Overcurrent protection device for protecting consumers arranged in a direct current electrical network

Abstract

The invention relates to an overcurrent protection device for protecting a consumer (11, 12; 13, 14) arranged in a DC voltage network (1), wherein the consumer (11, 12; 13, 14) is coupled via the overcurrent protection device (11S, 13S) to a supply bus (10V) which is connected or connectable to a supply potential of the DC voltage network (1). The overcurrent protection device (11S, 13S) is designed to determine a current trigger value on the basis of a detected value of a current (I 11 , I 13 ) flowing through the overcurrent protection device (11S, 13S) and on the basis of a current-dependent trigger characteristic curve associated with the consumer (11, 12; 13, 14), to compare the current trigger value with a previously determined threshold value, and to trigger or not trigger the overcurrent protection device in dependence on the result of the comparison. In the trigger characteristic curve, the current is taken into account together with a first or a second coefficient in dependence on the direction of the current.

Description

Technical Field

[0001] The present invention relates to an overcurrent protection device for protecting power consumers arranged in a DC power grid, a DC power grid, and a method for operating the overcurrent protection device and the DC power grid. Background Technology

[0002] Load devices powered by a direct current (DC) grid are particularly useful in industrial applications. The advantage of powering load devices from a DC grid lies in the ability to respond flexibly and robustly to fluctuating grid quality and energy supply through smart grid control and integrated memory. In particular, renewable energy generators, such as battery storage devices and / or photovoltaic equipment, can be easily integrated into the DC grid. Here, conversion losses from AC to DC voltage can be prevented. Energy savings are achieved through the possibility of buffering braking energy (e.g., from the drive unit of the generator).

[0003] Energy distribution in a DC grid proceeds similarly to that in an AC grid used to date. In a tree-like DC grid, the current intensity and the required cable cross-section gradually decrease from the power source or supply bus to the feeder and the consumer. With each change in conductor cross-section, i.e., after each branch, a controlled overcurrent protection device is typically installed, which quickly shuts off if an overcurrent is detected in the subsequent conductor branch. Overcurrents in conductor branches occur not only when there is a fault in the conductor branch, but also when the consumers in different conductor branches differ significantly, for example, when one consumer enters generator operation and temporarily feeds current into another conductor branch. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an overcurrent protection device and method for operation in a DC power grid, which is functionally and / or structurally improved in terms of its protection function. Furthermore, the technical problem to be solved by the present invention is to provide a DC power grid having such an overcurrent protection device and a method for operating the DC power grid, which is functionally and / or structurally improved.

[0005] The aforementioned technical problems are solved by the overcurrent protection device according to the present invention, the DC power grid according to the present invention, the method for operating the overcurrent protection device according to the present invention, the computer program product according to the present invention, the method for operating the DC power grid according to the present invention, and the computer program product according to the present invention. The present invention also provides advantageous design solutions.

[0006] According to a first aspect of the invention, an overcurrent protection device is provided for protecting power consumers arranged in a DC power grid. The power consumer is, in particular, one or more capacitive power consumers. Such a capacitive power consumer is, for example, an inverter that generates a three-phase voltage or at least one AC voltage from a voltage supplied by the DC power grid to a load (e.g., a motor). In addition to several switching elements, such an inverter typically has one or more capacitors for its operation.

[0007] In a DC power grid, power consumers are coupled to a power supply bus via overcurrent protection devices. This power supply bus is connected to, or can be connected to, the power supply potential of the DC power grid. Therefore, the power supply bus can be directly connected to the power supply potential without the need for an intermediate connection of additional electronic components. Alternatively, the power supply bus can be connected to the power supply potential via additional electronic components, particularly controllable switching elements. The presence of a controllable switching element between the power supply bus and the power supply potential allows for the separation of the power supply bus from the power supply potential.

[0008] Overcurrent protection devices are controllable overcurrent protection devices that can disconnect power consumers from the power supply bus in the event of an overcurrent. For this purpose, overcurrent protection devices may include controllable switching elements, particularly power electronic components. To detect overcurrent, the overcurrent protection device preferably has a device capable of detecting the current value.

[0009] The overcurrent protection device is configured to determine the current trigger value based on a detected value of the current flowing through the overcurrent protection device and a current-related trigger characteristic curve associated with the power consumer. The current trigger value is a calculated value determined based on the detected value representing the current flowing through the overcurrent protection device and the current-related trigger characteristic curve. Therefore, the current trigger value represents a measure of the thermal load on the system related to the current flowing through the overcurrent protection device and thus through the power consumer to be protected.

[0010] The current trigger value is compared with a previously determined threshold. The previously determined threshold represents the triggering criterion. The overcurrent protection device then triggers or does not trigger based on the comparison result. For example, if the calculated current trigger value increases with the increase of the current flowing through the overcurrent protection device, the overcurrent protection device triggers when the previously determined threshold is exceeded, thereby electrically isolating the power consumer from the power supply bus. The overcurrent protection device will not trigger as long as the current trigger value does not exceed the previously determined threshold. The previously determined threshold can be determined, for example, by experimentation or by numerical determination. Here, the previously determined threshold can be permanently stored in the memory of the overcurrent protection device. The previously determined threshold is, for example, selected such that it is a pre-given percentage value above the trigger value generated at rated current.

[0011] Here, in the trigger characteristic curve, the current is considered, or processed, along with a first or second coefficient, depending on the current direction. This consideration of the current's direction allows for weighting using the first and second coefficients, thus better mapping the thermal processes in the overcurrent protection device. Consequently, it offers higher availability at the same protection level compared to safety fuses used to date.

[0012] By considering the current along with a first or second coefficient in the trigger characteristic curve based on the current direction, different current trigger values ​​are generated depending on the current direction. Thus, for example, the cooling effect on power consumption caused by the current direction can be reliably considered. The first and second coefficients are determined, for example, through experimentation or simulation. The first and second coefficients are typically different.

[0013] According to a suitable design, an overcurrent protection device includes a controllable switching element and a current measuring device connected in series therewith. The current measuring device detects the magnitude of the current flowing through the controllable switching element during the on-state of the controllable switching element and provides said magnitude as a detected value. According to this design, the overcurrent protection device itself includes a current measuring device that determines and provides the detected value required to determine the current trigger value. In another design, the current value and the detected value may also be provided by a current measuring device external to the overcurrent protection device. To accurately detect the direction of current flowing through the power consumer, the current measuring device may include a Hall effect sensor.

[0014] Another suitable design scheme specifies that the first and / or second coefficients are parameterized or can be parameterized based on the power consumption to be protected. The first and / or second coefficients can be determined based on the type and / or function and / or power rating of the power consumption for the current-related triggering characteristic curve associated with the power consumption. Typically, the first and second coefficients have different absolute values. However, in some cases, the first and second coefficients can also have the same absolute value, thus the current triggering value is the same regardless of the direction of current flow through the power consumption.

[0015] Another suitable design scheme specifies that the first and / or second coefficients are parameterized or can be parameterized based on the trend of the trigger characteristic curve. For example, a trigger characteristic curve individually determined for the corresponding power consumption can be selected based on the type and / or function and / or rated power. For example, the trigger characteristic curve can be based on linear or quadratic consideration of the current flowing through the power consumption. For example, some power consumptions have trigger characteristic curves that are quadratically dependent on the current flowing through them, while others have trigger characteristic curves that take into account a linear dependence on the current.

[0016] Furthermore, it is preferable that the previously determined threshold is parameterized or can be parameterized based on the power consumption to be protected. As described above, the previously determined threshold can be used to determine under what conditions the overcurrent protection device will be triggered or not, conditions which typically depend on temperature.

[0017] When this specification refers to parameterization or parameterizability of different parameters, it should be understood that for each power consumer or overcurrent protection device, the corresponding parameters are stored in the memory of the computing unit executing the method. This may occur once when the overcurrent protection device is delivered or initially put into use. Alternatively, it may be specified that the parameterization can be changed during continuous operation.

[0018] Specifically, the trigger characteristic curve represents the modeling of the heat generation of the power consumption to be protected.

[0019] According to the second aspect, a DC power grid is proposed, comprising a power supply bus and load devices including at least one power consumer, the power supply bus being connected to or potentially connected to the power supply potential of the DC power grid. Each of the power consumers is coupled to the power supply bus via an associated, controllable overcurrent protection device. A current-related trigger characteristic curve is associated with each of the power consumers. The overcurrent protection device is constructed according to the type described herein.

[0020] This type of DC power grid has the same advantages as those described above in conjunction with the overcurrent protection device according to the invention.

[0021] According to a suitable design for a DC power grid, the power supply bus is connected to, or can be connected to, the supply potential of the DC power grid via an overcurrent protection device of the type described herein, wherein the overcurrent protection device is configured to handle the current-dependent triggering characteristic curves associated with the load device. According to this design, the overcurrent protection device is not associated with a single power consumer, but with the entire load device having multiple power consumers. Therefore, the overcurrent protection device described herein is located in an upstream conductor branch that supplies current to several loads of the load device.

[0022] Another suitable design scheme specifies that, in the case of multiple power consumers, each power consumer is associated with a corresponding current-related trigger characteristic curve, which may be identical or different in pairs. Alternatively or additionally, in the case of multiple power consumers, each power consumer may be associated with a corresponding pre-determined threshold, which may be identical or different in pairs. In other words, identical or different current-related trigger characteristic curves may be associated with power consumers. Similarly, power consumers may be associated with identical or different pre-determined thresholds for performing the above methods. This is particularly important when power consumers with a wide range of different rated power are installed in a DC grid. Here, the operating state of power consumers with high rated power may generate feedback to conductor branches of power consumers with low rated power (e.g., under generator operation). By parameterizing in the manner described, these different operating conditions can be taken into account, thereby avoiding unnecessary and / or premature disconnection or triggering of overcurrent protection devices.

[0023] According to a third aspect of the invention, a method is provided for operating an overcurrent protection device to protect electrical appliances disposed in a DC power grid. In the DC power grid, the electrical appliances are coupled to a power supply bus via the overcurrent protection device, the power supply bus being connected to or potentially connected to the power supply potential of the DC power grid. In this method, a current trigger value is determined based on a detected value of the current flowing through the overcurrent protection device and based on a current-related trigger characteristic curve associated with the electrical appliance, wherein the current, depending on the current direction, is considered along with a first or second coefficient in the trigger characteristic curve. Furthermore, in this method, the current trigger value is compared with a previously determined threshold. Finally, the overcurrent protection device is either triggered or not triggered based on the result of the comparison.

[0024] This method has the same advantages as those described above in conjunction with the overcurrent protection device according to the present invention.

[0025] According to a fourth aspect, the present invention provides a computer program product that can be directly loaded into the internal memory of the digital control unit of an overcurrent protection device and includes a software code portion. When the product is run on the control unit, the software code portion executes the steps of the method described herein. The computer program product may be embodied in the form of a storage medium, such as a USB memory stick, DVD, CD-ROM, or memory card. The computer program product may also exist in the form of a signal that can be loaded via a wireless or wired communication connection.

[0026] According to a fifth aspect of the invention, a method for operating a DC power grid is provided, the method comprising a power supply bus and a load device including at least one power consumer, the power supply bus being connected to or potentially connected to the power supply potential of the DC power grid, wherein each of the power consumers is coupled to the power supply bus via an associated controllable overcurrent protection device, and wherein a current-related trigger characteristic curve is associated with each of the power consumers. In this method, for each of the at least one power consumer, the following steps are performed independently: determining a current trigger value based on a detected value of the current flowing through the overcurrent protection device associated with the power consumer and based on the current-related trigger characteristic curve associated with the corresponding power consumer, wherein in the trigger characteristic curve, the current is considered together with a first or second coefficient according to the current direction; comparing the current trigger value with a threshold previously determined for the corresponding power consumer; and, based on the result of the comparison, either triggering or not triggering the overcurrent protection device associated with the corresponding power consumer.

[0027] This method has the same advantages as those described above.

[0028] In a suitable design, this method is executed by the central control unit of the DC power grid or by the corresponding computing unit of the overcurrent protection device. Task allocation is also conceivable.

[0029] According to a sixth aspect, the present invention provides a computer program product that can be directly loaded into the internal memory of a digital control unit and includes a software code portion that, when the product is running on the control unit, executes the previously described steps using the software code portion. The computer program product can be embodied in the form of a storage medium, such as a USB flash drive, DVD, CD-ROM, or memory card. The computer program product can also exist in the form of a signal that can be loaded via a wireless or wired communication connection. Attached Figure Description

[0030] The invention will now be described in more detail with reference to the embodiments shown in the accompanying drawings. In the drawings:

[0031] Figure 1 A schematic diagram of an exemplary overcurrent protection device for protecting power consumers arranged in a DC power grid is shown.

[0032] Figure 2 A schematic diagram of an exemplary DC power grid is shown, comprising multiple power consumers protected by corresponding overcurrent protection devices.

[0033] Figure 3 A line graph is shown, in which exemplary current-related trigger characteristic curves for determining trigger criteria are displayed; and

[0034] Figure 4A flowchart is shown, illustrating the steps of the method according to the invention. Detailed Implementation

[0035] Figure 1 A schematic diagram of an overcurrent protection device 11S for protecting power consumers arranged in a DC power grid is shown. The DC power grid 1 (DC grid) provides a DC voltage at a power supply bus of 10V. In the schematic diagram, the DC voltage is provided by a battery 5, exemplarily. It should be understood that the battery 5 represents only any energy source or combination of multiple energy sources providing a DC voltage at its terminals. The energy source may be, for example, a photovoltaic device and / or a battery storage device, but may also be a rectifier that generates a DC voltage by rectifying an AC voltage generated by an AC voltage source.

[0036] In this embodiment, the power consumer is represented by inverter 11, to which a three-phase motor 12 is connected. Inverter 11 converts the DC voltage supplied by the DC grid into the three-phase voltage or AC voltage required by the motor 12 in a known manner. For this purpose, inverter 11 has several controllable switching elements (not shown) and at least one capacitor (not shown) and thus represents a capacitive power consumer.

[0037] It should be understood that the power consumption devices shown herein are merely exemplary and other power consumption devices, such as resistive and / or inductive loads, may also be used alternatively.

[0038] The overcurrent protection device 11S includes a controllable switching element 15 and a current measuring device 16 connected in series therewith. The controllable switching element 15 can be switched on or off by a control unit (not shown here, either the overcurrent protection device 11S itself or a higher-level control unit). If the controllable switching element is switched on, the power consumers 11, 12 (i.e., the related unit consisting of the inverter 11 and the motor 12 connected thereto) are connected to the power supply bus 10V, causing the current I to... 11 Current flows into the power consumers 11 and 12 via the controllable switching element 15 and the current measuring device 16. In the event of an overcurrent, the controllable switching element 15 is switched off by the control unit, thereby preventing the flow of current into the power consumers 11 and 12.

[0039] The controllable switching element 15 is a power electronic component, such as a MOSFET (metal-oxide-silicon field-effect transistor), an IGBT (insulated-gate bipolar transistor), etc. The power electronic component can be n-channel, p-channel, npn, or pnp. The semiconductor material can be based on silicon (Si), gallium nitride (GaN), or the like. The controllable switching element can include one or more power electronic components of the above types, particularly in anti-series or parallel connections.

[0040] The current-dependent triggering characteristic curve is associated with power consumers 11 and 12. The current-dependent triggering characteristic curve represents the modeling of the heat generation of the power consumer to be protected. The current-dependent triggering characteristic curve is... Figure 3 The diagram exemplifies the current trigger value MM of two different current-dependent trigger characteristic curves MM1 and MM2, representing the current-dependent trigger value MM over time. The upper characteristic curve, represented by MM1, represents the current-dependent characteristic curve, which has a linear dependence on the current flowing through the power consumer. The lower characteristic curve, represented by MM2, represents the characteristic curve, which has a quadratic dependence on the current flowing through the power consumer. These characteristic curves are chosen exemplarily and for illustrative purposes only. The actual trajectory of the characteristic curves representing heating as a function of time and the current flowing through the power consumer may differ in practice.

[0041] Figure 1 The overcurrent protection device 11S shown is configured to be used for the current I flowing through the overcurrent protection device 11S and therefore through the power consumers 11 and 12. 11 The current trigger value is determined by the detected value and the current-related trigger characteristic curve (MM1 or MM2) associated with the power consumers 11 and 12. The current trigger value is calculated by the control unit (mentioned but not shown) based on the actual current and, for example, the calculation rules of the current-related trigger characteristic curve stored in memory. Figure 4 Step S1 in the flowchart). In the next step ( Figure 4 In step S2 of the flowchart, the currently determined trigger value is compared with a previously determined threshold. The previously determined threshold is called the trigger discrimination and is stored in the memory of the control unit. The threshold can be predetermined in advance through experimentation or given in advance by the manufacturer for the power consumption under consideration. In step S3, the current trigger value is compared with the previously determined threshold ( Figure 4 Step S3). Then, based on the comparison result, the overcurrent protection device is triggered, where triggering is understood as switching the controllable switching element 15 to cut off ( Figure 4Step S4 in the process.

[0042] Here, in the trigger characteristic curve, the current I, which is currently determined as the actual current by the current measuring device according to the current direction, is... 11 It is considered together with the first coefficient or a second coefficient that is different from it. For example, the cooling effect can be achieved by considering the direction of the current. Thus, instead of static triggering of the overcurrent protection device as in the case of, for example, conventional safety fuses, overcurrent triggering is more precisely adjusted according to the operating conditions.

[0043] The advantage of the described process is that it allows for the initial adjustment of multiple parameters when the overcurrent protection device is put into use and / or when the power consumers in the DC power grid 1 are put into use, and / or even during operation. For example, the first and / or second coefficients can be parameterized or can be parameterized based on the power consumer to be protected. Alternatively or additionally, the first or second coefficients can be parameterized or can be parameterized based on the trend of the trigger characteristic curve (MM1 or MM2). Alternatively or additionally, the previously determined threshold can be parameterized or can be parameterized based on the power consumer to be protected. This allows the overcurrent protection device to be accurately matched to its associated power consumers 11, 12. By analyzing different current directions, not only can device discrepancies be saved, but the selectivity desired by the customer can also be achieved. This means that only the protection device closest to the fault is triggered and disconnects the fault.

[0044] In order to perform current direction-dependent weighting when determining the current trigger value, the current measuring device 16 must be configured to identify the sign, i.e., the direction, of the current flowing through it. This can be achieved, for example, by a current measuring device comprising a Hall effect sensor. Such a highly integrated Hall effect sensor is described, for example, in EP 2 619 595 B1.

[0045] As shown in the figure, the controllable switching element 15 and the current measuring device 16 are preferably constructed as a component. However, this is not mandatory.

[0046] Figure 2 A schematic diagram of an exemplary DC power grid 1 is shown, exemplarily illustrating a load device connected to the DC power grid having two different power consumers 11, 12 and 13, 14. The entire assembly consisting of power consumers 11, 12 and 13, 14 and the overcurrent protection devices 11S and 13S associated with said power consumers is currently referred to as load device 10. It is readily apparent from the schematic diagram that power consumers 13, 14 are an inverter 13 and a motor 14 powered therefrom. Motors 12, 14 could, for example, be motors with significantly different rated power.

[0047] Each of the power consumers 11, 12 and 13, 14 is connected to the 10V bus via its respective associated overcurrent protection device 11S, 13S. Additionally, another overcurrent protection device 10S is provided, which connects the 10V bus to the battery 5. The configuration of all overcurrent protection devices 10S, 11S, and 13S corresponds to the already combined... Figure 1 The structure described is clear. Therefore, no further explanation is needed.

[0048] Unlike the previous embodiments, the detection values ​​SI11, SI12, and SI10 provided by the corresponding current measuring devices 16, 18, and 26 of the respective overcurrent protection devices 11S, 13S, and 10S are transmitted to the central computing unit 20 of the DC power grid for processing. In this embodiment, the control unit 20 analyzes all detection values ​​and performs a combination for each power consumer 11, 12 and 13, 14, and the load device 10 as a whole. Figure 1 The described method, wherein, for each of the power consumers 11, 12 and 13, 14 or the load device 10, the respective associated (same or different) current-related trigger characteristic curves and the respective previously determined (same or different) thresholds and (same or different) first and second coefficients are processed.

[0049] Then, if an overcurrent is detected in one of the branches, the relevant controllable switching elements 15 and 16 or 25 can be switched off by the control unit 20. For clarity, only one control signal STS for controlling the controllable switching element 25 of the overcurrent protection device 10S is shown.

[0050] Corresponding detection values ​​SI11, SI12, and SI10 are provided at input terminals 21, 23, and 24 of control unit 20. A control signal STS for the controllable switching element 25 of overcurrent protection device 10S is provided to output terminal 22 of control unit 20. It should be understood that corresponding output terminals providing corresponding control signals are also provided at control unit 20 for the corresponding controllable switching elements 15 and 17 of overcurrent protection devices 11S and 13S.

[0051] like Figure 2 The central processing unit shown for executing the method according to the invention is merely exemplary. (In conjunction with...) Figure 1 The described method can also be executed in the corresponding calculation unit of each overcurrent protection device 11S, 13S, and 10S. Combinations of different task distributions are also conceivable.

[0052] The central control unit facilitates the parameterization of multiple different overcurrent protection devices and power consumers.

Claims

1. An overcurrent protection device for protecting an electrical consumer (11, 12; 13, 14) arranged in a direct current electrical network (1), wherein In the direct current network (1), the consumers (11, 12; 13, 14) are coupled via the overcurrent protection devices (11S, 13S) to a supply bus (10V) which is connected or connectable to a supply potential of the direct current network (1), wherein the overcurrent protection devices (11S, 13S) are designed to - determining a current triggering value on the basis of a detected value of the current (I 11 , I 13 ) flowing through the overcurrent protection device (11S, 13S) and on the basis of a triggering characteristic curve associated with the current of the consumer (11, 12; 13, 14); - compare the current trigger value with a previously determined threshold value; and - trigger if the current trigger value exceeds the threshold value and not trigger if the current trigger value does not exceed the threshold value; - wherein, when determining the current trigger value from the trigger characteristic curve, the detected value of the current flowing through the overcurrent protection device is taken into account together with a first or second factor depending on the current direction.

2. The overcurrent protection device of claim 1, wherein The overcurrent protection device comprises a controllable switching element (15, 17) and a current measuring device (16, 18) connected in series with the controllable switching element, wherein the current measuring device (16, 18) detects the magnitude of the current flowing through the controllable switching element (15, 17) during the on phase of the controllable switching element (15, 17) and provides the magnitude as a detected value (S111, S113).

3. The overcurrent protection device of claim 2, wherein, The current measuring device (16, 18) comprises a sensor based on the Hall principle.

4. The overcurrent protection device of any one of claims 1 to 3, wherein, The first and / or second factor is or can be parameterized depending on the consumer (11, 12; 13, 14) to be protected.

5. The overcurrent protection device of any one of claims 1 to 3, wherein, The first and / or second factor is or can be parameterized depending on the course of the trigger characteristic curve.

6. The overcurrent protection device of any one of claims 1 to 3, wherein, The previously determined threshold value is or can be parameterized depending on the consumer (11, 12; 13, 14) to be protected.

7. The overcurrent protection device of any one of claims 1 to 3, wherein, The trigger characteristic curve represents a model of the heating of the consumer (11, 12; 13, 14) to be protected.

8. A direct current network, comprising: - a supply bus (10V) which is connected or connectable to a supply potential of the direct current network (1); - a load device (10) comprising at least one consumer (11, 12; 13, 14), wherein each of the consumers (11, 12; 13, 14) is coupled via an associated controllable overcurrent protection device (11S, 13S) to the supply bus (10V), and wherein a current-dependent trigger characteristic curve is associated with each of the consumers (11, 12; 13, 14); characterized in that the overcurrent protection devices (11S, 13S) are designed as overcurrent protection devices according to any one of claims 1 to 7.

9. The direct current electrical grid according to claim 8, characterized in that, The supply bus (10V) is connected or connectable via a further overcurrent protection device to the supply potential of the direct current network (1), wherein the further overcurrent protection device is designed for processing the current-dependent trigger characteristic curves associated with the load device, wherein the further overcurrent protection device is designed as an overcurrent protection device according to any one of claims 1 to 7.

10. The direct current power grid according to claim 8 or 9, characterized in that In the case of a plurality of consumers (11, 12; 13, 14), each consumer (11, 12; 13, 14) is associated with a respective current-dependent triggering characteristic curve, which can be identical or different from pair to pair.

11. The direct current power grid according to claim 8 or 9, characterized in that In the case of a plurality of consumers (11, 12; 13, 14), each consumer (11, 12; 13, 14) is associated with a respective previously determined threshold value, which can be identical or different from pair to pair.

12. A method for operating an overcurrent protection device for protecting an electrical consumer (11, 12; 13, 14) arranged in a direct current electrical network (1), wherein In the direct current network (1), the consumers (11, 12; 13, 14) are coupled to a supply bus (10V) via the overcurrent protection devices (11S, 13S), which is connected or connectable to a supply potential of the direct current network (1), wherein - determining a current triggering value on the basis of a detected value of the current (I 11 , I 13 ) flowing through the overcurrent protection device (11S, 13S) and on the basis of a triggering characteristic curve associated with the current of the consumer (11, 12; 13, 14), wherein in determining the current triggering value from the triggering characteristic curve, depending on the current direction, the detected value of the current flowing through the overcurrent protection device is considered together with a first or second coefficient; - the current triggering value is compared with the previously determined threshold value; and - the overcurrent protection device is triggered if the current triggering value exceeds the threshold value, and is not triggered if the current triggering value does not exceed the threshold value.

13. A computer program product which is directly loadable into the internal memory of a digital control unit of an overcurrent protection device and comprises software code portions with which the steps according to claim 12 are performed when the product is run on the control unit.

14. A method for operating a direct current network, the direct current network comprising - a supply bus (10V) which is connected or connectable to a supply potential of the direct current network (1), and - a load device (10) comprising at least one consumer (11, 12; 13, 14), wherein each of the consumers (11, 12; 13, 14) is coupled to the supply bus (10V) via an associated controllable overcurrent protection device (11S, 13S), and wherein a current-dependent triggering characteristic curve is associated with each of the consumers (11, 12; 13, 14), wherein for each of at least one of the consumers (11, 12; 13, 14) independently of one another - determining a current triggering value on the basis of a detected value of the current (I 11 , I 13 ) flowing through an overcurrent protection device (11S, 13S) associated with the consumer and on the basis of a current-dependent triggering characteristic curve associated with the respective consumer (11, 12; 13, 14), wherein in determining the current triggering value from the triggering characteristic curve, depending on the current direction, the detected value of the current flowing through the overcurrent protection device is considered together with a first or second coefficient; - the current triggering value is compared with a threshold value previously determined for the respective consumer (11, 12; 13, 14); and - the overcurrent protection device associated with the respective consumer (11, 12; 13, 14) is triggered if the current triggering value exceeds the threshold value, and is not triggered if the current triggering value does not exceed the threshold value.

15. The method of claim 14, wherein, The method is performed by a central control unit (20) or by a computing unit of the overcurrent protection devices.

16. A computer program product which is directly loadable into the internal memory of a digital control unit and comprises software code portions with which the steps according to claim 14 or 15 are performed when the product is run on the control unit.

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