Power converter, method for operating a power converter, and system comprising a DC energy source, a DC network and a power converter
Patent Information
- Application Number
- EP2023738030
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-07-04
- Filing Date
- 2023-07-04
- Publication Date
- 2025-05-14
AI Technical Summary
Existing power converter systems face challenges in managing the interaction between DC networks and AC supply networks, particularly in industrial settings, where requirements for grid stability and regulatory compliance can lead to conflicts and increased costs due to the need for complex AC/DC converters that may limit active and reactive power supply, risking undersupply and voltage collapse in DC networks.
A power converter system with a DC/DC controller and switching devices that allows selective connection between a DC energy source and a DC network, enabling separation from the AC supply network when necessary, thereby avoiding regulatory classification as an energy generation system and ensuring stable power supply through the DC energy source, and includes a DC/AC converter for feeding regeneratively generated power into the AC supply network.
This solution allows for reliable and efficient operation of DC networks as consumers, simplifying regulatory compliance and preventing undersupply by enabling the DC network to be operated independently or supported by the AC supply network as needed, reducing the complexity and cost of AC/DC converter design and ensuring stable power delivery.
Smart Images
Figure 1.1
Abstract
Description
[0001] POWER CONVERTER, METHOD FOR OPERATING A POWER CONVERTER AND SYSTEM WITH A DC ENERGY SOURCE, A DC GRID AND A POWER CONVERTER
[0002] TECHNICAL FIELD
[0003] The application relates to a power converter, a method for operating a power converter and a system with a DC energy source (DC, direct current), a DC network and a power converter.
[0004] STATE OF THE ART
[0005] A DC energy source, e.g., a photovoltaic (PV) system, an electrical storage device, a fuel cell, or a generator, can be connected to a DC grid and feed power into the DC grid. The DC energy source can be coupled to the local DC grid, in particular via a power converter with a DC / DC controller. A PV system can, for example, feed PV power from the PV generator into the local DC grid via such a power converter. A PV system can have one or more PV generators, which can be connected in series or in series. Such a system consisting of a DC grid and a DC energy source, in particular a PV installation such as a PV generator, is generally considered an energy generation system.
[0006] A DC grid usually comprises a number of electrical consumers. In order to supply the DC grid and thus the consumers with electrical power, a DC grid can be connected to an AC supply grid. If the DC grid is to be treated as a power generation plant due to a connected DC energy source, an AC / DC converter, e.g. an active rectifier, which is arranged between the AC supply grid (AC, alternating current / alternating voltage) and the DC grid and supplies the DC grid with electrical power from the AC supply grid, is required to operate in a grid-friendly manner towards the AC supply grid, particularly if it cannot be ruled out that...AC / DC converters: Electrical (surplus) power flows from the DC grid into the AC supply grid. For regulatory reasons, a power generation plant may only be connected to a public AC supply grid if the plant meets the requirements defined in the relevant standards, for example, by making defined changes to the power generation plant's output in response to irregularities in the AC supply grid in order to counteract these irregularities. To this end, the AC / DC converter, in particular, must meet all specifications and approval requirements of the respective grid operator for a grid-connected power generation plant.
[0007] Possible requirements of the grid operator for grid service may include, for example, grid support through active power adjustment (e.g., in the event of frequency fluctuations) and / or the provision of reactive power (e.g., in the event of voltage fluctuations). In addition, there may be special requirements for the interconnection point to the utility's grid (NAP), such as (secure) communication, single-fault tolerance, and similar.
[0008] Due to the required grid serviceability, conflicting objectives can arise between the behavior required by the AC grid operator at the AC grid connection point (NAP) and the requirements of the DC grid regarding the power available therein. If the AC / DC converter, as an interface between the DC grid and the AC supply grid, has a grid-service effect towards the AC supply grid, e.g. by having to provide reactive power to the AC supply grid in the event of a voltage deviation in the AC supply grid, the AC / DC converter can reach its apparent power limit, meaning that the active power taken from the AC supply grid for the DC grid would have to be reduced in favor of reactive power for the AC supply grid, meaning that the power in the DC grid would no longer be sufficient to supply all consumers in the DC grid.This can be particularly undesirable for an industrial DC grid, for example, as it can lead to an undersupply of the DC grid and a subsequent collapse of the DC grid voltage. Furthermore, the required grid-friendly behavior of the AC / DC converter places increased demands on the AC / DC converter, increasing its design cost.
[0009] TASK
[0010] The application is based on the object of improving a power converter with a DC / DC controller and a system with a DC network, a DC energy source and a power converter with a DC / DC controller or of providing improved operation of a power converter with a DC / DC controller and a system with a DC network, a DC energy source and a power converter with a DC / DC controller.
[0011] SOLUTION
[0012] The object is achieved by a power converter having the features of claim 1, a system according to claim 9, and a method having the features of independent claim 10. Embodiments are specified in the dependent claims. DESCRIPTION
[0013] A power converter for transmitting electrical power has a first side for connection to a DC energy source and a second side for connection to a DC grid. The power converter has a DC / DC converter and a first switching device. The DC / DC converter is configured to exchange electrical power between the first and second sides. The first switching device is configured to connect the first side to the second side via the DC / DC converter. The power converter is designed to disconnect the connection via the first switching device when the DC grid is provided for exchanging electrical power with an AC supply grid, and to establish the connection via the first switching device when no exchange of electrical power with the AC supply grid is provided for the DC grid.
[0014] The DC energy source can, for example, be designed as a PV generator of a PV system. The DC energy source can also be designed as a DC storage device, a fuel cell, a DC generator, or similar. The power converter described makes it possible to switchably connect the DC energy supply to the DC grid. This can be particularly advantageous for industrial DC grids in order to ensure a supply of electrical energy when no other supply of electrical power to the DC grid is available. In particular, when the DC grid is supplied from an AC supply grid, it is possible to keep the DC energy source separate from the DC grid during normal operation, i.e. when the DC grid is supplied from the AC supply grid. This can make it possible for the system with the DC grid not to be classified as an energy generation system from a regulatory or normative perspective.An AC / DC converter connecting the AC supply grid to the DC grid only needs to supply electrical loads during grid operation. From the perspective of the higher-level grid, the DC grid is thus considered a purely electrical load, subject to fewer regulatory or normative requirements. For example, the grid-friendly response to grid events can be dispensed with, thus avoiding, in particular, conflicts of objectives between the requirements of the DC grid and any requirements of the AC supply grid. In the event of a failure of the AC supply grid and a disconnection of the DC grid from the AC supply grid, the DC grid can be supplied with electrical energy from the DC energy source as an alternative by establishing the connection via the first switching device.
[0015] The DC grid, e.g. an industrial DC grid, can be supplied from the AC supply grid in grid operation via the AC / DC converter, which can be designed as an active rectifier. This means that the AC / DC converter can build up the DC grid and provide electrical power to operate the loads in the DC grid. The AC / DC converter is responsible for supplying the DC grid from the AC supply grid and can be designed so that no reverse power flow is provided. The DC grid therefore does not represent a power generation plant, but can be operated purely as a consumer, which significantly simplifies the connection of the DC grid to the AC supply grid by the AC grid operator and, if necessary, the approval thereof. Such an AC / DC converter is designed, for example, as an active rectifier. An active rectifier uses controlled components that can, in particular, be designed as semiconductor switches.
[0016] In a further development, the power converter has a third side for connection to the AC supply network. The power converter further has a DC / AC converter and a second switching device. The DC / DC controller can be integrated into the DC / AC converter or vice versa or can be designed as a separate unit of the power converter. The DC / AC converter and the second switching device are arranged between the DC / DC converter and the third side of the power converter. The DC / DC controller and the DC / AC converter are intended to exchange electrical power between the first side and the third side by first converting electrical DC power from the DC energy source by means of the DC / DC converter into DC power with a DC voltage that may differ from the DC voltage of the DC source and then by means of the DC / AC converter into AC power that can be fed into the AC supply network via the second switching device.The second switching device is configured to connect the third side to the first side for the exchange of electrical power via the DC / AC converter and the DC / DC controller. The advantage of this embodiment is that electrical power from the DC energy source can be fed into the AC supply grid via the third side. This is particularly advantageous when the DC energy source is designed as a PV generator, in that the regeneratively generated power of the PV generator can always be used effectively by feeding it into the AC supply grid, even if the power converter cannot feed into the DC grid due to a separate switching device. The DC / AC converter provided in the power converter is designed for grid feeding, i.e.It can act in a grid-friendly manner and, in particular, react by changing the power fed in depending on parameters of the AC supply grid and in response to any grid events. The power converter and the DC energy source form a DC energy supply connected to the AC supply grid, which complies with all specifications and / or guidelines of the grid operator of the AC supply grid for a power generation plant. It is connected to the AC supply grid according to common standards and, if an AC supply grid is available, can be operated in a grid-friendly manner or in a grid-supporting manner for the AC supply grid. The first and second switching devices provided in or on the power converter make it possible to connect the DC energy source to the AC supply grid or to the DC grid as required.At the same time, by appropriately controlling the first switching device, it can be ensured that the DC grid is not connected to the AC supply grid if and as long as the DC energy source can feed electrical power into the DC grid via the DC / DC converter and a closed first switching device.
[0017] If necessary, it is also possible to feed electrical power generated by a PV generator as a DC energy source into the AC supply grid. This can be particularly the case if the DC grid is supplied with electrical power from the AC supply grid, i.e., is connected to it. In this case, the system can be designed so that the DC energy source is separated from the DC grid by an open first switching device and connected to the AC supply grid by a closed second switching device. It can feed electrical power into the AC supply grid accordingly and, if necessary, vary this power to benefit the grid.
[0018] In one embodiment, the power converter is configured to disconnect the connection via the first switching device before establishing the connection via the second switching device. In another embodiment, the power converter is configured to disconnect the connection via the second switching device before establishing the connection via the first switching device. These embodiments can ensure the safe and reliable connection and disconnection of the DC power supply to the DC grid or, alternatively, to the AC grid as needed.
[0019] In one embodiment, the DC / AC converter is arranged between the second switching device and the DC / DC converter. This offers the advantage that the DC / AC converter of the power converter can be disconnected from the AC supply network by the second switching device. This can offer advantages in terms of maintenance and / or operational reliability.
[0020] In one embodiment, the power converter is designed to receive a signal containing information about whether the DC grid is intended for an exchange of electrical power with the AC supply grid. A controller can then, in response to this received signal, control the first switching device directly or indirectly accordingly. The controller that controls the first and / or second switching device can be a controller of the power converter or a higher-level controller of the system or a higher-level controller at a remote location. The system can, for example, comprise the DC energy source, the DC grid and the power converter. Optionally, the system can further comprise the AC / DC converter and / or the DC / AC converter, via which power is transferred from the AC supply grid to the DC grid or from the DC energy source to the AC supply grid.The control of the first and / or second switching device of the power converter can be carried out, for example, by a control of the power converter, which also controls semiconductor switches of the DC / DC controller and the optional DC / AC converter of the power converter.
[0021] The signal can be received, for example, by a higher-level controller. A higher-level controller of the system can be located within the system and / or it can be located at a remote location and receive a communication medium.
[0022] In one embodiment, the first switching device has a thyristor, via which the DC / DC controller is connected to the second side of the power converter. The design of the first switching device as a thyristor makes it possible to control the first switching device by changing the output voltage of the DC / DC controller. In particular, the thyristor can be switched on by increasing the DC output voltage of the DC / DC controller to a value above the voltage of the DC grid. The thyristor can in particular be designed to be self-switching, i.e. it switches off, for example, when the current crosses zero, in particular when the voltage of the DC grid and the DC output voltage of the DC / DC controller are equal. This self-switching off of the thyristor when the input voltage of the DC power supply drops can contribute to the operational reliability of the system.
[0023] Alternatively or additionally, the first switching device can comprise semiconductor switches and / or electromechanical switches for establishing and / or breaking the connection. The second switching device can comprise semiconductor switches and / or electromechanical switches, in particular relays, for establishing and / or breaking the connection. The controller and / or higher-level controller described above can be configured to control the semiconductor switches and / or electromechanical switches.
[0024] In a method for operating the power converter, the connection via the first switching device is disconnected when the DC grid is intended to exchange electrical power with the AC supply grid, i.e. is electrically connected to the AC supply grid. Furthermore, the connection is established via the first switching device when no exchange of electrical power with the AC supply grid is intended for the DC grid, i.e. when the DC grid is disconnected from the AC supply grid. The advantage here is that an AC / DC converter which transfers electrical power between the AC supply grid and the DC grid as required does not have to be designed for the connection of an energy source to the AC supply grid, i.e. from a regulatory and normative point of view it does not constitute a power generation plant. This means that the system which comprises the DC grid can be designed more simply and cost-effectively in terms of planning, construction and / or approval.It is also possible to provide a supply to the DC grid via the DC energy source in the event of a failure of the AC supply grid.
[0025] In one embodiment of the method, in which the power converter has a DC / AC converter and a third side for connecting to the AC supply network, and the third side of the power converter is connectable to the AC supply network via a second switching device, a connection is established between the first side and the AC supply network via the DC / AC converter and the DC / DC controller by closing the second switching device.
[0026] In one embodiment, electrical power from the DC energy source is fed into the AC grid via the power converter. This is particularly advantageous when the DC energy source is configured as a PV generator.
[0027] In one embodiment of the method, the connection between the AC supply network and the DC network is separated. This can be the case, for example, if the supply of the DC network from the AC supply network can no longer be guaranteed, for example if the AC supply network fails. Then, in a further step, the connection between the power converter and the AC supply network can be separated. This separation of the power converter from the AC supply network can preferably take place by opening the second switching device. In a further step, the connection can then preferably be established via the first switching device and the DC energy source can be connected to the DC network via the power converter when the DC network is separated from the AC supply network.
[0028] In one embodiment of the method, the connection is established via the first switching device by increasing the DC voltage on the side of the first switching device facing the DC / DC controller by the DC / DC controller. If the DC voltage at the first switching device on the side facing the DC / DC controller is then higher than the DC voltage of the DC network, which is present on the other side of the first switching device, the first switching device, which is designed as a thyristor, is triggered. Triggering the thyristor means that the thyristor becomes conductive and the connection is established via the first switching device.
[0029] In one embodiment, the connection via the first switching device is broken by the DC / DC controller lowering the DC voltage on the side of the first switching device facing the DC / DC controller. This causes the switching device, which is designed as a thyristor, to be switched off as soon as the DC voltage at the first switching device on the side facing the DC / DC controller is equal to or less than the DC voltage of the DC network. Switching off the thyristor means that the thyristor is blocked and the first switching device is opened, i.e., the connection via the first switching device is broken.
[0030] BRIEF DESCRIPTION OF THE CHARACTERS
[0031] In the following, the teaching according to the application is further explained and described with reference to embodiments shown in the figures.
[0032] Fig. 1 shows schematically an embodiment of a system with DC energy source, DC / DC power converter and DC network,
[0033] Fig. 2 shows schematically another embodiment of a system with DC energy source, DC / DC and DC / AC power converter and DC network,
[0034] Fig. 3 shows schematically a method for operating a power converter.
[0035] In the figures, identical or similar elements are designated by the same reference numerals.
[0036] FIGURE DESCRIPTION
[0037] Fig. 1 shows a system 50 with a DC network 22, a power converter 10 and a DC energy source 20. The DC energy source 20 is connected to the DC network 22 via the power converter 10. The DC network 22 is, for example, an industrial DC network that supplies DC network devices 24 with direct voltage. The DC network devices are DC loads, also called consumers. In an industrial DC network 22, the DC network devices can be, for example, motor test benches, robots, production machines or other system consumers. In the example shown, the DC network devices 24 are connected to the DC network 22 via fuse switches. The DC network 22 with its DC network devices 24 can be supplied with electrical power from an AC supply network 30 via an AC / DC converter 26. The DC side of the AC / DC converter 26 is connected to the DC grid 22 via a fuse switch.The AC side of the AC / DC converter 26 is connected to the AC supply network 30 via a transformer T. The AC supply network 30 has, for example, an alternating voltage of 20 kV. The transformer T converts the alternating voltage of the AC supply network 30 to an alternating voltage of approximately 400 to approximately 1500 V, which is applied to the AC side of the AC / DC converter 26 and converted by the converter into a DC mains voltage in the range of 400 to 1500 V DC. The DC energy source 20 can also have a nominal DC voltage in the range of 400 to 1500 V DC at its output, particularly if it is a PV system.
[0038] The power converter 10 has a first side to which the DC energy source 20 is connected. The DC grid 22 is connected to a second side of the power converter. The power converter 10 has a DC / DC controller 12, via which a DC voltage output by the DC energy source 20 can be converted into the DC grid voltage. The DC / DC controller is also intended to transfer power from the DC energy supply 20 to the DC grid 22. A first switching device 14 is provided in the power converter 10, via which the DC / DC controller can be connected to and disconnected from the DC grid 22. In the example shown, the first switching device 14 is designed as a thyristor. This allows switching of the first switching device 14 by increasing the output voltage of the DC / DC controller 12 on its side facing the first switching device 14.If this voltage reaches the level of the DC voltage on the DC grid 22, the thyristor can be switched on by "firing" it, and the connection between the DC / DC converter 12 and the DC grid 22 is established. In the illustrated embodiment, the DC energy source 20 is, for example, a fuel cell, a DC storage device, a DC generator, or a PV system with or without a DC storage device.
[0039] So that the system 50 can be considered a pure consumer from the perspective of the AC supply network 30 and does not have to be classified as a power generation system, the power converter 10 is designed such that the connection between the DC / DC converter 12 and the DC network 22, i.e., the connection between the DC power supply 20 and the DC network 22, is only established if it is not intended or preferably excluded that the DC network 22 is connected to the AC supply network 30. In particular, the system can be designed such that the connection via the first switching device 14 is only established when the AC / DC converter 26 is disconnected from the DC network 22.
[0040] By switching the first switching device 14 as needed, it is possible to ensure that the DC grid 22 is supplied with electrical energy from the DC energy source 20 when needed, for example, in the event of a failure of the AC supply grid 30. At the same time, the DC grid 22, with its DC network devices 24, acts as a pure consumer with respect to the AC supply grid.
[0041] The DC grid 22 can thus be capable of operating as an island grid. The DC grid devices 24 can be operated in the DC grid 22 without the AC supply grid 30 using the electrical power from the DC energy supply 20. The DC / DC converter 12 can thus be operated in a grid-forming manner. The system 50 can also be capable of black start and start the DC grid 22. Black start capability here means that the DC grid 22 can be started from a switched-off state. This can be done without connection to the AC supply grid 30 from the DC energy source 20 via the power converter 10.
[0042] If the DC energy source 20 is, for example, a battery storage unit or a fuel cell, then this DC energy source can be operated to form the grid, and a DC / DC controller 12 connected to an (additionally present) PV generator 20 can be operated to follow the grid. The DC voltage of the DC / DC controller 12 connected to the PV generator 20 can be adjusted to the DC voltage of the DC grid 22 such that a current is fed into the DC grid 22 via the DC / DC controller 12. This current can be set using a setpoint. In particular, a control system can set the setpoint so that the PV generator 20 operates in the optimal range, i.e., delivers the maximum possible power. This is also referred to as the maximum power point and can be abbreviated to MPP.
[0043] The DC / DC converter 12 between the DC power source 20 and the DC grid 22 can, for example, be designed as a boost converter. In this case, the DC output voltage of the DC power source 20 is lower than the DC grid voltage of the DC grid 22 during normal operation. The DC / DC converter 12 can also be designed as a buck converter. In this case, the DC output voltage of the DC power supply 20 is higher than the DC grid voltage of the DC grid 22 during normal operation. The DC / DC converter can also be designed as a step-up / step-down converter. A step-up / step-down converter is also referred to as a buck-boost converter. It has the advantage that the voltage ratio between the DC output voltage of the DC power supply 20 and the DC grid voltage of the DC grid 22 can be freely selected. However, a step-up / step-down converter is comparatively complex to implement.
[0044] The operating range of the DC mains voltage of the DC mains 22 can be set by the AC / DC converter 26 when supplied from the AC supply network 30. In DC island network operation with supply from the DC energy source 20, the DC mains voltage of the DC mains 22 can be set by the DC / DC converter 12.
[0045] Fig. 2 shows a further embodiment of the system 50. In the embodiment shown in Fig. 2, the power converter 10 additionally has a DC / AC converter 16. The DC / AC converter 16 is connected to a third side of the power converter via a second switching device 18. In the example shown, the AC supply network 30 is connected to the third side of the power converter. In this embodiment, the DC energy source 20 can be embodied, for example, as a PV system with one or more PV generators. If, in the embodiment of Fig. 2, the DC network 22 is supplied with electrical energy from the AC supply network 30 via the AC / DC converter 26, the first switching device 14 is open, i.e. the DC energy source 20 is separated from the DC network 22 and can feed electrical power into the AC supply network 30 via the DC / DC controller 12 and the DC / AC converter 16 and the closed second switching device 18.
[0046] If the DC energy source 20 is disconnected from the AC supply network 30, e.g., by opening the second switching device 18, the DC energy source 20 can be connected to the DC network 22 via the first switching device 14 via the DC / DC converter 12. As a result, the DC energy source 20 no longer feeds energy into the AC supply network 30, but instead supplies the DC network 22 with electrical energy via the DC / DC converter 12 and the closed first switching device 14.
[0047] The DC energy source 20, which in the example shown is designed as a PV system, thus has, in addition to the connection to the AC supply grid, a DC connection via the power converter 10, via which it can be connected to the DC grid 22. With such a connection, the DC grid 22 can be supplied with electrical power from the DC energy source 20. The connection via the first switching device 14 is only conductive in the event of a disconnection of the DC grid 22 from the AC supply grid 30, for example, in the event of a power failure of the AC supply grid 30, i.e., only in this case is the connection between the DC energy source 20 and the DC grid 22 activated. Otherwise, an open first switching device 14 means there is no electrically conductive DC connection between the DC energy source 20 and the DC grid 22.
[0048] Alternatively or in addition to the PV system, a DC energy storage device can be arranged in the DC energy source 20. This can be DC-coupled to the PV system, for example, via a connection to a DC link of the DC / AC converter 16. In the event of a failure of the AC supply grid 30, such a DC energy storage device can then also be used as a backup source and support the possibly existing PV system in supplying the DC grid devices 24 or even replace them, for example, at night.
[0049] Fig. 3 schematically illustrates a method for operating the power converter 10. Such a method can, for example, be executed on a higher-level controller of the system 50. It is also possible to execute the method on a controller of the power converter 10, which, for example, simultaneously controls semiconductor switches of the DC / DC converter 12 and / or the DC / AC converter 16. The method is started in step 100. In step 102, a check is carried out to determine whether the DC grid 22 is connected to the AC supply grid 30. If this is affirmative, the system 50 is operated in AC grid mode in step 104. If the connection to the AC supply grid 30 is denied in step 102, a check is carried out in step 106 to determine whether the output voltage at the DC / DC converter 12 is greater than the DC grid voltage in the DC grid 22.If this is not the case, the DC voltage at the output of the DC / DC converter is increased in step 108 until the voltage on the side of the DC / DC converter 12 facing the first switching device 14 is higher than on the side of the first switching device 14 facing the DC network 22. If this is the case, the thyristor is triggered in step 110, i.e., it becomes conductive.
[0050] If in step 106 the voltage on the side of the DC / DC controller 12 facing the first switching device 14 is not yet high enough (branch "no"), it is increased in step 108 until the thyristor is triggered, i.e., can be switched on, in step 110. In step 112 the DC grid 22 is then supplied with electrical power from the DC energy source 20. In step 114 it is checked whether a connection to the AC supply grid 30 has been restored. If this is not the case (branch "no"), the system 50 remains in island operation with the supply from the DC energy source 20. If the connection to the AC supply grid 30 is restored (branch "yes" of step 114), the voltage at the DC / DC controller is reduced in step 116 until the thyristor switches off. The thyristor is switched off when the DC / DC controller 12 has reduced its output voltage to such an extent that it is the same on both sides of the first switching device 14.Then the thyristor switches off.
[0051] In step 102, a check is performed to determine whether the AC supply grid 30 is present. If this is the case, the system 50 is operated in step 104 in AC grid mode with a connection to the AC supply grid 30.
[0052] Optionally, in step 112, during DC mains operation, a check can be performed to determine whether the voltage on the DC / DC converter 12 side at the first switching device 14 is still high enough to keep the thyristor conducting. This can prevent an unwanted drop in voltage and an unwanted disconnection of the DC energy source 20 from the DC mains 22.
[0053] Power converter
[0054] DC / DC converter first switching device
[0055] DC / AC converter second switching device
[0056] DC energy source
[0057] DC grid
[0058] DC grid participants
[0059] AC / DC converter
[0060] AC supply network
[0061] system
[0062] T ransformator -116 process steps
Claims
PATENT CLAIMS Power converter (10) for transmitting electrical power, having a first side for connection to a DC energy source (20) and a second side for connection to a DC grid (22), wherein the power converter (10) has a DC / DC converter (12) and a first switching device (14), wherein the DC / DC converter (12) is configured to exchange electrical power between the first and the second side, and the first switching device (14) is configured to switchably connect the first side to the second side via the DC / DC converter (12), wherein the power converter (10) is configured to disconnect the connection via the first switching device (14) when the DC grid (22) is provided for exchanging electrical power with an AC supply grid (30), and to establish the connection via the first switching device (14) when no exchange of electrical power with the AC supply grid is provided for the DC grid (22). (30) is provided for,characterized in that the power converter (10) has a third side for connecting to the AC supply network (30), a DC / AC converter (16), and a second switching device (18), wherein the DC / AC converter (16) is provided in conjunction with the DC / DC controller (12) to exchange electrical power between the first side and the third side, and the second switching device (18) is configured to switchably connect the third side to the first side via the DC / AC converter (16) and the DC / DC controller (12). Power converter according to claim 1, wherein the power converter (10) is configured to disconnect the connection via the first switching device (14) before establishing the connection via the second switching device (18), and / or to disconnect the connection via the second switching device (18) before establishing the connection via the first switching device (14). Power converter according to claim 1 or 2,The DC / AC converter (16) is arranged between the second switching device (18) and the DC / DC controller (12). The power converter according to one of the preceding claims, wherein the power converter (10) is configured to receive a signal containing information about whether the DC network (22) is intended for an exchange of electrical power with the AC supply network (30). The power converter according to one of the preceding claims, wherein the first switching device (14) comprises a thyristor, via which the connection between the DC / DC controller (12) and the second side can be switched. The power converter according to claim 5, wherein the power converter (10) is configured to control the thyristor via an output voltage of the DC / DC controller (12). The power converter according to one of the preceding claims, wherein the DC energy source (20) is configured as a PV generator, a battery, or a fuel cell. The power converter according to one of the preceding claims, wherein the switching device (14) and the second side for connection to the DC grid (22) are arranged in a separate housing. A system (50) comprising a DC energy source (20), a DC grid (22), and a power converter (10) according to one of the preceding claims.Method for operating a power converter (10) with a first side for connection to a DC energy source (20) and with a second side for connection to a DC network (22), wherein the power converter (10) has a DC / DC controller (12) and a first switching device (14), wherein the DC / DC controller (12) is configured to exchange electrical power between the first and the second side, and the first switching device (14) is configured to switchably connect the first side to the second side via the DC / DC controller (12), comprising:. Disconnecting the connection via the first switching device (14) if the DC network (22) is intended to exchange electrical power with an AC supply network (30), and Establishing the connection via the first switching device (14) when no exchange of electrical power with the AC supply network (30) is provided for the DC network (22), characterized in that the power converter (10) has a DC / AC converter (16) and a third side for connecting to the AC supply network (30), wherein the third side of the power converter (10) is connectable to the AC supply network (30) via a second switching device (18), with the further steps: - Establishing a connection between the first side and the AC supply network (30) via the DC / AC converter (16) and the DC / DC controller (12), - feeding electrical power from the DC power supply (20) into the AC supply network (30) via the power converter (10), - Transferring electrical power from the AC supply network (30) to the DC network (22), preferably via an AC / DC converter (26), - Disconnecting the AC supply network (30) and the DC network (22), - Disconnect the power converter (10) and the AC supply network (30), if the DC network (22) is separated from the AC supply network (30), - Establishing the connection via the first switching device (14) when the DC network (22) is disconnected from the AC supply network (30). The method according to claim 10, wherein establishing the connection via the first switching device (14) is performed by the following steps: - increasing the DC voltage on the side of the first switching device (14) facing the DC / DC controller (12) by the DC / DC controller (12), so that the voltage applied to the side of the first switching device (14) facing the DC / DC controller (12) is higher than the DC voltage of the DC network, - firing the first switching device (14) designed as a thyristor when the DC voltage on the side of the first switching device (14) facing the DC / DC controller is higher than the DC voltage of the DC network, and wherein the separation of the connection via the first switching device (14) is carried out by the following step: - lowering the DC voltage on the side of the first switching device (14) facing the DC / DC controller (12) by the DC / DC controller (12) in order to extinguish the first switching device (14) designed as a thyristor.