Power flow control system for use in an electrical network

Abstract

A control module unit (30) for a power flow control system (90), designed for use in an electrical network (12) and for adjusting the voltage and / or current in at least one line (20) of the network (12), comprises two line connections (60) configured to electrically connect the control module unit (30) in series with the line (20) of the network (12), and a first control module (300, 302) and a further control module (300, 304) connected in series with the first control module (300, 302). The control module (300) is connected such that a galvanically defined connection can be established with a power supply unit (40) which is adjustable such that the potential of the control module (300) follows the potential of the line (20) of the network (12) in a predefined manner.The power supply unit (40) has several voltage modules (400), each voltage module (400) being designed and configured to supply energy to one or more control modules (300) of a power flow control system (90) in order to adjust the voltage and / or current in the line of an electrical network (12). Each voltage module (400) includes a network interface (410) for connection to the electrical network and a converter unit (500) for connection to at least one control module (300).

Description

[0001] The present invention relates to a voltage supply unit for a power flow control system, which is designed for use in an electrical network and for adjusting the voltage and / or current in at least one line of the network. The application further relates to a power flow control system for use in an electrical network, which comprises a control module and a voltage supply unit.

[0002] The utilization of electrical power grids, particularly medium-voltage and low-voltage grids, has been steadily increasing in recent years. Distributed power generation and decentralized power feed-in from solar panels on the one hand, and the increasing number of charging stations for electric vehicles on the other, are leading to this changing utilization. Individual outgoing lines in a distribution grid are therefore frequently overloaded. Laying new lines with larger cross-sections is to be avoided or often does not solve the problem. Similar problems exist in the high-voltage grid, which is now increasingly overloaded by energy generation (including offshore wind) away from the load centers and requires, for example, so-called redispatching. Therefore, voltage regulation can be achieved, for example, using tap changers on transformers. However, these can only change the load flow in the outgoing lines to a limited extent.

[0003] Emerging problems and solutions from the state of the art are presented, for example, in the scientific paper by Rivera et al. [S. Rivera et al., "Charging Infrastructure and Grid Integration for Electromobility" in Proceedings of the IEEE, doi: 10.1109 / JPROC.2022.3216362] and in Fang et al. [Fang et al., "State-Space Modeling and Control of Grid-Tied Power Converters With Capacitive / Battery Energy Storage and Grid-Supportive Services" in Journal of Emerging and Selected Topics in Power Electronics of the IEEE, doi: 10.1109 / JESTPE.2021.3101527].

[0004] EP 3 413 422, for example, proposes a distribution substation with a three-winding transformer to supply two separate busbars, each with a separate low-voltage winding. This allows for a response to a change in the power flow in the individual busbars.

[0005] Alternatively, variable-voltage transformers are known, but these require major modifications and an additional measuring unit for measuring the voltage in the busbar of the low-voltage network and the current at the feeder. However, a variable-voltage transformer still cannot provide selective control of individual supply lines.

[0006] In the meshed structures of local, distribution, and transmission grids, current flows via the individual inputs cannot be controlled. They adjust passively depending on the load. To change the voltage level of an outgoing network, mesh current controllers are used to raise or lower the voltage amplitude. The energy for the change is usually drawn from the grid itself. A change in voltage in a grid segment can be compensated by distributing the load between the various inputs. A mesh current controller is therefore a suitable means of actively shifting the load within a mesh. A mesh current controller therefore represents a voltage source connected in series with one or more phases of the grid, allowing uncontrollable current flows via the individual inputs in the individual meshes due to various loads to be regulated.However, the known mesh current regulators require a power transformer for series coupling to provide a voltage between the conductor and ground potential and to change the voltage amplitude. Such transformers, however, are structurally large and expensive.

[0007] The transformers used also lead to unwanted losses at higher frequency components, even though they are well-suited for low frequencies. However, to compensate for unwanted distortions in the grid, such as harmonics, higher frequencies must be injected or extracted to improve grid quality. However, the conventional mesh regulators are not suitable for this.

[0008] In addition to the low frequency limit and also the voltage limit, state-of-the-art solutions are unsuitable for fast applications or at high voltages, for example due to high mains voltages or high impedances to be overcome.

[0009] There is therefore still a need for cost-effective solutions that can improve network quality in meshed networks and adjust load distribution.

[0010] The present object is achieved by a control module unit for a power flow control system having the features of claim 1, by a voltage supply unit having a plurality of voltage modules having the features of claim 3 and by a power flow control system, configured for use in an electrical network and configured to adjust the voltage and / or current in at least one line of the network, having the features of claim 10.

[0011] In a first aspect, the present invention relates to a control module unit for a power flow control system, which is designed for use in an electrical network and for adjusting the voltage and / or current in at least one line of the network.

[0012] The control module unit comprises two line connections designed to electrically connect the control module unit in series with the network line. The control module unit has a first control module and a further control module connected in series with the first control module. Each control module of the control module unit comprises two module connections for serial connection to one of the line connections or to a module connection of an adjacent control module, two half-bridges consisting of several switching elements connected in series, an energy storage device connected in parallel between the half-bridges, and two energy connections for connection to a voltage supply unit. The half-bridges of each control module are each electrically connected to one of the module connections.The control module is wired in such a way that an electrical connection can be established with the power supply unit, allowing the potential of the control module to follow the potential of the network line. The connection can be controlled in such a way that the potential of the control module follows the potential of the line in a predefined manner.

[0013] Strictly speaking, not all parts of the module need to have the same potential. The lower rail has a potential lower than the upper rail by the module supply voltage. The voltage of the corresponding mains phase should lie in between. At least, this would be the case for just one module. Here, however, several modules are present together. In fact, the potential of the module closest to the line should be below the mains voltage with one supply rail and above the mains voltage with the other supply rail. This also applies to the edge module on the other side for that line. The modules in between should be positioned accordingly in terms of potential, which means that their connections are (approximately) potential-wise between the corresponding potentials of the supply rails (no strict inequalities, equality also applies).Because multiple modules are present, the line voltage of the "right" line does not have to be within the supply rails of the leftmost module. The series of modules adds their voltage and can therefore bridge, compensate, or regulate voltage differences between different networks well above the supply voltage of a control module.

[0014] According to the invention, the switching elements of the control modules are designed to increase or reduce the amplitude of the voltage on at least a first side of the line compared to a second side of the line in order to adjust the voltage, to shift the phase of the voltage and / or to control the current flow in the line accordingly.

[0015] For the purposes of the invention, a network line is understood as a phase of the network. A three-phase network therefore has three lines, with a control module provided for the serial connection of one of the network phases or one of the network lines.

[0016] The design of the control module unit with multiple control modules offers the advantage that the switching elements used, which are connected in half-bridges, use only a fraction of the mains voltage or the necessary differential voltage for floating coupling. The switching elements are usually semiconductor components, which can therefore be designed for low voltages. Transistors, for example, can be used.

[0017] The use of multiple control modules in the control module unit results in a significantly lower voltage at each control module that must be processed. With a large number of n control modules in the control module unit, the voltage to be processed in each individual control module is thus reduced to the nth part of the voltage. By connecting the individual control modules in series, the corresponding voltages of the modules are added together. The same applies to the currents when modules are connected in parallel.

[0018] According to a further aspect, the present invention relates to a voltage supply unit with multiple voltage modules. Each voltage module is designed and configured to supply one or more control modules of a control module unit or of a power flow control system with energy, in order to thereby adjust the voltage and / or current in the line of the electrical network. Each voltage module or voltage supply module of the voltage supply unit comprises a network interface for connection to an adjacent voltage module or an electrical network, preferably for connection to the electrical network for which the voltage supply unit is used, and a converter unit for connection to at least one control module of the control module unit.

[0019] Since the power supply unit comprises several voltage modules, the respective voltage of the network is broken down into smaller units, which are provided by series-connected voltage modules with lower voltages. It is also conceivable for the voltage modules to be used in a combination of series and parallel connection. In this case, only a lower voltage is provided. In series connection, the voltages of the modules add up accordingly, or in parallel connection, the currents of the individual modules add up.

[0020] While the interconnection of modules is already known in other areas of electronics, the invention has shown that the use of lower-voltage modules in a power supply unit is problematic. For example, the scientific papers by Fang et al. [J. Fang et al., "A Review of Multilevel Converters With Parallel Connectivity" in IEEE Transactions on Power Electronics, vol. 36, no. 11, pp. 12468-12489, Nov. 2021, doi: 10.1109 / TPEL.2021.3075211], Goetz et al. (2012) [SM Goetz et al., “Circuit topology and control principle for a first magnetic stimulator with fully controllable waveform,” 2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, San Diego, CA, USA, 2012, pp. 4700-4703, doi: 10.1109 / EMBC.2012.634 7016], Tashakor et al. [Tashakor et al., „Low-Frequency Scheduler for Optimal Conduction Loss in Series / Parallel Modular Multilevel Converters“ in IEEE Transactions on Power Electronics, vol. 37, no. 3, pp. 2551-2561, March 2022, doi: 10.1109 / TPEL.2021.3110213.], Goetz et al. (2014) [S. M. Goetz et al., „Modular Multilevel Converter With Series and Parallel Module Connectivity: Topology and Control“ in IEEE Transactions on Power Electronics, vol. 30, no.1, pp. 203-215, Jan. 2015, doi: 10.1109 / TPEL.2014.2310225], und Tashakor et al. [Tashakor et al., „Modular Multilevel Converter With Sensorless Diode-Clamped Balancing Through Level-Adjusted Phase-Shifted Modulation“ in IEEE Transactions on Power Electronics, vol. 36, no.7, pp. 7725-7735, July 2021, doi: 10.1109 / TPEL.2020.3041599.] diverse modulare Schaltungskonzepte. Insbesondere bei Schaltungen mit parallelen Verbindungsmodi ist ferner dem Fachmann aus dem Stand der Technik, beispielsweise Goetz et al. (2016) [S. M. Goetz et al., "Control of Modular Multilevel Converter with Parallel Connectivity - Application to Battery Systems" in IEEE Transactions on Power Electronics, vol. 32, no. 11, pp. 8381-8392, Nov. 2017, doi: 10.1109 / TPEL.2016.26458 84] that states, interconnection states, or modes can be defined as either module states or module connection states. This alternative definition of states and modes will also apply to the following description.

[0021] The energy supply and energy removal has proven to be challenging if the advantages of a very compact power supply are to be maintained. The present invention and design of the power supply unit, particularly when connecting the voltage modules in a star or delta configuration, solves this problem and realizes the desired advantages: a very compact design on the one hand, and the use of switching elements or semiconductor components designed only for low voltages on the other.

[0022] In this context, low voltages are voltages that are significantly below the mains voltage of the network for which the power supply unit is used. In practice, it has been shown that the voltage modules must be designed for voltages that are < 50% of the mains voltage, preferably < 25% of the mains voltage, more preferably < 10% of the mains voltage, and very preferably < 5% of the mains voltage.

[0023] It has proven advantageous to design the power supply unit in such a way that galvanic isolation is achieved from the control modules or the control module unit of the electrical network. This can be achieved, for example, by one or more high-frequency transformers, dual-active bridge converters, or LLC circuits.

[0024] According to a third aspect, the present invention relates to a power flow control system designed to be used in an electrical network and to adjust the voltage and / or current in at least one line of the network. The power flow control system comprises a control module unit with at least two control modules, preferably with a control module unit according to one of claims 1 or 2, and a voltage supply unit, preferably with a voltage supply unit according to one of claims 3 to 9. The voltage supply unit has at least two voltage modules or voltage supply modules for electrically supplying the control module unit. Preferably, there is galvanic isolation between a control module unit and a voltage supply unit. In other words, there is a galvanically isolated connection that allows the electrical potential of the control module unit to follow the potential of the line of the network.The connection can, for example, be of a magnetic nature, i.e. include a magnetic coupling.

[0025] The galvanic isolation between the power supply unit and the control module unit can be achieved via one or more high-frequency transformers. In this case, one module of the power supply unit or of a power supply unit can supply each control module (series coupling module) of the control module unit. A 1:1 assignment between the control module and the voltage module is realized. Alternatively, but equally preferred, one or more control modules can be supplied via a plurality of voltage modules. Using fewer transformers than modules, the fluxes can partially compensate each other, which is advantageous because smaller magnetic cores can be used.

[0026] Preferred embodiments of the invention are defined in the dependent claims. It is understood that the features mentioned above and those to be explained below can be applied not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the present invention.

[0027] In a preferred embodiment of the invention, the control module unit can be designed such that the first control module has a further half-bridge made up of switching elements connected in series. The switching elements are connected in parallel to the half-bridge connected to the adjacent control module via the module connection. The further control module of the control module unit has a further half-bridge made up of switching elements connected in parallel to each half-bridge. The further half-bridges are electrically connected to a further module connection of the control module. In this way, the control modules of the series coupling can be designed with a low-voltage DC link (often referred to by those skilled in the art as a DC intermediate circuit) and two low-voltage outputs with serial and parallel module connections.

[0028] The optional parallel mode of modules allows higher currents at low series voltages and series voltage phases (e.g., reactive power flows). Furthermore, parallel mode can enable better power distribution between modules and charge distribution, for example, to keep the module voltages similar. With parallel mode, each control module does not need to be electrically connected to a power supply module. Instead, such control modules without an electrically connected power supply module can be supplied by neighboring control modules via charge distribution. Parallel mode temporarily connects energy storage devices, such as capacitors, of neighboring modules in parallel, thus leading to a voltage-equalizing charge exchange.

[0029] According to a preferred embodiment of the invention, the voltage modules of the voltage supply unit are connected to one another in a star connection or in a delta connection.

[0030] At least two control modules, each with at least two half-bridges, allow the respective energy storage units of the control modules to be dynamically connected in series with each other, alternately in positive and negative polarity, and the resulting series unit of energy storage units to be electrically connected in series with a first and a second side of a line of an electrical network. Furthermore, the half-bridges allow the current within a control module to bypass the energy storage unit, which is referred to below as bypass mode.

[0031] Preferably, each voltage module is electrically connected to a control module, such that a control module is supplied with energy by a voltage module to effect an adjustment of the voltage and / or current in the line of the electrical network.

[0032] The voltage modules of the voltage supply unit, formed from the network interface and the converter unit, are preferably designed such that the converter unit comprises an inverter circuit and an inverter / rectifier unit, and preferably a (magnetic) transformer connected therebetween. This inverter / rectifier unit is referred to below as a balancing unit. Basically, the balancing unit preferably comprises at least one rectifier and is preferably arranged on the secondary side of a magnetic transmission. The inverter circuit and / or the balancing unit preferably has at least one half-bridge made of switching elements. A high-frequency transformer can preferably be provided between the inverter circuit and the balancing unit of the converter unit. Alternatively, it is possible that a separate high-frequency transformer is not provided for each voltage module.

[0033] A preferred embodiment of the voltage supply unit is designed such that at least one of the voltage modules has an LLC or dual-active bridge circuit which has a capacitance and two inductances as galvanic isolation between the inverter circuit and the balancing unit.

[0034] In a preferred embodiment, the voltage supply unit is constructed such that the voltage modules are connected in series with one another.

[0035] An alternative design of the power supply unit provides a dynamic serial and parallel connection between the voltage modules. In this case, for example, using an LLC circuit in the voltage module can provide galvanic isolation from the balancing unit and thus from the connected control module. However, other galvanically isolating converters are also possible for use in the voltage modules.

[0036] A preferred embodiment of the power flow control system has a converter unit which is connected to the energy terminals of a control module of the control module unit and which is connected between the control module and the grid interface.

[0037] Preferably, the converter unit of the voltage supply unit in the power flow control system is designed such that the converter unit has an inverter circuit with at least two inverters. In a preferred embodiment, each inverter comprises two transistors.

[0038] The switching elements used in the power flow control system as well as the switching elements of the control module unit or the individual control modules and the switching elements in the voltage supply unit or in the individual voltage modules can be semiconductor components, preferably transistors.

[0039] The transistors in the control modules are preferably designed for low or very low voltages. The design depends on the application of the control modules. When the control module is used in a low-voltage network with an effective peak voltage of 3 × 400 V, the switching elements are designed for voltages of no more than 100 V, preferably no more than 50 V, very preferably no more than 30 V, more preferably no more than 20 V, and most preferably no more than 10 V. The design of the transistors depends, among other things, on how many control modules are provided in the control module unit. For a series connection of, for example, eight control modules, the transistors can be designed for a maximum voltage of 50 V.

[0040] When using the control modules in a medium-voltage line with up to 30 kV, the transistors used are preferably designed for voltages of < 2.5 kV, preferably < 1 kV, more preferably not > 600 V, particularly preferably not > 200 V, and very preferably not > 50 V. Here, too, the design of the transistors depends on the number of control modules used in the control module unit. The same applies to the use of control modules in a high-voltage network with 220 to 400 kV with modules < 10 kV, preferably < 7 kV, particularly preferably < 3 kV.

[0041] The invention is described and explained in more detail below using a few selected exemplary embodiments in conjunction with the accompanying drawings. Reference is made here, by way of example but without limitation to generality, to a low-voltage network or distribution network as a possible example of an electrical AC network or network. However, this description and the example of the low-voltage network do not limit the generality of a voltage network or local network. These can therefore also refer to transmission networks or be used equivalently for them. The low-voltage network in the figures and in the description is one possible embodiment of a network and has an effective line-to-line voltage of 3 × 400 V. The drawings show: Fig. 1 a schematic diagram of a network segment with three lines and a power flow control module; Fig. 2 a detailed sketch of the network segment Fig. 1; Fig. 3 an alternative embodiment of a power supply unit; Fig. 4 a schematic diagram of a control module of a control module unit; Fig. 5 a schematic diagram of control modules with two voltage outputs; Fig. 6 a detailed drawing of a voltage module; and Fig. 7 another detailed drawing of a voltage module of a power supply unit.

[0042] Although in the Fig. 1 to 7 show a network segment of a voltage network or local network, the units and modules used can also be used in other areas. For example, it is possible for them to be used in the automotive sector or in vehicles, where voltages in the range of 400 V to 1 kV can also occur. The invention can be used here as a very efficient system to compensate for voltage fluctuations, for example in the on-board network or in part of the on-board network. This is particularly advantageous because the components used, in particular the transistors, only have to be designed for lower voltages and are therefore cost-effective. In addition, the system according to the present invention has the advantage of being very compact, requiring little installation space, and also being very lightweight, making it suitable for use in a vehicle.

[0043] Fig. 1 shows, by way of example, a network segment 10 of a three-phase electrical network 12 with three lines 20. In order to compensate for voltage fluctuations in the lines 20, a power flow control system 90 is used, which comprises a control module unit 30 and a voltage supply unit 40, wherein the voltage supply unit 40 supplies the control module unit 30 with energy in order to effect an adjustment of the voltage or current in the line 20.

[0044] The control module unit 30 comprises several control modules 300 connected in series. Fig. 1 shows three control modules 300 per line 20, for a total of nine control modules 300. For each line 20, the control module unit 30 comprises two line connections 60, with which the control module unit 30 is connected to the line 20. In total, therefore, there are three sets of two line connections 60.

[0045] Optional line filters 36 are provided between the control modules 300 and the respective line connection 60 of the control module unit 30. The optional line filters 36 can be, for example, inductors, PI filters, or similar.

[0046] Each control module 300 comprises an AC part 32 and a DC part 34, wherein the DC part 34 has two power connections 70 for connecting the respective control module 300 to a voltage module 400 of the voltage supply unit 40. This is done via lines 38. The AC part 32 can have at least two module connections 62.

[0047] The control module unit 30 comprises individual control modules 300, each of which must be designed for high currents but relatively low voltages. The currents must be of the same magnitude as the currents present in the network 12. However, the voltages can be reduced by connecting the individual (n total) control modules 300 in series per line 20, so that only one-nth of the voltage needs to be carried by the respective control module 300.

[0048] The power supply unit 40 comprises several voltage modules 400. In the Fig. 1, a total of nine voltage modules 400 are provided, so that each control module 300 can be supplied by its own voltage module 400.

[0049] Preferably, the voltage supply unit 40 has a plurality of isolated outputs or, as shown here, a plurality of voltage modules 400, with one output provided for each floating control module 300 of the control module unit 30. The voltage supply unit 40 with its voltage modules 400 can, in principle, be powered from any possible source. However, the embodiment shown here is particularly preferred, in which the voltage supply unit 40 is connected to the line 20 of the network 12 via a line 42.

[0050] The individual voltage modules 400 can be magnetically or galvanically coupled to one another, for example by using high-frequency transformers.

[0051] Fig. Figure 2 shows another embodiment of the power flow control system 90, in which the voltage supply unit 40 has a total of nine voltage modules 400 connected in a star configuration. A high-frequency transformer 600 is provided between each individual voltage module 400 and the control modules 300 of the control module unit 30 to realize a magnetic coupling and galvanic isolation between the voltage supply unit 40 and the control module unit 30.

[0052] Fig. 3 shows, in principle, the same structure of a power flow control system 90 with control module unit 30 and voltage supply unit 40. However, in the embodiment shown here, the individual voltage modules 400 are interconnected in a delta or delta circuit.

[0053] Fig. Figure 4 shows a detailed view of a control module 300. In the embodiment shown here, the control module 300 comprises two half-bridges 310, each formed from two switching elements 64 connected in series. The switching elements 64 are embodied as transistors 312. In a low-voltage network, the transistors 312 are low-voltage transistors or extra-low-voltage transistors. An energy storage device 68, which can be embodied as a capacitor 69, is connected between the two DC rails 66 of the control module 300.

[0054] The control module 300 has two module connections 62, wherein one module connection 62 of the first control module 302 is connected to the line connection 60, while the second module connection 62 is connected to the subsequent control module 304 or to its module connection 62.

[0055] Fig. 5 shows a further preferred embodiment of the control modules 300 of the control module unit 30 in detail.

[0056] The first control module 302 essentially has the Fig. 4. However, another half-bridge 320, which is also constructed from two series-connected transistors 312, is connected in parallel to the second half-bridge 310. In this case, a module connection 62 is formed between the two transistors 312 of the respective half-bridge 310 and 320, which is connected to the half-bridges of the further control module 304.

[0057] The control module 304 also essentially has the basic structure of the control module 302 according to Fig. 4. However, in addition to the respective half-bridges 310, a further half-bridge 320 consisting of two transistors 312 connected in series is provided.

[0058] The third control module 306 has the same structure as the control module 302, except that the two module connectors 62 are connected to each other. These are connected to the line connector 60, to which the control module unit 30 is connected to the respective line 20.

[0059] In this way, the overall design of the control module unit 30 is obtained in which the individual control modules 300 for a line 20 are connected both in series and in parallel.

[0060] The optional line filter 36 can be inserted between the coupled and interconnected module connections 62 and the line connection.

[0061] Fig. Figure 6 now shows in detail a voltage module of the voltage supply unit 40. The voltage module comprises a network interface 410 with two half-bridges 412, each formed by two series-connected transistors 414. A capacitor 416 is arranged between the two DC rails 415, forming an inverter intermediate circuit 418.

[0062] In addition to the network interface 410, the voltage module 400 also includes a converter unit 500, which includes an inverter 510, a balancing unit 520, and, for example, a dual-active bridge or LLC circuit 530. The inverter 510 is formed from two parallel half-bridges 512, each with two series-connected transistors 514. Alternatively, each LLC circuit according to the invention can also be a dual-active bridge, flyback, or other galvanically isolated DC-DC converter or transformer circuit.

[0063] The LLC circuit 530 includes a capacitor 532 (capacitance), an inductor 534, and a coupled inductor 536. The LLC circuit 530 serves to provide galvanic isolation between the inverter circuit, i.e., the inverter 510, and the balancing unit 520.

[0064] In the embodiment shown here, the balancing unit 520 comprises two parallel-connected half-bridges 522, each formed by two series-connected transistors 524. A capacitor 526 is provided in parallel with the two half-bridges. The outputs 528 are then connected to the power terminals 70 of the respective control module 300.

[0065] The embodiment shown here is based on purely serial interconnection between the respective modules. Parallel modes are also possible between some or all modes.

[0066] Fig. Figure 7 shows a particular embodiment of the voltage modules 400 in detail. The respective voltage modules 400 of the voltage supply unit 40 are connected in a star configuration and have a double star point. In this case, the parallel connection of the voltage modules can also be dynamically implemented between the individual strings. For the first modules, i.e., the voltage modules 400, which are connected directly to the lines 20, the module outputs 402 can be interconnected, as shown in Fig. 7 shown.

[0067] In total, the interface circuit, network interface 410, has four parallel-connected half-bridges 412, each constructed from two series-connected transistors 414. The (voltage) module outputs 402 are used for connection to line 20 or for connection to the adjacent voltage modules 400. The remaining structure of the voltage modules 400 is similar to that of Fig. 6.

[0068] In the embodiment shown here, galvanic isolation is again achieved by means of the LLC circuit 530, whereby dynamic serial and parallel connectivity between the modules is achieved.

[0069] Floating the voltage modules 400 of the voltage supply unit 40 according to the invention also has the advantage that the voltage supply unit 40 is very robust against overvoltages or lightning strikes. Thus, overvoltage protection and lightning protection are realized.

[0070] This is particularly important because the distribution grid or grid 12 can sometimes be very difficult to protect from lightning strikes. Medium-voltage lines, at least in rural areas, are designed as overhead lines with closely spaced conductors. These are unprotected against lightning strikes. Ground lines in a low-voltage network are also affected by lightning strikes, as the distribution transformers often transmit lightning strikes. Due to the lack of a ground reference and the galvanic isolation of the electronic phase feed-in modules (voltage modules 400), as well as the lack of potential reference between them, the voltage modules 400 also follow a voltage peak from a lightning strike or other potential fluctuations. The voltage modules 400 follow the potential peak, for example, even when several thousand volts are present. Accordingly, the voltage at each point on the voltage module 400 increases simultaneously by the ground voltage.However, the relevant differential voltages between points in the module remain constant, so that the voltage module 400 can still be constructed using only low-voltage components. The transistors 414 and capacitors 416 used, as well as the transistors 514 and 524, are therefore only designed for low voltages. For example, when used in low-voltage networks up to 400 V, the design can be reduced to 100 V, preferably to 50 V, very preferably to 20 V. For networks or lines with higher voltage, the number of control modules and / or the voltage of individual or all modules can be increased according to the invention. The product of the number of control modules and the average voltage of all modules preferably scales approximately with the peak voltage of the line.

[0071] Since the voltage modules are relatively small in size, for example smaller than a Euro board, no large capacitive or inductive voltage differences can build up within the modules, which could lead to damage.

[0072] Overall, the basic idea of ​​the invention is to use floating and transformer-free control modules and combine them in the individual modules. Each individual module is preferably supplied with a voltage module. This allows each individual module to be constructed with components that are well below the operating voltage or mains voltage. By combining the individual modules (control modules 300 and voltage modules 400), the medium-voltage and high-voltage ranges, i.e., voltage ranges from 20 kV to 400 kV, can also be served.

[0073] Even if in the embodiments described here only two or three modules per line were mentioned, in particular two or three control modules, in practice a structure will often be found which has five or more control modules connected in series and whose voltage supply unit 40 has a corresponding number of voltage modules 400.

[0074] Within the scope of the invention, it was discovered and demonstrated in tests that higher voltages can also be operated when the individual modules are cascaded, i.e. connected in series. For example, control modules can be designed for a voltage of 100 V, while the overall system has a voltage of 1 kV. In the medium voltage range up to approximately 30 kV, modules designed for a voltage of approximately 1 kV can be used. By reducing the voltage requirements in this way, inexpensive components and elements that are available in many different designs can be used. This makes the power flow control system 90 very cost-effective overall. In addition, the components can be placed in the smallest of spaces. This means that the voltage modules in the low voltage range can be mounted on a Euroboard. In the low kilovolt range, a module that is portable for people (for example, < 29 kg) can still be designed.Overall, the system is very small, produces little waste heat and can also be easily retrofitted into existing infrastructure.

[0075] The invention has been comprehensively described and explained with reference to the drawings and the description. The description and explanation are to be understood as exemplary and not restrictive. The invention is not limited to the disclosed embodiments. Other embodiments or variations will become apparent to those skilled in the art upon use of the present invention and upon careful analysis of the drawings, the disclosure, and the following claims.

[0076] In the patent claims, the words "comprising" and "having" do not exclude the presence of further elements or steps. The undefined article "a" or "an" does not exclude the presence of a plurality. A single element or unit can perform the functions of several of the units recited in the patent claims. An element, unit, device, and system can be implemented partially or entirely in hardware and / or software. For example, a control unit used for control can be implemented entirely or partially in software. The software or the corresponding computer program for control can be stored / distributed on a non-volatile data carrier, for example on an optical memory or on a semiconductor memory (flash, SSD). A computer program can be distributed together with hardware and / or as part of hardware, for example via the Internet.

[0077] The mere mention of some measures in several different dependent patent claims should not be understood to mean that a combination of these measures cannot also be used advantageously. Reference signs in the patent claims are not to be understood as limiting. Reference number 35 10 network segments 12 Network 20 Line 30 control module unit 32 AC part 34 DC part 36 line filters 38 Line 40 Power supply unit 42 Line 60 line connection 62 module connection 64 switching element 66 DC rail 68 energy storage 69 Capacitor 70 Energy connection 90 Power flow control system 300 control module 302 Control module 304 Control module 306 Control module 310 Half Bridge 312 transistors 320 Half Bridge 400 voltage module 402 module output 410 network interface 412 Half Bridge 414 Transistor 415 DC rail 416 Capacitor 418 Inverter intermediate circuit 420 inverters 422 Half Bridge 424 transistors 500 converter unit 510 Inverter 512 Half Bridge 514 transistors 520 balancing unit 522 Half Bridge 524 transistors 526 Capacitor 528 Exit 530 LLC circuit 532 Capacitor 534 Inductance 536 Inductance 600 high-frequency transformer QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 3 413 422

[0004] Cited non-patent literature

[0000] S. Rivera et al., “Charging Infrastructure and Grid Integration for Electromobility” in Proceedings of the IEEE, doi: 10.1109 / JPROC.2022.3216362

[0003] Fang et al., “State-Space Modeling and Control of Grid-Tied Power Converters With Capacitive / Battery Energy Storage and Grid-Supportive Services” in Journal of Emerging and Selected Topics in Power Electronics of the IEEE, doi: 10.1109 / JESTPE.2021.3101527

[0003] J. Fang et al., „A Review of Multilevel Converters With Parallel Connectivity“ in IEEE Transactions on Power Electronics, vol. 36, no.11, pp. 12468-12489, Nov.2021, doi: 10.1109 / TPEL.2021.3075211

[0020] S. M. Goetz et al., „Circuit topology and control principle for a first magnetic stimulator with fully controllable waveform“, 2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, San Diego, CA, USA, 2012, pp. 4700-4703, doi: 10.1109 / EMBC.2012.634 7016

[0020] Tashakor et al., „Low-Frequency Scheduler for Optimal Conduction Loss in Series / Parallel Modular Multilevel Converters“ in IEEE Transactions on Power Electronics, vol. 37, no. 3, pp. 2551-2561, March 2022, doi: 10.1109 / TPEL.2021.3110213

[0020] S. M. Goetz et al., „Modular Multilevel Converter With Series and Parallel Module Connectivity: Topology and Control“ in IEEE Transactions on Power Electronics, vol. 30, no.1, pp. 203-215, Jan. 2015, doi: 10.1109 / TPEL.2014.2310225

[0020] Tashakor et al., „Modular Multilevel Converter With Sensorless Diode-Clamped Balancing Through Level-Adjusted Phase-Shifted Modulation“ in IEEE Transactions on Power Electronics, vol. 36, no.7, pp. 7725-7735, July 2021, doi: 10.1109 / TPEL.2020.3041599

[0020] S. M. Goetz et al., „Control of Modular Multilevel Converter with Parallel Connectivity - Application to Battery Systems“ in IEEE Transactions on Power Electronics, vol. 32, no. 11, pp. 8381-8392, Nov. 2017, doi: 10.1109 / TPEL.2016.26458 84

[0020]

Claims

[1] Control module unit (30) for a power flow control system (90) which is designed for use in an electrical network (12) and for adjusting the voltage and / or current in at least one line (20) of the network (12), comprising two line connections (60) designed to electrically connect the control module unit (30) in series with the line (20) of the network (12), and a first control module (300, 302) and a further control module (300, 304) connected in series with the first control module (300, 302), each control module (300) comprising at least two module connections (62) for serial connection to one of the line connections (60) or to a module connection (62) of an adjacent control module (300), two half-bridges (310) comprising a plurality of switching elements (64) connected in series, an energy storage device (68) connected in parallel between the half-bridges (310) and two energy connections (70) for connection to a voltage supply unit (40), where the half-bridges (310) of the control module (300) are each electrically connected to one of the module terminals (62); the control module (300) is connected in such a way that an electrical connection can be established with the voltage supply unit (40), which allows the potential of the control module (300) to follow the potential of the line (20) of the network (12); and the switching elements (64) are designed to increase or reduce the amplitude of the voltage on at least a first side of the line (20) compared to a second side of the line (20) in order to adjust the voltage, to shift the phase of the voltage or to control the current flow in the line (20) accordingly. [2] Control module unit (30) according to claim 1, characterized by that the first control module (300, 302) has at least one further half-bridge (320) made up of series-connected switching elements (64), which is connected in parallel to the half-bridge (310) connected to the adjacent control module (300, 304) via the module connection (62), and the further control module (300) has a further half-bridge (320) connected in parallel to each half-bridge (310); wherein the further half-bridges (320) are electrically connected to a further module connection (62) of the control module (300). [3] Voltage supply unit (40) with a plurality of voltage modules (400), wherein each voltage module (400) is designed and configured to supply one or more control modules (300) of a power flow control system (90) with energy in order to effect an adjustment of the voltage and / or the current in the line (20) of an electrical network (12), and wherein each voltage module (400) comprises a network interface (410) for connection to an electrical network (12) and a converter unit (500) for connection to at least one control module (300). [4] Power supply unit (40) according to claim 3, characterized by that the voltage modules (400) are connected to each other in a star connection or in a delta connection. [5] Power supply unit (40) according to claim 3 or 4, characterized bythat each voltage module (400) is electrically connected to a control module (300) and supplies the one control module (300) with energy in order to adjust the voltage and / or current in the line (20) of an electrical network (12). [6] Power supply unit (40) according to one of claims 3 to 5, characterized by that the converter unit (500) comprises an inverter (510) with at least one half-bridge (512) made of switching elements (64) and a balancing unit (520) with at least one half-bridge (522) made of switching elements (64) and preferably has a high-frequency transformer (600) between the inverter (510) and the balancing unit (520). [7] Power supply unit (40) according to the preceding claim, characterized bythat at least one of the voltage modules (400) has an LLC circuit (530) comprising a capacitor and two coupled inductors (534, 536) or a transformer or a dual-active bridge circuit comprising two coupled inductors (534, 536) or a transformer as galvanic isolation between the inverter (510) and the balancing unit (520). [8] Power supply unit (40) according to one of the preceding claims, characterized by that the voltage modules (400) are connected in series. [9] Power supply unit (40) according to one of the preceding claims, characterized by that a dynamic serial and parallel connection is provided between the voltage modules (400). [10] Power flow control system (90), designed for use in an electrical network (12) and designed to adjust the voltage and / or the current in at least one line (20) of the network (12), comprising a control module unit (30) with at least two control modules (300), preferably according to one of claims 1 or 2, and a voltage supply unit (40), preferably according to one of claims 3 to 9, with at least two voltage modules (400) for electrically supplying the control module unit (30), wherein there is a galvanically isolated connection between the control module unit (30) and the voltage supply unit (40), which connection allows the electrical potential of the control module unit (30) to follow the potential of the line (20) of the network (12). [11] Power flow control system (90) according to the preceding claim, characterized bythat the converter unit (500) is connected to the energy connections (70) of a control module (300) and the converter unit (500) is connected between the control module (300) and the network interface (410). [12] Power flow control system (90) according to claim 10 or 12, characterized by that the converter unit (500) of the voltage supply unit (40) has an inverter (510) with at least two half-bridges (512), wherein preferably each half-bridge (512) comprises two transistors (514).

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