Controllable rectifier arrangement for hydrogen electrolysis

Abstract

The invention relates to a rectifier arrangement for hydrogen electrolysis, comprising a transformer (1) with a primary winding (2) for connecting an input alternating voltage and a secondary winding (3) for providing an output alternating voltage, and comprising a rectifier (4) connected to the secondary winding (3) for generating an output direct current IDC and an output direct voltage UDC, wherein at the primary winding (2) of the transformer (1) a number N > 1 of winding taps (5) are provided, and a load stage switch (6) connected to a controller (7) is provided which is designed for switching the winding taps (5) without interruption such that the transformation ratio of the transformer (1) can be switched via the controller (7) in N stages.

Description

[0001] Adjustable rectifier arrangement for hydrogen electrolysis

[0002] The invention relates to a controllable rectifier arrangement for hydrogen electrolysis.

[0003] State-of-the-art processes for producing hydrogen through electrolysis, particularly PEM (Proton Exchange Membrane) electrolysis and AEL (Alkaline Electrolysis), are known. Such processes require a high and essentially constant direct current, which, however, depends on the production conditions. Typically, direct currents of over 600 A and a power of over 1 MW are required.

[0004] To provide direct current, controllable rectifier arrangements are known that generate a direct current output from an alternating current input voltage. Today, rectifier arrangements with actively controlled electronic circuits, such as circuits with thyristors or IGBTs with or without DC / DC converters and downstream filter elements, are used for this purpose.

[0005] However, such rectifier arrangements suffer from the disadvantage of relatively high losses when converting the input AC voltage to the output DC voltage. Total losses, including measures for ensuring voltage quality and cooling, typically amount to up to 4%, which is problematic given the high energy requirements of hydrogen electrolysis.

[0006] The object of the invention is therefore to provide an improved rectifier arrangement that is particularly suitable for providing a substantially constant direct current with low residual ripple, low grid disturbances, and low losses for hydrogen electrolysis. These and other objects are achieved by a rectifier arrangement according to claim 1.

[0007] A rectifier arrangement according to the invention for hydrogen electrolysis comprises a transformer with a primary winding for connecting an input AC voltage and a secondary winding for providing an output AC voltage, as well as a rectifier connected to the secondary winding for generating an output DC current IDC and an output DC voltage UDC. The rectifier can be designed as a passive rectifier, in particular without actively controlled electronic circuits and filter elements. Preferably, the rectifier is designed as a passive multi-pulse diode bridge rectifier, in particular in the form of a two-pulse bridge rectifier circuit. A choke coil for smoothing the DC current can be arranged at the output of the rectifier.

[0008] Several winding taps are provided on the primary winding of the transformer, allowing the number of turns of the primary winding to be adjusted in N steps. Depending on the input AC voltage and the transformation ratio, the number of turns of the primary winding can be in the range of 1000 to 1500. The number of winding taps N can be greater than 10, preferably approximately 20. However, up to 35 winding taps can also be provided. The winding taps can be provided in a partial area of ​​the primary winding, so that, for example, only approximately 200 of approximately 1000 turns are tapped.

[0009] An on-load tap-changer connected to a regulator is provided, which is designed for uninterrupted switching of the winding taps. The regulator can thus adjust the transformation ratio N1:N2 of the transformer, and thus the output voltage of the rectifier arrangement, in N steps via the on-load tap-changer. The transformation ratio is defined as the ratio of the number of turns in the primary winding to the number of turns in the secondary winding of the transformer. The regulator can be connected to a voltmeter and an ammeter for measuring the output voltage and output current, allowing it to generate the required direct current by adjusting the on-load tap-changer in the transformer.

[0010] The advantage of the invention is that by dispensing with conventional rectifier arrangements with actively controlled electronic circuits and filter elements, electrical losses can be reduced and thus a more efficient provision of electrical energy can be achieved.

[0011] According to the invention, it can be provided that the rectifier arrangement enables coarse and fine adjustment.

[0012] For this purpose, the primary winding can comprise a first partial winding and a second partial winding connected in series, with a number N > 1 winding taps being provided on the first partial winding and a number M > 1 winding taps being provided on the second partial winding. The number of turns of the first and second partial windings can be the same or different.

[0013] In this embodiment, two on-load tap-changers connected to the regulator are provided. A first on-load tap-changer is designed for uninterrupted switching of the winding taps of the first partial winding, and a second on-load tap-changer is designed for uninterrupted switching of the winding taps of the second partial winding. The first partial winding is connected in series with the second partial winding via the second on-load tap-changer, so that the transformation ratio of the transformer can be switched in N x M steps. The number of winding taps N and M can be the same or different. The number of winding taps N and M can each be greater than 10, preferably approximately 20. However, up to 35 winding taps can also be provided each.To enable coarse and fine adjustment of the transformation ratio, the on-load tap-changers can be configured to switch a different number of turns per tap. For example, the first on-load tap-changer can switch a higher number of turns per tap than the second on-load tap-changer. Thus, the first on-load tap-changer can perform a coarse adjustment, while the second on-load tap-changer can perform a fine adjustment of the transformation ratio.

[0014] This can be achieved, on the one hand, by having the on-load tap-changers have an identical number of winding taps, but with the number of turns in the first partial winding being higher than the number of turns in the second partial winding. This allows the transformation ratio to be adjusted via the on-load tap-changers in N coarse steps and M fine steps. For example, the output voltage can be adjusted in 361 steps at N = M = 19, although the steps are not the same size due to the different number of turns per step of the coarse and fine adjustment.

[0015] On the other hand, it can also be provided that the number of turns of the partial windings is identical, but the on-load tap-changers have a different number of winding taps. For example, the number of winding taps of the first on-load tap-changer, N, can be greater than the number of winding taps of the second on-load tap-changer, M. This allows the transformation ratio to be adjusted in M ​​coarse steps and N fine steps.

[0016] These designs can also be combined, with the partial windings having different numbers of turns and the on-load tap-changers having a different number of winding taps. The only essential factor for implementing coarse and fine adjustment of the transformation ratio is that the number of switched turns of the on-load tap-changers is different for coarse and fine adjustment. By using such cascaded tap-changers, both the normal control range and stronger overvoltages and undervoltages on the grid side can be covered (+ / - 10% of the input voltage). Furthermore, the tap adjustment can be very fine in the control range, while the coarse taps can be accessed very quickly to make larger adjustments.

[0017] The number and distribution of the stages into fine and coarse stages can be individually adapted to the application area, although experience has shown that more than 125 stages are required for the inventive use in hydrogen electrolysis. Switching from one stage to the next under load can take up to several seconds, but this is not a problem for hydrogen electrolysis applications.

[0018] According to the invention, the transformer can be designed as a multi-phase, in particular a three-phase transformer. In this embodiment, a three-phase voltage serves as the input voltage, with the primary windings connected in a star or delta configuration. A number N > 1 winding taps are provided on each primary winding, and three on-load tap-changers connected to the regulator are provided, which are designed for uninterrupted switching of the winding taps. The on-load tap-changers can be designed essentially identically. Instead of several single-phase on-load tap-changers, one multi-phase on-load tap-changer can also be provided.

[0019] The secondary windings can also be connected in a star or delta configuration. Furthermore, in this embodiment, a multiphase bridge rectifier, particularly in the form of a six-pulse bridge rectifier (B6U circuit), can be provided to generate an output DC voltage.

[0020] Again, a regulator is provided which is connected to a voltmeter and an ammeter for measuring the output voltage and output current, so that it can generate the required direct current by adjusting the three on-load tap changers in the transformer. A choke coil can again be arranged at the output of the bridge rectifier to smooth the direct current. According to the invention, coarse and fine adjustment of the transformation ratio can also be provided when using a three-phase transformer. For this purpose, the primary windings can each comprise a first partial winding and a second partial winding, with a number N > 1 winding taps being provided on the first partial windings in each case, and a number M > 1 winding taps being provided on the second partial windings in each case.In this case, first on-load tap-changers are provided for coarse adjustment, which are connected to the regulator and designed for uninterrupted switching of the winding taps of the first partial windings.

[0021] In this case, second on-load tap-changers are provided for fine adjustment. These are connected to the regulator and designed for uninterrupted switching of the winding taps of the second partial winding. The first partial windings are connected in series with the second partial windings via the first on-load tap-changers, so that the transformer's transformation ratio and thus the output DC voltage can be adjusted in M ​​x N steps.

[0022] To achieve better rectification of the transformer's output voltages and to reduce AC grid interference, two or more secondary winding arrangements can be provided, each comprising three secondary windings connected in a star or delta configuration. The secondary winding arrangements can, in particular, be designed to generate output voltages phase-shifted by an angle Δrp. This allows the use of several separate rectifiers for the phase-shifted output voltages, so that the AC output voltage has lower ripple and lower harmonic grid interference. In this case, the use of a choke coil to smooth the DC output current may be unnecessary.

[0023] According to the invention, the output voltages of the secondary winding arrangements can be phase-shifted by a phase angle of Arp > 0°. The value of Acp is calculated as Acp = 60° divided by the number of secondary winding arrangements. With four secondary winding arrangements, the value of Acp is thus approximately 15°.

[0024] According to the invention, three, four, five, or six secondary winding arrangements can be provided. These can have secondary windings connected in a star or delta configuration, which are connected with a phase shift Acp in such a way that the harmonics generated on the primary side are canceled out as effectively as possible.

[0025] Preferably, a separate rectifier is provided for each secondary winding arrangement. The rectifiers can be connected in series to generate the output DC voltage. However, the rectifiers can also be connected in parallel to generate the output DC voltage.

[0026] The rectifiers can be designed as multi-phase diode bridge rectifiers, particularly as a six-pulse bridge rectifier with six diodes (B6U circuit). The number of B6U circuits can depend on the respective requirements for the quality of the output DC voltage and DC current.

[0027] For example, to achieve a ripple value of the output DC current of less than 1.2%, four B6U circuits can be provided, resulting in an effective pulse count of 24. In this case, the use of a choke coil on the secondary side may be unnecessary.

[0028] For a pulse count of 12, two phase-shifted secondary winding arrangements can be provided. For a pulse count of 18, three phase-shifted secondary winding arrangements can be provided.

[0029] For a pulse count of 24, four phase-shifted secondary winding arrangements can be provided. For a pulse count of 30, five phase-shifted secondary winding arrangements can be provided. For a pulse count of 36, six phase-shifted secondary winding arrangements can be provided. The secondary winding arrangements can each have a star configuration or a delta configuration, with a corresponding phase shift Acp to cancel harmonic system feedback.

[0030] The input AC voltage can, for example, have an amplitude of over 10 kV, in particular approximately 20 kV - 30 kV. The output DC voltage can range from 300 V to 1500 V, for example, approximately 625 V, depending on the stack type and the number of electrolysis cells to be supplied.

[0031] The transformation ratio can, for example, be adjustable around a nominal value of approximately N1:N2 = 48. Other, particularly higher, values ​​of the transformation ratio are of course also possible. For example, to transform an input AC voltage of approximately 30 kV to an output AC voltage of approximately 160 V, a transformation ratio of N1:N2 = 190 can be provided. The adjustable range can be, for example, + / - 10%. A coarse adjustment of + / - 10% and a fine adjustment of + / - 1% can also be provided, whereby in both cases a number M, N > 15 steps can be provided. In particular, it can be provided that approximately 20 - 40 turns per step are switched for the coarse adjustment. To enable fine adjustment, it can be provided that the on-load tap-changer is designed to switch from one to ten turns per step, in particular a single turn per step.

[0032] Depending on the electrolysis stack, the transformer can have a rated electrical output of approximately 6 MVA. When the secondary side is divided into several secondary winding arrangements, the rated output can be divided accordingly, so that, for example, three or four secondary winding arrangements are provided, each with a rated output of approximately 2 MVA or 1.5 MVA. According to the invention, it can further be provided that the rectifier arrangement comprises two or more transformers, wherein the output voltages of the transformers are phase-shifted by an angle Acp and wherein a dedicated rectifier is provided for each of the transformers to generate the output direct current IDC and the output direct voltage UDC. The transformers and the associated rectifiers can be single-phase or multi-phase, in particular three-phase.

[0033] In contrast to the use of a multi-pulse transformer with two or more phase-shifted secondary winding arrangements, this allows for a simpler transformer design. Only a single secondary winding arrangement is required per transformer, which can optionally be designed with a primary winding and at least one partial winding to implement coarse and fine adjustment. To achieve reduced output voltage ripple, the transformers are designed with a phase shift. The transformers can be designed to achieve an output voltage that is phase-shifted by an angle of Acp, where Acp is equal to 60° divided by the number of transformers. For example, a 24-pulse circuit can be implemented with four transformers, four dedicated rectifier bridges, and two tap changers per transformer.

[0034] Such a rectifier arrangement is particularly suitable for power outputs of 10 MW to 50 MW, as the construction and transport of multi-pulse transformers of this size is difficult. Furthermore, additional load balancing control can be easily implemented by adjusting each bridge current of the rectifier bridges using the fine-tuning tap changers. The setpoint of the generated direct currents can thus be evenly distributed among the individual rectifier bridges by fine-tuning the tap changers of the transformer's partial windings, thus reducing grid perturbations and ripple. The need for balancing chokes can be avoided, and the rectifier bridges can be manufactured more simply.

[0035] The invention further relates to the use of a rectifier arrangement according to the invention for generating an output direct current IDC of more than approximately 600 A, preferably more than approximately 2000 A, at an output direct voltage in the range of approximately 300 V to approximately 1500 V for hydrogen electrolysis, in particular PEM electrolysis or alkaline electrolysis. Further features of the invention emerge from the claims, the description of the embodiments, and the figures. The invention is explained below with reference to figures showing exemplary embodiments:

[0036] Fig. 1 shows a first embodiment of a rectifier arrangement according to the invention;

[0037] Fig. 2 shows a second embodiment of a rectifier arrangement according to the invention;

[0038] Fig. 3 shows a third embodiment of a rectifier arrangement according to the invention;

[0039] Fig. 4 shows a fourth embodiment of a rectifier arrangement according to the invention;

[0040] Fig. 5 shows a fifth embodiment of a rectifier arrangement according to the invention;

[0041] Figs. 6a - 6b show further embodiments of a rectifier arrangement according to the invention.

[0042] Fig. 1 shows a first embodiment of a rectifier arrangement according to the invention for hydrogen electrolysis. This comprises a transformer 1 with a primary winding 2 for connecting an input AC voltage Ui and a secondary winding 3 for providing an output AC voltage U2, as well as a rectifier 4 connected to the secondary winding 3 for generating an output DC current IDC and an output DC voltage UDC. A PEM stack (not shown) for generating hydrogen is connected to the output of the rectifier.

[0043] A number N = 8 winding taps 5 are provided on the primary winding 2 of transformer 1. An on-load tap changer 6 connected to a regulator 7 is provided, which is designed for uninterrupted switching of the winding taps 5, so that the transformation ratio of transformer 1 can be switched in 8 steps via regulator 7. The regulator 7 is connected via data lines to a voltmeter 14 and an ammeter 15 on the output side of rectifier 4.

[0044] In this embodiment, rectifier 4 is designed as a single-phase diode bridge rectifier. Controller 7 receives a desired output direct current as a target variable and adjusts on-load tap changer 6 on the primary side of transformer 1 such that this value is achieved at the output of rectifier 4.

[0045] Fig. 2 shows a second embodiment of a rectifier arrangement according to the invention. In this embodiment, the primary winding 2 comprises a first partial winding 8 and a second partial winding 9, wherein a number N = 8 winding taps 10 are provided on the first partial winding 8, and a number M = 6 winding taps 11 are provided on the second partial winding 9.

[0046] A first on-load tap-changer 12 is provided, which is connected to a controller 7 and designed for uninterrupted switching of the winding taps 10 of the first partial winding 8. Furthermore, a second on-load tap-changer 13 is provided, which is connected to the controller 7 and designed for uninterrupted switching of the winding taps 11 of the second partial winding 9. The controller 7 is connected to both on-load tap-changers 12, 13 via data lines and can operate them.

[0047] The first partial winding 8 is connected in series with the second partial winding 9 via the second on-load tap-changer 13. The partial windings 8, 9 are thus cascaded, so that the transformation ratio of the transformer 1 can be switched in 8 x 6 = 48 steps. In this example, the number of turns of the first partial winding 8 is identical to the number of turns of the second partial winding 9, so that the first on-load tap-changer 12 switches fewer turns per step than the second on-load tap-changer 13. The second on-load tap-changer 13 thus effects a coarse adjustment, and the first on-load tap-changer a fine adjustment of the transformation ratio Ui : U2. In this exemplary embodiment, the rectifier 4 is designed as a single-phase diode bridge rectifier. The regulator 7 is connected via data lines to a voltmeter 14 and an ammeter 15 on the output side of the rectifier 4.The controller 7 receives a desired output DC voltage or a desired output DC current as a target value and sets the on-load tap changers 12, 13 on the primary side of the transformer 1 such that these values ​​are achieved at the output of the rectifier 4.

[0048] Fig. 3 shows a third embodiment of a rectifier arrangement according to the invention. In this embodiment, a three-phase transformer is used to transform a three-phase input AC voltage U12, U23, U13 into a three-phase output AC voltage Ui2', Ui23', Ui3'. In the present embodiment, the primary windings 2, 2', 2" and the secondary windings 3, 3', 3" are connected in a delta configuration. Again, a number N = 8 winding taps 5, 5', 5" are provided on each primary winding 2, 2', 2".

[0049] Three on-load tap changers 6, 6', 6" connected to the controller 7 are designed for the uninterrupted switching of these winding taps 5, 5', 5" on the primary side of the transformer, so that the controller 7 can set the transformation ratio of the transformer Ui2:Ui2' = U23:U23' = Uis:Ui3' in N = 8 steps, whereby the steps are of different sizes.

[0050] The three secondary windings 3, 3', 3" are connected in a delta configuration and form a secondary winding arrangement 16. In an embodiment of the invention not shown, the primary windings 2, 2', 2" and also the secondary windings 3, 3', 3" are connected in a star configuration.

[0051] In this embodiment, the rectifier 4 is designed as a three-phase diode bridge rectifier. The regulator 7, in turn, is connected via data lines to a voltmeter 14 and an ammeter 15 on the output side of the rectifier 4. The regulator 7 receives a desired output DC voltage or a desired output DC current as a target variable and adjusts the on-load tap changers 6, 6', 6" on the primary side of the transformer 1 such that these values ​​are achieved at the output of the rectifier 4.

[0052] Fig. 4 shows a fourth embodiment of a rectifier arrangement according to the invention. In this embodiment, a three-phase transformer is used to transform a three-phase input AC voltage into a three-phase output AC voltage. In the present embodiment, the primary windings 2, 2', 2" and the secondary windings 3, 3', 3" are connected in a delta configuration.

[0053] The primary windings 2, 2', 2" each comprise a first partial winding 8, 8', 8" and a second partial winding 9, 9', 9". A number N = 4 winding taps 10, 10', 10" are provided on the first partial windings 8, 8', 8". A number M = 8 winding taps 11, 11', 11" are provided on the second partial windings 9, 9', 9". Each partial winding can itself be subdivided into several individual windings.

[0054] Three first on-load tap-changers 12, 12', 12" are provided, which are connected to the controller 7 via data lines and are designed for uninterrupted switching of the winding taps 10, 10', 10" of the first partial windings 8, 8', 8". The three first on-load tap-changers 12, 12', 12" can also be implemented as a single three-phase on-load tap-changer.

[0055] Furthermore, three second on-load tap-changers 13, 13', 13" are provided, which are connected to the controller 7 via data lines and are designed for uninterrupted switching of the winding taps 11, 11', 11" of the second partial winding 9, 9', 9". The three second on-load tap-changers 13, 13', 13" can also be implemented as a single three-phase on-load tap-changer. The first partial windings 8, 8', 8" are connected in series with the second partial windings 9, 9', 9" via the first on-load tap-changers 12, 12', 12", so that a cascading of the first and second partial windings results, and the transformation ratio of the transformer 1 can be switched in M ​​x N = 8 x 4 = 32 steps. The controller 7 can thus set the transformation ratio of the transformer 1 in 32 steps, whereby the steps have different sizes.

[0056] In embodiments of the invention not shown, the values ​​of N and M are greater than 15, in particular greater than 20, so that the controller 7 can adjust the transformation ratio of the transformer 1 in more than 225, in particular in more than 400 steps.

[0057] In the illustrated embodiment, the primary windings 2, 2', 2" are connected in a delta configuration. On the secondary side, four secondary winding arrangements 16, 16', 16", 16'", each electrically phase-shifted by 15°, are provided. The phase shifts are, for example, +22.5°, +7.5°, -7.5°, -22.5° relative to the primary side. The secondary windings 3, 3', 3" of the first two secondary winding arrangements 16, 16' are connected in a delta configuration. The secondary windings 3, 3', 3" of the third and fourth secondary winding arrangements 16", 16'" are connected in a star configuration.

[0058] Each of the four secondary winding arrangements 16, 16', 16", 16'" is connected to a rectifier 4, 4', 4", 4'". In this embodiment, the rectifiers 4, 4', 4", 4'" are designed as three-phase diode bridge rectifiers with six diodes each, resulting in a 24-pulse rectification of the input AC voltage.

[0059] In embodiments of the invention not shown, two, three, five, or six secondary winding arrangements can be combined, each with a three-phase diode bridge rectifier with six diodes each, resulting in 12-, 18-, 30-, or 36-pulse rectification of the input AC voltage. In this embodiment, transformer 1 has a rated electrical output of approximately 6 MVA at an input voltage of approximately 30 kV. By dividing the secondary side into four secondary winding arrangements 16, 16', 16", 16'", the rated output is divided into approximately 1.5 MVA each.

[0060] The regulator 7 is in turn connected via data lines to a voltmeter 14 and an ammeter 15 on the output side of the rectifier 4.

[0061] The regulator 7 receives a desired output DC voltage or a desired output DC current as a target variable and sets the first on-load tap changers 12, 12', 12" and the second on-load tap changers 13, 13', 13" on the primary side of the transformer 1 such that the desired values ​​are achieved at the output of the rectifier 4.

[0062] Fig. 5 shows a fifth embodiment of a rectifier arrangement according to the invention. This embodiment corresponds to that of Fig. 4 with the difference that the secondary winding arrangements 16, 16', 16", 16'" are connected in parallel. This results in a higher voltage of the secondary winding arrangements, and a lower transformation ratio N1:N2 is required. Again, the secondary winding arrangements 16, 16', 16", 16'" are each designed with a phase offset of 15°. The rectifiers 4, 4', 4", 4'" are again designed as three-phase diode bridge rectifiers, each with six diodes, resulting in 24-pulse rectification of the input AC voltage. Inter-phase transformers (IPT) with coils 17, 17', 17", 17'" are provided in the output lines to balance the direct currents supplied by the four phase-shifted rectifiers connected in parallel before they are combined.

[0063] Fig. 6a shows a further embodiment of a rectifier arrangement according to the invention. In this embodiment, two single-phase transformers 1, T are provided, whose output voltages are phase-shifted by an angle Acp = 30°. Each transformer 1, T is designed according to the embodiment in Figure 2 and comprises a primary winding 2 divided into two partial windings 8, 9 and correspondingly cascaded on-load tap changers 12, 13. The output AC voltages U2, U2 £The outputs of the transformers 1, T are converted into a DC voltage by dedicated rectifiers 4, 4', with the rectifiers 4, 4' in turn being designed as passive bridge rectifiers. A separate rectifier 4, 4' is provided for each of the transformers 1, T to generate the output DC current IDC and the output DC voltage UDC. A regulator ? is in turn connected via data lines to a voltmeter 14 and an ammeter 15 on the output side of the rectifiers 4, 4'.

[0064] Fig. 6b shows a further embodiment of a rectifier arrangement according to the invention, which essentially corresponds to the embodiment of Fig. 6a. In this embodiment, four multiphase transformers 1, T, 1", T" are provided, whose output voltages are phase-shifted by an angle Acp = 15°. According to the exemplary embodiment in Figure 4, each transformer 1, T, 1", T" is provided with a primary winding 2, 2', 2" divided into two partial windings 8, 8', 8", 9, 9', 9" and correspondingly cascaded on-load tap changers 12, 12', 12", 13, 13', 13". The output AC voltages of the transformers 1, T, 1", 1 '" are converted into a DC voltage by dedicated rectifiers 4, 4', 4", 4'", wherein the rectifiers 4, 4', 4", 4'" are in turn designed as passive bridge rectifiers.For each of the transformers 1, T, 1", 1, a separate rectifier 4, 4', 4", 4'" is provided to generate the output DC current IDC and the output DC voltage UDC. A regulator 7 is in turn connected via data lines to a voltmeter 14 and an ammeter 15 on the output side of the rectifiers 4, 4'.

[0065] The invention is not limited to the embodiments presented here, but encompasses any rectifier arrangement within the scope of the following patent claims.

[0066] 1 , 1', 1", 1'" transformer

[0067] 2, 2', 2" primary winding

[0068] 3, 3', 3" secondary winding

[0069] 4.4', 4", 4- rectifier

[0070] 5, 5', 5" winding taps of the primary windings

[0071] 6, 6', 6" on-load tap changer of the primary windings

[0072] 7 controls

[0073] 8, 8', 8“ First partial winding

[0074] 9, 9', 9“ Second partial winding

[0075] 10, 10', 10“ Winding taps of the first partial winding

[0076] 11 , 11', 11“ Winding taps of the second partial winding

[0077] 12, 12', 12" On-load tap-changer of the first partial winding

[0078] 13, 13', 13“ On-load tap changer of the second partial winding

[0079] 14 voltmeters

[0080] 15 ammeters

[0081] 16, 16', 16", 16'" secondary winding arrangement

[0082] 17, 17', 17", 17'" interphase transformer coil

Claims

Patent claims 1. Rectifier arrangement for hydrogen electrolysis, comprising a. a transformer (1) with a primary winding (2) for connecting an input AC voltage and a secondary winding (3) for providing an output AC voltage, and b. a rectifier (4) connected to the secondary winding (3) for generating an output DC current IDC and an output DC voltage UDC, characterized in that c. a number N > 1 winding taps (5) are provided on the primary winding (2) of the transformer (1), and d. an on-load tap changer (6) connected to a regulator (7) is provided, which is designed for the uninterrupted switching of the winding taps (5), so that the transformation ratio of the transformer (1) can be switched in N steps via the regulator (7).

2. Rectifier arrangement according to claim 1, characterized in that a. the primary winding (2) comprises a first partial winding (8) and a second partial winding (9), wherein b. a number N > 1 winding taps (10) are provided on the first partial winding (8), and a number M > 1 winding taps (11) are provided on the second partial winding (9), wherein c. a first on-load tap changer (12) is provided which is connected to a regulator (7) and is designed for uninterrupted switching of the winding taps (10) of the first partial winding (8), and d. a second on-load tap changer (13) is provided which is connected to a regulator (7) and is designed for uninterrupted switching of the winding taps (11) of the second partial winding (9), wherein e.the first partial winding (8) is connected in series with the second partial winding (9) via the second on-load tap changer (13), so that the transformation ratio of the transformer (1) can be switched in N x M steps.

3. Rectifier arrangement according to claim 2, characterized in that the number of windings switched by the on-load tap changers (12, 13) is different for each stage, so that the transformation ratio can be adjusted in coarse steps and in fine steps via the on-load tap changers (12, 13).

4. Rectifier arrangement according to one of claims 1 to 3, characterized in that the transformer (1) is designed as a multi-phase, in particular as a three-phase transformer with primary windings (2, 2', 2") connected in a star or delta configuration and secondary windings (3, 3', 3") connected in a star or delta configuration, wherein a number N > 1 winding taps (5, 5', 5") are provided on each primary winding (2, 2', 2"), and one multi-phase or several, preferably three, single-phase on-load tap changers (6, 6', 6") connected to the regulator (7) are provided, which are designed for the uninterrupted switching of the winding taps (5, 5', 5").

5. Rectifier arrangement according to claim 4, characterized in that a. the primary windings (2, 2', 2") each comprise a first partial winding (8, 8', 8") and a second partial winding (9, 9', 9"), wherein b. a number N > 1 winding taps (10, 10', 10") are provided on the first partial windings (8, 8', 8"), and c. a number M > 1 winding taps (11, 11', 11") are provided on the second partial windings (9, 9', 9"), wherein d. first on-load tap changers (12, 12', 12") are provided, which are connected to the regulator (7) and are designed for the uninterrupted switching of the winding taps (10, 10', 10") of the first partial windings (8, 8', 8"), and e. second on-load tap changers (13, 13', 13") are provided, which are connected to the controller (7) and are designed for the uninterrupted switching of the winding taps (11, 11', 11") of the second partial winding (9, 9', 9"), wherein f.the first partial windings (8, 8', 8") are connected in series with the second partial windings (9, 9', 9") via the first on-load tap changers (12, 12', 12"), so that the transformation ratio of the transformer (1) can be switched in M ​​x N steps.

6. Rectifier arrangement according to claim 4 or 5, characterized in that two or more secondary winding arrangements (16, 16', 16", 16'") each comprising three secondary windings (3, 3', 3") connected in a star or delta configuration with pivoting are provided, wherein the secondary winding arrangements (16, 16', 16", 16'") are designed to generate output voltages phase-shifted by an angle Acp.

7. Rectifier arrangement according to claim 6, characterized in that the output voltages of the secondary winding arrangements (16, 16', 16", 16'") are phase-shifted by an angle of Acp, where Acp is equal to 60° divided by the number of secondary winding arrangements (16, 16', 16", 16'").

8. Rectifier arrangement according to claim 6 or 7, characterized in that three, four, five or six secondary winding arrangements (16, 16', 16", 16'") are provided.

9. Rectifier arrangement according to one of claims 6 to 8, characterized in that a separate rectifier (4, 4', 4", 4'") is provided for each secondary winding arrangement (16, 16', 16", 16'"), wherein the rectifiers (4, 4', 4", 4'") are connected in series.

10. Rectifier arrangement according to one of claims 6 to 8, characterized in that a separate rectifier (4, 4', 4", 4'") is provided for each secondary winding arrangement (16, 16', 16", 16'"), wherein the rectifiers (4, 4', 4", 4'") are connected in parallel.

11. Rectifier arrangement according to one of claims 1 to 10, characterized in that the rectifiers (4, 4', 4", 4'") are designed as single-phase or multi-phase diode bridge rectifiers.

12. Rectifier arrangement according to one of claims 1 to 11, characterized in that the regulator (7) is connected to an ammeter (15) of the output current IDC and optionally to a voltmeter (14) for measuring the output voltage UDC.

13. Rectifier arrangement according to one of claims 1 to 12, characterized in that the input AC voltage has an amplitude of more than 10 kV, in particular about 20 kV to 30 kV, and the output DC voltage has a nominal value of about 300 V to about 1500 V, for example about 625 V.

14. Rectifier arrangement according to one of claims 1 to 13, characterized in that the transformation ratio is adjustable by a nominal value of at least approximately N1 :N2 = 48, in particular N1 :N2 = 190.

15. Rectifier arrangement according to one of claims 1 to 14, characterized in that the transformer (1) has a rated electrical power of more than approximately 1 MVA, preferably more than approximately 6 MVA.

16. Rectifier arrangement according to one of claims 1 to 15, characterized in that, to enable fine adjustment, the on-load tap changers (6, 12, 13) are designed to switch less than ten, less than five, in particular a single winding per stage.

17. Rectifier arrangement according to one of claims 1 to 16, characterized in that two or more transformers (1, T, 1", T") are provided, the output voltages of the transformers (1, T, 1", T") being phase-shifted by an angle Acp and a rectifier (4, 4', 4", 4'") being provided for each of the transformers (1, T, 1", 1'") to generate the output direct current IDC and the output direct voltage UDC.

18. Rectifier arrangement according to claim 17, characterized in that the transformers (1, T, 1", T") and the rectifiers (4, 4', 4", 4'") are multi-phase, in particular three-phase.

19. Use of a rectifier arrangement according to one of claims 1 to 18 for generating an output direct current IDC of more than about 600 A, preferably more than about 2000 A at an output direct voltage in the range of about 300 V to 1500 V for hydrogen electrolysis, in particular PEM electrolysis or alkaline electrolysis.

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