CN115896803A

CN115896803A - Control method and device for virtual synchronous PEM (proton exchange membrane) water electrolysis hydrogen production module

Info

Publication number: CN115896803A
Application number: CN202210954697.0A
Authority: CN
Inventors: 宋天琦; 吕志鹏; 刘海涛; 周珊; 王岗; 宋振浩; 刘文龙; 马韵婷
Original assignee: China Online Shanghai Energy Internet Research Institute Co ltd
Current assignee: China Online Shanghai Energy Internet Research Institute Co ltd
Priority date: 2022-08-10
Filing date: 2022-08-10
Publication date: 2023-04-04

Abstract

The invention discloses a control method of a virtual synchronous PEM (polymer electrolyte membrane) water electrolysis hydrogen production module, and discloses a device with the control method of the virtual synchronous PEM water electrolysis hydrogen production module, wherein the control method of the virtual synchronous PEM water electrolysis hydrogen production module is controlled by integrating a PWM (pulse-width modulation) three-phase converter with a load virtual synchronous control function into the conventional PEM water electrolysis hydrogen production device, so that the conventional PEM water electrolysis hydrogen production module has the autonomous operation and active management functions of active-frequency and reactive-voltage output on each time scale, and has the external operation characteristics of inertia, damping characteristic, active frequency modulation, reactive voltage regulation and the like of a synchronous unit, and can respond to the voltage/frequency regulation of a power grid and provide active and reactive support for the power grid. Friendly interaction between the PEM hydrogen production module and a power grid is promoted, and active power balance and voltage stability are improved in a power-assisted manner.

Description

Control method and device for virtual synchronous PEM (proton exchange membrane) water electrolysis hydrogen production module

Technical Field

The invention relates to the field of gas-electricity fusion and adjustable load active support, in particular to a control method and a device for a virtual synchronous PEM (proton exchange membrane) water electrolysis hydrogen production module.

Background

In recent years, with the continuous progress of science and technology, the construction work of novel electric power systems in China is also rapidly advanced. Since the 21 st century, power electronic devices represented by new energy grid-connected inverters and controllable load rectifiers have been rapidly connected to the power grid. The conventional converter is high in response speed, but almost has no rotational inertia, is difficult to participate in power grid regulation, and cannot provide necessary voltage and frequency support for a distributed power supply and a novel power system with a rising renewable energy power generation ratio. The small-inertia, quick and high-frequency power electronic system is connected with a large-inertia, low-speed and power-frequency power system, so that various adaptability problems such as no participation in power grid regulation, no support on power grid fault recovery, difficult management and control, frequent plugging and unplugging, weak robustness in a dynamic and steady process and the like are generated. Therefore, the active supporting potential of the adjustable load is inevitably excavated under the background of large access of new energy and controllable load.

Meanwhile, the energy crisis and the environmental pollution are increasingly severe, and the development of renewable energy and the sustainable development path become the research focus of various national scholars. Promoting the structural reform of energy sources and realizing the low-carbon and clean energy sources are necessary ways for the sustainable development of China. However, due to the intermittent and intermittent nature and the difficult storage and transportation of renewable energy sources such as solar energy, wind energy and the like, an efficient and clean energy carrier is needed as a bridge between the renewable energy sources and users. Hydrogen energy is recognized as the most potential energy carrier in the future due to its clean and efficient characteristics. Among the various current hydrogen production technologies, the use of electrical energy generated by renewable energy sources as a power to electrolyze water is the most mature and potential technology, considered the best path to the hydrogen economy. Electrolysis of water is a process of splitting water into hydrogen and oxygen powered by electrical energy. The overall reaction formula is: 2H2O + electrical energy

→2H2+O2。

Proton Exchange Membrane (PEM) is the most interesting technology in various water electrolysis technologies, and has the advantages of high current density, reproducibility, no pollution, high starting speed and the like compared with alkaline electrolytic cells and solid oxide electrolytic cells. The advantages of the PEM electrolytic cell in the aspects of power regulation range, power change adaptability and the like determine that the PEM electrolytic cell has wide application prospects in a novel power system in the future. Particularly, as a new energy storage technology, the device can realize large-scale long-period energy storage in the wind/light power generation field, and can also be used as a green hydrogen preparation device for actively supporting a power grid when being coupled with a wind/light power generation system.

Therefore, the PEM water electrolysis hydrogen production device is a load-type resource which cannot be ignored in a future power system and has good adjustability. The power grid-friendly virtual synchronous PEM water electrolysis hydrogen production product is developed, the full consumption of renewable energy power generation is promoted, and meanwhile, the power grid is supported in an all-around active mode, so that the method is an urgent need in the context of constructing a novel power system.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a PEM (proton exchange membrane) water electrolysis hydrogen production method based on a virtual synchronous control technology, so that the conventional PEM water electrolysis hydrogen production module has the functions of autonomous operation and active management of active-frequency and reactive-voltage output on each time scale; and the existing PEM hydrogen production device has the external operation characteristics of inertia, damping characteristic, active frequency modulation, reactive voltage regulation and the like of a synchronous unit, can respond to the voltage/frequency adjustment of a power grid, and provides active and reactive support for the power grid. The friendly interaction between the PEM hydrogen production module and a power grid is promoted, and the active power balance and the voltage stability are improved in a boosting manner; meanwhile, the power grid has more adjustable load resources for actively supporting the power grid, and renewable energy consumption and green hydrogen preparation are promoted.

The invention also provides a device with the control method of the virtual synchronous PEM water electrolysis hydrogen production module.

The control method of the virtual synchronous PEM water electrolysis hydrogen production module according to the embodiment of the first aspect of the invention is characterized by comprising the following steps:

combining a PWM three-phase converter with a load virtual synchronous control function with a PEM hydrogen production device;

the PEM hydrogen production module can sense the state of a power grid and automatically adjust the absorbed power;

the high-frequency PWM rectification circuit is connected to a power supply system;

adjusting target grid-connected frequency based on autonomous active frequency modulation control;

and regulating the amplitude of the target output voltage based on the autonomous reactive power voltage regulation control.

The control method of the virtual synchronous PEM electrolyzed water hydrogen production module according to the embodiment of the invention at least has the following beneficial effects: when the PEM water electrolysis hydrogen production module transformed by the method is connected to a target energy system, the PEM water electrolysis hydrogen production module can autonomously operate on each time scale from active-frequency and reactive-voltage output, and actively manage the power quality of a power grid. The application of the boosting PEM water electrolysis hydrogen production device further relieves the fluctuation and randomness of a renewable energy system in a future comprehensive energy application scene, and provides more green hydrogen resources. The reserve capacity and the cost of equipment devices of the energy storage and grid connection part of the comprehensive energy system are reduced.

According to some embodiments of the invention, in the step of combining the PWM three-phase converter with the load virtual synchronous control function with the PEM hydrogen production device, the electrolyzed water hydrogen production module can simulate the intrinsic electromagnetic conversion mechanism and the extrinsic operation characteristics of the synchronous generator, so that the PEM hydrogen production device block has an inertia mechanism.

According to some embodiments of the invention, the high frequency PWM rectifier circuit comprises an ac interface and a dc interface, wherein:

the alternating current interface adopts an H-bridge AC/DC rectifying circuit and is used for rectifying the power grid voltage into direct current voltage of 600V;

the direct current interface adopts an isolation type DC/DC converter and is used for converting direct current voltage of 600V into direct current voltage required by a PEM electrolyzer.

According to some embodiments of the invention, the torque control is a cascaded frequency-torque double closed loop structure, consisting of a frequency inner loop and a torque outer loop.

According to some embodiments of the invention, the reactive power control adopts a double closed loop control structure, and is composed of a power outer loop and a current inner loop.

The control device of the virtual synchronous PEM water electrolysis hydrogen production module according to the embodiment of the second aspect of the invention is characterized by comprising the following components:

the virtual synchronization module is used for combining a PWM three-phase converter with a load virtual synchronization control function with the PEM hydrogen production device;

the power adjusting module can sense the state of a power grid by applying a PEM hydrogen production module of a virtual synchronous motor technology and automatically adjust the speed of absorbed power;

the wiring module can be connected to a power supply system based on the high-frequency PWM rectification circuit;

the frequency adjusting module can adjust target grid-connected frequency based on autonomous active frequency modulation control;

the torque control module can perform torque control based on a simulation synchronous generator rotor motion equation;

and the voltage regulating module can regulate the amplitude of the target output voltage based on the autonomous reactive power voltage regulation control.

The control device of the virtual synchronous PEM electrolyzed water hydrogen production module according to the embodiment of the invention at least has the following beneficial effects: when the virtual synchronous PEM water electrolysis hydrogen production module is connected to a target energy system, the module can autonomously operate on each time scale from active-frequency and reactive-voltage output, and actively manage the power quality of a power grid. And limits the volatility and randomness of renewable energy systems in future integrated energy application scenarios while providing green hydrogen on-site. The reserve capacity and the cost of equipment devices of the energy storage and grid connection part of the comprehensive energy system are reduced, and the hydrogen storage and transportation cost is reduced.

According to some embodiments of the invention, the virtual synchronization module enables the water electrolysis hydrogen production module to simulate the intrinsic electromagnetic conversion mechanism and the extrinsic operation characteristic of a synchronous generator, so that the PEM hydrogen production device block has an inertia mechanism.

the alternating current interface adopts an H-bridge AC/DC rectification circuit and is used for rectifying the power grid voltage into 600V direct current voltage;

the direct current interface adopts an isolation type DC/DC converter and is used for converting direct current voltage of 600V into direct current voltage required by a PEM electrolytic cell.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic diagram illustrating steps of a control method of a virtual synchronous PEM water electrolysis hydrogen production module according to an embodiment of the invention;

FIG. 2 is a diagram of a grid-connected control structure of a virtual synchronous PEM water electrolysis hydrogen production module according to an embodiment of the invention;

FIG. 3 is a diagram of a main power supply circuit of an electrolyzer of a virtual synchronous PEM water electrolysis hydrogen production module according to an embodiment of the invention;

FIG. 4 is a control schematic diagram of a virtual synchronous PEM electrohydrogen production module according to an embodiment of the invention;

FIG. 5 is a schematic diagram of a voltage-current dual closed-loop control structure according to an embodiment of the present invention;

FIG. 6 is a voltage rotation vector diagram according to an embodiment of the present invention;

FIG. 7 is a schematic structural diagram of a clock phase synchronization controller according to an embodiment of the present invention;

FIG. 8 is a schematic diagram of an amplitude synchronization controller according to an embodiment of the present invention;

FIG. 9 is a schematic diagram of a primary voltage regulation curve of a synchronous generator according to an embodiment of the present invention;

fig. 10 is a schematic diagram of a reactive loop control structure according to an embodiment of the present invention;

fig. 11 is a schematic structural block diagram of a control device of a virtual synchronous PEM electrolytic water hydrogen production module according to an embodiment of the invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

In the description of the present invention, the meaning of a plurality of means is one or more, the meaning of a plurality of means is two or more, and larger, smaller, larger, etc. are understood as excluding the number, and larger, smaller, inner, etc. are understood as including the number. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.

The invention provides a control method of a virtual synchronous PEM (proton exchange membrane) water electrolysis hydrogen production module, which at least comprises the following steps:

and S100, connecting a PWM three-phase converter with a load virtual synchronous control function with a PEM hydrogen production device.

A PWM three-phase converter with a load virtual synchronous control function is integrated in an existing PEM hydrogen production device for control, so that the intrinsic electromagnetic conversion mechanism and the extrinsic operation characteristic of a synchronous generator are simulated, and a PEM hydrogen production device block has an inertia mechanism.

And S200, enabling the PEM hydrogen production module to sense the state of a power grid and automatically adjusting the speed of absorbed power.

Referring to fig. 2, the PEM hydrogen production module applying the virtual synchronous motor technology can sense the state of the power grid and acquire frequency and voltage information of the connected power grid in real time. The main circuit is consistent with the main circuit of the traditional PWM rectifier, consists of a three-phase bridge circuit and an L filter, and mainly comprises a voltage source converter, a filter inductor, a direct current filter, an alternating current filter and the like.

And step S300, connecting the rectification circuit to a power supply system based on the high-frequency PWM.

The circuit is a high-frequency isolated PWM rectification circuit, the PWM rectification circuit comprises an alternating current interface and a direct current interface, and the alternating current interface adopts an H-bridge AC/DC rectification circuit and is used for rectifying the power grid voltage into 600V direct current voltage; the direct current interface adopts an isolation type DC/DC converter and is used for converting direct current voltage of 600V into direct current voltage required by a PEM electrolytic cell.

Referring to fig. 3, the virtual synchronous PEM water electrolysis hydrogen production module electrolyzer power supply main circuit is provided with PWM rectification at the front stage and an isolated DC/DC circuit at the rear stage, and finally supplies power to the electrolyzer.

And S400, simulating a motion equation of the rotor of the synchronous generator to control the torque.

The active power control is a cascaded frequency-torque double closed-loop structure and consists of a frequency inner ring and a torque outer ring.

And S500, regulating the amplitude of the target output voltage based on the autonomous reactive power voltage regulation control.

The method adopts autonomous reactive power voltage regulation control to regulate the amplitude of target output voltage, and the reactive power control adopts a double closed loop control structure and consists of a power outer loop and a current inner loop.

The method takes the hydrogen production by using the electrolyzed water under the condition of the expressway energy network containing the photovoltaic power generation system as an example. A250 kW virtual synchronous PEM electrolytic water hydrogen production system can be configured according to the supply condition required by a fuel cell automobile.

Further, for the purpose of describing the subject matter of the present application in more detail, the present application provides a control structure diagram of a load virtual synchronous machine shown in fig. 4, and the control is mainly divided into five parts: direct current side voltage loop, rotor equation of motion (active loop), reactive loop, electromagnetic equation and current inner loop control.

(1) DC side voltage loop control

The voltage on the direct current side is controlled by PI to obtain a direct current given value, and the direct current given value is multiplied by the inverse number of the voltage given value to obtain a given value P of active power _set ：

P _set ＝-U _dc ^* (U _dc ^* -U _dc )(K _p +K _i /s) (1)

In the formula of U _dc * Is a reference value of the DC side voltage; u shape _dc Is a direct current side voltage; k _p And K _i Proportional and integral coefficients of the PI controller, respectively.

The control method of the load virtual synchronous machine directly controls the output voltage and frequency through the active control loop and the reactive control loop, and unification of the off-grid and grid-connected control modes is achieved. The quasi-power control mode is simple and feasible, but loses the control on the side voltage and current of the load virtual synchronous machine to a certain extent, and cannot reflect the rapidness and the accuracy of power electronic control. Therefore, in order to quickly and accurately control the voltage and the current of the system and improve the dynamic characteristics of the system, the control characteristics of the load virtual synchronous generator are fused, and voltage and current double closed-loop control is further cascaded on the basis of a power loop of the load virtual synchronous generator.

A control block diagram of the voltage and current double closed loop in the synchronous dq rotation coordinate system is shown in fig. 5, wherein the amplitude of the voltage output by the reactive loop is used as a reference instruction value of the voltage outer loop, the reference instruction value is compared with the voltage value of the fed back capacitor, and the deviation is output as a reference instruction value of the current inner loop after being subjected to PI regulation. The command value is compared with the current value of the feedback inductor, and then a voltage modulation wave signal is generated through a proportion link. And finally, generating a PWM signal through modulation to drive the on-off of the switching tube. The non-difference regulation of an alternating current system is realized by combining abc-dq coordinate transformation with a PI regulator, and the cross decoupling of the d-axis electric quantity and the q-axis electric quantity is realized by coupling item feedback.

(2) Rotor equation of motion (active ring control)

The active loop output of the load virtual synchronous machine is the frequency of the rectifier modulation wave, the number of pole pairs of the virtual synchronous machine is set to be 1, the rotor inertia and the damping factor are generally simulated by a second-order model of the synchronous motor, and a torque equation of the synchronous motor, namely a rotor motion equation, can be expressed as follows:

wherein: theta is the power angle, rad, of the generator; omega mechanical angular velocity, i.e. the electrical angular velocity of the synchronous motor, rad/s; omega _n Is the synchronous angular velocity of the power grid, rad/s; j is the moment of inertia of the synchronous motor, kg.m 2; t is _e 、T _m And T _d Electromagnetic torque, mechanical torque and damping torque of the synchronous motor are respectively N.m; the electromagnetic torque of the machine can be derived from the electromagnetic power, i.e. T _e ≈P _e /ω _n ；D _p The damping coefficient is N.m/s/rad of the virtual synchronous motor. Due to constants J and D _p The virtual synchronous machine of the load shows mechanical inertia and the capability of damping power oscillation in the process of power grid voltage/frequency disturbance and load switching.

Obtainable from formula (2)

θ＝(P _ref -P _e +D _p ω _n )/s/(Js+D _p ) (3)

In the formula, theta is the power angle of the generator, rad/s; j is the moment of inertia of the synchronous motor, kg.m 2; p is a radical of _ref The control output is the control output of the DC bus voltage PI regulator; d _p The damping coefficient is the damping coefficient of the virtual synchronous motor, nm/s/rad; omega _n And the synchronous angular speed of the power grid is rad/s.

By applying mechanical torque T to the virtual synchronous machine _m Regulation of the ac interface, i.e. of active commandsAdjusting; t is _m Commanded by rated torque T ₀ And a frequency deviation feedback command delta T, wherein T ₀ Expressed as:

T ₀ ＝P _ref /ω (4)

wherein, P _ref For active command of the grid-connected inverter, in the charging and discharging circuit, P _ref Namely the control output of the direct current bus voltage PI regulator; the adjustment of the frequency response is realized by a virtual frequency modulation unit, which is taken as a proportional link, i.e. the mechanical torque deviation command Δ T is expressed as:

ΔT＝k _f (f-f ₀ ) (5)

wherein f is the frequency of the terminal voltage of the virtual synchronous motor, f ₀ For the rated frequency, k, of the grid _f Is a frequency response coefficient, which is a constant negative number.

The direct current side voltage is controlled through PI to obtain a current given value, and the current given value is multiplied by the voltage given value to obtain the T of the active power _e Given values:

in the formula of U _abcref Is a given value of the DC side voltage; u shape _dc ^* A reference value for the dc side voltage; u shape _dc Is a direct current side voltage; k _p And K _i Proportional and integral coefficients of the PI controller, respectively.

According to the instantaneous power calculation formula

First consider the synchronous control of frequency and phase. Since the phase and the frequency can be mutually converted by integration and differentiation, the synchronization of the inverter frequency and the phase can be considered to be realized in one controller. Fig. 6 is a frequency phase relationship diagram between the grid voltage vector and the output voltage vector of the load virtual synchronous machine. Wherein the network voltage is at an angleFrequency omega _g Rotation in phase of

The output voltage of the load virtual synchronous machine rotates at an angular frequency omega, and the phase is theta. With grid voltage vector as d-axis and omega _g And establishing a synchronous rotation coordinate system for the rotation angular speed, wherein the phase difference between the output voltage of the load virtual synchronous machine and the power grid voltage is delta theta. As can be seen from FIG. 6, the component of the output voltage vector of the load virtual synchronous machine on the d-axis is V _d If the frequency phase of the virtual synchronous machine is consistent with the frequency phase of the power grid voltage and the virtual synchronous machine and the power grid voltage synchronously rotate, the asynchronous quantity between the load virtual synchronous machine and the power grid voltage is represented as a q-axis component V _q . If can control V _q And the voltage is reduced to zero, the voltage vector of the power grid can be tracked by the voltage of the load virtual synchronous machine, and synchronous operation is kept. Therefore, the frequency-phase synchronization controller can be designed from the viewpoint of controlling the q-axis component.

Fig. 6 illustrates a frequency phase synchronization controller as used herein. The voltage vectors of the power grid and the load virtual synchronous machine rotate at respective rotating speeds, the inverter output voltage vector needs to be accelerated through control, and the phase locking of the power grid voltage is needed firstly. The typical software phase-locked loop SPLL and the power grid voltage V under a two-phase synchronous rotating coordinate system are adopted _ga ，V _gb ，V _gc And obtaining dq component values under a rotating coordinate system through a CLARK transformation and a PARK transformation. Q-axis component V _gq After the difference is made with the reference value 0, the correction value of the angular frequency omega is obtained through PI regulation and is compared with the reference value omega _n And (usually, a rated value is taken) and added to obtain the angular frequency of the power grid, the angular frequency of the power grid is obtained after integration, and the value is subjected to forward and reverse chord calculation and then participates in PARK transformation calculation, which is a calculation process of a typical phase-locked loop. Output voltage U for load virtual synchronous machine _ca ，U _cb ，U _cc After the grid phase angle value calculated by the phase-locked loop is used as an angle reference to carry out PARK conversion, the dq component value U under the grid rotating coordinate system is obtained _cgd ，U _cgq . Due to the phase difference between the microgrid voltage and the power grid voltage, the calculated q-axis component is not 0, and the value reflects the frequency phase difference between the microgrid voltage and the power grid voltage. When the q-axis component is 0, the voltage vector diagramThe voltage of the upper micro grid and the voltage of the power grid are on the d axis and are superposed, and the phase difference is 0. Therefore, the q-axis component U is converted into _cgq The compensation amount omega of the angular frequency can be obtained by PI regulation after taking 0 as a reference value for difference _comp The frequency and the phase of the output voltage of the inverter can be adjusted by adding the frequency and the phase into the output angular frequency omega of the active control loop, and the voltage of the power grid is finally tracked to achieve the synchronization of the frequency phase and the power grid.

As shown in fig. 7, the main idea of the frequency and phase synchronization controller is to calculate the frequency compensation amount required by the terminal voltage of the load virtual synchronous machine to track the power grid voltage, and obtain the frequency correction amount through phase locking and PI adjustment, which involves two variables of frequency and phase, and has many conversion links. The required adjustment amount of the amplitude synchronous controller is one voltage amplitude, and the control can be relatively simplified.

Fig. 8 is a synchronous controller of voltage magnitude. Compared with frequency phase synchronization, the amplitude synchronization structure is simpler. Compared with FIGS. 2-11, the reference voltage amplitude is adjusted during synchronization

Replacement for the mains voltage amplitude->

Meanwhile, one-time voltage regulation is equivalent to a proportional link, so that the method is poor in regulation and cannot accumulate errors. In order to achieve the purpose of no-difference tracking of the output voltage of the rectifier on the voltage of a power grid, an integral link K is added _i /s(K _i As an integral coefficient) and droop element D _q Together form a PI regulator, calculate the reactive compensation quantity delta Q, participate in the control of the reactive loop and change the output voltage command value of the reactive loop>

The rectifier output voltage amplitude is synchronized with the grid.

When the synchronous effect of the frequency phase and the voltage amplitude reaches the precision requirement, the switch can be switched on, so that the inverter is smoothly connected to the grid. It should be mentioned that, after synchronization is successfully performed, the synchronization controller should be removed, the frequency reference value and the voltage amplitude reference value are restored to the local artificial set values, and the control structure of the load virtual synchronous machine is restored, so that the load virtual synchronous machine simulates a synchronous generator, and the output power is automatically adjusted according to the deviation between the local voltage and the grid voltage, and the output power participates in the adjustment of the grid.

(3) Reactive loop control

The load virtual synchronous motor control strategy is as follows: obtaining virtual synchronous motor transient electric potential E in active regulation, reactive regulation and mechanical equation and electromagnetic equation _p And the power angle delta (or the mechanical angle theta of the rotor) of the virtual synchronous motor, and then obtaining the potential voltage e _abc On the basis, obtaining the instruction value of the three-phase output current of the power grid, and then ensuring the actual grid-connected three-phase output current i under the action of a proportional resonance control strategy _abc For its instruction value i _refabc The tracking of (2).

The reactive loop mainly simulates the reactive-voltage droop characteristic of a virtual synchronous machine to obtain the voltage amplitude:

E _s ＝(Q _set +D _u (U _ref -U _n )-Q _e )/K _q s+E ₀ (8)

and then according to the output E of the reactive loop _s And theta obtained by the active loop to obtain a three-phase modulated wave e _am 、e _bm And e _cm The expression of (c) is:

in the formula: e.g. of the type _abc The method is characterized in that the potential of a virtual synchronous motor, namely three phases on the alternating current side of a converter; u. of _abc The terminal voltage of the synchronous motor, namely the three-phase voltage of the PCC point, is similar to the terminal voltage of the synchronous motor; e _m The effective value of the electromotive force of the virtual synchronous machine of the load.

Due to the voltage dividing effect of the synchronous reactance and the resistor, the output voltage of the synchronous generator is reduced when the output current is increased. The synchronous generator controls the transient potential by changing the magnitude of the exciting current, and maintains the stability of the output voltage. In the topology of the rectifier, the stability of the capacitor voltage can be maintained by controlling the output voltage of the middle point of the bridge arm, and the excitation control function of the synchronous generator can be simulated.

The synchronous generator excitation controller controls the amount of current, while the equivalent in the inverter is the amount of voltage. Therefore, by simulating the excitation current control method of the synchronous generator, the control equation of the midpoint voltage of the bridge arm of the inverter can be obtained as follows:

wherein: e is the effective value of the output phase voltage of the bridge arm of the inverter, U _ref Is an effective value of a reference voltage of a capacitor of the converter, U _o For the effective value of the actual capacitor voltage, G(s) is the transfer function of the power control regulator. Compared with an active control loop, an excitation control link can be analogized to an inertia integral link in the active loop, and meanwhile, a PI controller is selected for G(s) in order to realize no-difference regulation.

Likewise, the first order voltage regulation equation for a synchronous generator is as follows:

wherein: q _e Reactive power, Q, actually output by the synchronous generator _set For a set value of reactive power, D _u Is a reactive-voltage droop coefficient, U _n Is the rated effective value of the output voltage. Combining the formulas (10) and (11) to eliminate the common quantity U _ref After finishing, a reactive-voltage control equation combining the primary voltage regulation and excitation control functions can be obtained:

considering the similarity with the active control loop structure, the reactive droop coefficient is combined with the excitation regulator transfer function, and the order D is _u G(s) = Ks, then equation (12) can be written as:

wherein, U ₀ For outputting an effective value of the voltage, U _n Is the rated voltage effective value. Q _set For given reactive power, Q _e For the rectifier output of real reactive power, D _u And introducing grid-connected voltage variation to provide grid-connected voltage amplitude reference for a droop coefficient through a droop mechanism. G(s) is a regulator of the excitation controller, and is selected to be an integral regulator.

In contrast to equation (2-23), K can be equivalent to the inertia factor of the reactive-voltage control loop. The reactive loop control structure of the load virtual synchronous machine can be designed according to the formula (13) as shown in fig. 10.

For sag factor D _q The selection of (1) takes into account two stable states before and after the voltage amplitude and reactive power change. When the device is in stable operation,

Q _set and U _n Is a fixed value, D can be calculated from the difference between the front and rear steady states according to equation (13) _u ：

According to the formula (14), the droop coefficient D can be designed according to the reactive power requirement corresponding to the voltage amplitude variation _u . For the reactive inertia coefficient K, the adjustment rate of the output voltage instruction under the action of the control loop is reflected to the action of a primary voltage regulation link, and the adjustment rate can be selected according to the requirement of the actual voltage change speed. Similar to the active control loop, the calculation of the reactive power can be obtained by the theoretical calculation of the instantaneous power:

Q _e ＝1.5(v _d i _q -v _q i _d ) (15)

compared with the primary voltage regulation of the traditional droop control, the reactive loop control of the load virtual synchronous machine considers the electromagnetic transient characteristic of the synchronous generator and simulates the excitation regulation function. The introduction of the inertia link is beneficial to voltage smoothing and slow waveThe move transitions to a new steady state. Inertial parameter K _q Flexible and variable, and can adapt to the control requirements of different power levels and adjusting speeds. Output value of reactive loop

And participating in subsequent control calculation as a command value of the amplitude value of the voltage modulation wave.

The three-phase voltage modulation wave E can be generated by combining the phase angle value theta obtained by the calculation of the active control loop and the voltage value obtained by the calculation of the reactive loop _a 、E _b 、E _c As shown in formula (16):

(4) Electromagnetic equation:

by generator convention, the electromagnetic equation for a synchronous machine can be expressed as:

i _abc ＝(e _abc -u _abc )/(Ls+R) (17)

in the formula i _abc Outputting current, namely three-phase alternating-current side current, for the virtual synchronous machine; in the formula, L is a stator inductor of the synchronous motor, namely a filter inductor of an alternating current interface; and R is the resistance of the synchronous motor, namely the parasitic resistance of the alternating current interface filter.

According to kirchhoff principle, the electromagnetic equation of the load virtual synchronous machine is expressed as:

the synchronous motor adjusts the reactive output and the terminal voltage thereof through the excitation controller. Similarly, the virtual potential E of the virtual synchronous machine model can be adjusted _p To regulate its terminal voltage and reactive power. Virtual potential command E for a virtual synchronous machine _p The method comprises the following steps: no-load potential E of the motor ₀ Reactive power regulation potential delta E _Q And the voltage regulation potential Delta E at the end of the reactor _U 。

Reactive power regulated partial potentialΔE _Q Expressed as:

ΔE _Q ＝k _q (Q _ref -Q) (19)

wherein k is _q For a reactive regulation factor, delta E _Q For the reactive instruction of the alternating current interface, Q is the instantaneous reactive power output by the end of the alternating current interface, and Q is expressed as:

wherein: u. of _a 、u _b And u _c Three-phase machine terminal voltages of the load virtual synchronous motor are respectively;

reactor terminal voltage regulation potential Delta E _U ，ΔE _U An automatic excitation regulator (AVR) equivalent to a load virtual synchronous motor, wherein the automatic excitation regulator is simplified into a proportional link, and then delta E _U Expressed as:

ΔE _U ＝k _v (U _ref -U) (21)

wherein, U _ref And U is the command value and the true value of the effective value of the terminal line voltage, k _v Is a voltage regulation factor;

the virtual synchronous machine potential is:

E _p ＝E ₀ +ΔE _Q +ΔE _U (22)

(5) Current inner loop control

The reference value i of the output current of the virtual synchronous machine can be obtained by an electromagnetic equation _abcref And under the action of the PR controller, a three-phase modulation signal is obtained, so that the switching tube of the inverter is controlled to be switched on or off. The actual value of the grid-connected current tracks the given value quickly and accurately, and the harmonic current of the power grid interaction current can be effectively reduced.

According to kirchhoff's law, a mathematical model of the single-side converter station under a three-phase static coordinate system can be obtained:

in the formula: l is a stator inductor of the synchronous motor, namely a filter inductor of an alternating current interface; r is the resistance of the synchronous motor, namely the parasitic resistance of the alternating current interface filter; i.e. i _abc Outputting current, namely three-phase alternating-current side current, for the virtual synchronous machine; u. u _abc The voltage is the terminal voltage of the synchronous motor, namely the three-phase voltage of a PCC point; e.g. of the type _abc The method comprises the following steps of (1) setting a virtual synchronous motor potential, namely three-phase voltage at the alternating current side of a converter; c _dc A direct current side filter capacitor; u shape _dc Is a direct current side voltage; i is _dc Is the current flowing to the current transformer; I.C. A _L Is the load current.

When the loss of the converter reactor is ignored and the power grid connected with the rectifier is regarded as an infinite system, the famous value active power P and the reactive power Q transmitted between the alternating current power grid and the rectifier are respectively

In the formula: u shape _G The voltage is an effective value of the phase voltage of the alternating current power grid; e is the effective value of the alternating-current side phase voltage of the converter; delta is U _G And E; x is the sum of the impedances between the converter station and the ac system.

As can be seen from the formula (25), the active power depends mainly on U _G And E, while the reactive power depends mainly on the converter voltage amplitude E. Therefore, the synchronous motor can be regarded as a synchronous motor, and the active power injected into the network can be changed by changing the phase angle difference between the internal potential of the synchronous motor and the voltage of the power grid. And the excitation of the synchronous motor is adjusted, and the transmission of reactive power can be influenced by changing the terminal voltage of the motor.

Yet another embodiment of the present application provides a virtual synchronous PEM electrolyzed water hydrogen production module control apparatus, as shown in fig. 11, the apparatus 20 comprises: a virtual synchronization module 201, a power adjustment module 202, a wiring module 203, a torque control module 204, a voltage regulation module 205.

The virtual synchronization module 201 is used for connecting a PWM three-phase converter with a load virtual synchronization control function with the PEM hydrogen production device;

the power adjusting module 202 can sense the state of a power grid by applying a PEM hydrogen production module of a virtual synchronous motor technology and automatically adjust the speed of absorbed power;

the wiring module 203 can be connected to a power supply system based on a high-frequency PWM rectification circuit;

a torque control module 204 capable of performing torque control based on the simulated synchronous generator rotor equations of motion;

the voltage regulation module 205 may be capable of regulating the target output voltage amplitude based on autonomous reactive voltage regulation control.

When the virtual synchronous PEM electrolyzed water hydrogen production module is connected to a target energy system, the module can autonomously run on each time scale from the aspects of active-frequency output and reactive-voltage output, and the power quality of a power grid is actively managed. And limits the volatility and randomness of renewable energy systems in future integrated energy application scenarios while providing green hydrogen on-site. The reserve capacity and the cost of equipment and devices of the energy storage and grid connection part of the comprehensive energy system are reduced, and the hydrogen storage and transportation cost is reduced.

Further, the virtual synchronization module enables the water electrolysis hydrogen production module to simulate the intrinsic electromagnetic conversion mechanism and the extrinsic operation characteristic of a synchronous generator, so that the PEM hydrogen production device block has an inertia mechanism.

Further, the high frequency PWM rectifier circuit includes an ac interface and a dc interface, wherein:

Furthermore, the torque control is a cascaded frequency-torque double closed loop structure and is composed of a frequency inner loop and a torque outer loop.

Furthermore, the reactive power control adopts a double closed-loop control structure and consists of a power outer loop and a current inner loop.

The embodiments of the present invention have been described in detail with reference to the drawings, but the present invention is not limited to the embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.

Claims

1. A control method of a virtual synchronous PEM water electrolysis hydrogen production module is characterized by comprising the following steps:

2. The method as claimed in claim 1, wherein the step of connecting the PWM three-phase converter with load virtual synchronous control function with the PEM hydrogen production device enables the water electrolysis hydrogen production module to simulate the intrinsic electromagnetic conversion mechanism and the extrinsic operation characteristics of a synchronous generator, thereby providing inertia mechanism and damping resources for the PEM hydrogen production device block.

3. The method of claim 1, wherein the high frequency PWM rectifier circuit comprises an ac interface and a dc interface, wherein:

4. The method of claim 1, wherein the torque control is a cascaded frequency-torque double closed loop structure consisting of a frequency inner loop and a torque outer loop.

5. The method of claim 1, wherein the reactive power control is in a double closed loop control configuration consisting of a power outer loop and a current inner loop.

6. A virtual synchronous PEM water electrolysis hydrogen production module control device is characterized by comprising:

the virtual synchronization module can combine a PWM three-phase converter with a load virtual synchronization control function with the PEM hydrogen production device;

the power adjusting module can enable the PEM hydrogen production module to sense the state of a power grid and automatically adjust the speed of absorbed power;

the frequency adjusting module can adjust the target grid-connected frequency based on the autonomous active frequency modulation control;

7. The device of claim 6, wherein the virtual synchronization module enables the water electrolysis hydrogen production module to simulate intrinsic electromagnetic conversion mechanism and extrinsic operation characteristics of a synchronous generator, thereby providing inertia mechanism and damping resource for the PEM hydrogen production device block.

8. The apparatus of claim 6, wherein the high frequency PWM rectifier circuit comprises an AC interface and a DC interface, wherein:

9. The apparatus of claim 6, wherein the torque control is a cascaded frequency-torque double closed loop structure consisting of a frequency inner loop and a torque outer loop.

10. The apparatus of claim 6, wherein the reactive power control is in a double closed loop control structure, and is composed of a power outer loop and a current inner loop.