Converter connection with a balancing circuit
First Claim
1. A converter connection for conversion between alternating voltage and direct voltage, especially at high-voltage direct current, for connection to at least one power network having a neutral pole and at least one pole energized by direct voltage in relation to the neutral pole, said converter connection comprising a voltage-source converter with two direct-voltage terminals, connected to an alternating-voltage network without an intermediate separate winding transformer, a control device for control of said converter and a capacitor connected between said direct-voltage terminals, and at least one of the direct-voltage terminals of the converter is connected by means of an electric pole conductor to at least one of the poles of the power network energized by direct voltage, two valves mutually series-connected at a common point of connection, each of said valves comprising a gate turn-off semiconductor valve and a diode valve connected thereto in anti-parallel connection, said series connection being connected to said direct-voltage terminals, and a reactor with an essentially inductive impedance, with a first terminal connected to said connection point and a second terminal which communicates with said neutral pole in an electrically conducting connection, the control device generating control signals to said gate turn-off semiconductor valves in such a way that the time-average value of the voltage at said connection point becomes substantially equal to the average value of the voltage which occurs across the two terminals of the capacitor.
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Accused Products
Abstract
A converter connection for conversion between alternating voltage and direct voltage, for connection to a power network (DCN) having a neutral pole (P0) and at least one pole (P+,P-) energized by direct voltage in relation to the neutral pole, comprises a voltage-source converter (VC) with two direct-voltage terminals (DP, DM). At least one of the direct-voltage terminals of the converter is connected by means of an electric pole conductor (W1, W12, W11, W21, W2) to at least one of the poles of the power network which are energized by direct voltage. The converter connection further comprises two valves (V7, V8) mutually series-connected at a common point of connection (J), each of said valves comprising a gate turn-off semiconductor valve (T1) and a diode valve (D1) connected thereto in anti-parallel connection, said series connection being connected between the direct-voltage terminals of the converter, and a reactor (SL) with a first terminal (T1) connected to the connection point and a second terminal (T2) which communicates with the neutral pole in an electrically conducting connection. The converter connection may be accommodated in a converter station (SR1 and SR2, respectively) included in an installation for transmission of high-voltage direct current. (FIG. 2)
15 Citations
7 Claims
- 1. A converter connection for conversion between alternating voltage and direct voltage, especially at high-voltage direct current, for connection to at least one power network having a neutral pole and at least one pole energized by direct voltage in relation to the neutral pole, said converter connection comprising a voltage-source converter with two direct-voltage terminals, connected to an alternating-voltage network without an intermediate separate winding transformer, a control device for control of said converter and a capacitor connected between said direct-voltage terminals, and at least one of the direct-voltage terminals of the converter is connected by means of an electric pole conductor to at least one of the poles of the power network energized by direct voltage, two valves mutually series-connected at a common point of connection, each of said valves comprising a gate turn-off semiconductor valve and a diode valve connected thereto in anti-parallel connection, said series connection being connected to said direct-voltage terminals, and a reactor with an essentially inductive impedance, with a first terminal connected to said connection point and a second terminal which communicates with said neutral pole in an electrically conducting connection, the control device generating control signals to said gate turn-off semiconductor valves in such a way that the time-average value of the voltage at said connection point becomes substantially equal to the average value of the voltage which occurs across the two terminals of the capacitor.
- 5. An installation for transmission of high-voltage direct current, comprising at least a first and a second converter station, and a common dc connection, at least the first converter station comprising a voltage-source converter with two direct-voltage network terminals connected to a first alternating-voltage network without an intermediate separate winding transformer, a control device for control of said converter and a capacitor connected between said direct-voltage terminals, and the second converter station is connected to a second alternating-voltage network and exhibits a neutral pole and at least one pole energized by direct voltage in relation to the neutral pole, and at least one of the direct-voltage terminals of the converter being connected by means of a first electric pole conductor to at least one of the poles of the second converter station energized by direct voltage, at least the first converter station further comprises two valves mutually series-connected at a common point of connection, each of said valves comprising a gate turn-off semiconductor valve and a diode valve connected thereto in anti-parallel connection, said series connection being connected between said direct-voltage terminals, and a reactor with an essentially inductive impedance, with a first terminal connected to said connection point and a second terminal which communicates with the neutral pole of the second converter station in an electrically conducting connection, the control device generating control signals to said gate turn-off semiconductor valves in such a way that the time-average value of the voltage at said connection point becomes substantially equal to the average value of a voltage which occurs across the two terminals of the capacitor.
Specification