METHOD AND ARRANGEMENT TO REVERSE THE POWER FLOW OF A DIRECT CURRENT POWER TRANSMISSION SYSTEM
First Claim
1. A method to reverse a power flow between a first and a second converter station which are coupled to each other via a direct current link, where each converter station comprises a first or second line commutated converter, respectively, the method comprising:
- operating the first converter as a rectifier before power reversal and as an inverter after power reversal,operating the second converter as an inverter before power reversal and as a rectifier after power reversal,controlling in the first station a direct current,controlling in the second station an extinction angle of the second converter or controlling a direct voltage,carrying out during power reversal a change in the first station from control of the direct current to control of the extinction angle of the first converter or to control of the direct voltage, which is performed in synchronization with a change in the second station from control of the extinction angle of the second converter or from control of the direct voltage to control of the direct current.
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Accused Products
Abstract
A direct current power transmission system includes a first and a second converter station that are coupled to each other via a direct current link. Each converter station includes a first or second line commutated converter, respectively. Before power reversal the first converter is operated as a rectifier and the direct current is controlled in the first station, while the second converter is operated as an inverter and in the second station the extinction angle of the second converter or the direct voltage is controlled. After power reversal, the first converter is operated as an inverter and the second converter as a rectifier. During power reversal a change is carried out in the first station from control of the direct current to control of the extinction angle of the first converter or to control of the direct voltage, which is performed in synchronization with a change in the second station from control of the extinction angle of the second converter or from control of the direct voltage to control of the direct current.
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Citations
13 Claims
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1. A method to reverse a power flow between a first and a second converter station which are coupled to each other via a direct current link, where each converter station comprises a first or second line commutated converter, respectively, the method comprising:
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operating the first converter as a rectifier before power reversal and as an inverter after power reversal, operating the second converter as an inverter before power reversal and as a rectifier after power reversal, controlling in the first station a direct current, controlling in the second station an extinction angle of the second converter or controlling a direct voltage, carrying out during power reversal a change in the first station from control of the direct current to control of the extinction angle of the first converter or to control of the direct voltage, which is performed in synchronization with a change in the second station from control of the extinction angle of the second converter or from control of the direct voltage to control of the direct current. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An arrangement to reverse a power flow between a first and a second converter station which are coupled to each other via a direct current link, where each converter station comprises a first or second line commutated converter, the arrangement comprising:
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a first control unit adapted to control the operation of the first station and a second control unit adapted to control the operation of the second station, wherein the first control unit is adapted to before power reversal operate the first converter as a rectifier and to control the direct current and the second control unit is adapted to before power reversal operate the second converter as an inverter and to control the extinction angle in the second converter or the direct voltage, the first control unit is adapted to after power reversal operate the first converter as an inverter and the second control unit is adapted to after power reversal operate the second converter as a rectifier, the first control unit is adapted to during power reversal change from control of the direct current to control of the extinction angle of the first converter and the second control unit is adapted to during power reversal change from control of the extinction angle of the second converter or from control of the direct voltage to control of the direct current, while the first and the second control unit are adapted to perform the changes during power reversal synchronized with each other. - View Dependent Claims (11, 12, 13)
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Specification