Hydrogen production power supply device with electric energy quality treatment function and control method

Abstract

The invention discloses a hydrogen production power supply device with an electric energy quality control function and a control method, the device comprises a bridge rectifier module, a PWM rectifier module, a rectifier transformation module and a control module, the input end of the bridge rectifier module is connected with an alternating current power supply through the rectifier transformation module, and the output end of the bridge rectifier module is connected with an electrolytic bath to supply power to the electrolytic bath; the output end of the bridge rectifier module is further connected with the PWM rectifier module through the control module, and the control module controls the output current of the PWM rectifier module according to the harmonic voltage / current state of the bridge rectifier module so as to carry out electric energy quality management. The invention has the advantages of simple and compact structure, low cost, small volume and weight, low control complexity, high reliability and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production power supply, and in particular to a hydrogen production power supply device with power quality management function and a control method. Background Art

[0002] Hydrogen production by water electrolysis is inseparable from the hydrogen production power supply. The hydrogen production power supply usually adopts the thyristor rectifier power supply, which has the advantages of high reliability, fewer devices, simple circuits, etc. However, the phase-shifting rectification technology needs to be used in the thyristor rectifier power supply, while the traditional phase-shifting rectification technology has the disadvantages of low efficiency, low power factor, large grid harmonics, slow load response, etc., and cannot adapt to the rapid regulation of system energy power fluctuations.

[0003] In the prior art, the following two types of rectifier power supplies are usually used:

[0004] 1. Thyristor rectifier power supply

[0005] The thyristor rectifier mainly adopts a three-phase fully controlled bridge rectifier power supply. Its principle is based on the forward controllable conduction characteristics of the thyristor. It sends trigger pulses by tracking the changes in the input three-phase AC voltage amplitude to achieve the output of DC. Due to the blocking effect of the thyristor, a discontinuous sine wave flows through the winding of the rectifier transformer, which is composed of fundamental current and higher harmonic current. Therefore, the feedback flowing into the power grid is also a non-sinusoidal current containing harmonic current. The power quality problem of the thyristor rectifier will greatly increase the loss of the transformer and busbar, and will also cause the subsequent thyristor power supply to fail to connect to the grid. Therefore, in order to reduce the harmonics of the power grid, it is usually necessary to provide a stable load current to the electrolyzer through a multi-pulse transformer and a rectifier. In order to improve the power factor of the power grid, on the one hand, it is necessary to use additional on-load tap-changing transformers to cope with changes in the power grid or load so that the thyristor rectifier is in a good trigger angle state (α≤15°). On the other hand, it is also necessary to configure SVG or FC devices at the high-voltage assessment point of the power grid to improve the power quality of the system. This not only has high implementation costs and large hardware overhead, but also the overall size and weight of the system are large, and the control is relatively complex.

[0006] Taking a typical thyristor rectifier hydrogen production power source as an example, it is usually composed of two 12-pulse thyristor rectifiers connected to a 24-pulse rectifier transformer and two phase-shifting rectifier transformers. The 48 pulses are composed of 4 rectifiers that start and stop synchronously and control the same power. The thyristor conduction angle + on-load tap changer are used to coordinate the output voltage / current. Due to the high harmonic content of the voltage and current of the 35kV bus, an additional dynamic reactive power automatic compensation device is set to compensate for the reactive power and harmonics below the 13th order of the 35kV bus. However, in the above scheme, since 24-pulse and 48-pulse rectifier transformers must be used, the manufacturing process of the rectifier transformer and the parameter deviation of the electrolytic cell will lead to the problem that the 5th and 7th current harmonics cannot be completely offset. Solving the harmonic problem by setting up an additional dynamic reactive power automatic compensation device will also lead to high implementation cost and hardware overhead, and the 4 rectifiers need to be coordinated (synchronous start and stop, same power control), which is difficult to implement and highly complex.

[0007] 2. PWM Rectification Hydrogen Power Supply

[0008] The PWM rectifier hydrogen production power supply adopts the AC / DC circuit topology, which can achieve a smooth output voltage between DC 1200 and 1500V, in which the AC / DC link adopts a three-level PWM rectifier circuit. The DC output end of the converter is equipped with a DC electric isolating switch, which also has the ability to disconnect on load. When the converter fails, its on-load disconnection can be controlled by the DCU. However, the PWM rectifier hydrogen production power supply will have problems such as complex system, large volume and weight, high device cost, poor power quality before the electrolyzer is polarized and when the electrolyzer is under low load, low reliability, and narrow DC voltage adjustment range. If a larger voltage regulation range is to be obtained, the AC / DC+DC / DC two-stage topology is usually adopted, which will further increase the system cost and affect the system efficiency. Summary of the invention

[0009] The technical problem to be solved by the present invention is: in response to the technical problems existing in the prior art, the present invention provides a hydrogen production power supply device with a power quality management function which has a simple and compact structure, low cost, small volume and weight, low control complexity and high reliability, as well as a control method with a simple implementation method and high control efficiency, which can enable the hydrogen production power supply device to have a power quality management function and improve the power quality and system efficiency of the hydrogen production power supply.

[0010] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0011] A hydrogen production power supply device with power quality management function includes a bridge rectifier module, a PWM rectifier module, a rectifier transformer module and a control module. The input end of the bridge rectifier module is connected to an AC power supply through the rectifier transformer module, and the output end is connected to an electrolyzer to supply power to the electrolyzer. The output end of the bridge rectifier module is also connected to the PWM rectifier module through the control module. The control module controls the output current of the PWM rectifier module according to the harmonic voltage / current state of the bridge rectifier module to perform power quality management.

[0012] Furthermore, the PWM rectifier module includes a full-bridge rectifier circuit and a supporting capacitor connected in parallel, the full-bridge rectifier circuit includes three chopper bridge arms, and each of the chopper bridge arms is connected to the bridge rectifier module and the AC power supply through an AC filter inductor.

[0013] Furthermore, each of the chopper bridge arms constitutes a two-level chopper circuit or a three-level chopper circuit or a multi-level chopper circuit.

[0014] Furthermore, the bridge rectifier module is a thyristor rectifier circuit or a diode rectifier circuit.

[0015] Furthermore, the control module includes a harmonic detection submodule, a compensation control submodule and a driving submodule connected in sequence. The harmonic detection submodule is used to detect the harmonic voltage and / or harmonic current of the bridge rectifier module and output it to the compensation control submodule. The compensation control submodule extracts the content of each harmonic current based on the detected harmonic voltage and / or harmonic current, generates a harmonic current instruction, and drives and controls the phase of the output current of the PWM rectifier module through the driving submodule.

[0016] Furthermore, the compensation control submodule includes an instruction extraction unit and a control unit that are interconnected. The instruction extraction unit is used to respectively receive the active component and reactive component of the current harmonics of the bridge rectifier module, extract the harmonic active current and reactive current and output them to the control unit. The control unit respectively receives the extracted harmonic active current and the active component of the output current fed back by the PWM rectifier module, and the extracted harmonic reactive current and the reactive component of the output current fed back by the PWM rectifier module for comparison. The comparison result is subjected to PI control to obtain the control instructions for the active component and reactive component of the final output current, which are respectively provided to the PWM rectifier module.

[0017] Further, the instruction extraction unit includes an active current extraction subunit and a reactive current extraction subunit. The active current extraction subunit includes a first harmonic extraction circuit, a first adder, a first PI controller and a second adder. The input end of the first harmonic extraction circuit inputs the active component of the current harmonic of the bridge rectifier module, so as to remove the fundamental component through Fourier transform to obtain the harmonic component of the active current. The output end is connected to an input end of the first adder. The second adder is respectively connected to the reference voltage Udcref of the intermediate DC voltage of the PWM converter and the measured intermediate DC voltage Udc of the PWM converter. The output end is connected to the other input end of the first adder through the first PI controller. The output end of the first adder outputs the extracted harmonic active current. The reactive current extraction subunit includes a second harmonic extraction circuit. The second harmonic extraction circuit inputs the reactive component of the current harmonic of the bridge rectifier module, so as to remove the fundamental component through Fourier transform to obtain the harmonic component of the reactive current, and outputs the extracted harmonic reactive current.

[0018] Furthermore, the control unit includes two control branches for respectively controlling the control instructions for generating the active component and reactive component of the output current. Each of the control branches includes an input side adder, a second PI controller and an output side adder. The input side adder is respectively connected to the active / reactive components of the current harmonics of the bridge rectifier module, and outputs the difference between the active / reactive current calculation value and the actual current. The output end of the input side adder is connected to an input end of the output side adder through the second PI controller. The other two input ends of the output side adder respectively input the current component modulation wave and the output result of the current component of the output current of the PWM rectifier module after passing through the PWM converter filter. The output end of the output side adder outputs the triangular carrier of the active / reactive component of the current harmonics.

[0019] Furthermore, the bridge rectifier module is an N-pulse rectifier circuit, the PWM rectifier module includes N / 6 groups, N is a multiple of 6, and the AC side of each 6-pulse rectifier circuit in the bridge rectifier module is correspondingly connected to the AC side of a group of PWM rectifier modules.

[0020] Furthermore, the PWM rectifier module is arranged on the high voltage side of the rectifier transformer.

[0021] Furthermore, a control switch and / or a filter circuit is also provided on the AC side of the PWM rectifier module.

[0022] Furthermore, an isolating switch is provided on the output side of the bridge rectifier module.

[0023] Furthermore, when N>6, the rectifier transformer module is a split transformer, and the split transformer includes N / 6 low-voltage windings, and each of the low-voltage windings is correspondingly connected to a 6-pulse rectifier circuit in the bridge rectifier module.

[0024] A control method for the above-mentioned hydrogen production power supply device with power quality management function, comprising the following steps:

[0025] Detecting the harmonic voltage and / or harmonic current of the bridge rectifier module;

[0026] Extracting the content of each harmonic current according to the detected harmonic voltage and / or harmonic current to generate a harmonic current instruction;

[0027] The phase of the output current of the PWM rectifier module is driven and controlled according to the harmonic current instruction to perform harmonic compensation and achieve power quality management.

[0028] Further, the extracting the content of each harmonic current according to the detected harmonic voltage and / or harmonic current includes:

[0029] The active component of the current harmonics input into the bridge rectifier module is subjected to harmonic extraction, and the result of comparing the reference voltage Udcref with Udc is added to the result of harmonic extraction after PI control to obtain the extracted harmonic active current;

[0030] After the reactive component of the current harmonics input to the bridge rectifier module is subjected to harmonic extraction, the extracted harmonic reactive current is output.

[0031] Furthermore, the harmonic current generation instruction includes: respectively connecting the active / reactive components of the current harmonics of the bridge rectifier module, subtracting the output result of the active / reactive component modulation wave vsd and the current component of the output current of the PWM rectifier module after PI control through the PWM converter filter, and outputting the active / reactive components of the current harmonics.

[0032] Compared with the prior art, the advantages of the present invention are:

[0033] 1. The present invention fully integrates the bridge rectifier module and the PWM rectifier module, with the bridge rectifier module as the main power source and the PWM rectifier module as the grid-side power quality management device. The output of the PWM rectifier module is controlled according to the harmonic state of the bridge rectifier module to perform harmonic compensation to achieve power quality management, so that the hydrogen production power supply device can have a power quality management function, thereby ensuring the quality of the electric energy provided to the electrolyzer. At the same time, there is no need to set up an additional power quality management device, which can effectively reduce the size, weight and implementation cost of the device, and the control complexity of the device can also be greatly reduced.

[0034] 2. The present invention further improves the system reliability and stability by combining the thyristor rectifier circuit with the PWM rectifier to form a hydrogen production power supply device. The DC voltage can be quickly adjusted from 0V to the rated voltage by controlling the trigger angle. When the green grid voltage fluctuates, the temperature of the grid side voltage can be ensured by adjusting the voltage on the AC side. At the same time, power quality management can be achieved by controlling the output of the PWM rectifier module. While improving the power quality, the transformer and busbar losses can be effectively reduced, thereby improving the system efficiency. At the same time, the system does not need to be equipped with an on-load voltage regulator, that is, it can quickly respond to the fluctuating load demand of green electricity, thereby achieving a fast and efficient power quality management effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the structural principle of a hydrogen production power supply device with power quality management function according to Example 1 of the present invention.

[0036] Figure 2 It is a specific circuit structure diagram of the hydrogen production power supply device with power quality management function according to Example 1 of the present invention.

[0037] Figure 3 It is a schematic diagram of the structural principle of the control module controlling the PWM rectifier module in Example 1 of the present invention.

[0038] Figure 4 It is a schematic diagram of the specific structural principle of the compensation control submodule in Example 1 of the present invention to achieve harmonic control.

[0039] Figure 5 It is a structural schematic diagram of the first (three-level) hydrogen production power supply device in Example 2 of the present invention.

[0040] Figure 6 It is a structural schematic diagram of the second (two-level) hydrogen production power supply device in Example 2 of the present invention.

[0041] Figure 7 It is a structural schematic diagram of the hydrogen production power supply device in Example 3 of the present invention.

[0042] Figure 8 It is a structural schematic diagram of the hydrogen production power supply device in Example 4 of the present invention.

[0043] Legend: 1. Bridge rectifier module; 2. PWM rectifier module; 3. Rectifier transformer module; 4. Control module; 401. Harmonic detection submodule; 402. Compensation control submodule; 421. Instruction extraction unit; 422. Control unit; 403. Drive submodule. DETAILED DESCRIPTION

[0044] The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

[0045] Of the two types of hydrogen production power sources, the thyristor rectifier power source has power quality problems. In order to improve the power quality problem, it is necessary to use an additional on-load voltage-changing transformer and configure SVG or FC devices at the high-voltage test point of the power grid. This not only has high implementation costs and large hardware overhead, but also has large overall volume and weight of the system, and is relatively complex to control. The PWM rectifier hydrogen production power source also has problems of complex system, large volume and weight, and high device cost. It also has problems such as poor power quality before the electrolyzer is polarized and when the electrolyzer is under low load, low reliability, and a narrow DC voltage adjustment range. At the same time, considering that PWM rectification can control and adjust the output current, it can provide harmonic compensation for the rectifier power source. The present invention fully integrates the rectifier power supply and PWM rectification by taking into account the above-mentioned characteristics of the two types of hydrogen production power supplies. The rectifier power supply is used as the main power supply, and the PWM rectification is used as the grid-side power quality management device. The output of the PWM rectification is controlled according to the harmonic state of the rectifier power supply to perform harmonic compensation to achieve power quality management, so that the hydrogen production power supply device can have a power quality management function, thereby ensuring the quality of the electric energy provided to the electrolyzer, solving the problems of poor power quality of traditional thyristor rectifier hydrogen production power supplies and poor power quality of traditional PWM rectifier hydrogen production power supplies before polarization and under low load conditions. At the same time, there is no need to set up an additional power quality management device, which can effectively reduce the size, weight and implementation cost of the device. Since the PWM rectification and the rectifier power supply are integrated in the hydrogen production power supply device, only one set of controller is required to achieve coordinated control between the two, and the control complexity of the device can also be greatly reduced.

[0046] Embodiment 1:

[0047] like Figure 1 As shown, the hydrogen production power supply device with power quality management function in this embodiment includes a bridge rectifier module 1, a PWM rectifier module 2, a rectifier transformer module 3 and a control module 4. The input end of the bridge rectifier module 1 is connected to the AC power supply through the rectifier transformer module 3, and the output end is connected to the electrolyzer to supply power to the electrolyzer. The output end of the bridge rectifier module 1 is also connected to the PWM rectifier module 2 through the control module 4, and the control module 4 controls the output current of the PWM rectifier module 2 according to the harmonic voltage / current state of the bridge rectifier module 1 to perform power quality management.

[0048] like Figure 2As shown, the bridge rectifier module 1 is an N=6-pulse rectifier circuit, the PWM rectifier module 2 is a group, and the AC side of the bridge rectifier module 1 (6-pulse rectifier circuit) is connected to the AC side of the PWM rectifier module 2, that is, the PWM rectifier module 2 is connected in parallel with the bridge rectifier module 1. In this embodiment, the bridge rectifier module 1 is specifically a thyristor rectifier circuit, which is designed by combining a thyristor rectifier and a PWM rectifier. The thyristor rectifier is used as the main power source, and the PWM rectifier is used as the grid-side power quality management device. The thyristor rectifier and the PWM rectifier cooperate with each other to form a hydrogen production power supply device with power quality management function, solve the grid-side power quality problem of the thyristor rectifier, improve the power quality of the output power of the hydrogen production power supply, and can also reduce the volume and weight of the overall device.

[0049] In this embodiment, only one thyristor power supply is required to meet the power supply demand for hydrogen production. A single thyristor power supply has lower harmonics and stronger independence, which can improve the reliability and stability of the system. By controlling the trigger angle, the DC voltage can be quickly adjusted from 0V to the rated voltage. When the green grid voltage fluctuates, the temperature of the grid side voltage can be ensured by adjusting the voltage on the AC side. At the same time, power quality management is achieved by combining the PWM rectifier module 2. While improving the power quality, it can effectively reduce the transformer and busbar losses and improve the system efficiency. At the same time, the system does not need to be equipped with an on-load voltage regulator, that is, it can quickly respond to the fluctuating load demand of green electricity (the specific speed can reach milliseconds), and can achieve fast and efficient power quality management effects.

[0050] In the present embodiment, the PWM rectifier module 2 specifically includes a full-bridge rectifier circuit and a supporting capacitor connected in parallel, and the full-bridge rectifier circuit includes three chopping bridge arms, each of which is connected to the bridge rectifier module 1 and the three phases (u, v, w) of the AC power supply through an AC filter inductor, and each chopping bridge arm constitutes a three-level chopping circuit. It can be understood that the PWM rectifier module 2 can also adopt a two-level chopping circuit or a multi-level chopping circuit, which can be specifically configured according to actual needs.

[0051] See also Figure 2In this embodiment, the bridge rectifier module 1 is specifically a 6-pulse three-phase thyristor full-bridge circuit, the PWM rectifier module 2 is specifically a PWM three-phase full-bridge circuit, and the rectifier transformer module 3 is specifically a no-load voltage-regulating rectifier transformer. The high-voltage side of the rectifier transformer is connected to the photovoltaic, wind power and other new energy power grids through the high-voltage switch cabinet, and the high-voltage switch cabinet is used to protect the hydrogen production power system. The low-voltage side is connected to the AC input side of the thyristor rectifier. The 6-pulse three-phase thyristor full bridge and the PWM converter are connected in parallel. A circuit breaker is set on the PWM converter side on the AC side. The DC side of the PWM converter device is a supporting capacitor. The DC side of the thyristor rectifier is connected to the electrolyzer, and an isolating switch is set between the two. By adopting a no-load voltage-regulating rectifier transformer, a no-load voltage regulation mode can be achieved, so that the full-through short-circuit impedance is only about 8%, and the device response speed can be further improved, so that it can reach the millisecond level.

[0052] In order to realize the integrated design of thyristor rectification and PWM conversion, it is necessary to determine the capacity of the PWM rectification module 2. The capacity of the PWM rectification module 2 can be calculated as follows:

[0053] Get the active power (kW) Pc and power factor before compensation and reactive power (kvar) Qc1,

[0054] After compensation, the active power (kW) Pc remains unchanged, and the power factor is Reactive power (kvar) Qc2 is

[0055] The capacity that needs to be compensated is:

[0056]

[0057] in, is the phase difference between voltage and current before compensation, is the phase difference between the voltage and current after compensation.

[0058] The power factors corresponding to different pulse numbers and trigger angles of the thyristor rectifier are shown in Table 1 below. Under the worst working conditions of 6 pulses and 30° trigger angle, the power factor is 0.827. Usually, the hydrogen production system requires a power factor of 0.95 or above. It can be concluded from the above formula (1) that the PWM rectifier module 2 only needs to be configured with 30% of the rated capacity of the thyristor. That is, on the basis of the thyristor rectifier circuit, only a 30% capacity AC / DC converter needs to be configured, and there is no need to set up a voltage regulator and SVG device, which can greatly reduce the system cost.

[0059] Table 1: Thyristor rectifier pulse number-firing angle and power factor

[0060]

[0061] In this embodiment, the control module 4 collects the system harmonic voltage and harmonic current, calculates and extracts the content of each harmonic current, generates a harmonic current instruction, and generates a compensation current with the same amplitude and opposite direction as the harmonic current through the power actuator to achieve harmonic compensation. In this embodiment, a 6-pulse thyristor rectifier is specifically used. The characteristic harmonics of the 6-pulse thyristor rectifier are the 5th and 7th order, so the PWM converter module 2 is controlled to generate the 5th and 7th order currents in opposite directions for compensation. If it is a thyristor rectifier with other pulses, the PWM converter module 2 is controlled accordingly to generate a current with the same amplitude and opposite direction as the thyristor rectifier for compensation. The working principle of harmonic control in this embodiment is: by detecting the voltage and current of the object (bridge rectifier module 1), the command signal of the compensation current is calculated, and the signal is passed through the compensation amplifier circuit to obtain the compensation current. The compensation current is offset by the harmonics and reactive currents to be compensated in the load current, and the desired power supply current is finally compensated.

[0062] like Figure 3 As shown, the control module 4 in this embodiment specifically includes a harmonic detection submodule 401, a compensation control submodule 402 and a driving submodule 403 which are connected in sequence. The harmonic detection submodule 401 is used to detect the harmonic voltage and harmonic current of the bridge rectifier module 1, and output them to the compensation control submodule 402. The compensation control submodule 402 extracts the content of each harmonic current according to the detected harmonic voltage and harmonic current, generates a harmonic current instruction, and drives the phase of the output current of the PWM rectifier module 2 through the driving submodule 403, so that the harmonics and reactive currents to be compensated can be offset, thereby ensuring the power quality of the power output by the hydrogen production power supply.

[0063] like Figure 4 As shown, in this embodiment, the compensation control submodule 402 includes an interconnected instruction extraction unit 421 and a control unit 422. The instruction extraction unit 421 is used to respectively receive the active component and reactive component of the current harmonics of the bridge rectifier module 1, extract the harmonic active current and reactive current and output them to the control unit 422. The control unit 422 respectively receives the extracted harmonic active current, the active component of the output current fed back by the PWM rectifier module 2, and the extracted harmonic reactive current, The reactive component of the output current fed back by the PWM rectifier module 2 is compared, and the comparison result is obtained through PI control. The control instructions of the active component and reactive component of the final output current are provided to the PWM rectifier module 2.

[0064] In this embodiment, the instruction extraction unit 421 specifically includes an active current extraction subunit and a reactive current extraction subunit. The active current extraction subunit includes a first harmonic extraction circuit, a first adder, a first PI controller, and a second adder. The input end of the first harmonic extraction circuit inputs the active component i of the current harmonic of the bridge rectifier module 1. ld , which is used to remove the fundamental component through Fourier transform to obtain the harmonic component of the active current, the output end is connected to an input end of the first adder, and the second adder is respectively connected to the reference voltage U of the intermediate DC voltage of the PWM converter dcref And the measured intermediate DC voltage U of the PWM converter dc The output end is connected to the other input end of the first adder through the first PI controller, and the output end of the first adder outputs the extracted harmonic active current i d * The reactive current extraction subunit includes a second harmonic extraction circuit, which inputs the reactive component i of the current harmonic of the bridge rectifier module 1. lq , which is used to remove the fundamental component through Fourier transform to obtain the harmonic component of reactive current, and output the extracted harmonic reactive current i q * .

[0065] In this embodiment, the control unit 422 specifically includes two control branches for controlling the control instructions for generating the active component and reactive component of the output current, respectively. Each control branch includes an input side adder, a second PI controller, and an output side adder. The input side adder is respectively connected to the active / reactive component i of the current harmonic of the bridge rectifier module 1. d * / i q * The output end outputs the difference ed / eq between the calculated active / reactive current and the actual current. The output end of the input side adder is connected to one input end of the output side adder through the second PI controller. The other two input ends of the output side adder are respectively input with the active / reactive component modulation wave (v sd / v sd ), the active / reactive components of the output current of the PWM branch (PWM rectifier module 2) (i fd / i fq ) The output result after the internal filter of the PWM rectifier module 2, the output end of the output side adder outputs the active / reactive component triangular carrier of the current harmonic (v rd / v rq ).

[0066] Taking the control branch corresponding to active current control as an example, the input side adder is respectively connected to the active component i of the current harmonic of the bridge rectifier module 1 d* The output end outputs the difference ed between the calculated active current value and the actual current. The output end of the input side adder is connected to one input end of the output side adder through a PI controller. The other two input ends of the output side adder input the active component modulation wave v sd 、The active component i of the PWM branch output current fd The output after the PWM converter filter, w l is the impedance value of the PWM converter filter, the output side adder output current harmonic active component triangular carrier v rq .

[0067] The first and second PI controllers are proportional integral regulators, which are used to adjust the deviation convergence between the measured feedback value and the control target value. The control object is specifically a PWM rectifier of a single L filter.

[0068] like Figure 3 , 4 As shown, L is the output inductance of the three phases, R is the resistance value of the filter, C is the DC side capacitor, and the instruction extraction unit i ld is the active component of the thyristor branch current harmonic after being converted from the triangular coordinate system to the dq coordinate system, i lq is the reactive component of the thyristor branch current harmonic after it is converted from the triangular coordinate system to the dq coordinate system, i fd is the active component of the PWM branch output current, i fq The reactive component of the PWM branch output current is sent to the PWM converter control object for decoupling control. d * , reactive current i q * and the feedback of the PWM rectifier of the control object fq and i fd By comparison, the system gradually converges.

[0069] This embodiment is based on the above device and specifically adopts a feedforward decoupling algorithm to implement decoupling control. The expression can be expressed as:

[0070]

[0071]

[0072] Among them, k p is the proportional coefficient of the PI controller, k i / s is the integral coefficient of the PI controller.

[0073] This embodiment adopts the above-mentioned control module 4, collects the phase of the system harmonic voltage and harmonic current, controls the phase of the output current of the PWM rectifier module 2, and performs capacitive or inductive reactive power compensation, so that the power factor on the grid side can reach above 0.95, effectively solving the power quality problem on the grid side of the thyristor rectifier circuit.

[0074] It can be understood that the control module 4 in this embodiment is implemented by a discrete controller, and in other embodiments it can also be implemented by the control system of the PWM rectifier module 2 itself, and the specific implementation form can be configured according to actual needs.

[0075] In this embodiment, a control switch, such as a circuit breaker, is further provided on the AC side of the PWM rectifier module 2, so that the circuit breaker can be promptly disconnected in the event of a fault or other working condition to avoid the expansion of the fault.

[0076] Considering the influence of the higher harmonics of the PWM converter on the RC filter circuit of the thyristor rectifier, this embodiment further provides a filter circuit on the AC side of the PWM rectifier module 2 to reduce the influence of the higher harmonics of the PWM rectifier module 2 on the RC filter circuit of the bridge rectifier module 1. The RC filter synchronizer is a low-pass filter, which is very sensitive to higher harmonics. This embodiment specifically adopts an LCL filter, which can also be combined with a SHEPWM harmonic suppression algorithm to further improve the filtering effect.

[0077] In this embodiment, an isolating switch is further provided on the output side of the bridge rectifier module 1 to provide an obvious breakpoint for convenient maintenance of the electrolytic cell.

[0078] In this embodiment, a heat dissipation system is further provided in the hydrogen production power supply device. Specifically, the heat dissipation system can be water-cooled to reduce the system volume and cost.

[0079] In this embodiment, the bridge rectifier module 1 is a three-phase bridge rectifier circuit, and the AC side is connected to three-phase AC power. In other embodiments, the bridge rectifier module 1 can also be a single-phase bridge rectifier circuit to connect to single-phase AC power.

[0080] Embodiment 2:

[0081] This embodiment is basically the same as embodiment 1, except that Figure 5 , 6As shown, the bridge rectifier module 1 is a 12-pulse thyristor rectifier circuit, that is, N=12, and the PWM rectifier module 2 is specifically configured with two groups (PWM rectifier device 1, PWM rectifier device 2), and the AC side of each PWM rectifier device is correspondingly connected to the AC side of a 6-pulse thyristor rectifier circuit. Specifically, the AC side of the PWM rectifier device 1 is connected to the AC side (U1, V1, W1) of the first 6-pulse thyristor rectifier circuit through an AC inductor, and the AC side of the PWM rectifier device 2 is connected to the AC side (U2, V2, W2) of the second 6-pulse thyristor rectifier circuit through an AC inductor. The rectifier transformer is a split transformer, and the split transformer includes 2 (N / 6=2) low-voltage windings, and each low-voltage winding is correspondingly connected to a 6-pulse thyristor rectifier circuit. The PWM rectifier module 2 can adopt a three-level chopper circuit, such as Figure 4 As shown, a two-level chopper circuit can also be used, such as Figure 5 As shown, of course, a multi-level chopper circuit can also be used.

[0082] It is understandable that in other embodiments, the bridge rectifier module 1 can also adopt other pulse thyristor rectifier circuits, such as 18-pulse, 24-pulse, etc., and correspondingly configure N / 6 groups of PWM rectifier modules 2, and the AC side of each group of PWM rectifier modules 2 is correspondingly connected to the AC side of the 6-pulse thyristor rectifier circuit.

[0083] Embodiment 3:

[0084] This embodiment is basically the same as the embodiment 2, except that the PWM rectifier module 2 is arranged on the high voltage side of the rectifier transformer module 3. Figure 7 That is, the PWM rectifier module 2 can be arranged on the low voltage side of the rectifier transformer module 3 and connected in parallel with the bridge rectifier module 1 as in the first embodiment, or it can be arranged on the high voltage side of the rectifier transformer module 3 .

[0085] Embodiment 4:

[0086] This embodiment is basically the same as the embodiment 1, except that the bridge rectifier module 1 is a diode rectifier circuit, such as Figure 8 As shown, the bridge rectifier module 1 can use a thyristor rectifier circuit or a diode rectifier circuit, and of course, can also use a rectifier circuit composed of other controllable or uncontrollable switch tubes. The type of the diode rectifier in this embodiment is specifically 12 pulses, and of course, other types of pulse diode rectifier circuit structures such as 6 pulses, 18 pulses, and 24 pulses can also be used.

[0087] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment, it is not intended to limit the present invention. Therefore, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A hydrogen production power supply device with power quality management function, characterized in that: The invention comprises a bridge rectifier module (1), a PWM rectifier module (2), a rectifier transformer module (3) and a control module (4); the input end of the bridge rectifier module (1) is connected to an AC power source via the rectifier transformer module (3); the output end is connected to an electrolytic cell to supply power to the electrolytic cell; the output end of the bridge rectifier module (1) is also connected to the PWM rectifier module (2) via the control module (4); the control module (4) controls the output current of the PWM rectifier module (2) according to the harmonic voltage / current state of the bridge rectifier module (1) to perform power quality management.

2. The hydrogen production power supply device with power quality management function according to claim 1 is characterized in that: The PWM rectifier module (2) comprises a full-bridge rectifier circuit and a supporting capacitor connected in parallel, the full-bridge rectifier circuit comprises three chopping bridge arms, each of the chopping bridge arms is connected to the bridge rectifier module (1) and an AC power supply via an AC filter inductor.

3. The hydrogen production power supply device with power quality management function according to claim 2 is characterized in that: Each of the chopper bridge arms forms a two-level chopper circuit, a three-level chopper circuit, or a multi-level chopper circuit.

4. The hydrogen production power supply device with power quality management function according to claim 1 is characterized in that: The bridge rectifier module (1) is a thyristor rectifier circuit or a diode rectifier circuit.

5. The hydrogen production power supply device with power quality management function according to claim 1 is characterized in that: The control module (4) comprises a harmonic detection submodule (401), a compensation control submodule (402) and a driving submodule (403) which are connected in sequence. The harmonic detection submodule (401) is used to detect the harmonic voltage and / or harmonic current of the bridge rectifier module (1) and output it to the compensation control submodule (402). The compensation control submodule (402) extracts the content of each harmonic current based on the detected harmonic voltage and / or harmonic current, generates a harmonic current instruction, and drives and controls the phase of the output current of the PWM rectifier module (2) through the driving submodule (403).

6. The hydrogen production power supply device with power quality management function according to claim 5 is characterized in that: The compensation control submodule (402) comprises an instruction extraction unit (421) and a control unit (422) which are connected to each other. The instruction extraction unit (421) is used to respectively receive the active component and reactive component of the current harmonics of the bridge rectifier module (1), extract the harmonic active current and reactive current, and output them to the control unit (422). The control unit (422) respectively receives the extracted harmonic active current and the active component of the output current fed back by the PWM rectifier module (2), and the extracted harmonic reactive current and the reactive component of the output current fed back by the PWM rectifier module (2), and compares them. The comparison result is subjected to PI control to obtain control instructions for the active component and reactive component of the final output current, which are respectively provided to the PWM rectifier module (2).

7. The hydrogen production power supply device with power quality management function according to claim 6 is characterized in that: The instruction extraction unit (421) comprises an active current extraction subunit and a reactive current extraction subunit. The active current extraction subunit comprises a first harmonic extraction circuit, a first adder, a first PI controller and a second adder. The input end of the first harmonic extraction circuit inputs the active component of the current harmonic of the bridge rectifier module (1) so as to remove the fundamental component through Fourier transform to obtain the harmonic component of the active current. The output end is connected to an input end of the first adder. The second adder is respectively connected to the reference voltage Udcref of the intermediate DC voltage of the PWM converter and the measured intermediate DC voltage Udc of the PWM converter. The output end is connected to the other input end of the first adder through the first PI controller. The output end of the first adder outputs the extracted harmonic active current. The reactive current extraction subunit comprises a second harmonic extraction circuit. The second harmonic extraction circuit inputs the reactive component of the current harmonic of the bridge rectifier module (1) so as to remove the fundamental component through Fourier transform to obtain the harmonic component of the reactive current. The extracted harmonic reactive current is output.

8. The hydrogen production power supply device with power quality management function according to claim 6 is characterized in that: The control unit (422) comprises two control branches for respectively controlling the control instructions for generating the active component and reactive component of the output current. Each of the control branches comprises an input side adder, a second PI controller and an output side adder. The input side adder is respectively connected to the active / reactive components of the current harmonics of the bridge rectifier module (1) and outputs the difference between the active / reactive current calculation value and the actual current. The output end of the input side adder is connected to an input end of the output side adder through the second PI controller. The other two input ends of the output side adder respectively input the current component modulation wave and the output result of the current component of the output current of the PWM rectifier module (2) after passing through the PWM converter filter. The output end of the output side adder outputs the triangular carrier of the active / reactive component of the current harmonics.

9. The hydrogen production power supply device with power quality management function according to any one of claims 1 to 8, characterized in that: The bridge rectifier module (1) is an N-pulse rectifier circuit, the PWM rectifier module (2) comprises N / 6 groups, N being a multiple of 6, and the AC side of each 6-pulse rectifier circuit in the bridge rectifier module (1) is correspondingly connected to the AC side of a group of PWM rectifier modules (2).

10. The hydrogen production power supply device with power quality control function according to any one of claims 1 to 8, characterized in that: The PWM rectifier module (2) is arranged on the high voltage side of the rectifier transformer.

11. The hydrogen production power supply device with power quality control function according to any one of claims 1 to 8, characterized in that: The AC side of the PWM rectifier module (2) is also provided with a control switch and / or a filter circuit.

12. The hydrogen production power supply device with power quality management function according to any one of claims 1 to 8, characterized in that: An isolating switch is also provided on the output side of the bridge rectifier module (1).

13. The hydrogen production power supply device with power quality control function according to any one of claims 1 to 8, characterized in that: When N>6, the rectifier transformer module (3) is a split transformer, and the split transformer comprises N / 6 low-voltage windings, each of which is connected to a 6-pulse rectifier circuit in the bridge rectifier module (1).

14. A control method for a hydrogen production power supply device with power quality control function according to any one of claims 1 to 13, characterized in that the steps include: Detecting the harmonic voltage and / or harmonic current of the bridge rectifier module (1); Extracting the content of each harmonic current according to the detected harmonic voltage and / or harmonic current to generate a harmonic current instruction; The phase of the output current of the PWM rectifier module (2) is driven and controlled according to the harmonic current instruction to perform harmonic compensation and achieve power quality management.

15. The control method according to claim 14, characterized in that: The step of extracting the content of each harmonic current according to the detected harmonic voltage and / or harmonic current comprises: The active component of the current harmonics input into the bridge rectifier module (1) is subjected to harmonic extraction, and a comparison result of a reference voltage Udcref of the intermediate DC voltage of the PWM converter and an intermediate DC voltage Udc actually measured by the PWM converter is added to the harmonic extraction result after PI control to obtain an extracted harmonic active current; After the reactive components of the current harmonics input into the bridge rectifier module (1) are subjected to harmonic extraction, the extracted harmonic reactive current is output.

16. The control method according to claim 14 or 15, characterized in that: The harmonic current generating instruction comprises: respectively connecting the active / reactive components of the current harmonics of the bridge rectifier module (1), subtracting the result after PI control from the active / reactive component modulation wave vsd and the output result after the current component of the output current of the PWM rectifier module (2) passes through the PWM converter filter, and outputting the triangular carrier of the active / reactive component of the current harmonics.

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