Apparatus for switching a direct current in a pole of a DC voltage network
A DC voltage switch may include: a first node and a second node for series integration into a pole of a DC voltage line; a third node for the other pole of the line; a mechanical switch between the first and second nodes; a pulse-current module in parallel with the switch; four semiconductor switches connected as bridges comprising two series of two semiconductor switches; a pulse-current capacitor in parallel with the two series; and a switchable semiconductor element. The pulse-current module includes three module nodes. Potential points between the semiconductor switches of the two series correspond to the first and second module node and the outer ends of the two series of in each case two of the semiconductor switches are connected in pairs to a fourth module node and a fifth module node and the semiconductor element is between the fifth and third module node.
1. A DC voltage switch comprising:
a first node;
a second node for series integration with the first node into a pole of a DC voltage line;
a third node for connection to the other pole of the DC voltage line;
a mechanical switch arranged between the first node and the second node;
a pulse current module arranged between the first node and the second node and in parallel with the mechanical switch;
wherein the pulse-current module
includes three module nodes, the first module node is connected to the first node and the second module node is connected to the second node and the third module node is connected to the third node;
four semiconductor switches connected as bridges comprising two series of two of the semiconductor switches;
wherein potential points between the semiconductor switches of the two series correspond to the first and second module node and the outer ends of the two series of in each case two of the semiconductor switches are connected in pairs to a fourth module node and a fifth module node;
a pulse current capacitor connected in parallel with the two series of in each case two of the semiconductor switches; and
a switchable semiconductor element between the fifth and third module node.
2. The DC voltage switch as claimed in claim 1 , further comprising:
a first freewheeling diode between the third node and the first node; and
a second freewheeling diode between the third node and the second node.
3. The DC voltage switch as claimed in claim 1 , further comprising a resistor arranged in series with the pulse-current capacitor for load current limitation.
4. The DC voltage switch as claimed in claim 1 , further comprising a plurality of pulse-current modules connected in series with the corresponding first modules nodes and second module nodes and the series is arranged between the first node and second node.
5. The DC voltage switch as claimed in claim 1 , wherein the mechanical switch has an associated switching time of less than 5 ms.
6. The DC voltage switch as claimed in claim 1 , wherein the switchable semiconductor element comprises a thyristor.
7. The DC voltage switch as claimed in claim 1 , further comprising a control device configured to:
open the mechanical switch for isolation of the DC voltage line; and
switch on two of the four semiconductor switches for generating a current pulse in the opposite direction to a current in the DC voltage line.
8. The DC voltage switch as claimed in claim 6 , wherein the control device is further configured to switch on the switchable semiconductor element upon isolation of the DC voltage line.