Patent ID: 12217919

DETAILED DESCRIPTION

An electrical network, according to at least one example embodiment of the invention, has feed-in devices, loads and a distribution network, which is arranged therebetween and has at least one busbar and at least one apparatus for opening or closing a DC circuit. The apparatus comprises:an electrical switch for opening or closing the DC circuit,a fault current detection device,a tripping unit,a pre-charging apparatus, anda control unit for automatically closing the electrical switch after pre-charging,

wherein, if a fault current is detected by the fault current detection device, the electrical switch opens the DC circuit via the tripping unit, and the pre-charging apparatus restores the voltage on the busbar before the electrical switch is closed, wherein a plurality of loads can each individually be electrically disconnected via an electromechanical switch, and a plurality of loads can be electrically disconnected as a group via the at least one apparatus.

An electrical network, according to at least one example embodiment of the invention, has an advantage that the number of electrical switches, for example of solid-state switches, can be reduced, and both costs and power losses can thus be reduced. The fault current can be interrupted quickly, within 10 μs (microseconds), wherein the fault itself can be isolated more slowly using conventional electromechanical switches. After the loads are very quickly disconnected from the feed-in devices in the event of a fault, the actual isolation of the fault takes place via the electromechanical switches at a reduced fault current, or even at zero current in certain applications. As a result, the proposed electromechanical switches can have much smaller dimensions in comparison with switches in conventional networks. A further advantage is that the voltage on the busbar200is maintained and the rest of the system which is unaffected by the fault remains operable. Recharging the group is a much faster process than recharging the entire system.

In one configuration, the electrical switch of the at least one apparatus is a semiconductor switch.

In a further configuration, the at least one apparatus further comprises a communication unit.

The at least one apparatus may further comprise a control unit for a switch-on transient. This unit can suppress the switch-on transient.

In a further configuration, the pre-charging apparatus restores the voltage on the busbar after a first waiting time. Alternatively, the pre-charging apparatus can restore the voltage on the busbar after receiving a command. The pre-charging apparatus can receive this command via the communication unit.

In one configuration, the pre-charging apparatus interrupts the pre-charging operation if the voltage on the busbar does not rise, which indicates a fault that still exists.

In a further configuration, the control unit for automatically closing the electrical switch automatically closes said switch after a second waiting time. Alternatively, the control unit for automatically closing the electrical switch closes said switch after a voltage on the busbar above a threshold value has been restored.

In a further configuration, the electrical network is a DC circuit.

FIG.2shows an electrical network1000, according to at least one example embodiment of the invention. This network1000is provided with feed-in devices1010;1011;1012;1013;1014;1015and loads1050;1051;1052;1053;1054;1055;1056;1057and a distribution network2000, which is arranged therebetween. The distribution network2000comprises busbars200;200′;200″, to which the feed-in devices1010;1011;1012;1013;1014;1015and loads1050;1051;1052;1053;1054;1055;1056;1057are electrically connected.

The distribution network2000comprises both apparatuses2010;2011for opening or closing a DC circuit and also electromechanical switches2020;2021;2022;2023;2024;2025. Protection devices2050;2051;2052;2053;2054;2055;2056;2057;2058;2059are furthermore included in the distribution network2000.

A plurality of loads1050;1051;1052;1053;1054;1055;1056;1057of the electrical network1000, according to at least one example embodiment of the invention, form a respective group. For example, the loads1050;1051;1052form a first group. A second group is formed by the loads1053;1054;1055.

In the event of a fault, each of these loads1050;1051;1052;1053;1054;1055can be disconnected from the distribution network2000via an electromechanical switch2020;2021;2022,2023;2024;2025. The electromechanical switch2020is associated with the load1050, the electromechanical switch2021is associated with the load1051, and the electromechanical switch2022is associated with the load1052. The electromechanical switches2020;2021;2022are electrically connected to a first busbar200′, which in turn is electrically connected to an apparatus2010for opening or closing a DC circuit by the busbar200of the distribution network2000.

The same applies to the second group of loads1053;1054;1055. The load1053is connected to the second busbar200″ via the electromechanical switch2023. The load1054is connected to the second busbar200″ by the electromechanical switch2024, and the load1055is also connected to the second busbar200″ by the electromechanical switch2025. This second busbar200″, in turn, is electrically connected to an apparatus2011for opening or closing a DC circuit by the busbar200of the distribution network2000.

The mode of operation of the electrical network1000according to at least one example embodiment of the invention, will be discussed on the basis of an exemplary fault in the connection between the load1050and the electromechanical switch2020. This fault is detected by the apparatus2010for opening or closing a DC circuit and also by the electromechanical switch2020. On account of the faster trip behavior of the apparatus2010for opening or closing a DC circuit, the apparatus2010is opened immediately and thus prevents any further flow of current in the direction of the fault from the other feed-in devices.

Meanwhile, the electromechanical switch2020also trips in order to isolate the fault. A fast-switching electromechanical switch2020, which has a switching time in the region of a few ms (milliseconds), is preferred for this purpose. The apparatus2010for opening or closing a DC circuit can then be switched on again either after a fixedly defined period of time or in response to a command, which indicates that the fault has been eliminated.

The apparatus2010for opening or closing a DC circuit can recharge the first busbar200′ via the pre-charging apparatus140and then be switched on again. If the apparatus2010for opening or closing a DC circuit still detects a fault current, this apparatus2010can open once again and remain open.

An advantage of a method, according to at least one example embodiment of the invention, is that the feed-in devices and loads in the remaining part of the electrical network1000, which are not affected by the fault, can continue to be operated and do not exhibit any failure. The loads in the group with the fault exhibit a brief failure, depending on the switch-off speed of the associated electromechanical switch and the time required for switching the apparatus for opening or closing a DC circuit on again. The downtime should be limited to a few tens of ms (milliseconds). Uninterruptible power supplies (UPSs) can be provided for very sensitive loads, for which the current should not be interrupted. Other loads should be able to withstand these brief downtimes, since these downtimes are already standard.

FIG.3illustrates an example embodiment of the apparatus2010;2011for opening or closing a DC circuit, which has at least one busbar200;200′;200″. The apparatus2010;2011additionally comprises an electrical switch110for opening or closing the DC circuit, a fault current detection device120, a tripping unit130and a pre-charging apparatus140, wherein if a fault current is detected by the fault current detection device120, the electrical switch110opens the DC circuit via the tripping unit130, and wherein the pre-charging apparatus140restores the voltage on the busbar200;200′;200″ before the electrical switch110is closed. For automatic closing, the apparatus2010;2011is further provided with a control unit150, which can automatically close the electrical switch110after pre-charging.

The electrical switch110of the apparatus2010;2011may, for example, be a solid-state switch or a semiconductor switch. For example, it may be a silicon (Si)-based, silicon carbide (SiC)-based or gallium nitride (GaN)-based semiconductor switch.

As is illustrated inFIG.3, the apparatus2010;2011may further comprise a communication unit180. This communication unit180can receive commands from a superordinate control unit and/or coordinate apparatuses2010;2011arranged in a distribution network2000.

The apparatus2010;2011may further comprise a control unit160for a switch-on transient. For example, the control unit160can suppress the switch-on transient.

The apparatus2010;2011may further comprise a measurement unit170for measuring current and/or voltage values.

The pre-charging apparatus140may restore the voltage on the busbar200;200′;200″ after a first waiting time. Alternatively, the pre-charging apparatus140restores the voltage on the busbar200;200′;200″ after receiving a command. The command can be given to the pre-charging apparatus140via the communication unit180.

The control unit150for automatically closing the electrical switch110may automatically close said switch after a second waiting time. The control unit150for automatically closing the electrical switch110may also close said switch after a voltage on the busbar200;200′;200″ above a threshold value has been restored. For this purpose, the control unit150for automatically closing an electrical switch110may receive the voltage values on the busbar200;200′;200″ from the measurement unit170. If the voltage on the busbar200;200′;200″ does not rise during the pre-charging operation, this indicates that the fault has not yet been fixed. In this case, the pre-charging operation has to be interrupted.

The various components of the apparatus100, according to at least one example embodiment of the invention, are supplied with electrical energy via the power supply190. The power supply190may be external or internal.