New energy electrolytic hydrogen production rectifier with off-grid adaptive capacity and control method

Abstract

The invention discloses a new energy electrolytic hydrogen production rectifier with off-grid adaptive capacity and a control method, and the rectifier comprises an inverter with droop control, a transformer, an uncontrolled rectifier, a DC / DC converter and a controller, can adapt to a new energy fluctuation power supply environment, and supports off-grid operation. The control method comprises the following steps: S1, rectifying alternating current, and inputting the rectified alternating current to a DC / DC converter; s2, collecting a real-time frequency value, and calculating a frequency deviation value; s3, generating a direct current instruction value; s4, collecting an actual output current value; s5, generating a PWM control signal, and adjusting the output current; and S6, realizing variable speed regulation of the output power of the uncontrolled rectifier. The method can achieve the effect of assisting in stabilizing the frequency of the off-grid micro-grid, can adapt to the working condition of off-grid new energy electrolytic hydrogen production in the scene of off-grid new energy electrolytic hydrogen production, enables the hydrogen production load end to follow the high fluctuation of new energy power generation, and meanwhile assists in stabilizing the frequency of an off-grid system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rectifier control, in particular to a new energy electrolytic hydrogen production rectifier with off-grid adaptability and a control method. BACKGROUND

[0002] Hydrogen energy, as a zero-carbon green renewable energy, has the advantages of high energy density and high conversion efficiency, and can realize zero emission and zero pollution in the whole process from development to utilization. The preparation of hydrogen is an important link in the hydrogen energy industry chain. Existing hydrogen production technologies mainly include fossil fuel and chemical by-product hydrogen production, biomass hydrogen production, and water electrolysis hydrogen production. Compared with other hydrogen production methods, water electrolysis hydrogen production has the advantages of near-zero emission and high hydrogen purity, and can also be combined with photovoltaic and wind renewable energy generation, effectively absorbing unstable energy such as wind power and photovoltaic power, and alleviating the impact of their volatility on the power grid, which has important economic and social benefits.

[0003] As the core device of water electrolysis hydrogen production, the performance of the rectifier power supply directly affects the efficiency and cost of hydrogen production. The output direct current of the hydrogen production energy is used for electrolytic hydrogen production, and meets the characteristics of low voltage, large current output, high reliability, and high efficiency. At present, the industrial high-power electrolytic hydrogen production thyristor rectifier usually uses a step-up transformer with load regulation. The step-up transformer has many regulation gears, which can adjust the voltage level under load. The output power of the thyristor rectifier is adjusted by adjusting the gear of the transformer and the trigger angle of the thyristor rectifier. However, the gear adjustment of the step-up transformer is realized by switching mechanical switches, and the time required for gear adjustment is relatively long. When wind power, photovoltaic power and other fluctuating renewable energy sources are used to power the electrolytic hydrogen production rectifier power supply, the electrolytic hydrogen production power needs to be adjusted according to the change of the renewable energy generation power. However, the dynamic response speed of the step-up transformer is slow, and it is unable to follow the renewable energy generation power. In addition, in the off-grid condition, the stability of the AC bus frequency is also an extremely important factor, and the new energy electrolytic hydrogen production rectifier with off-grid adaptability can adjust the power at a relatively fast speed, so it can better stabilize the frequency of the off-grid microgrid AC bus.

[0004] In order to realize the fast regulation of the output power of the rectifier power supply, there is a method to adopt a transformer with a fixed variable ratio, and only by adjusting the trigger angle of the thyristor rectifier to realize the regulation of the output power of the rectifier. Although the method can realize the fast regulation of the output power of the rectifier, when the trigger angle is large, the grid-connected current harmonic, power factor and the like of the rectifier power supply will be poor, so that it cannot meet the grid-connected requirements. And when in the off-grid micro-grid state, the stability of the frequency of the AC bus is also difficult to guarantee because the power cannot be quickly controlled and adjusted, and the instability of the frequency may even lead to the collapse of the off-grid micro-grid, so the control means of the rectifier also needs to be solved. Therefore, the present rectifier and control method are proposed to adapt to the off-grid working condition and have better control flexibility. The traditional thyristor rectifier mainly controls the DC output voltage and current by adjusting the trigger angle, and the control flexibility is low. At the same time, the present rectifier can realize the accurate control of the output DC current, reduce the ripple component of the DC current, and improve the hydrogen production efficiency of the electrolytic stack. SUMMARY

[0005] The present application aims to provide a new energy electrolytic hydrogen production rectifier and control method with off-grid adaptability, which can solve the problem of slow dynamic response speed caused by the load transformer with thyristor power supply currently adopted, and cannot quickly follow the power fluctuation of renewable energy sources. At the same time, when in the off-grid working condition of the micro-grid of wind, light and other new energy power generation, the AC side frequency and the DC / DC output current can be coupled through the method of droop control, thereby effectively solving the problem of frequency fluctuation of the off-grid micro-grid bus.

[0006] The new energy electrolytic hydrogen production rectifier with off-grid adaptability according to the embodiment of the present application comprises:

[0007] The inverter with droop control is connected with the AC bus at the output end, and is used to provide an AC power output under the condition of simulating off-grid power grid;

[0008] The transformer is connected with the AC bus at the input end, and is used to realize voltage transformation. The low-voltage side output end of the transformer is connected with the input end of the uncontrolled rectifier.

[0009] The uncontrolled rectifier is connected with the low-voltage side output end of the transformer at the input end, and is connected with the input end of the DC / DC converter at the output end, and is used to rectify the AC power into DC power.

[0010] The DC / DC converter is connected with the output end of the uncontrolled rectifier at the input end, and is connected with the electrolytic cell at the output end, and is used to provide adjustable DC power to the electrolytic cell.

[0011] A controller is connected with the inverter with droop control and the DC / DC converter respectively, used to collect the frequency information of the AC bus in real time, and generate current control instructions according to the droop control mode, and output PWM control signals to the DC / DC converter.

[0012] Optionally, the uncontrolled rectifier adopts a diode rectifier, and the DC / DC converter adopts a buck circuit to realize the voltage reduction effect of the DC / DC converter.

[0013] The new energy electrolytic hydrogen production control method with off-grid adaptability according to the embodiment of the application comprises the following steps:

[0014] S1, rectifying the AC power output by the transformer through the uncontrolled rectifier to obtain DC voltage input to the DC / DC converter;

[0015] S2, collecting the real-time frequency value of the AC bus on the output side of the inverter with droop control, and calculating the frequency deviation value;

[0016] S3, generating a DC current instruction value according to the frequency deviation value to indicate the target output current of the DC / DC converter;

[0017] S4, collecting the actual output current value of the DC / DC converter, and inputting the actual output current value and the DC current instruction value to the controller;

[0018] S5, generating a PWM control signal through the controller after calculation, and sending the PWM control signal to the DC / DC converter to adjust the output current;

[0019] S6, based on the adjustment result of the output current of the DC / DC converter, realizing the variable speed regulation of the output power of the uncontrolled rectifier, and completing the real-time response and balance adjustment of the electrolytic hydrogen production load to the frequency change of the new energy AC bus.

[0020] Optionally, the S2 specifically comprises:

[0021] S21, collecting the AC bus signal from the output end of the inverter with droop control, and extracting the real-time frequency value f of the AC bus through a phase-locked loop;

[0022] S22, inputting the real-time frequency value f into the frequency processing module of the controller, and performing difference operation with the preset frequency reference value f ref to obtain the frequency deviation value Δf.

[0023] Optionally, the S3 specifically comprises:

[0024] S31, inputting the frequency deviation value Δf into the current instruction generation module in the controller;

[0025] S32, set the rated output current of the DC / DC converter as I0 in the current instruction generation module, and set the droop control coefficient as k droop ;

[0026] S33, calculate the DC current instruction value I droop according to the frequency deviation value Δf, the rated output current I0 and the droop control coefficient k ref :

[0027]

[0028] S34, output the DC current instruction value I ref to the current control module of the controller, indicating the target output current of the DC / DC converter.

[0029] Optionally, the S4 specifically comprises:

[0030] S41, collect the current actual output current value I of the DC / DC converter, and measure it in real time through the controller connected with the current sampling circuit;

[0031] S42, input the actual output current value I and the DC current instruction value I ref to the current control module of the controller together;

[0032] S43, perform difference operation on the actual output current value I and the DC current instruction value I ref in the current control module of the controller, to obtain the current error signal ΔI;

[0033] S44, input the current error signal ΔI to the PI controller and the PR controller of the PWM control signal generation module, to drive the output process of the PWM control signal.

[0034] Optionally, the S5 specifically comprises:

[0035] S51, set the PWM modulation parameters according to the current error signal ΔI in the PWM control signal generation module, including the adjustment range of the switching frequency f down and the duty cycle D;

[0036] S52, generate the PWM control signal sequence for driving the DC / DC converter through modulation calculation according to ΔI and the PWM modulation parameters;

[0037] S53, send the PWM control signal sequence to the power driving unit of the DC / DC converter, adjust the actual current value output by the converter, and apply the target current to the electrolytic cell.

[0038] Optionally, the S6 specifically comprises:

[0039] S61, collect the DC / DC converter output current value after the PWM signal is driven, and determine whether it has approached the current command value I ref ;

[0040] S62, when the error between the output current value and the DC current command value I ref is lower than the set threshold value epsilon, it is determined that the DC / DC converter has reached a stable output state;

[0041] S63, the actual current value in the stable output state is taken as the basis for the current output power of the uncontrolled rectifier, and the current actual output power P out ;

[0042] S64, the actual output power P out is fed back to the inverter droop control logic, and the AC bus frequency is adjusted to form a real-time adaptive droop balance between the uncontrolled rectifier load power and the new energy power supply frequency.

[0043] The beneficial effects of the present application are:

[0044] Through the above-mentioned new energy electrolytic hydrogen rectifier with off-grid adaptive ability and control method, the inverter with droop control is used in the front stage to simulate the case of using renewable energy as power supply, and the DC / DC converter is used in the rear stage, so as to realize the rapid change of the power of the electrolytic tank; when the power generation of the electrolytic hydrogen appears unstable, the electrolytic hydrogen power needs to be quickly adjusted to change with the fluctuation of the new energy power generation power, and the frequency stability of the new energy off-grid microgrid with droop control also needs to rely on the rapid change of the power.

[0045] Compared with the thyristor rectifier of the traditional on-load voltage regulating transformer, the present application can quickly change the voltage level by controlling the output of the DC / DC converter, so as to realize the rapid change of the power of the electrolytic tank; it can realize the power supply of wind, light and other new energy as power supply, and when the power generation of the electrolytic hydrogen appears unstable, the electrolytic hydrogen power needs to be quickly adjusted to change with the fluctuation of the new energy power generation power; and when the off-grid microgrid AC bus frequency is unstable, it can help to stabilize the frequency of the AC bus; the thyristor rectifier usually needs to be adjusted with the on-load voltage regulating switch of the transformer, and its dynamic response speed is relatively slow, which may cause the system to be unstable when the renewable energy power fluctuates greatly.

[0046] The rectifier can adapt to the environment under off-grid working condition and other different regulation requirements, has better control flexibility, greatly reduces the time required for conversion voltage level, accelerates the matching of electrolytic cell to new energy power generation, and provides good support to the frequency of AC bus; the traditional thyristor rectifier mainly controls the DC output voltage and current by adjusting the trigger angle, and has low control flexibility. Meanwhile, the rectifier can realize accurate control of the output DC current, reduce the ripple component of the DC current, and improve the hydrogen production efficiency of the electrolytic stack. In the off-grid new energy electrolytic hydrogen production scene, the working condition of off-grid new energy electrolytic hydrogen production can be adapted, so that the hydrogen production load end can follow the high volatility of new energy power generation, and at the same time assist in stabilizing the frequency of off-grid system. BRIEF DESCRIPTION OF DRAWINGS

[0047] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, illustrate the application, and are used to explain the application together with the embodiments of the application, and do not constitute a limitation on the application. In the drawings:

[0048] Figure 1 The circuit topology block diagram of the new energy electrolytic hydrogen production rectifier with off-grid adaptability proposed in the application;

[0049] Figure 2 The overall flowchart of the new energy electrolytic hydrogen production control method with off-grid adaptability proposed in the application. DETAILED DESCRIPTION

[0050] The application will now be described in further detail with reference to the drawings. These drawings are all simplified schematic diagrams, and only schematically show the basic structure of the application, and therefore only show the components related to the application.

[0051] REFERENCE Figure 1 The circuit topology block diagram of the new energy electrolytic hydrogen production rectifier with off-grid adaptability, comprising:

[0052] The inverter with droop control, the output end of which is connected with the AC bus, is used to provide AC power output under simulated off-grid grid conditions;

[0053] The transformer, the input end of which is connected with the AC bus, is used to realize voltage conversion, and the low-voltage side output end of the transformer is connected with the input end of the uncontrolled rectifier;

[0054] The uncontrolled rectifier, the input end of which is connected with the low-voltage side output end of the transformer, is connected with the input end of the DC / DC converter, and is used to rectify AC to DC;

[0055] The DC / DC converter, the input end of which is connected with the output end of the uncontrolled rectifier, is connected with the electrolytic cell, and is used to provide adjustable DC power to the electrolytic cell;

[0056] A controller is connected with the inverter with droop control and the DC / DC converter respectively, used for collecting frequency information of the AC bus in real time, and generating current control instructions according to the droop control mode, and outputting PWM control signals to the DC / DC converter.

[0057] The new energy electrolytic hydrogen production rectifier with off-grid adaptability provided by the application can flexibly select the DC / DC converter in the case of the inverter with droop control, and can adopt a buck circuit to complete the function of DC voltage reduction. In the case of using the above device, the droop control is added to control the rectifier, which can achieve the function of quickly adjusting the power, and also plays the role of auxiliary stabilizing the frequency of the new energy AC bus.

[0058] The new energy electrolytic hydrogen production rectifier of the method of the application associates the frequency of the AC bus with the current at the load end of the new energy electrolytic hydrogen production rectifier by using the control logic in the figure, and designs a droop relationship equation between the change value of the frequency of the AC bus and the instruction value of the current, and then realizes the purpose of controlling the instruction value of the current at the load end of the new energy electrolytic hydrogen production rectifier by detecting the real-time frequency value of the AC bus.

[0059] It should be pointed out that in the embodiment, the frequency of the AC bus of the inverter with droop control can be collected by using a phase-locked loop (PLL), and the real-time current instruction value is obtained after the actual frequency value obtained is compared with the set frequency reference value, and then the droop relationship equation is controlled. The control relationship between the AC bus frequency and the rectifier in the rear stage is realized. The frequency of the AC bus is associated with the output current of the DC / DC converter by using the principle of droop control, and the change value of the frequency of the AC bus and the instruction value of the output current of the DC / DC converter are listed by using the droop relationship, so that the real-time frequency value of the AC bus can be detected to control the output current instruction value of the DC / DC converter. After obtaining the current instruction value, the PWM wave providing the control signal to the DC / DC converter is generated by using the PI and PR controllers after the current instruction value and the real-time current collected, the output current control of the DC / DC converter is realized, and then the control relationship between the AC bus frequency and the rectifier in the rear stage is realized, so that the droop balance between the new energy AC bus frequency and the load power is realized.

[0060] When encountering a new energy power mutation, the rectifier will quickly adjust the rectifier power according to the control method of the application, and when the electrolytic hydrogen rectifier output power is adjusted, the real-time current value and the current command value are restored to stability under the action of the droop control of the rectifier, and the droop relationship between the load current and the AC bus frequency is also restored to stability. At the same time, due to the droop relationship of the inverter, after the power consumption of the rectifier load is reduced, the frequency of the AC bus is effectively restored and reaches a new stability.

[0061] Reference Figure 2 The new energy electrolytic hydrogen control method with off-grid adaptability comprises the following steps:

[0062] S1, rectify the AC power output by the transformer through the uncontrolled rectifier to obtain DC voltage input to the DC / DC converter;

[0063] S2, collect the real-time frequency value of the AC bus on the output side of the inverter with droop control, and calculate the frequency deviation value;

[0064] S3, generate a DC current command value according to the frequency deviation value to indicate the target output current of the DC / DC converter;

[0065] S4, collect the actual output current value of the DC / DC converter, and input the actual output current value and the DC current command value to the controller;

[0066] S5, generate a PWM control signal through the controller after calculation, and send it to the DC / DC converter to adjust the output current;

[0067] S6, based on the adjustment result of the DC / DC converter output current, realize the variable speed adjustment of the uncontrolled rectifier output power, and complete the real-time response and balance adjustment of the electrolytic hydrogen load to the frequency change of the new energy AC bus.

[0068] In the embodiment, the S2 specifically comprises:

[0069] S21, collect the AC bus signal from the output end of the inverter with droop control, and extract the real-time frequency value f of the AC bus through the phase-locked loop;

[0070] S22, input the real-time frequency value f into the frequency processing module of the controller, and perform difference operation with the preset frequency reference value f ref to obtain the frequency deviation value Δf.

[0071] In the embodiment, the S3 specifically comprises:

[0072] S31, input the frequency deviation value Δf into the current command generation module in the controller;

[0073] S32, set the rated output current of the DC / DC converter as I0 in the current instruction generation module, and set the droop control coefficient as k droop ;

[0074] S33, calculate the DC current instruction value I droop according to the frequency deviation value Δf, the rated output current I0 and the droop control coefficient k ref :

[0075]

[0076] S34, output the DC current instruction value I ref to the current control module of the controller, indicating the target output current of the DC / DC converter.

[0077] In the embodiment, the S4 specifically comprises:

[0078] S41, collect the actual output current value I of the DC / DC converter, which is measured in real time by the controller connected with the current sampling circuit;

[0079] S42, input the actual output current value I and the DC current instruction value I ref to the current control module of the controller;

[0080] S43, perform difference operation on the actual output current value I and the DC current instruction value I ref in the current control module of the controller, to obtain the current error signal ΔI;

[0081] S44, input the current error signal ΔI to the PI controller and the PR controller of the PWM control signal generation module, to drive the output process of the PWM control signal.

[0082] In the embodiment, the S5 specifically comprises:

[0083] S51, set the PWM modulation parameters according to the current error signal ΔI in the PWM control signal generation module, including the adjustment range of the switching frequency f down and the duty cycle D;

[0084] S52, generate the PWM control signal sequence for driving the DC / DC converter by modulation calculation according to ΔI and the PWM modulation parameters;

[0085] S53, send the PWM control signal sequence to the power driving unit of the DC / DC converter, to adjust the actual current value output by the converter and apply the target current to the electrolytic cell.

[0086] In the embodiment, the S6 specifically comprises:

[0087] S61, collect the DC / DC converter output current value after the PWM signal is driven, and determine whether it has approached the current command value I ref ;

[0088] S62, when the error between the output current value and the DC current command value I ref is lower than the set threshold value ε, it is determined that the DC / DC converter has reached a stable output state;

[0089] S63, the actual current value in the stable output state is taken as the basis for the current output power of the uncontrolled rectifier, and the current actual output power P out is calculated through the uncontrolled rectifier power feedback module;

[0090] S64, the actual output power P out is fed back to the inverter droop control logic, and the AC bus frequency is adjusted to form a real-time adaptive droop balance between the uncontrolled rectifier load power and the new energy power supply frequency.

[0091] In the embodiment of the application, by using the pre-stage rectifier with droop control, the middle stage adopts a diode rectifier, and the rear stage uses a DC / DC converter, the output of the DC / DC converter can be quickly controlled to change the voltage level, so as to realize the rapid change of the power of the electrolytic cell; the wind, light and other new energy can be used as power supply, when the generated power is unstable, the electrolytic hydrogen power can be quickly adjusted to change with the fluctuation of the new energy generated power; and when the off-grid micro-grid AC bus frequency is unstable, it can help to stabilize the frequency of the AC bus; the thyristor rectifier usually needs to be matched with a transformer on-load voltage regulating switch for adjustment, and the dynamic response speed is relatively slow, which may cause the system to be unstable when the renewable energy power fluctuates greatly. The rectifier can adapt to the environment under off-grid working conditions, has better control flexibility, greatly reduces the time required for changing the voltage level, speeds up the matching of the electrolytic cell to the new energy generated power, and provides good support to the frequency of the AC bus; the traditional thyristor rectifier mainly controls the DC output voltage and current by adjusting the trigger angle, and the control flexibility is low. At the same time, the rectifier can realize accurate control of the output DC current, reduce the ripple component of the DC current, and improve the hydrogen production efficiency of the electrolytic stack. In the off-grid new energy electrolytic hydrogen production scene, the working condition of off-grid new energy electrolytic hydrogen production can be adapted, the hydrogen production load end can follow the high volatility of new energy generation, and the frequency of the off-grid system can be stabilized.

[0092] Example 1:

[0093] In order to verify the feasibility of the application in implementation, the application is applied to a certain new energy off-grid demonstration hydrogen station in a certain area. The station is provided with unstable renewable energy by a wind farm (installed capacity 30 MW) and a photovoltaic array (installed capacity 20 MW) for driving electrolytic cells for hydrogen production. Due to the influence of the northwest plateau climate in this area all year round, the wind speed changes frequently, the light condition is significantly affected by the rapid change of the cloud layer, the power frequency fluctuates greatly, and the load response capacity is poor. Therefore, when the traditional thyristor rectifier is operated in combination with the transformer voltage regulation, there are problems such as frequency instability, current response lag, and low electrolysis efficiency.

[0094] In this embodiment, the new energy electrolytic hydrogen rectifier with off-grid adaptability provided by the application is adopted, which includes a droop control inverter, a transformer, an uncontrolled rectifier, a Buck type DC / DC converter and a controller combination. The front stage of the rectifier provides a constant DC bus voltage in an uncontrolled diode rectification mode, the controller acquires the frequency of the inverter output alternating current bus in real time, calculates the frequency deviation through the droop control algorithm, and then generates a current command value dynamically according to the deviation to drive the DC / DC converter to output accurate DC current, so that the electrolytic cell load dynamically tracks the renewable energy power fluctuation, and supply-demand matching is realized.

[0095] In the continuous operation test, we selected the daily load curves under typical off-grid operation conditions such as "strong wind-weak light", "weak wind-strong light", "night-weak wind" and the like for comparison test, and recorded the following key indicators: rectifier response time, electrolytic cell current ripple, electrolytic hydrogen production efficiency, electrolytic current deviation value (error with command value) and bus frequency fluctuation range.

[0096] Through the acquisition of the control system log and the hydrogen flowmeter data, we compared the traditional thyristor rectification scheme and found that the application has significant advantages in multiple key performances.

[0097] Table 1: Performance comparison table of the system of the application and the traditional thyristor rectification system

[0098]

[0099]

[0100] As can be clearly seen from the measured data of the new energy off-grid hydrogen station shown in Table 1, the control system proposed by the application is significantly better than the traditional thyristor rectification scheme in multiple key operation indicators, and shows good stability, dynamic response capability and system robustness.

[0101] Taking the load response time as an example, the average response time of the traditional system is more than 13 seconds in the wind speed mutation scene, and even reaches 17.2 seconds in some extreme cases, while the system of the application compresses the value to within 3.6 seconds, and the response speed is increased by nearly 80%. Especially in the scene of night wind speed drop and other unstable power grids, the traditional system often causes frequency collapse or system protective shutdown due to adjustment lag, while the system relies on the frequency-current closed-loop mechanism and can complete adaptive adjustment within 4.1 seconds to realize safe and continuous operation of the system.

[0102] In terms of current ripple coefficient, the system controls the output direct current ripple within 4% in all test scenarios, which is more than 50% lower than the traditional scheme, significantly reduces the loss of electrolytic stack, prolongs the service life of the system, and reduces the frequency of operation and maintenance.

[0103] In terms of electrolysis efficiency, the traditional system is limited by frequent voltage fluctuations and slow adjustment, and the efficiency is maintained at 81-83% during the period of photovoltaic disturbance or rapid wind speed change; and the system maintains a stable efficiency of more than 88% through dynamic instruction value control and PWM fine adjustment strategy, and the peak value measured in a special scene is as high as 89.1%, which shows excellent energy utilization capability.

[0104] In addition, the bus frequency fluctuation range in the traditional system generally exceeds ±1.5Hz, and even exceeds 3Hz in extreme environments, which is easy to trigger microgrid interlocking protection; while the system of the application is controlled within ±0.7Hz during the whole operation process, and the highest deviation is only 1.2Hz, which proves that it has high frequency self-stabilization ability and is suitable for complex off-grid operation environment.

[0105] In terms of current error index, i.e. the deviation control of actual output current and instruction value, the system is controlled within ±3% in most scenarios, while the error of the traditional system often reaches more than 5-7%, showing strong hysteresis. Especially in the fine hydrogen production load working condition, the tracking ability of the system to I ref guarantees the uniformity and process continuity of hydrogen production.

[0106] In summary, the control strategy verified in the embodiment solves the problems of slow response, large current fluctuation and lack of frequency control of the traditional rectifier, and enables the hydrogen production system to remain efficient, safe and stable in operation in the extreme environment of frequent and drastic fluctuations of power grid frequency and alternating changes of light and wind speed.

[0107] The embodiment verifies that the application has high adaptability and engineering application potential in the new energy off-grid electrolytic hydrogen production scene. The system architecture and control method are particularly suitable for wind-solar complementary hydrogen production scenes, remote independent power grid areas, hydrogen production facilities in extreme climates, and the like, and provide solid technical support for constructing a high-reliability and high-efficiency clean hydrogen energy supply system.

[0108] The above is only the preferred embodiment of the application, and does not constitute a limitation on the protection scope of the application. Any equivalent transformation and improvement of the application based on the disclosure of the application shall fall within the protection scope of the application.

Claims

1. A new energy electrolytic hydrogen generator rectifier with off-grid adaptability, characterized in that, The application relates to a hydrogen production system based on electrolysis, which comprises the following components: an inverter with droop control, the output end of which is connected with an AC bus, and which is used for providing an AC power output in a simulated off-grid power grid condition; a transformer, the input end of which is connected with the AC bus, and which is used for realizing voltage transformation, and the low-voltage side output end of the transformer is connected with the input end of an uncontrolled rectifier; the uncontrolled rectifier, the input end of which is connected with the low-voltage side output end of the transformer, and the output end of which is connected with the input end of a DC / DC converter, and which is used for rectifying AC power into DC power; the DC / DC converter, the input end of which is connected with the output end of the uncontrolled rectifier, and the output end of which is connected with an electrolytic cell, and which is used for providing adjustable DC power to the electrolytic cell; a controller, which is connected with the inverter with droop control and the DC / DC converter respectively, and which is used for collecting frequency information of the AC bus in real time, and generating a current control instruction according to a droop control mode, and outputting a PWM control signal to the DC / DC converter.

2. The new energy electrolytic hydrogen production rectifier with off-grid adaptability according to claim 1, characterized in that, The uncontrolled rectifier adopts a diode rectifier, and the DC / DC converter adopts a buck circuit to realize the voltage reduction effect of the DC / DC converter.

3. A new energy electrolytic hydrogen production control method with off-grid adaptability, characterized in that, The application further discloses a method for realizing speed regulation of an electrolytic hydrogen production load, which comprises the following steps: S1, rectifying AC power output by the transformer through the uncontrolled rectifier to obtain DC voltage input to the DC / DC converter; S2, collecting a real-time frequency value of an AC bus on the output side of the inverter with droop control, and calculating a frequency deviation value; S3, generating a DC current instruction value according to the frequency deviation value, and indicating a target output current of the DC / DC converter; S4, collecting a current actual output value of the DC / DC converter, and inputting the current actual output value and the DC current instruction value to the controller; S5, generating a PWM control signal through the controller after calculation, and sending the PWM control signal to the DC / DC converter to adjust the output current; S6, based on the adjustment result of the output current of the DC / DC converter, realizing speed regulation of the output power of the uncontrolled rectifier, and completing real-time response and balance adjustment of the electrolytic hydrogen production load to the frequency change of the new energy AC bus.

4. The new energy electrolytic hydrogen production control method with off-grid adaptability according to claim 3, characterized in that, The S2 specifically comprises the following steps: S21, collecting an AC bus signal from the output end of the inverter with droop control, and extracting a real-time frequency value f of the AC bus through a phase-locked loop; S22, input the real-time frequency value f into the frequency processing module of the controller, and compare it with the preset frequency reference value f ref Carry out difference operation to obtain the frequency deviation value Δf.

5. The new energy electrolytic hydrogen production control method with off-grid adaptability according to claim 3, characterized in that, The S3 specifically comprises the following steps: S31, inputting the frequency deviation value Delta f into a current instruction generation module in the controller; S32, set the rated output current of the DC / DC converter as I0 and set the droop control coefficient as k in the current instruction generation module droop ; S33、According to the frequency deviation value Δf, the rated output current I0 and the droop control coefficient k droop , the DC current command value I ref : S34, the direct current command value I ref The current control module outputs a target output current of the DC / DC converter to the controller.

6. The new energy electrolytic hydrogen production control method with off-grid adaptability according to claim 3, characterized in that, The S4 specifically comprises the following steps: S41, collecting a current actual output value I of the DC / DC converter, and measuring the current actual output value in real time through the controller connected with a current sampling circuit; S42, the actual output current value I and the DC current command value I ref a current control module of the input controller; S43. In the current control module of the controller, the actual output current value I and the DC current command value I are compared. ref Perform the difference calculation to obtain the current error signal ΔI; S44, inputting a current error signal Delta I into a PI controller and a PR controller of a PWM control signal generation module, and driving the output process of the PWM control signal.

7. The new energy electrolytic hydrogen production control method with off-grid adaptability according to claim 3, characterized in that, The S5 specifically comprises the following steps: S51, setting PWM modulation parameters including switching frequency f in the PWM control signal generation module according to the current error signal ΔI down and the adjustment range of the duty cycle D; S52, generating a PWM control signal sequence for driving the DC / DC converter according to Delta I and PWM modulation parameters through modulation calculation; S53, sending the PWM control signal sequence to a power driving unit of the DC / DC converter, adjusting the actual current value output by the converter, and applying a target current to the electrolytic cell.

8. The new energy electrolytic hydrogen production control method with off-grid adaptability according to claim 3, characterized in that, The S6 specifically comprises the following steps: S61, collect the DC / DC converter output current value after the PWM signal driving, and determine whether it has approached the current command value I ref ; S62, when the error between the output current value and the direct current command value I ref is lower than a set threshold value ε, it is determined that the DC / DC converter has reached a stable output state. S63, the actual current value in the stable output state is taken as the basis of the current output power of the uncontrolled rectifier, and the current actual output power P is calculated through the uncontrolled rectifier power feedback module out ; S64, the actual output power P out The feedback to the inverter droop control logic, linkage adjustment AC bus frequency, forming a real-time adaptive droop balance between the uncontrolled rectifier load power and new energy supply frequency.

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