CN119906161A

CN119906161A - Hydrogen production power supply system and control method thereof

Info

Publication number: CN119906161A
Application number: CN202510400810.4A
Authority: CN
Inventors: 袁庆伟; 吴扣林; 葛健; 刘磊; 王宇; 钱为
Original assignee: NR Electric Co Ltd; NR Engineering Co Ltd; Changzhou NR Electric Power Electronics Co Ltd
Current assignee: NR Electric Co Ltd; NR Engineering Co Ltd; Changzhou NR Electric Power Electronics Co Ltd
Priority date: 2025-04-01
Filing date: 2025-04-01
Publication date: 2025-04-29
Anticipated expiration: 2045-04-01
Also published as: CN119906161B

Abstract

The present application provides a hydrogen production power supply system and a control method thereof, including: an AC transformer, configured to distribute and output a second AC voltage after transforming a first AC voltage input from an AC power grid; a voltage regulating branch, configured to convert and adjust the second AC voltage to obtain a second DC voltage; a constant voltage branch, configured to convert the second AC voltage to obtain a first DC voltage; a switching device, configured to connect the output end of the voltage regulating branch in series with the output end of the constant voltage branch to form a total output voltage output to the electrolyzer; an energy storage device, configured to access the total output voltage and be connected in parallel to the electrolyzer; wherein the switching device is also configured to adjust the number of connected voltage regulating branches and/or constant voltage branches according to the working voltage of the electrolyzer. Through the above scheme, the hydrogen production power supply system of the present application can invest a corresponding number of constant voltage branches and voltage regulating branches according to the load condition of the electrolyzer, thereby improving the operating efficiency of the hydrogen production power supply.

Description

Hydrogen production power supply system and control method thereof

Technical Field

The application relates to the technical field of hydrogen production, in particular to a hydrogen production power supply system and a control method thereof.

Background

The hydrogen energy is a clean, carbon-free, flexible, efficient and application-scene-rich secondary energy source and an important industrial raw material. The new energy is utilized to supply power, the electrolytic water hydrogen production is a more convenient method for preparing hydrogen, has the characteristics of environmental protection, flexible production, high purity and the like, and is an ideal green hydrogen production mode. The hydrogen production power supply is used as core equipment for connecting the electrolytic tank and the new energy power grid, and the control performance and reliability of the hydrogen production power supply are directly related to the efficiency and safety of the whole hydrogen production system.

Meanwhile, along with the continuous improvement of the process and technical level of an electrolytic tank manufacturer, the hydrogen production amount of an alkaline electrolytic tank is gradually improved from 1000Nm ³/h to 3000Nm ³/h、5000Nm³/h, the direct-current voltage and current specification of the electrolytic tank are also continuously improved, and the output voltage and current level of a hydrogen production power supply matched with the electrolytic tank also need to be correspondingly improved.

In the related technology, the technical scheme of the hydrogen production power supply adopts three forms of thyristor rectification, diode rectification, insulated gate bipolar transistor (Insulated Gate Bipolar Transistor, IGBT) chopping, full IGBT rectification and chopping, wherein the thyristor rectification is in a one-stage topological structure, and the other two types are in a two-stage topological structure. When the thyristor scheme is adopted for rectifying power supply, a large amount of low-order harmonic waves are injected into an alternating current power grid and a large amount of reactive power is absorbed, the output direct current voltage is low in regulating speed and contains a large amount of current ripple, the hydrogen production efficiency of the electrolytic cell is affected, and the method is not suitable for being applied to the field of green electricity hydrogen production. When a two-stage topological circuit is adopted for rectifying power supply, a plurality of branches are generally required to be connected in parallel for supplying power to meet the current and voltage requirements of the electrolytic tank, the two-stage topological circuit has two energy change links of alternating current-direct current (AC-DC) conversion and fixed direct current voltage conversion into variable direct current voltage (DC-DC), the plurality of branches are simultaneously used for supplying power, and the overall efficiency of the hydrogen production power supply is influenced, particularly under the working condition of lower hydrogen production of the electrolytic tank.

In view of this, in order to promote popularization and application of the high-capacity electrolytic tank in the green hydrogen field, a new hydrogen production power topology scheme needs to be researched so as to meet the requirements of a green electricity hydrogen production system on a hydrogen production power source with high response speed, high efficiency, high power factor, wide output voltage and current range and excellent grid-related characteristics.

Disclosure of Invention

The embodiment of the application provides a hydrogen production power supply system and a control method thereof, which are used for solving the problem that the overall efficiency of the hydrogen production power supply is affected by adopting a plurality of branch circuits to supply power to meet the use requirement of an electrolytic tank in the related art.

In order to solve the problems, the technical scheme provided by the application is as follows:

in a first aspect, the present application provides a hydrogen production power supply system comprising:

The alternating current transformation device is configured to transform a first alternating current voltage input by an alternating current power grid and then distribute and output a second alternating current voltage;

The voltage regulating branch is electrically connected with the alternating current transformer and is configured to convert and regulate the second alternating current voltage to obtain a second direct current voltage;

the constant-voltage branch circuit is electrically connected with the alternating-current transformer device and is configured to convert the second alternating-current voltage into a first direct-current voltage;

A switching device configured to serially connect the output end of the voltage regulating branch with the output end of the constant voltage branch to form a total output voltage to be output to the electrolytic tank, and

An energy storage device configured to be connected to the total output voltage and connected in parallel with the electrolytic cell;

the switching device is further configured to adjust the number of the connected voltage regulating branches and/or constant voltage branches according to the working voltage of the electrolytic tank.

In an embodiment, the hydrogen production power supply system includes one voltage regulating branch or two voltage regulating branches, and the voltage regulating branches include:

a first AC-DC converter configured to convert the second AC voltage into an initial DC voltage, and

And the direct current transformer is electrically connected with the first alternating current-direct current converter and is configured to adjust the initial direct current voltage to obtain the second direct current voltage.

In one embodiment, the dc transformer includes:

a chopper circuit configured to switch in and regulate the initial DC voltage, and

A discharge circuit electrically connected to the chopper circuit, the discharge circuit configured to discharge electrical energy of the chopper circuit;

wherein, the discharge circuit comprises an insulated gate bipolar transistor and a power resistor which are connected in series.

In one embodiment, the hydrogen production power supply system includes a plurality of constant voltage branches including:

and a second ac-dc converter configured to convert the second ac voltage into a first dc voltage.

In an embodiment, the switching device comprises a plurality of switching circuits, the switching circuits and the electrolytic tank are connected in series, and each voltage regulating branch and each constant voltage branch are connected with one switching circuit;

the switching circuit comprises a positive electrode input end, a negative electrode input end, a positive electrode output end and a negative electrode output end;

In the adjacent switching circuits, the negative electrode output end of one switching circuit is connected with the positive electrode output end of the other switching circuit.

In one embodiment, the switching circuit is a mechanical switching circuit, or

The switching circuit is an electronic switching circuit for realizing switching by controlling the on-off of the insulated gate bipolar transistor.

In an embodiment, the switching circuit further comprises:

A bypass switch connected between the positive input end and the positive output end of the switching circuit and/or between the negative input end and the negative output end of the switching circuit, and

And the first end of the bipolar switch is connected between the positive electrode output end and the negative electrode output end of the switching circuit.

In an embodiment, the bypass switch and the bipolar switch have different switch states.

In an embodiment, the first dc voltage and the second dc voltage satisfy:

Udc1=Udc2=Udc/(N+1),Udc≥Ups:

Wherein Udc1 is a constant value of the first direct current voltage, udc2 is a maximum value of the second direct current voltage, udc is a maximum value of the total output voltage, N is the number of the constant voltage branches, and Ups is the working voltage of the electrolytic tank.

In a second aspect, the present application provides a control method of a hydrogen production power supply system, which is implemented by the hydrogen production power supply system of any embodiment of the first aspect, including:

step-up control, namely, the total output voltage of the hydrogen production power supply system is increased from 0 to the working voltage of the electrolytic tank;

Step-down control of reducing the total output voltage of the hydrogen production power supply system from the operation voltage of the electrolytic tank to 0, and

And (3) voltage regulation control, namely regulating the output voltage of the hydrogen production power supply from the initial working condition voltage of the electrolytic tank to the target working condition voltage.

In an embodiment, the voltage regulating branch comprises a first voltage regulating branch and a second voltage regulating branch.

In one embodiment, the step of boost control includes:

All the pressure regulating branches and the constant pressure branches are in an exit state;

Unlocking a first alternating current-direct current converter and a direct current transformer of the first voltage regulating branch or the second voltage regulating branch, putting the voltage regulating branch in an unlocking state, and gradually lifting the voltage at two ends of the electrolytic tank from 0 to Ups when Ups is less than or equal to Udc 2;

When Ups is larger than Udc2 and Ups is smaller than or equal to 2Udc2, respectively unlocking the first AC-DC converter and the DC transformer of the first voltage regulating branch and the second voltage regulating branch, wherein the output voltage of the first voltage regulating branch and the output voltage of the second voltage regulating branch are 0, unlocking one constant voltage branch, the output voltage of which is Udc2, then throwing the first voltage regulating branch, gradually lifting the voltage at two ends of the electrolytic tank from 0 to Udc2, then throwing the first voltage regulating branch, throwing one constant voltage branch and the second voltage regulating branch in an unlocking state, outputting constant voltage Udc2 by one constant voltage branch in the unlocking state, gradually lifting the output voltage of the constant voltage branch from 0 to Ups-Udc2, lifting the voltage at two ends of the electrolytic tank from Udc2 to Ups, locking a chopper circuit in the DC transformer of the first voltage regulating branch, and reducing the output voltage of the first voltage regulating branch to 0 through a chopper circuit in the DC transformer of the first voltage regulating branch;

When Ups is larger than m Udc2 and Ups is less than or equal to (m+1) Udc2 (1<m is less than or equal to N, and m is an integer), according to the input method of the constant voltage branch and the switching and the input and the withdrawal method of the voltage regulating branch when Ups is larger than Udc2 and Ups is less than or equal to 2Udc2, all the constant voltage branches and one voltage regulating branch are input in sequence, and the voltage at two ends of the electrolytic tank is gradually raised from 0 to Ups.

In one embodiment, the step-down control is to decrease the output voltage of the hydrogen production power supply from the voltage Ups corresponding to the current working condition of the electrolytic tank to 0, and the step of the step-down control includes:

when Ups is less than or equal to Udc2, assuming that the first voltage regulating branch is in an unlocking and putting state, regulating the output voltage of the first voltage regulating branch, and gradually reducing the voltage at the two ends of the electrolytic tank from Ups to 0;

When Ups is larger than Udc2 and Ups is smaller than or equal to 2Udc2, assuming that the second voltage regulating branch and one constant voltage branch are in an unlocking and throwing state, firstly unlocking the first voltage regulating branch and outputting voltage Udc2, secondly reducing the output voltage of the second voltage regulating branch from Ups-Udc2 to 0, reducing the voltages at two ends of the electrolytic tank from Ups to Udc2, then withdrawing the constant voltage branch and the second voltage regulating branch which are in the unlocking and throwing state, throwing the first voltage regulating branch, and then regulating the output voltage of the first voltage regulating branch, and reducing the voltages at two ends of the electrolytic tank from Udc2 to 0;

When Ups is larger than m Udc2 and Ups is less than or equal to (m+1) Udc2 (1<m is less than or equal to N, and m is an integer), according to the withdrawal method of the constant voltage branch and the switching and throwing-in/out method of the voltage regulating branch when Ups is larger than Udc2 and Ups is less than or equal to 2Udc2, withdrawing the constant voltage branch m-1 and throwing in one voltage regulating branch in sequence, and gradually reducing the voltage at two ends of the electrolytic tank from Ups to 0.

In one embodiment, the step of voltage regulation control includes:

Assuming that the number of the constant voltage branches into which the hydrogen production power supply outputs the current voltage Ups1 is y, y=floor (Ups 1/Udc 2), determining that the number of the constant voltage branches into which the hydrogen production power supply outputs the target voltage Ups2 is z, z=floor (Ups 2/Udc 2), and floor is a downward rounding operator;

When z=y, adjusting the output voltage of the voltage adjusting branch circuit in the unlocking state, and adjusting the voltage at two ends of the electrolytic tank from Ups to Ups;

When z is greater than y, gradually increasing the input quantity of the constant voltage branch from y to z according to the input method of the constant voltage branch and the switching, switching and regulating methods of the voltage regulating branch in the boost control, regulating the output voltage of the voltage regulating branch in an unlocking state, and raising the voltage at two ends of the electrolytic tank to Ups;

And when z is less than y, gradually reducing the input quantity of the constant voltage branch from y to z according to the constant voltage branch exit method and the switching, switching and regulating methods of the voltage regulating branch in the step-down control, regulating the output voltage of the voltage regulating branch in an unlocking state, and reducing the voltage at two ends of the electrolytic tank to Ups.

The embodiment of the application provides a hydrogen production power supply system and a control method thereof, wherein the hydrogen production power supply system comprises an alternating current transformer device, a constant voltage branch, a voltage regulating branch, a switching device and an energy storage device, wherein the alternating current transformer device is configured to transform a first alternating current voltage input by an alternating current power grid and then distribute and output a second alternating current voltage, the constant voltage branch is electrically connected with the alternating current transformer device and is configured to convert the second alternating current voltage to obtain a first direct current voltage, the voltage regulating branch is electrically connected with the alternating current transformer device and is configured to convert and regulate the second alternating current voltage to obtain a second direct current voltage, the switching device is configured to serially connect an output end of the voltage regulating branch and an output end of the constant voltage branch to form a total output voltage to be output to an electrolytic tank, the energy storage device is configured to be connected into the total output voltage and is connected with the electrolytic tank in parallel, and the switching device is further configured to regulate the number of the voltage regulating branch and/or the constant voltage branch which are connected according to the working voltage of the electrolytic tank. Through the scheme, the output power capacity of the hydrogen production power supply is equally divided according to the resistance load characteristic of the electrolytic tank, and different numbers of power branches are input according to the operation working condition of the electrolytic tank, so that the operation efficiency of the hydrogen production power supply is improved, and the requirements of the hydrogen production power supply of the high-capacity electrolytic tank in the field of green electricity hydrogen production are met.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of an alternative hydrogen generation power supply in accordance with an embodiment of the present application;

FIG. 2 is a schematic diagram of an alternative hydrogen generation power supply in accordance with an embodiment of the present application;

FIG. 3 is a schematic diagram of a two-level three-phase bridge circuit of an AC/DC converter according to an embodiment of the present application;

FIG. 4 is a schematic diagram of a three-level three-phase bridge circuit of an AC/DC converter according to an embodiment of the present application;

FIG. 5 is a schematic circuit diagram of a DC transformer based on a two-level three-phase AC side parallel chopper circuit in an embodiment of the application;

FIG. 6 is a schematic circuit diagram of a DC transformer based on a three-phase bridge diode rectification chopper circuit in an embodiment of the application;

FIG. 7 is a schematic circuit diagram of a DC transformer based on a dual active bridge resonant chopper circuit in accordance with an embodiment of the present application;

FIG. 8 is a schematic diagram of a circuit structure of a constant voltage branch circuit in an embodiment of the application;

FIG. 9 is a schematic circuit diagram of a voltage regulating branch circuit in an embodiment of the present application;

FIG. 10 is a schematic diagram of a single two-level electronic switching circuit in an embodiment of the application;

FIG. 11 is a schematic diagram of a plurality of electronic switching circuits with two levels connected in parallel in an embodiment of the present application;

FIG. 12 is a schematic diagram of a single three-level electronic switching circuit in an embodiment of the present application;

FIG. 13 is a schematic diagram of a plurality of three-level electronic switching circuits connected in parallel in an embodiment of the present application;

FIG. 14 is a diagram showing a connection relationship between a two-level AC/DC converter and a switching circuit in an embodiment of the present application;

FIG. 15 is a diagram showing a connection relationship between a three-level AC/DC converter and a switching circuit in an embodiment of the present application;

FIG. 16 is a diagram showing the connection relationship between the voltage regulating branch and the switching circuit in the embodiment of the present application;

FIG. 17 is a schematic diagram of a circuit of multiple parallel modules of an AC/DC converter according to an embodiment of the present application;

fig. 18 is a schematic circuit diagram of a multi-module parallel connection of dc transformers according to an embodiment of the present application.

Reference numerals in the drawings illustrate:

1. a hydrogen production power supply system;

100. an alternating current transformer;

200. A constant pressure branch; 210, a second ac-dc converter;

300. a pressure regulating branch; 310, a first AC-DC converter, 320, a DC transformer, 321, a chopper circuit, 322, and a discharge circuit;

400. switching device, 410, switching circuit, 411, bypass switch, 412, bipolar switch;

500. An energy storage device.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

The terms "comprises" and "comprising" when used in the specification and claims of the present application are taken to specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Referring to fig. 1 and 2, according to a first aspect of the present application, there is provided a hydrogen production power supply system 1, the hydrogen production power supply system 1 being applicable to a large-capacity electrolytic tank, the hydrogen production power supply system 1 including an alternating current voltage transformation device 100, a voltage regulation branch 300, a constant voltage branch 200, a switching device 400, and an energy storage device 500.

The ac transformer 100 is configured to transform a first ac voltage input by an ac power grid and then distribute the transformed first ac voltage to output a second ac voltage, and in some specific examples, the ac transformer 100 employs a multi-winding transformer, where primary windings of the multi-winding transformer are connected to the ac power grid, and each set of secondary windings is connected to one voltage regulating branch 300 or one constant voltage branch 200, respectively.

The voltage regulating branch 300 is electrically connected to the ac transformer 100, and the voltage regulating branch 300 is configured to convert and regulate the second ac voltage to obtain a second dc voltage. Specifically, the voltage regulating branch 300 includes a first ac-dc converter 310 and a dc transformer 320, the first ac-dc converter 310 is configured to convert the second ac voltage into an initial dc voltage, the dc transformer 320 is electrically connected to the first ac-dc converter 310, and the dc transformer 320 is configured to regulate the initial dc voltage to obtain the second dc voltage. The first ac-dc converter 310 can convert the ac current into dc with constant voltage, and perform reactive power compensation, harmonic suppression, and the like on the ac power grid, and the dc transformer 320 can convert the initial dc voltage with constant voltage output by the first ac voltage conversion into the second dc voltage with variable voltage amplitude. Referring to fig. 3 or 4, in some embodiments of the present application, the circuit of the first ac-dc converter 310 is a two-level three-phase bridge circuit or a three-level three-phase bridge circuit based on insulated gate bipolar transistor Pulse Width Modulation (PWM) rectification.

Referring to fig. 5-7, in some embodiments of the present application, a dc transformer 320 includes a chopper circuit 321 and a discharge circuit 322, wherein the chopper circuit 321 is configured to switch in and regulate an initial dc voltage, the discharge circuit 322 is electrically connected to the chopper circuit 321, the discharge circuit 322 is configured to discharge power from the chopper circuit 321, and the discharge circuit 322 includes an insulated gate bipolar transistor and a power resistor connected in series. Referring to fig. 5, the chopper branches may be DC-DC converters based on interleaved parallel connection of multiphase bridge arms, three-phase bridge diode rectification DC-DC converters shown in fig. 6, or double-active bridge resonance DC-DC converters shown in fig. 7, in which the positive electrodes of the output terminals of the chopper circuit 321 are connected to the positive electrode of the discharge circuit 322, and the negative electrodes are connected to the negative electrode of the discharge circuit 322.

The discharge circuit 322 is formed by connecting an insulated gate bipolar transistor and a power resistor in series, wherein the collector of the insulated gate bipolar transistor is connected with the positive electrode of the discharge circuit 322, the emitter of the insulated gate bipolar transistor is connected with one end of the power resistor, and the other end of the power resistor is connected with the negative electrode of the discharge circuit 322. It should be noted that the insulated gate bipolar transistor acts as a switch in the discharging circuit 322, and the control system triggers the insulated gate bipolar transistor to turn on when detecting that the voltage at the output end of the chopper circuit 321 is too high or that quick release of the discharging energy is required. Once the insulated gate bipolar transistor is turned on, the circuit forms a low impedance path so that current can flow through the power resistor, which consumes excess electrical energy by converting the current into thermal energy, thereby reducing the voltage and current in the circuit, and this process of consuming excess electrical energy is fast and controllable, ensuring that the system responds quickly to overvoltage or overcurrent conditions.

The constant voltage branch 200 is electrically connected to the ac transformer 100, and the constant voltage branch 200 is configured to convert the second ac voltage to a first dc voltage. In the hydrogen production power supply system 1 of the present application, the constant voltage branch 200 is provided with a plurality of pieces, and the constant voltage branch 200 includes a second ac/dc converter 210 configured to convert the second ac voltage into the first dc voltage. The output ends of the voltage regulating branch 300 and the constant voltage branch 200 are connected in series to supply power to the electrolytic tank, and the currents flowing through the output ends of the voltage regulating branch 300 and the constant voltage branch 200 are equal, so that the voltage regulating branch 300 and the constant voltage branch 200 have the same active output capability. Therefore, the second ac/dc converter 210 and the first ac/dc converter 310 can have the same circuit structure and effect, and the disclosure is not repeated here.

The switching device 400 is configured to serially connect the output end of the voltage regulating branch with the output end of the constant voltage branch to form a total output voltage, and output the total output voltage to the electrolytic tank. The switching device 400 includes a plurality of switching circuits 410, the switching circuits 410 are connected in series with the electrolytic cell, and each voltage regulating branch 300 and each constant voltage branch 200 are connected with one switching circuit 410.

Specifically, the switching circuits 410 include a positive input end, a negative input end, a positive output end, and a negative output end, and in the adjacent switching circuits 410, the negative output end of one switching circuit 410 is connected to the positive output end of the other switching circuit 410. The positive and negative poles of the dc input end of the switching circuit 410 are respectively connected to the positive and negative poles of the dc output end of the second ac/dc converter 210, and the positive and negative poles of the dc output end of the first ac/dc converter 310 of the voltage regulating branch 300 are respectively connected to the positive and negative poles of the dc input end of the dc transformer 320, and the positive and negative poles of the dc output end of the dc transformer 320 are respectively connected to the positive and negative poles of the dc input end of the switching circuit 410, as shown in fig. 8.

In some embodiments of the present application, the switching circuit 410 is a mechanical switching circuit 410, or the switching circuit 410 is an electronic switching circuit 410 that performs switching by controlling on/off of an insulated gate bipolar transistor.

In some embodiments of the present application, the switching circuit 410 further comprises a bypass switch 411 and a bipolar switch 412, wherein the bypass switch 411 is connected between the positive input terminal and the positive output terminal of the switching circuit and/or between the negative input terminal and the negative output terminal of the switching circuit, and the first terminal of the bipolar switch 412 is connected between the positive output terminal and the negative output terminal of the switching circuit. The bypass switch 411 is used for connecting the constant voltage branch or the voltage regulating branch to the series circuit of the connecting electrolytic tank, and the bipolar switch 412 is used for disconnecting the constant voltage branch or the voltage regulating branch from the series circuit of the connecting electrolytic tank. It should be noted that, although the switching circuit 410 is divided into several switches in the embodiment of the present application, in the practical application process, the switching circuit may be a general mechanical switch or an electronic switch formed by a plurality of IGBTs connected in series and parallel.

In addition, the switching device 400 is further configured to adjust the number of connected voltage regulation branches and/or constant voltage branches according to the operating voltage of the electrolytic tank, and according to the function of the switching circuit 410, it is necessary to make the bypass switch 411 and the bipolar switch 412 have different switch states.

In some embodiments of the present application, the bypass switch 411 and the bipolar switch 412 are mechanical switches, specifically, the bypass switch 411 includes a first switch and a second switch, the bipolar switch 412 includes a third switch, the first switch is connected between the positive input terminal and the positive output terminal of the switching circuit 410, the second switch is connected between the negative input terminal and the negative output terminal of the switching circuit 410, the first terminal of the third switch is connected on a connection line between the first switch and the positive output terminal of the switching circuit, and the second terminal of the third switch is connected on a connection line between the second switch and the negative output terminal of the switching circuit. In this embodiment, it is necessary to have the first switch and the second switch have the same switch state, and the first switch and the third switch have different switch states. When the mechanical switching circuit 410 exits, the first switch and the second switch are closed, the third switch is opened, and the voltage regulating branch 300 or the constant voltage branch 200 is disconnected from the outer loop.

In some embodiments of the present application, when the switching circuit 410 is an electronic switching circuit 410, the bipolar communication function and the bypass function are implemented by controlling the on/off of the IGBT.

Referring to fig. 10, in some embodiments of the present application, a two-level electronic switching circuit 410 is provided, wherein the IGBT upper tube Q1 is turned on when the relevant branch is switched on, the lower tube Q2 is blocked, and the IGBT upper tube Q1 is blocked and the lower tube Q2 is turned on when the relevant branch is exited. In this embodiment, the Q1 tube is a bypass switch 411 and the Q2 tube is a bipolar switch 412. On this basis, referring to fig. 11, when the branch output current is large, a plurality of IGBTs may be directly connected in parallel to enhance the current capacity of the switching circuit 410.

Referring to fig. 12, in some embodiments of the present application, a three-level electronic switching circuit 410 is provided, wherein Q1 and Q4 are turned on and Q2 and Q3 are latched when the associated leg is switched on, and Q1 and Q4 are latched and Q2 and Q3 are turned on when the associated leg is withdrawn. In this embodiment, the Q1 and Q4 tubes are bypass switches 411, and the Q2 and Q3 tubes are bipolar switches 412. On this basis, referring to fig. 13, when the output current of the branch circuit is large, a plurality of three-level bridge arms can be directly connected in parallel to improve the current capacity of the switching circuit 410.

In some embodiments of the present application, referring to fig. 14, the second ac/dc converter 210 in the constant voltage circuit may be connected to the two-level electronic switching circuit 410 when it is a two-level three-phase bridge circuit, and referring to fig. 15, the second ac/dc converter 210 in the constant voltage circuit may be connected to the three-level electronic switching circuit 410 when it is a three-level three-phase bridge circuit.

Accordingly, referring to fig. 16, in the voltage regulating circuit, when the dc transformer 320 includes the chopper circuit 321 based on the two-level three-phase bridge arm interleaved parallel connection, it may be connected to the two-level electronic switching circuit 410.

Furthermore, in some embodiments of the present application, the first ac-dc converter 310 or the second ac-dc converter 210 may include one or more module ac sides and dc sides respectively connected in parallel using the same PWM rectified current circuit. Referring to fig. 17, when a single PWM rectifying module cannot meet the power requirement of a branch, the multiple PWM rectifying modules can be connected in parallel on the ac side and the dc side, so as to improve the power transmission capability of the branch.

Likewise, in some embodiments of the present application, the dc transformer 320 in the voltage regulating circuit may also include one or more input sides and output sides respectively connected in parallel with the same chopper circuit 321. When the dc transformer 320 of the voltage regulating branch 300 needs to boost the transmission power, the input sides and the output sides of the chopper circuits 321 and the discharge circuit 322 can be connected in parallel, and the specific circuit structure is shown in fig. 18.

The energy storage device 500 is configured to be connected to the total output voltage and in parallel with the electrolyzer, and in some specific examples, the energy storage device 500 is a support capacitor, the positive electrode of the support capacitor is connected to the positive electrode of the electrolyzer, and the negative electrode of the support capacitor is connected to the negative electrode of the electrolyzer. By setting the supporting capacitor as the instantaneous energy storage, the impact of power mutation on the system can be buffered, the interruption of the hydrogen production process is avoided, and the stability of the hydrogen production efficiency is ensured.

In the foregoing embodiment, the total output voltage uout of the hydrogen production power supply ranges from 0 to Udc, the output voltage of the constant voltage branch 200 is constant to Udc1, the output voltage of the voltage regulating branch 300 ranges from 0 to Udc2, the output voltages of the voltage regulating branch 300 and the constant voltage branch 200 satisfy the following relationship that udc1=udc2=udc/(n+1), and the highest voltage Udc output by the hydrogen production power supply is greater than or equal to the required working voltage Ups of the electrolytic tank.

In view of the foregoing, the present application provides two specific embodiments as follows:

example 1

Referring to fig. 1, the hydrogen production power supply system 1 comprises 2 voltage regulating branches 300 and N constant voltage branches 200, wherein the ac input end of each branch is connected with a set of secondary windings of the multi-winding isolation transformer, the positive and negative poles of the dc output ends of adjacent branches are respectively connected in series and then are connected with the positive and negative poles of the supporting capacitor, and the positive and negative poles of the supporting capacitor are connected with the positive and negative poles of the electrolytic tank. When the output voltage of the hydrogen production power supply changes, the first voltage regulating branch circuit and the second voltage regulating branch circuit alternately switch back and forth, so that the output voltage is continuously regulated.

In this embodiment, the specific structures of the voltage regulating branch 300, the constant voltage branch 200 and the switching circuit 410 may be a combination of circuits that can be implemented in the foregoing embodiments, and the present application is not limited herein.

Example 2

Referring to fig. 2, the hydrogen production power supply comprises 1 voltage regulating branch 300 and N constant voltage branches 200, wherein the ac input end of each branch is connected with a set of secondary windings of the multi-winding isolation transformer, the positive and negative poles of the dc output ends of adjacent branches are respectively connected in series and then connected with the positive and negative poles of the supporting capacitor, and the positive and negative poles of the supporting capacitor are connected with the positive and negative poles of the electrolytic tank. When the output voltage of the hydrogen production power supply is reduced, if the output voltage of the voltage regulating branch 300 reaches 0V, the voltage regulating branch 300 is withdrawn, the output voltage of the voltage regulating branch 300 is regulated to Udc2, then the voltage regulating branch 300 is put into operation and the number of the put-in constant voltage branches 200 is reduced by 1, and when the output voltage of the hydrogen production power supply is increased, if the voltage of the voltage regulating branch 300 reaches Udc2, the voltage regulating branch 300 is withdrawn and the number of the put-in constant voltage branches 200 is increased by 1, and the output voltage of the voltage regulating branch 300 is reduced to 0V and then put into operation.

In this embodiment, the specific structures of the voltage regulating branch 300, the constant voltage branch 200 and the switching circuit 410 may also be a combination of circuits that can be implemented in the foregoing embodiments, and the present application is not limited herein.

In a second aspect, the present application also provides a control method of the hydrogen production power supply system 1, including boost control, buck control, and voltage regulation control.

Taking example 1 as an example, the step-up control is to raise the direct-current voltage output by the hydrogen production power supply from 0 to the voltage Ups required by the target working condition of the electrolytic tank, and the step-up control includes:

1) All the voltage regulating branches 300 and the constant voltage branches 200 are in an exit state;

2) When Ups is less than or equal to Udc2, unlocking the first AC-DC converter 310 and the DC transformer 320 of the first voltage regulating branch or the second voltage regulating branch, wherein the output voltage of the first voltage regulating branch or the second voltage regulating branch is 0 at the moment, putting the voltage regulating branch 300 in an unlocking state into the electric tank, and gradually lifting the voltage at two ends of the electric tank from 0 to Ups;

3) When Ups is larger than Udc2 and Ups is smaller than or equal to 2Udc2, the first ac-dc converter 310 and the dc-transformer 320 of the first voltage regulating branch and the second voltage regulating branch are unlocked firstly, the output voltage of the voltage regulating branch 300 is 0, and the required constant voltage branches 200 are unlocked secondly, wherein the number of the unlocked constant voltage branches 200 can be one and can be the first constant voltage branch adjacent to the voltage regulating branch, the constant voltage branches 200 are marked as first constant voltage branches, and the constant voltage branches 200 which are sequentially connected subsequently are marked as second to Nth constant voltage branches. The method comprises the steps of firstly, setting a first constant voltage branch to output a constant voltage Udc2, then, putting the first constant voltage branch into the device, gradually raising the voltage at two ends of the electrolytic tank from 0 to Udc2, then, withdrawing the first constant voltage branch, putting the first constant voltage branch and a second constant voltage branch into the device, outputting the constant voltage Udc2 by the first constant voltage branch, gradually raising the output voltage of the second constant voltage branch from 0 to Ups-Udc2, raising the voltage at two ends of the electrolytic tank from Udc2 to Ups, and locking a chopper circuit 321 in a direct current transformer 320 of the first constant voltage branch, and reducing the output voltage of the first constant voltage branch to 0 by a discharge circuit 322;

4) When Ups is larger than m Udc2 and Ups is less than or equal to (m+1) Udc2 (1<m is less than or equal to N, and m is an integer), according to the input method of the constant voltage branch 200 and the switching and the input and the withdrawal method of the voltage regulating branch when Ups is larger than Udc2 and Ups is less than or equal to 2Udc2, sequentially inputting the 1~m th constant voltage branch 200 and one voltage regulating branch, and gradually lifting the voltage at two ends of the electrolytic tank from 0 to Ups.

Taking example 1 as an example, the step-down control is to decrease the output voltage of the hydrogen production power supply from the voltage Ups corresponding to the current working condition of the electrolytic tank to 0, and the step of the step-down control includes:

1) When Ups is less than or equal to Udc2, assuming that the first voltage regulating branch is in an unlocking and putting state, regulating the output voltage of the first voltage regulating branch, and gradually reducing the voltage at the two ends of the electrolytic tank from Ups to 0;

2) When Ups is larger than Udc2 and Ups is smaller than or equal to 2Udc2, the second voltage regulating branch and the first constant voltage branch are in unlocking and throwing states, the first voltage regulating branch is firstly unlocked and outputs voltage Udc2, the output voltage of the second voltage regulating branch is secondly reduced to 0 from Ups-Udc2, the voltages at two ends of the electrolytic tank are reduced to Udc2 from Ups, the first constant voltage branch and the second voltage regulating branch are then withdrawn, the first voltage regulating branch is thrown, the output voltage of the first voltage regulating branch is then regulated, the voltages at two ends of the electrolytic tank are reduced to 0 from Udc2, and the constant voltage branch in unlocking and throwing states can be the first constant voltage branch or any other constant voltage branch 200.

3) When Ups is larger than m Udc2 and Ups is less than or equal to (m+1) Udc2 (1<m is less than or equal to N, and m is an integer), according to the withdrawal method of the constant voltage branch 200 and the switching and withdrawal method of the voltage regulating branch when Ups is larger than or equal to Udc2 and Ups is less than or equal to 2Udc2, withdrawing the m-1 constant voltage branch 200 and throwing one voltage regulating branch in sequence, and gradually reducing the voltage at two ends of the electrolytic tank from Ups to 0.

Taking embodiment 1 as an example, the step of voltage regulation control is to regulate the output voltage of the hydrogen production power supply from the voltage Ups corresponding to the current working condition of the electrolytic tank to the voltage Ups corresponding to the target working condition, where the step of voltage regulation control includes:

1) Assuming that the number of constant voltage branches 200 input by the hydrogen production power supply to output the current voltage Ups1 is y, y=floor (Ups 1/Udc 2), determining that the number of constant voltage branches 200 input by the hydrogen production power supply to output the target voltage Ups2 is z, z=floor (Ups 2/Udc 2), and floor is a downward rounding operator;

2) When z=y, the output voltage of the voltage regulating branch 300 in the unlocking state is regulated, and the voltage at the two ends of the electrolytic tank is regulated from Ups to Ups2;

3) When z > y, gradually increasing the input quantity of the constant-voltage branches 200 from y to z according to the input method of the constant-voltage branches 200 and the switching, switching and regulating methods of the voltage regulating branches 300 in the step-up control, regulating the output voltage of the voltage regulating branches 300 in the unlocking state, and raising the voltage at two ends of the electrolytic tank to Ups < 2 >;

4) When z < y, according to the method for exiting the constant voltage branch 200 and the method for switching, switching and adjusting the voltage regulating branch in the step-down control, the input quantity of the constant voltage branch 200 is gradually reduced from y to z, the output voltage of the voltage regulating branch 300 in the unlocking state is adjusted, and the voltage at two ends of the electrolytic tank is reduced to Ups < 2 >.

In the related art, the technical scheme of the hydrogen production power supply adopts three forms of thyristor rectification, diode rectification, insulated gate bipolar transistor (Insulated Gate Bipolar Transistor, IGBT) chopping, full IGBT rectification and chopping, wherein the thyristor rectification is of a one-stage topological structure, and the other two types are of a two-stage topological structure. When the thyristor scheme is adopted for rectifying power supply, as the thyristor rectifier is a nonlinear load and the output voltage is regulated by controlling the conduction angle, the control mode can lead the current waveform to deviate from a sine waveform, and harmonic waves are generated. And since the thyristor starts to conduct after the zero crossing of the voltage, the current lags behind the voltage, which phase difference can lead to reactive power absorption. Besides injecting a large amount of low-order harmonic waves into an alternating current power grid and absorbing a large amount of reactive power, the output direct current voltage of the alternating current power grid is low in regulating speed and contains a large amount of current ripple waves, so that the hydrogen production efficiency of the electrolytic cell is affected, and the alternating current power grid is not suitable for being applied to the field of green electricity hydrogen production. When rectifying power supply is performed by adopting a two-stage topological circuit, a plurality of branches are generally required to be connected in parallel for power supply to meet the current and voltage requirements of an electrolytic tank, and the two-stage topological circuit has two energy change links of alternating current-direct current (AC-DC) conversion and fixed direct current voltage conversion into variable direct current voltage (DC-DC), so that the plurality of branches are simultaneously powered, and the overall efficiency of the hydrogen production power supply is affected. According to the application, the output power capacity of the hydrogen production power supply is equally divided according to the resistance load characteristic of the electrolytic tank, and different numbers of power branches are input according to the operation working condition of the electrolytic tank, so that the operation efficiency of the hydrogen production power supply is improved. Meanwhile, the voltage regulating branch 300 with the voltage regulating function and the output end of the constant voltage branch 200 with the constant voltage and the constant voltage are connected in series, so that a hydrogen production power supply solution with high response speed, excellent grid-related characteristic and high overall efficiency is provided for the high-capacity electrolytic tank, and the requirement of the green electricity hydrogen production field on the hydrogen production power supply of the high-capacity electrolytic tank is met.

In summary, although the present application has been described in terms of the preferred embodiments, the above-mentioned embodiments are not intended to limit the application, and those skilled in the art can make various modifications and alterations without departing from the spirit and scope of the application, so that the scope of the application is defined by the appended claims.

Claims

1. A hydrogen production power supply system, characterized by comprising:

An AC transformer, configured to transform a first AC voltage input from an AC power grid and distribute the transformed voltage to output a second AC voltage;

a constant voltage branch, electrically connected to the AC transformer, the constant voltage branch being configured to convert the second AC voltage into a first DC voltage;

A voltage regulating branch, electrically connected to the AC transformer, the voltage regulating branch being configured to convert and adjust the second AC voltage to obtain a second DC voltage;

A switching device configured to connect the output end of the voltage regulating branch and the output end of the constant voltage branch in series to form a total output voltage to be output to the electrolytic cell; and

an energy storage device configured to be connected to the total output voltage and connected in parallel with the electrolyzer;

Wherein, the switching device is also configured to adjust the number of the connected voltage regulating branches and/or constant voltage branches according to the working voltage of the electrolytic cell.

2. The hydrogen production power supply system according to claim 1, characterized in that:

The hydrogen production power supply system includes one voltage regulating branch or two voltage regulating branches, and the voltage regulating branch includes:

a first AC-DC converter configured to convert the second AC voltage into an initial DC voltage; and

A DC transformer is electrically connected to the first AC-DC converter, and the DC transformer is configured to adjust the initial DC voltage to obtain the second DC voltage.

3. The hydrogen production power supply system according to claim 2, characterized in that:

The DC transformer comprises:

a chopper circuit configured to access and regulate the initial DC voltage; and

a discharge circuit, electrically connected to the chopper circuit, the discharge circuit being configured to release electrical energy of the chopper circuit;

Wherein, the discharge circuit includes an insulated gate bipolar transistor and a power resistor connected in series.

4. The hydrogen production power supply system according to claim 2, characterized in that:

The hydrogen production power supply system comprises a plurality of constant voltage branches, and the constant voltage branches comprise:

The second AC/DC converter is configured to convert the second AC voltage into a first DC voltage.

5. The hydrogen production power supply system according to claim 4, characterized in that:

The switching device comprises a plurality of switching circuits, the plurality of switching circuits are connected in series with the electrolytic cell, and each of the voltage regulating branches and each of the constant voltage branches is connected with a switching circuit;

The switching circuit comprises a positive input terminal, a negative input terminal, a positive output terminal and a negative output terminal;

In adjacent switching circuits, the negative output terminal of one switching circuit is connected to the positive output terminal of another switching circuit.

6. The hydrogen production power supply system according to claim 5, characterized in that:

The switching circuit is a mechanical switching circuit; or

The switching circuit is an electronic switching circuit that realizes switching by controlling the on and off of an insulated gate bipolar transistor.

7. The hydrogen production power supply system according to claim 6, characterized in that:

The switching circuit also includes:

a bypass switch connected between the positive input terminal and the positive output terminal of the switching circuit, and/or connected between the negative input terminal and the negative output terminal of the switching circuit; and

A bipolar switch, wherein a first end of the bipolar switch is connected between a positive output end and a negative output end of the switching circuit.

8. The hydrogen production power supply system according to claim 7, characterized in that:

The bypass switch and the bipolar switch have different switching states.

9. The hydrogen production power supply system according to claim 1, characterized in that:

The first DC voltage and the second DC voltage satisfy:

Udc1=Udc2=Udc/(N+1), Udc≥Ups:

Among them, Udc1 is the constant value of the first DC voltage, Udc2 is the maximum value of the second DC voltage, Udc is the maximum value of the total output voltage, N is the number of the constant voltage branches, and Ups is the working voltage of the electrolytic cell.

10. A control method for a hydrogen production power system, implemented based on the hydrogen production power system of any one of claims 1 to 9, characterized in that it comprises:

Boost control: increasing the total output voltage of the hydrogen production power supply system from 0 to the working voltage of the electrolyzer;

Voltage reduction control: reducing the total output voltage of the hydrogen production power system from the operating voltage of the electrolyzer to 0; and

Voltage regulation control: adjust the output voltage of the hydrogen production power supply from the initial operating voltage of the electrolyzer to the target operating voltage.

11. The control method according to claim 10, characterized in that the voltage regulating branch comprises a first voltage regulating branch and a second voltage regulating branch.

12. The control method according to claim 11, characterized in that the step of boost control comprises:

All the voltage regulating branches and the constant pressure branches are in the exit state;

When Ups≤Udc2: unlock the first AC-DC converter and the DC transformer of the first voltage regulating branch or the second voltage regulating branch, put the unlocked voltage regulating branch into operation, and gradually raise the voltage across the electrolytic cell from 0 to Ups;

When Ups>Udc2 and Ups≤2Udc2: respectively unlock the first AC-DC converter and the DC transformer of the first voltage regulating branch and the second voltage regulating branch, and the output voltage of the first voltage regulating branch and the second voltage regulating branch is 0; then unlock one of the constant voltage branches, and the output voltage is Udc2; then put the first voltage regulating branch into operation, and gradually raise the voltage at both ends of the electrolytic cell from 0 to Udc2; then withdraw the first voltage regulating branch, and put one of the constant voltage branches in the unlocked state and the second voltage regulating branch into operation, and the constant voltage branch in the unlocked state outputs a constant voltage Udc2, and the second voltage regulating branch gradually raises the output voltage from 0 to Ups-Udc2, and raises the voltage at both ends of the electrolytic cell from Udc2 to Ups; lock the chopper circuit in the DC transformer of the first voltage regulating branch, and reduce the output voltage of the first voltage regulating branch to 0 through the discharge circuit;

When Ups>m*Udc2 and Ups≤（m+1）*Udc2 (1<m≤N, m is an integer), according to the method of putting the constant voltage branch into operation and the method of switching and putting the voltage regulating branch into operation when Ups>Udc2 and Ups≤2Udc2, all the constant voltage branches and one of the voltage regulating branches are put into operation in sequence to gradually raise the voltage across the electrolytic cell from 0 to Ups.

13. The control method according to claim 12, characterized in that the voltage reduction control is to reduce the output voltage of the hydrogen production power supply from the voltage Ups corresponding to the current working condition of the electrolyzer to 0, and the voltage reduction control steps include:

When Ups≤Udc2: assuming that the first voltage regulating branch is in an unlocked and put-in-place state, the output voltage of the first voltage regulating branch is adjusted to gradually reduce the voltage across the electrolytic cell from Ups to 0;

When Ups>Udc2 and Ups≤2Udc2, it is assumed that the second voltage regulating branch and one of the constant voltage branches are in unlocked and put-in states; first, the first voltage regulating branch is unlocked and outputs a voltage of Udc2; secondly, the output voltage of the second voltage regulating branch is reduced from Ups-Udc2 to 0, and the voltage across the electrolytic cell is reduced from Ups to Udc2; then, the constant voltage branch and the second voltage regulating branch in the unlocked and put-in states are withdrawn, and the first voltage regulating branch is put in; then, the output voltage of the first voltage regulating branch is adjusted, and the voltage across the electrolytic cell is reduced from Udc2 to 0;

When Ups>m*Udc2 and Ups≤（m+1）*Udc2 (1<m≤N, m is an integer), according to the exit method of the constant voltage branch and the switching and investment and withdrawal method of the voltage regulating branch when Ups>Udc2 and Ups≤2Udc2, m constant voltage branches are exited and one voltage regulating branch is invested in turn, and the voltage across the electrolytic cell is gradually reduced from Ups to 0.

14. The control method according to claim 13, characterized in that the voltage regulation control step comprises:

Assuming that the number of constant-voltage branches put into use when the hydrogen production power supply outputs the current voltage Ups1 is y, y=floor(Ups1/Udc2), determine that the number of constant-voltage branches required to be put into use when the hydrogen production power supply outputs the target voltage Ups2 is z, z=floor(Ups2/Udc2), where floor is a rounding-down operator;

When z=y, the output voltage of the voltage regulating branch currently in the unlocked state is adjusted to adjust the voltage across the electrolytic cell from Ups1 to Ups2;

When z>y, according to the constant voltage branch input method and the switching, input and output and adjustment method of the voltage regulating branch in the boost control, the number of the constant voltage branches input is gradually increased from y to z, and the output voltage of the voltage regulating branch in the unlocked state is adjusted to raise the voltage across the electrolytic cell to Ups2;

When z<y, according to the constant voltage branch exit method and the voltage regulating branch switching, activation and regulation method in the voltage reduction control, the number of constant voltage branches activated is gradually reduced from y to z, and the output voltage of the voltage regulating branch in the unlocked state is adjusted to reduce the voltage across the electrolytic cell to Ups2.