Hydrogen production power supply based on multi-level current source converter

Abstract

The invention relates to the technical field of hydrogen production, in particular to a hydrogen production power source and device based on a multi-level current source converter and a photovoltaic hydrogen production system. The hydrogen production power source comprises N current source modules connected to a low-voltage alternating-current bus in parallel; the current source module adopts multi-level modulation and comprises a three-phase bridge type commutator module and an RC (Resistance-Capacitance) filtering submodule which are connected in parallel on a low-voltage alternating-current bus; and the output ports of the current source modules are connected in parallel and then are used as the output of the hydrogen production power supply. The novel multi-level current source converter is small in harmonic wave, can be well matched with the power grid requirement, and can better meet the power grid harmonic wave requirement.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production, and in particular to a hydrogen production power supply, device and photovoltaic hydrogen production system based on a multi-level current source converter. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] At present, photovoltaic power is connected to the grid through boosting and inverter, and then rectified by a semi-controlled thyristor rectifier source. After rectification, it is equipped with electrolysis equipment to produce hydrogen. This traditional thyristor rectifier power supply has large grid-side current harmonic content, small grid-side power factor, and requires a large amount of reactive power and filtering equipment. In addition, the dynamic response speed is slow, and the power regulation response speed is more than 10s, which makes it difficult to quickly match the volatility of new energy. At present, large-scale photovoltaic grid-connected hydrogen production involves multiple links such as inversion, boosting grid connection, transmission, step-down, and rectification hydrogen production. The system has high losses, complex operation and maintenance, and poor grid friendliness, and there are certain technical limitations. Summary of the invention

[0004] In order to overcome the shortcomings of the background technology, the present invention provides a hydrogen production power supply, device and photovoltaic hydrogen production system based on a multi-level current source converter. By adopting a new multi-level current source converter, the harmonics are small and can be well matched with the requirements of the power grid, thereby better meeting the harmonic requirements of the power grid.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] In a first aspect, a hydrogen production power supply based on a multi-level current source converter is provided, wherein the hydrogen production power supply comprises N current source modules connected in parallel on a low-voltage AC bus;

[0007] The current source module adopts multi-level modulation, and the current source module includes a three-phase bridge rectifier module and an RC filter module connected in parallel on the low-voltage AC bus;

[0008] The output ports of the current source modules are connected in parallel and serve as the output of the hydrogen production power supply.

[0009] Further,

[0010] The semiconductor device in the three-phase bridge rectifier module is any one of a reverse resistance IGCT, an asymmetric IGCT, a press-fit IGBT, a modular IGBT and SiC.

[0011] Further,

[0012] The semiconductor device in the three-phase bridge rectifier module adopts a 2500V / 3500A reverse resistance IGCT, the maximum output current of a single current source module is 2000A, and the output voltage range is 0 to +650V.

[0013] Further,

[0014] A three-phase MOV is installed at the AC busbar inlet of the low-voltage AC busbar.

[0015] Further,

[0016] Each of the current source modules adopts water cooling for heat dissipation;

[0017] A heat sink is arranged in the current source module, and the semiconductor device and the heat sink are pressed and connected into a standardized component.

[0018] In a second aspect, a hydrogen production device based on a multi-level current source converter is also provided, the hydrogen production device comprising the aforementioned hydrogen production power supply based on a multi-level current source converter;

[0019] The output end of the hydrogen production power supply is connected to an electrolytic cell group or multiple electrolytic cell groups in parallel;

[0020] The electrolyzer group comprises a first electrolyzer and a second electrolyzer, wherein the first electrolyzer and the second electrolyzer are connected in series to the output end of the hydrogen production power supply, and the midpoints of the two electrolyzers are grounded.

[0021] In a third aspect, a photovoltaic hydrogen production system is also provided, comprising the aforementioned hydrogen production power source based on a multi-level current source converter, and also comprising a photovoltaic collection subsystem, a step-down transformer and a hydrogen production electrolyzer;

[0022] The photovoltaic collection subsystem collects the new energy power from the low-voltage side and transmits it to the medium-voltage AC bus;

[0023] The low-voltage AC bus inlet terminal in the hydrogen production power supply is connected to the medium-voltage AC bus through the step-down transformer;

[0024] The hydrogen production electrolyzer is powered by the output of the hydrogen production power supply.

[0025] Further,

[0026] The photovoltaic collection subsystem includes photovoltaic modules, photovoltaic combiner boxes and inverter boost devices;

[0027] The photovoltaic module adopts a photovoltaic array with MPPT function;

[0028] The photovoltaic combiner box is used for photovoltaic collection, and collects and transmits the electric energy generated by the photovoltaic components to the inverter boost device;

[0029] The inverter boost device converts and boosts the collected electric energy and then transmits it to the medium voltage AC bus.

[0030] Further,

[0031] The medium voltage AC busbar is also connected to an AC grid for supplementary power supply.

[0032] Further,

[0033] The step-down transformer adopts Y connection or Yg connection.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. Adopting MCSC (i.e. multi-level current source converter) topology, through modular design and parallel connection, a power supply with low voltage and high current output characteristics suitable for electrolyzer equipment is obtained; by adopting a new multi-level current source converter, the harmonics are small, which can be well matched with the requirements of the power grid and can better meet the harmonic requirements of the power grid;

[0036] 2. The hydrogen production power supply is composed of multiple current source modules connected in parallel. The number of modules N depends on the parameter requirements of the hydrogen production power supply system and is suitable for larger current expansion;

[0037] 3. The current source module is composed of a three-phase bridge rectifier module (i.e., semiconductors such as IGCT of three-phase six-bridge arms) and an RC filter module (i.e., used for RC filtering), which can well convert the stepped-down AC power into the low-voltage and high-current DC power required for hydrogen production;

[0038] 4. A photovoltaic hydrogen production system solution based on a new multi-level current source converter is adopted, which has excellent matching characteristics with the electrolysis equipment, is friendly and convenient to cooperate with the large power grid, and can save a large amount of filtering equipment. Therefore, it is more suitable for large-scale photovoltaic hydrogen production application scenarios.

[0039] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings.

[0040] The present invention will be further described below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0042] Figure 1 A topological schematic diagram of a hydrogen production power supply according to an embodiment of the present invention;

[0043] Figure 2 A topological schematic diagram of a hydrogen production device according to an embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of the architecture of a photovoltaic hydrogen production system according to an embodiment of the present invention;

[0045] Figure 4 The topological diagram of a photovoltaic hydrogen production system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the implementation of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] like Figure 1 As shown, the first embodiment of the present invention provides a hydrogen production power supply based on a multi-level current source converter, wherein the hydrogen production power supply includes N current source modules connected in parallel on a low-voltage AC bus; the current source module adopts multi-level modulation, and the current source module includes a three-phase bridge rectifier module and an RC filter module connected in parallel on the low-voltage AC bus; the output ports of each of the current source modules are connected in parallel as the output of the hydrogen production power supply.

[0048] The above technical solution adopts MCSC (Multilevel current source converter, abbreviated as MCSC) topology, and obtains a power supply with low-voltage and high-current output characteristics suitable for electrolyzer equipment through modular design and parallel connection; the current source module is composed of a three-phase bridge rectifier module (i.e., semiconductors such as IGCT of three-phase six-bridge arms) and an RC filter module (i.e., used for RC filtering). The current source module is the core energy conversion unit of the current source, which can well convert the alternating current after voltage reduction into the low-voltage and high-current direct current required for hydrogen production. In this embodiment, the connection method of the RC filter module is Y connection, which can better realize RC filtering; in module 1, Lp1 and La1 are upper and lower bridge arm inductors, and inductors are required in the current source module for smoothing current.

[0049] The current source module of the embodiment of the present invention is a multi-level current source converter, which realizes harmonic optimization and reduces the modulation frequency through the current multi-level technology. The current source modules in the prior art are mostly thyristor and PWM, which have problems such as harmonics. The current source module of the embodiment of the present invention is a fully controlled device PWM mode, and adopts a multi-level modulation scheme, which can reduce the switching frequency and be applicable to high current scenarios.

[0050] The above-mentioned hydrogen production power supply is formed by connecting a plurality of current source modules in parallel, and the number of modules N depends on the parameter requirements of the hydrogen production power supply system, which is suitable for larger current expansion. The parameter requirements of the hydrogen production power supply system are determined by the electrolyzer. How large is the current and voltage required by the electrolyzer? The above-mentioned hydrogen production power supply can output the corresponding current and voltage to meet the application requirements by connecting a corresponding number of current source modules in parallel; the hydrogen production power supply in the embodiment of the present invention is suitable for larger current expansion because this topology of the embodiment of the present invention is dual to MMC (Modular Multilevel Converter, referred to as MMC). In principle, the number of parallel modules is sufficient to output an infinite current. At present, there is no such large demand for electrolyzer applications, and it is mainly within 10kA.

[0051] The above-mentioned hydrogen production power supply adopts a new multi-level current source converter, which has small harmonics and can be well matched with the requirements of the power grid, and can better meet the harmonic requirements of the power grid. The embodiment of the present invention adopts a new multi-level current source converter with small harmonics compared with the traditional thyristor rectifier power supply in the electrolytic aluminum industry, because the semi-controlled device requires a filtering device; the new multi-level current source converter is a fully controlled device PWM mode, and the essential feature of this mode is that due to the large number of modules at high current, the level is closer to the AC sine wave, and there is no risk of excessive harmonics.

[0052] In the embodiment of the present invention, the output ports of each current source module are connected in parallel as the output of the hydrogen production power supply, so that the entire hydrogen production power supply forms a DC port to power the hydrogen production electrolyzer. This is the current mainstream power supply solution. Because the voltage and current of the electrolyzer are relatively small, based on the high voltage and high current characteristics of the hydrogen production power supply in the embodiment of the present invention, an application solution of series and parallel connection of electrolyzers is also proposed. For details, please refer to the second embodiment section below.

[0053] As a preferred technical solution, the semiconductor device in the three-phase bridge rectifier module is any one of a reverse resistance IGCT, an asymmetric IGCT, a press-fit IGBT, a modular IGBT and SiC.

[0054] The semiconductor devices in the three-phase bridge rectifier module of this embodiment preferably use reverse-resistance IGCT devices based on customized development. The MCSC hydrogen production power supply based on reverse-resistance IGCT devices has high efficiency and is easy and convenient to implement. The semiconductor devices in the three-phase bridge rectifier module of the present invention are also suitable for using other semiconductor devices, such as high-power semiconductor devices, including but not limited to asymmetric IGCT, press-fit IGBT, modular IGBT, SIC devices, etc.

[0055] In some embodiments, the semiconductor device in the three-phase bridge rectifier module adopts a 2500V / 3500A reverse resistance IGCT, the maximum output current of a single current source module is 2000A, and the output voltage range is 0V to +650V. When a 2500V / 3500A reverse resistance IGCT is used in this embodiment, the maximum output current of a single module is 2000A, and the output voltage range is 0V to +650V. This voltage range can meet the power supply requirements of most current mainstream electrolysis equipment. The parameter design here is based on the parameter requirements of the current mainstream electrolytic cell, and a margin is left.

[0056] As a preferred technical solution, a three-phase MOV is installed at the AC busbar inlet of the low-voltage AC busbar. The topology of this embodiment is to install a three-phase MOV at the AC busbar inlet, which can absorb the energy of the transformer leakage inductance + the incoming busbar, and can effectively protect the safety of the device. In this embodiment, the connection method of the three-phase MOV adopts the Δ connection method, which is conducive to protecting the safety of the device.

[0057] As a preferred technical solution, each of the current source modules adopts water cooling for heat dissipation; a heat sink is provided in the current source module, and the semiconductor device and the heat sink are pressed into a standardized component. The module unit in the topology of this embodiment adopts water cooling for heat dissipation, and the semiconductor device and the heat sink are pressed into a standardized component form, which has a good heat dissipation effect and can well meet the actual working conditions.

[0058] like Figure 2 As shown, the second embodiment of the present invention provides a hydrogen production device based on a multi-level current source converter, wherein the hydrogen production device includes the aforementioned hydrogen production power supply based on a multi-level current source converter;

[0059] The output end of the hydrogen production power supply is connected to an electrolytic cell group or multiple electrolytic cell groups in parallel;

[0060] The electrolyzer group comprises a first electrolyzer and a second electrolyzer, the first electrolyzer and the second electrolyzer are connected in series at the output end of the hydrogen production power supply, and the midpoints of the two electrolyzers are grounded.

[0061] In this embodiment, the semiconductor devices in the three-phase bridge rectifier module adopt customized IGCT reverse resistance devices. The incoming end of the low-voltage AC bus is connected to the medium-voltage AC bus through a step-down transformer. The step-down transformer adopts Yg connection. At the same time, the output midpoint is grounded to realize the series design of two electrolytic cells. This technical solution can be applied to the current mainstream electrolytic cells for series and parallel design, and can be flexibly configured to adapt to the system capacity.

[0062] The DC bus voltage of this embodiment is ±650V. Therefore, for electrolyzer 1, the positive electrode characteristics are used to realize the output of 0V to 650V by MCSC. For electrolyzer 2, the negative electrode characteristics are used to realize the output of -650V to 0V by MCSC. The midpoints of the two electrolyzers are grounded to meet the location requirements of the electrolysis equipment. In this embodiment, by boosting the device voltage, the converter (i.e., the current source module) can output a higher voltage, or it can be understood as a voltage of 0V to 1300V, and ±650V can be achieved through the main circuit grounding point.

[0063] This embodiment can realize the use of two 5MW electrolysis equipment in series. The series current is determined by the number of modules. Every two 5MW electrolysis equipment form an electrolyzer group. Multiple electrolyzer groups are connected in parallel to the output port of the hydrogen production power supply. The topological structure of this embodiment takes N current source modules and M electrolyzer groups as an example. Figure 2 shown.

[0064] The above-mentioned application scheme of series-parallel connection of electrolytic cells allows multiple electrolytic cells to use one power supply, which has great advantages in technical and economic efficiency, because most of the electrolytic cells currently are equipped separately.

[0065] like Figure 3 to Figure 4 As shown, the third embodiment of the present invention provides a photovoltaic hydrogen production system, including the aforementioned hydrogen production power supply based on a multi-level current source converter (i.e., a modular current source converter), and also includes a photovoltaic collection subsystem, a step-down transformer, and a hydrogen production electrolyzer;

[0066] The photovoltaic collection subsystem collects the new energy power from the low-voltage side and transmits it to the medium-voltage AC bus;

[0067] The low-voltage AC bus inlet terminal in the hydrogen production power supply is connected to the medium-voltage AC bus through the step-down transformer;

[0068] The hydrogen production electrolyzer is powered by the output of the hydrogen production power supply.

[0069] The above technical solution proposes a system design method for photovoltaic collection, inverter inversion, AC grid bus transmission, current source hydrogen production power supply and hydrogen production, providing a feasible new idea for photovoltaic hydrogen production (i.e., new energy development and utilization). The photovoltaic hydrogen production system solution in the above technical solution adopts a new multi-level current source converter with small harmonics, which is well matched with the grid requirements and meets the grid harmonic requirements. It is developed through customized devices (this embodiment adopts customized IGCT reverse resistance devices) and has high system efficiency; the hydrogen production system solution based on the new multi-level current source converter has excellent matching with the characteristics of the electrolysis equipment, is friendly and convenient to cooperate with the large power grid, and saves a lot of filtering equipment. Therefore, it is suitable for large-scale photovoltaic hydrogen production application scenarios.

[0070] The above-mentioned photovoltaic hydrogen production system adopts a hydrogen production power supply with an MCSC topology. The voltage of the device itself is large enough, and the modules are connected in parallel to meet the large current demand. The voltage and current can be adjusted from 0 as required. The reason why it is friendly to the grid is that it has small harmonics and strong controllability, which is an advantage over traditional thyristor rectifier power supplies.

[0071] like Figure 3 and Figure 4 As shown, the embodiment of the present invention takes a 10MW photovoltaic hydrogen production system as an example. The photovoltaic side of the system is composed of 2.5MW photovoltaic arrays, which are boosted to a 10kV AC bus through a photovoltaic inverter (i.e., an inverter boost device), transmitted through the AC bus, and adapted to electrolysis equipment for hydrogen production through the conversion technology of the MCSC topology. Figure 4 The hydrogen production power source and electrolyzer are only for illustration. The specific topology can be directly adopted. Figure 2 The topology shown.

[0072] The above photovoltaic hydrogen production system will be further described below.

[0073] As a preferred technical solution, the photovoltaic collection subsystem includes photovoltaic modules, photovoltaic combiner boxes and inverter boost devices; the photovoltaic modules adopt photovoltaic arrays with MPPT function; the photovoltaic combiner boxes are used for photovoltaic collection, and the electric energy generated by the photovoltaic modules is collected and transmitted to the inverter boost device; the inverter boost device converts the collected electric energy into voltage and boosts it before transmitting it to the medium voltage AC bus.

[0074] As a preferred technical solution, the medium voltage AC bus is also connected to an AC grid for supplementary power supply.

[0075] As a preferred technical solution, the step-down transformer adopts Y connection or Yg connection. In this embodiment, the step-down transformer adopts Y connection or Yg connection, the negative pole of the output of MCSC (i.e., current source module) is grounded, and the output of the converter (i.e., current source module) realizes 0V~650V operation. The step-down transformer adopts Y connection or Yg connection, which can well convert the medium-voltage AC power transmitted by the medium-voltage AC bus into low-voltage AC power and enter the low-voltage AC bus.

[0076] In this embodiment, the photovoltaic components in each photovoltaic collection subsystem are intelligent photovoltaic components, which are composed of a 2.5MW photovoltaic sub-array. The photovoltaic array has an MPPT function, wherein MPPT realizes maximum power tracking and boost conversion realizes the front-stage voltage control function; voltage conversion and boosting are performed through a photovoltaic inverter (i.e., an inverter boost device); the medium-voltage AC bus can collect and transmit electric energy; the MCSC converter (i.e., the hydrogen production power supply in the embodiment of the present invention) converts the stepped-down AC power into low-voltage and high-current DC power required for hydrogen production; the hydrogen production equipment adopts an alkaline water electrolysis hydrogen production equipment with a capacity of 5MW or more; the 10kV bus (i.e., the medium-voltage AC bus) is connected to the AC power grid, and through the energy management system, when photovoltaic power generation is high, power can be fed to the power grid. When the photovoltaic output is low, the electrolyzer is prevented from operating in a low-efficiency range, and a certain amount of electric energy can be supplemented by the power grid to operate the electrolysis equipment, thereby avoiding shutdown or frequent start-stop of the electrolysis system.

[0077] In this embodiment, the off-grid system uses an inverter to control the AC 10kV voltage and frequency. The MCSC hydrogen production power supply achieves power balance with the electrolysis equipment (i.e., hydrogen production electrolyzer) by controlling the current or power, and there is power regulation. Since there is AC power grid access, the electrolysis equipment can basically ensure that the power operates in a constant mode, and the hydrogen production efficiency is guaranteed.

[0078] It should be noted that the embodiment of the present invention takes the 10kV AC voltage level as an example, and is not limited to the 10kV voltage level during specific implementation; the embodiment of the present invention takes the 10MW electrolysis equipment as an example for explanation, and the present invention is also applicable to the series and parallel connection of electrolysis equipment of other capacities and other types; the embodiment of the present invention takes photovoltaic hydrogen production as an example, but is not limited to the photovoltaic hydrogen production scenario, and the present invention is applicable to 10kV or 35kV AC systems.

[0079] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0080] Parts not involved in the above embodiments are the same as the prior art or can be implemented by using the prior art, and will not be further described here.

[0081] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A hydrogen production power supply based on a multi-level current source converter, characterized in that: The hydrogen production power supply comprises N current source modules connected in parallel on a low-voltage AC bus; The current source module adopts multi-level modulation, and the current source module includes a three-phase bridge rectifier module and an RC filter module connected in parallel on the low-voltage AC bus; The output ports of the current source modules are connected in parallel and serve as the output of the hydrogen production power supply.

2. A hydrogen production power supply based on a multi-level current source converter according to claim 1, characterized in that: The semiconductor device in the three-phase bridge rectifier module is any one of a reverse resistance IGCT, an asymmetric IGCT, a press-fit IGBT, a modular IGBT and SiC.

3. The hydrogen production power supply based on a multi-level current source converter according to claim 1, characterized in that: The semiconductor device in the three-phase bridge rectifier module adopts a 2500V / 3500A reverse resistance IGCT, the maximum output current of a single current source module is 2000A, and the output voltage range is 0 to +650V.

4. The hydrogen production power supply based on a multi-level current source converter according to claim 1, characterized in that: A three-phase MOV is installed at the AC busbar inlet of the low-voltage AC busbar.

5. A hydrogen production power supply based on a multi-level current source converter according to any one of claims 1 to 4, characterized in that: Each of the current source modules adopts water cooling for heat dissipation; A heat sink is arranged in the current source module, and the semiconductor device and the heat sink are pressed and connected into a standardized component.

6. A hydrogen production device based on a multi-level current source converter, characterized in that: The hydrogen production device comprises a hydrogen production power supply based on a multi-level current source converter according to any one of claims 1 to 5; The output end of the hydrogen production power supply is connected to an electrolytic cell group or multiple electrolytic cell groups in parallel; The electrolyzer group comprises a first electrolyzer and a second electrolyzer, wherein the first electrolyzer and the second electrolyzer are connected in series to the output end of the hydrogen production power supply, and the midpoints of the two electrolyzers are grounded.

7. A photovoltaic hydrogen production system, characterized in that: A hydrogen production power source based on a multi-level current source converter according to any one of claims 1 to 5, further comprising a photovoltaic collection subsystem, a step-down transformer and a hydrogen production electrolyzer; The photovoltaic collection subsystem collects the new energy power from the low-voltage side and transmits it to the medium-voltage AC bus; The low-voltage AC bus inlet terminal in the hydrogen production power supply is connected to the medium-voltage AC bus through the step-down transformer; The hydrogen production electrolyzer is powered by the output of the hydrogen production power supply.

8. A photovoltaic hydrogen production system according to claim 7, characterized in that: The photovoltaic collection subsystem includes photovoltaic modules, photovoltaic combiner boxes and inverter boost devices; The photovoltaic module adopts a photovoltaic array with MPPT function; The photovoltaic combiner box is used for photovoltaic collection, and collects and transmits the electric energy generated by the photovoltaic components to the inverter boost device; The inverter boost device converts and boosts the collected electric energy and then transmits it to the medium voltage AC bus.

9. A photovoltaic hydrogen production system according to claim 7, characterized in that: The medium voltage AC busbar is also connected to an AC grid for supplementary power supply.

10. A photovoltaic hydrogen production system according to claim 7, characterized in that: The step-down transformer adopts Y connection or Yg connection.

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