is configured for input of three phase AC, and wherein each modular CSC cell comprises six switch positions, two per AC phase.
16. The CSC of claim 3 , wherein the AC side is configured for input of single phase AC, and wherein each modular CSC cell comprises four switch positions.
17. The CSC of claim 4 , wherein the AC side is configured for input of three phase AC, and wherein each modular CSC cell comprises six switch positions, two per AC phase.
18. The CSC of claim 4 , wherein the AC side is configured for input of single phase AC, and wherein each modular CSC cell comprises four switch positions.
19. A high voltage direct current, HVDC, power transmission system comprising at least one HVDC transmission line extending between two AC to DC converter stations, the HVDC power transmission system further comprising a multilevel current source converter, CSC, for controlling electrical power transmission in the HVDC transmission line, the CSC comprising:
an alternating current, AC, side connected to an AC supply for input/output of AC to/from the CSC;
a direct current, DC, side connected to the HVDC transmission line for input/output of DC to/from the CSC;
a plurality of modular CSC cells connected in parallel with each other between the AC side and the DC side of the CSC, each modular cell comprising a plurality of switches; and
a thyristor diverter comprising a plurality of thyristors at the DC side of the CSC and connected to the plurality of modular CSC cells,
wherein the CSC is configured for being connected in series with an HVDC transmission line and for injecting a voltage in series with the HVDC transmission line at the DC side of the CSC, and
wherein the thyristor is configured to allow the CSC to inject the voltage in series with the HVDC transmission line regardless of the direction in which a current flows in said HVDC transmission line.
20. A method for controlling electrical power transmission in a high voltage direct current, HVDC, transmission line in an HVDC transmission system, the method comprising the steps of:
providing a current source converter, CSC, comprising:
an alternating current, AC, side for input/output of AC to/from the CSC,
a direct current, DC, side for input/output of DC to/from the CSC, and
a plurality of modular CSC cells connected in parallel with each other between the AC side and the DC side of the CSC, each modular cell comprising a plurality of switches;
connecting the CSC in series with the HVDC transmission line; and
injecting a positive voltage from the CSC in series with the HVDC transmission line to reduce current flow in the line, and/or
injecting a negative voltage from the CSC in series with the HVDC transmission line to increase current flow in the line, where the voltage is allowed, through the use of a thyristor diverter, to be inject in series with the HVDC transmission line regardless of in which direction a current flows in said HVDC transmission line.