Hybrid power supply unit

Abstract

The present invention relates to a hybrid mobile power supply device (1) for supplying alternating current to a consumer connection (2). It comprises the consumer connection (2), a generator unit (3) with a generator (13) and a generator switch (14), a battery unit (4) with a battery (5) and a battery switch (21), a first power supply unit (6) with a first power switch (16) and a first power connection (15) to which a three-phase four-wire power supply (7) can be connected, a second power supply unit (8) with a second power switch (23) and a second power connection (22) to which a TN charging network (9) can be connected for charging the battery (5), an AC busbar (11) with a primary busbar section (11.1), a secondary busbar section (11.2) and a coupling switch (12), and a control unit by means of which the switches (12, 14, 16, 21, 23) can be switched. The primary rail section (11.1) and the secondary busbar section (11.2) can be disconnected from each other and connected to each other via the coupling switch (12). The primary busbar section (11.1) has a primary PEN conductor (17). The first power supply unit (6) and the generator unit (3) are connected to the primary busbar section (11.1). The battery unit (4), the second power supply unit (8), and the consumer connection (2) are connected to the secondary busbar section (11.2). The second power supply connection (22) and the secondary busbar section (11.2) can be disconnected from each other and connected to each other via the second power supply switch (23). The control unit (10) is configured to switch the second power supply switch (23) and the coupling switch (12) such that when the second power supply switch (23) is closed, i.e., when the second power supply connection (22) and the secondary busbar section (11.2) are disconnected from each other and connected to each other, the primary busbar section (11.2) is closed.2) are connected to each other on all poles, the coupling switch (12) is open, so that the primary rail section (11.1) and the secondary rail section (11.2) are disconnected from each other on all poles.

Description

The present invention relates to a hybrid, in particular mobile, power supply device for supplying alternating current to a consumer connection. Mobile power supply units are used to temporarily provide consumers with electricity via a consumer connection when the regular power supply is unavailable. The mobile power supply unit, often mounted on a vehicle trailer, can be towed to the site of use by a towing vehicle. A typical use case is supplying power to consumers connected to a local substation while it is undergoing maintenance. During the maintenance work, the power supply to these consumers is ensured via the consumer connection of the mobile power supply unit instead of via the local substation of the generation network. To ensure an uninterrupted power supply even during switchover, the mobile power supply unit has a (first) grid connection for the generation network. A generation network is typically designed as a three-phase alternating current system (L1, L2, L3) with a neutral conductor (N) (three-phase four-wire system). The consumer network provided by the local network station is typically a TN network, i.e. a three-phase alternating current system (L1, L2, L3) with neutral conductor (N) and protective conductor (PE) (five-wire system), in which the neutral conductor and the protective conductor are connected to earth at one point in the system via a so-called PEN bridge. Once the local substation has been disconnected for maintenance, the mobile power supply unit must completely replace the generating network and the local substation. Therefore, for safety reasons, the mobile power supply unit must have a PEN conductor connected to earth. Mobile power supply units are typically equipped with a generator unit powered by an internal combustion engine or a fuel cell. To reduce the combustion engine's pollutant and CO2 emissions and avoid inefficient part-load operation, hybrid power supply units also include a battery. When consumer power demand is low, the combustion engine can be switched off and the required power supplied from the battery. To charge the battery before field deployment, the mobile power supply unit is equipped with a second mains connection for connecting to a charging network. A charging network is typically a TN system and includes a PEN conductor. Therefore, for safety reasons, the PEN conductor of the power supply unit must be removed during the charging process. This is typically done by trained personnel who remove the PEN conductor before charging and reinstall it afterward. German patent application DE 10 2010 000 502 A1 describes a backup power supply system for connection to a power grid and for supplying alternating current to a consumer, comprising a generator and a battery unit. The power grid and the generator can be connected to or disconnected from a conductor of the backup power supply system via contactors provided for this purpose. Against the background of this prior art, the present invention is based on the objective of providing a hybrid, mobile power supply device which is characterized by improved practicality, in particular with regard to simplified operation, improved occupational safety and reliability. This problem is solved by the hybrid mobile power supply device according to the invention for supplying a (three-phase) alternating current at a consumer connection according to claim 1. Particularly preferred embodiments can be found in the dependent claims. The hybrid, in particular mobile, power supply unit comprises: - the consumer connection, - a generator unit with a generator and a generator switch, - a battery unit with a battery and a battery switch, - a first network unit with a first network switch and a first network connection to which a power network, in particular a three-phase four-wire power network, can be connected, - a second network unit with a second network switch and a second network connection to which a charging network, in particular a TN charging network, can be connected to charge the battery, - an AC busbar with a primary busbar section, a secondary busbar section and a coupling switch, wherein the primary busbar section and the secondary busbar section can be disconnected from each other and connected to each other by means of the coupling switch, - a control unit by means of which at least the second network switch and the coupling switch can be switched.wherein: - the primary busbar section has a primary PEN conductor, - the first network unit and the generator unit are connected to the primary busbar section, - the first network connection and the primary busbar section can be disconnected from each other and connected to each other on all poles by the first network switch, - the generator and the primary busbar section can be disconnected from each other and connected to each other on all poles by the generator switch, - the battery unit, the second network unit and the consumer connection are connected to the secondary busbar section, - the battery and the secondary busbar section can be disconnected from each other and connected to each other on all poles by the battery switch, - the second network connection and the secondary busbar section can be disconnected from each other and connected to each other on all poles by the second network switch, and - the control unit is configured to switch the second network switch and the coupling switch in such a manner,that when the second mains switch is closed, i.e., when the second mains connection and the secondary busbar section are connected to each other on all poles, the coupling switch is open, so that the primary busbar section and the secondary busbar section are disconnected from each other on all poles. The synergistic combination of the features according to the invention makes it possible to provide a hybrid mobile power supply unit in which it is possible to switch between two operating modes by opening and closing the coupling switch, so that it is not necessary to remove the PEN bridge by trained personnel to charge the battery and then reinstall it. When the coupling switch is open, the two sections of the AC busbar are completely isolated from each other. The PEN conductor located in the primary busbar section is thus electrically isolated from the secondary busbar section, to which the (TN) charging network is connected via the second power supply unit. The mobile power supply unit is therefore operated in a first operating mode, and the battery can be charged without any problems, without the need to remove the PEN conductor of the power supply unit for safety reasons. If the mobile power supply unit is subsequently disconnected from the (TN) charging network, transported to the deployment site and connected there to a three-phase four-wire generator network via the first network unit, the PEN bridge of the power supply unit can be used immediately without having to be reinstalled beforehand by trained personnel. This eliminates the need for trained personnel to charge the power supply unit's battery. The power supply unit can therefore be charged by laypersons, simplifying its use, preventing errors, and increasing both workplace and operational safety. The following defines and explains some aspects and features of the hybrid mobile power supply unit in more detail. A hybrid power supply unit is a power supply unit which, in addition to a generator unit that can be powered, for example, by an internal combustion engine or a fuel cell, has a battery unit that can be charged by the generator unit and / or whose power can be supplied via the consumer connection. A mobile power supply unit is defined as a power supply unit designed to be transported to a deployment site by a towing vehicle. For this purpose, the mobile power supply unit can, in particular, be mounted on a vehicle trailer. The generator provides (three-phase) alternating current, in particular includes an internal combustion engine or a fuel cell, and can be connected to or disconnected from the primary bus section on all poles by the generator switch. The battery unit comprises the battery, the battery switch, and a bidirectional inverter, which allows the battery to be connected to the secondary section of the AC busbar. A bidirectional inverter is a device capable of converting electrical energy from direct current (DC) to alternating current (AC) and vice versa. The battery switch allows the battery and / or the bidirectional inverter to be connected to or disconnected from the secondary section of the busbar on all poles. A three-phase four-wire power grid is a three-phase alternating current system (L1, L2, L3) with neutral conductor (N) and is also referred to here as a generator (power) grid. A TN network is a three-phase alternating current system (L1, L2, L3) with neutral conductor (N) and protective conductor (PE), in which the neutral conductor and the protective conductor are connected to the earth (earth potential) at one point in the system via a so-called PEN bridge. The AC busbar typically has four conductors (poles): three phase conductors (L1, L2, L3) and a common conductor for the neutral conductor (N) and the protective earth (PE). It is also conceivable that the AC busbar has five conductors (poles): three phase conductors (L1, L2, L3) and a separate neutral conductor (N) and protective earth (PE). All-pole separation or connection of two network sections means the separation or connection of all conductors (poles) of the two network sections. A PEN conductor is a PEN bridge that connects the neutral conductor and the protective conductor and can be connected to the electrical earth, i.e., to the earthing point, the earth potential. An earthing point is a physical point where an electrical conductor is connected to the earth to form an earthing system. The earthing point can be, in particular, a grounding electrode that is driven into the ground to establish an electrical connection to earth potential. According to a first preferred embodiment of the invention, it is provided that the control unit has two measuring devices suitable for detecting the voltage profile in the primary rail section and in the secondary rail section, and that the control unit is configured such that the coupling switch is only closed when the voltage profiles in the primary rail section and in the secondary rail section are synchronous. This allows both sections of the AC busbar to be synchronized before they are connected to each other on all poles by closing the coupling switch. Furthermore, it may be provided that the consumer connection has a residual current device (RCD). A residual current device (RCD), also known as a ground fault circuit interrupter (GFCI), is an electrical safety device designed to protect people from electric shocks caused by fault currents. The RCD continuously monitors the current flow in a section of the electrical network and detects differences between the incoming and outgoing current, indicating a fault current. If a fault current exceeding a predefined threshold is detected, the circuit is interrupted within milliseconds. Furthermore, the hybrid power supply device can advantageously be suitable for supplying alternating current via the first grid connection to a connected power grid, in particular a three-phase four-wire power grid. An embodiment of a hybrid mobile power supply device according to the invention is explained in more detail below with reference to the drawing. Figures 1A-2B show the circuit diagram of the first embodiment in different operating states. The hybrid mobile power supply unit 1 comprises a consumer connection 2, a generator unit 3, a battery unit 4 with a battery 5, a first power supply unit 6 to which a three-phase four-wire power network 7 can be connected, a second power supply unit 8 to which a TN charging network 9 can be connected to charge the battery 5, a control unit 10 and an AC busbar 11 with a primary busbar section 11.1, a secondary busbar section 11.2 and a coupling switch 12. The AC busbar 11 comprises three live phases, a neutral conductor, and a protective conductor. The primary busbar section 11.1 and the secondary busbar section 11.2 can be disconnected from each other and connected to each other on all poles by the coupling switch 12. The generator unit 3 comprises a generator 13 with an internal combustion engine and a generator switch 14. The generator 13 provides three-phase alternating voltage and can be connected to or disconnected from the primary bus section 11.1 of the AC bus 11 via the generator switch 14. The first network unit 6 comprises a first network connection 15 and a first network switch 16. The three-phase, four-wire power network 7 can be connected to the first network connection 15. The first network switch 16 allows the first network connection 15 and the primary busbar section 11.1 to be disconnected from each other or connected to each other on all poles. The hybrid power supply unit 1 is suitable for supplying alternating current via the first network connection 15 to the three-phase, four-wire power network 7 connected there. The primary busbar section 11.1 has a primary PEN conductor 17 which connects the neutral conductor and the protective conductor of the AC busbar 11 and can be connected to a first earthing point 18. The battery unit 4 comprises the (of course rechargeable) battery, a bidirectional inverter 20 and a battery switch 21. The battery switch 21 allows the bidirectional inverter 20 to be connected to or disconnected from the secondary rail section 11.2 on all poles. The second power supply unit 8 comprises a second power connection 22 and a second power switch 23. The TN charging network 9 can be connected to the second power connection 22 to charge the battery 5 of the battery unit 4. The second power switch 23 allows the second power connection 22 and the secondary busbar section 11.2 to be disconnected from each other or connected to each other on all poles. Consumer connection 2 is connected to the secondary busbar section 11.2 and provides a TN network, comprising three AC phases, a neutral conductor, and a protective conductor. Consumer connection 2 also includes a residual current device (RCD) 24. A consumer 25 can be connected to consumer connection 2. The control unit 10 is suitable for switching the switches, namely the generator switch 14, the battery switch 21, the coupling switch 12, the second mains switch 23 and the first mains switch 16, and is arranged such that when the second mains switch 23 is closed, i.e. when the second mains connection 22 and the secondary busbar section 11.2 are connected to each other on all poles, the coupling switch 12 is open, so that the primary busbar section 11.1 and the secondary busbar section 11.2 are disconnected from each other on all poles. Fig. 1A shows the first embodiment of the hybrid mobile power supply unit 1 in “charging mode”, Fig. 1B in “supply mode”. In charging mode according to Fig. 1A, the TN charging network 9 is connected to the second network connection 22. The TN charging network 9 has a PEN bridge 26, which connects the protective conductor and the neutral conductor to earth potential via the second earthing point 27. The second mains switch 23 and the battery switch 21 are closed, so that the battery 5 can be charged via the bidirectional inverter 20 through the TN charging network 9. The TN charging network 9 and the inverter 20 are connected to the secondary busbar section 11.2 of the AC busbar 11 via all poles. The control unit 10 is configured such that when the second mains switch 23 is closed, the coupling switch 12 is open. The primary busbar section 11.1 and the secondary busbar section 11.2 are thus completely isolated from each other. While in the area of ​​the primary busbar section 11.1, the neutral conductor and the protective conductor are connected to each other via the primary PEN bridge 17, this is not the case in the disconnected secondary busbar section 11.2. The charging operation shown in Fig. 1A occurs, for example, when the mobile power supply unit 1 is being prepared for an upcoming deployment on factory premises by charging the battery 5 of the power supply unit 1. The TN charging network 9 can be connected to the second mains connection 22, in particular via a CEE plug, an IEC plug, or a Type 2 plug. At the deployment site, the power supply unit 1 is switched to grid-parallel operation, as shown in Fig. 1B. The second grid connection 22 is no longer connected to a charging network, and the second grid switch 23 is open. However, the three-phase, four-wire power grid 7 (generation grid) is now connected to the first grid connection 15. The first mains switch 16, the generator switch 14, the battery switch 21, and the coupling switch 12 are closed. The generator 13 supplies synchronized alternating current to the generating network 7. Depending on the control by the control unit 10, the battery 5 can absorb power and be charged, or deliver power and be discharged. Consumers 25 are connected to the consumer terminal 2. The primary PEN conductor 17 is connected to the earth potential via the first earthing point 18, so that a TN network can be provided to the consumers 25 at the consumer connection 2. The coupling switch 12 can also be used advantageously when the power supply unit 1 supplies consumers in island operation according to Fig. 2A and Fig. 2B. As shown in Fig. 2A, the loads 25 connected to the load terminal 2 are supplied with alternating current via the battery 5 and the inverter 20. If the generator unit 3 is now to take over the power supply to the loads 25 (at least partially), the generator unit 3 must be connected to the load terminal 2 by closing the coupling switch 12. For safety reasons, the control unit 10 is designed to close the coupling switch 12 only when the voltage waveforms in the primary bus section 11.1 and in the secondary bus section 11.2 are synchronized. For this purpose, the control unit 10 has two measuring devices suitable for detecting the voltage waveforms in the primary bus section 11.1 and in the secondary bus section 11.2. Reference symbol list 1 Power supply unit 2 Consumer connection 3 Generator unit 4 Battery unit 5 Battery 6 First power supply unit 7 Three-phase four-wire power network 8 Second power supply unit 9 TN charging network 10 Control unit 11 AC busbar 11.1 Primary busbar section 11.2 Secondary busbar section 12 Coupling switch 13 Generator 14 Generator switch 15 First network connection 16 First network switch 17 Primary PEN conductor 18 First earthing point 20 Bidirectional converter 21 Battery switch 22 Second network connection 23 Second network switch 24 Residual current circuit breaker 25 Consumer 26 PEN bridge 27 Second earthing point

Claims

Hybrid power supply unit (1) for supplying alternating current to a consumer connection (2) comprising: - the consumer connection (2), - a generator unit (3) with a generator (13) and a generator switch (14), - a battery unit (4) with a battery (5) and a battery switch (21), - a first network unit (6) with a first network switch (16) and a first network connection (15) to which a power network can be connected, - a second network unit (8) with a second network switch (23) and a second network connection (22) to which a charging network can be connected in order to charge the battery (5), - an AC busbar (11) with a primary busbar section (11.1), a secondary busbar section (11.2) and a coupling switch (12), and - a control unit (10) by means of which at least the second network switch (23) and the coupling switch (12) can be switched, wherein - the primary busbar section (11.1) and the secondary busbar section (11.2)2) are all-pole disconnectable and connectable via the coupling switch (12),- the primary busbar section (11.1) has a primary PEN conductor (17),- the first network unit (6) and the generator unit (3) are connected to the primary busbar section (11.1),- the first network connection (15) and the primary busbar section (11.1) are all-pole disconnectable and connectable via the first network switch (16),- the generator (13) and the primary busbar section (11.1) are all-pole disconnectable and connectable via the generator switch (14),- the battery unit (4), the second network unit (8) and the consumer connection (2) are connected to the secondary busbar section (11.2),- the battery (5) and the secondary busbar section (11.2) are all-pole disconnectable and connectable via the battery switch (21),- the second network connection (22) and the secondary rail section (11.2) are all-pole disconnectable and connectable by the second mains switch (23), and the control unit (10) is configured to switch the second mains switch (23) and the coupling switch (12) such that when the second mains switch (23) is closed, i.e. when the second mains connection (22) and the secondary busbar section (11.2) are all-pole connected, the coupling switch (12) is open, so that the primary busbar section (11.1) and the secondary busbar section (11.2) are all-pole disconnected. Hybrid power supply device (1) according to claim 1, wherein the control unit (10) has two measuring devices suitable for detecting the voltage profile in the primary rail section (11.1) and in the secondary rail section (11.2), and the control unit (10) is configured such that the coupling switch (12) is closed only when the voltage profiles in the primary rail section (11.1) and in the secondary rail section (11.2) are synchronous. Hybrid power supply device (1) according to one of the preceding claims, wherein the consumer connection (2) has a residual current circuit breaker (24). Hybrid power supply device (1) according to one of the preceding claims, suitable for supplying alternating current via the first network connection (15) to a power grid connected therein, in particular a three-phase four-wire power grid (7). Hybrid power supply device (1) according to one of the preceding claims, wherein the power supply device (1) is mobile. Hybrid power supply device (1) according to one of the preceding claims, wherein the power grid is a three-phase four-wire power grid (7). Hybrid power supply device (1) according to one of the preceding claims, wherein the charging network is a TN charging network (9).

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