Control method and computer device for secondary frequency modulation based on photovoltaic hydrogen production system

Abstract

This application discloses a control method and computer device for secondary frequency regulation based on a photovoltaic hydrogen production system. The method determines the target power for secondary frequency regulation based on the secondary frequency regulation command signal and the maximum frequency regulation bid capacity. It then determines a first reference power and a second reference power based on the target power, the maximum power point of the photovoltaic power generation unit, and the rated power point of the alkaline electrolysis hydrogen production unit. A first controller controls the photovoltaic power generation unit based on the first reference power, and a second controller controls the alkaline electrolysis hydrogen production unit based on the second reference power. This allows for efficient and stable secondary frequency regulation based on the photovoltaic hydrogen production system, improving grid frequency stability while generating frequency regulation revenue, reducing photovoltaic hydrogen production costs, and increasing system efficiency.

Description

Technical Field

[0001] This application relates to the field of energy technology, and in particular to a control method and computer device for secondary frequency regulation based on a photovoltaic hydrogen production system. Background Technology

[0002] Green hydrogen based on renewable energy sources (such as photovoltaics) holds promise as a crucial pathway for decarbonization in the chemical and transportation industries. However, the volatility, intermittency, and large-scale integration of renewable energy generation systems into the grid through power electrification lead to reduced power system inertia and frequency degradation. Photovoltaic-alkaline electrolysis hydrogen production systems, due to their wide-range and rapid load-changing capabilities, hold promise for providing secondary frequency regulation (SFR). However, currently, there is a lack of system design and real-time control methods for photovoltaic-alkaline electrolysis hydrogen production systems to participate in secondary frequency regulation, primarily due to the following issues:

[0003] Existing controllers for alkaline electrolytic hydrogen production systems are primarily current-closed-loop controllers. This is because the hydrogen production rate of the electrolysis system is directly related to the electrolysis current. However, this cannot meet the requirements for rapid power signal tracking in secondary frequency regulation. The nonlinear voltage-current curve of the alkaline fuel cell stack presents challenges for controller design. Regarding response speed, due to the presence of double-layer capacitance in the electrolysis system, the response speed of the superimposed voltage slows down when the current controller setpoint changes, resulting in a slower power response of the electrolysis system. The double-layer effect is formed by charge accumulation in the electrodes and electrolyte. In terms of response accuracy, due to significant fluctuations in temperature, pressure, and superimposed voltage during variable load operation, a current controller alone cannot accurately control the power of the electrolysis system.

[0004] In photovoltaic-alkaline electrolytic hydrogen production systems, photovoltaic modules convert solar energy into direct current (DC) energy through the photoelectric effect. This DC voltage is often mismatched with the DC bus voltage of the microgrid and the operating voltage of the alkaline electrolytic hydrogen production system, necessitating a DC / DC converter for voltage conversion and power control of the photovoltaic-alkaline DC hydrogen production system. Existing photovoltaic control primarily relies on MPPT controllers, mainly employing a voltage-current dual closed-loop method to track the maximum power point. For photovoltaic systems to participate in secondary frequency regulation, they need to flexibly and rapidly change their output power based on external commands. The strong nonlinearity and sensitivity to illumination conditions of photovoltaic systems also pose challenges to controller design. Summary of the Invention

[0005] This application provides a control method and computer device for secondary frequency regulation based on a photovoltaic hydrogen production system. The method determines the target power for secondary frequency regulation based on the secondary frequency regulation command signal and the maximum frequency regulation bid capacity. The method determines a first reference power and a second reference power based on the target power for secondary frequency regulation, the maximum power point of the photovoltaic power generation unit, and the rated power point of the alkaline electrolysis hydrogen production unit, so as to perform secondary frequency regulation based on the photovoltaic hydrogen production system.

[0006] In a first aspect, a control method for secondary frequency regulation based on a photovoltaic hydrogen production system is provided. The photovoltaic hydrogen production system includes a photovoltaic power generation unit equipped with a first controller and an alkaline electrolysis hydrogen production unit equipped with a second controller. The photovoltaic power generation unit is connected to the power grid via a DC / DC converter and a first rectifier, and the alkaline electrolysis hydrogen production unit is connected to the power grid via a second rectifier. The control method includes: operating the photovoltaic power generation unit at its maximum power point based on the first controller, and operating the alkaline electrolysis hydrogen production unit at its rated power point based on the second controller; in response to receiving a secondary frequency regulation command signal, determining a secondary frequency regulation target power based on the secondary frequency regulation command signal and a maximum frequency regulation bid capacity, wherein the maximum frequency regulation bid capacity is less than the smaller of the maximum power point and the rated power point; determining a first reference power corresponding to the photovoltaic power generation unit and a second reference power corresponding to the alkaline electrolysis hydrogen production unit based on the secondary frequency regulation target power, the maximum power point, and the rated power point; controlling the photovoltaic power generation unit based on the first reference power based on the first controller, and controlling the alkaline electrolysis hydrogen production unit based on the second controller based on the second reference power.

[0007] In a second aspect, a computer device is provided, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the control method for secondary frequency modulation based on a photovoltaic hydrogen production system as described in the first aspect.

[0008] By applying the above technical solutions, the photovoltaic power generation unit operates at its maximum power point based on the first controller, and the alkaline electrolysis hydrogen production unit operates at its rated power point based on the second controller. In response to receiving a secondary frequency regulation command signal, the target power for secondary frequency regulation is determined based on the secondary frequency regulation command signal and the maximum frequency regulation bid capacity, where the maximum frequency regulation bid capacity is less than the smaller of the maximum power point and the rated power point. Based on the target power, the maximum power point, and the rated power point, a first reference power corresponding to the photovoltaic power generation unit and a second reference power corresponding to the alkaline electrolysis hydrogen production unit are determined. The photovoltaic power generation unit is controlled based on the first reference power by the first controller, and the alkaline electrolysis hydrogen production unit is controlled based on the second reference power by the second controller. This photovoltaic hydrogen production system achieves efficient and stable secondary frequency regulation, improving grid frequency stability while obtaining frequency regulation benefits, reducing photovoltaic hydrogen production costs, and improving system efficiency. Attached Figure Description

[0009] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 This is a flowchart of a control method for secondary frequency modulation based on a photovoltaic hydrogen production system, as described in an embodiment of this application.

[0011] Figure 2 This is a flowchart of a control method for secondary frequency modulation based on a photovoltaic hydrogen production system according to another embodiment of this application;

[0012] Figure 3 This is a schematic diagram of the photovoltaic hydrogen production system according to an embodiment of this application;

[0013] Figure 4 This is a schematic diagram of the structure of the first controller according to an embodiment of this application;

[0014] Figure 5 This is a schematic diagram of the DC-DC converter interface model of the photovoltaic power generation unit in an embodiment of this application;

[0015] Figure 6 This is an equivalent circuit diagram of the photovoltaic power generation unit in an embodiment of this application;

[0016] Figure 7 This is a schematic diagram of the structure of the second controller according to an embodiment of this application;

[0017] Figure 8 This is a structural block diagram of a computer device according to an embodiment of this application. Detailed Implementation

[0018] Various embodiments and features of this application are described herein with reference to the accompanying drawings.

[0019] It should be understood that various modifications can be made to the embodiments described herein. Therefore, the above description should not be considered as limiting, but merely as an example of embodiments. Other modifications within the scope and spirit of this application will be apparent to those skilled in the art.

[0020] The accompanying drawings, which are included in and form part of this specification, illustrate embodiments of the present application and, together with the general description of the present application given above and the detailed description of the embodiments given below, serve to explain the principles of the present application.

[0021] These and other features of this application will become apparent from the following description of preferred forms of embodiments given as non-limiting examples, with reference to the accompanying drawings.

[0022] It should also be understood that although this application has been described with reference to some specific examples, those skilled in the art can certainly implement many other equivalent forms of this application.

[0023] The above and other aspects, features and advantages of this application will become more apparent when taken in conjunction with the accompanying drawings and in view of the following detailed description.

[0024] Specific embodiments of this application are described thereafter with reference to the accompanying drawings; however, it should be understood that the claimed embodiments are merely examples of this application, which can be implemented in various ways. Well-known and / or repeated functions and structures are not described in detail to avoid unnecessary or redundant details that could obscure the application. Therefore, the specific structural and functional details claimed herein are not intended to be limiting, but merely serve as the basis and representative basis for the claims to teach those skilled in the art to use this application in a variety of substantially any suitable detailed structures.

[0025] This specification may use the phrases “in one embodiment,” “in another embodiment,” “in yet another embodiment,” or “in other embodiments,” all of which may refer to one or more of the same or different embodiments according to this application.

[0026] This application discloses a control method for secondary frequency regulation based on a photovoltaic hydrogen production system. The method determines the target power for secondary frequency regulation based on the secondary frequency regulation command signal and the maximum frequency regulation bid capacity. It then determines a first reference power and a second reference power based on the target power, the maximum power point of the photovoltaic power generation unit, and the rated power point of the alkaline electrolysis hydrogen production unit. A first controller controls the photovoltaic power generation unit based on the first reference power, and a second controller controls the alkaline electrolysis hydrogen production unit based on the second reference power. This method enables efficient and stable secondary frequency regulation based on the photovoltaic hydrogen production system, improving grid frequency stability while generating frequency regulation revenue, reducing photovoltaic hydrogen production costs, and increasing system efficiency.

[0027] like Figure 3 As shown, the photovoltaic hydrogen production system includes a photovoltaic power generation unit equipped with a first controller and an alkaline electrolysis hydrogen production unit equipped with a second controller. The photovoltaic power generation unit is connected to the power grid via a DC / DC converter and a first rectifier, and the alkaline electrolysis hydrogen production unit is connected to the power grid via a second rectifier. Figure 1 As shown, the control method includes the following steps:

[0028] Step S101: Based on the first controller, the photovoltaic power generation unit is operated at the maximum power point, and based on the second controller, the alkaline electrolysis hydrogen production unit is operated at the rated power point.

[0029] In this embodiment, before performing secondary frequency regulation, the photovoltaic power generation unit and the alkaline electrolysis hydrogen production unit are initialized. The photovoltaic power generation unit is made to operate at the maximum power point based on the first controller, and the alkaline electrolysis hydrogen production unit is made to operate at the rated power point based on the second controller. Subsequently, the photovoltaic hydrogen production system participates in secondary frequency regulation based on the maximum power point and the rated power point.

[0030] Step S102: In response to obtaining the secondary frequency modulation command signal, determine the secondary frequency modulation target power based on the secondary frequency modulation command signal and the maximum frequency modulation bid capacity, wherein the maximum frequency modulation bid capacity is less than the smaller value between the maximum power point and the rated power point.

[0031] In this embodiment, the secondary frequency modulation command signal can be an automatic generation control signal (i.e., an AGC signal) or a secondary frequency modulation command signal issued by the user. The maximum frequency modulation bid capacity is less than the smaller of the maximum power point and the rated power point. Specifically, if the maximum power point is... Rated power point is The maximum frequency modulation bidding capacity is C bid ,but After obtaining the secondary frequency modulation command signal, the target power for secondary frequency modulation is determined based on the secondary frequency modulation command signal and the maximum frequency modulation bid capacity.

[0032] Step S103: Based on the secondary frequency modulation target power, the maximum power point, and the rated power point, determine the first reference power corresponding to the photovoltaic power generation unit and the second reference power corresponding to the alkaline electrolysis hydrogen production unit.

[0033] After determining the target power for secondary frequency regulation, the first reference power and the second reference power are determined based on the target power, the maximum power point, and the rated power point. Subsequently, the photovoltaic power generation unit and the alkaline electrolysis hydrogen production unit are controlled with the first reference power and the second reference power as targets.

[0034] Step S104: Based on the first controller, control the photovoltaic power generation unit according to the first reference power, and based on the second controller, control the alkaline electrolysis hydrogen production unit according to the second reference power.

[0035] In this embodiment, the output voltage of the photovoltaic power generation unit is controlled by the first controller according to the first reference power, and the operating current of the alkaline electrolysis hydrogen production unit is controlled by the second controller according to the second reference power, thereby achieving participation in secondary frequency regulation.

[0036] This application's embodiment of the control method for secondary frequency regulation based on a photovoltaic hydrogen production system involves using a first controller to operate the photovoltaic power generation unit at its maximum power point and a second controller to operate the alkaline electrolysis hydrogen production unit at its rated power point. In response to receiving a secondary frequency regulation command signal, a target power for secondary frequency regulation is determined based on the command signal and the maximum frequency regulation bid capacity, where the maximum bid capacity is less than the smaller of the maximum power point and the rated power point. Based on the target power, the maximum power point, and the rated power point, a first reference power corresponding to the photovoltaic power generation unit and a second reference power corresponding to the alkaline electrolysis hydrogen production unit are determined. The first controller controls the photovoltaic power generation unit according to the first reference power, and the second controller controls the alkaline electrolysis hydrogen production unit according to the second reference power. This method achieves efficient and stable secondary frequency regulation based on the photovoltaic hydrogen production system, improving grid frequency stability while obtaining frequency regulation benefits, reducing photovoltaic hydrogen production costs, and increasing system efficiency.

[0037] In some embodiments of this application, a first reference power corresponding to the photovoltaic power generation unit and a second reference power corresponding to the alkaline electrolysis hydrogen production unit are determined based on the secondary frequency modulation target power, the maximum power point, and the rated power point, such as... Figure 2 As shown, it includes the following steps:

[0038] Step S1031: If the secondary frequency modulation target power is greater than zero, the maximum power point is determined as the first reference power, and the difference between the rated power point and the secondary frequency modulation target power is determined as the second reference power.

[0039] In this embodiment, if the target power of the secondary frequency regulation is greater than zero, it means that power needs to be output to the grid. At this time, the maximum power point is determined as the first reference power, so that the photovoltaic power generation unit is maintained at the maximum power point and outputs power to the grid to the maximum extent. At the same time, the difference between the rated power point and the target power of the secondary frequency regulation is determined as the second reference power, reducing the power absorbed by the alkaline electrolysis hydrogen production unit, thereby achieving accurate response to the secondary frequency regulation command signal.

[0040] Step S1032: If the secondary frequency modulation target power is not greater than zero, the sum of the maximum power point and the secondary frequency modulation target power is determined as the first reference power, and the rated power point is determined as the second reference power.

[0041] In this embodiment, if the target power of the secondary frequency regulation is not greater than zero, it means that the power output from the grid needs to be consumed. At this time, the sum of the maximum power point and the target power of the secondary frequency regulation is determined as the first reference power to reduce the power output from the photovoltaic power generation unit to the grid. At the same time, the rated power point is determined as the second reference power to keep the alkaline electrolysis hydrogen production unit at the rated power point, so as to absorb the power output from the grid to the maximum extent and thus achieve accurate response to the secondary frequency regulation command signal.

[0042] For example, if the maximum power point is Rated power point is Use P AGC To represent the target power of secondary frequency modulation, use The second reference power is represented by... Let the first reference power be, then,

[0043] If P AGC >0, then

[0044] If P AGC ≤0, then,

[0045] Alternatively, besides determining the difference between the rated power point and the secondary frequency modulation target power as the second reference power, or determining the sum of the maximum power point and the secondary frequency modulation target power as the first reference power, another alternative is to determine a target power value associated with the secondary frequency modulation target power. For example, the target power value could be 95% or 105% of the secondary frequency modulation target power. If the secondary frequency modulation target power is greater than zero, the maximum power point is determined as the first reference power, and the difference between the rated power point and the target power value is determined as the second reference power. Conversely, if the secondary frequency modulation target power is not greater than zero, the sum of the maximum power point and the target power value is determined as the first reference power, and the rated power point is determined as the second reference power. This increases the adjustment margin and allows for more flexible secondary frequency modulation.

[0046] In some embodiments of this application, the value range of the secondary frequency modulation command signal is [-1, 1]. Determining the secondary frequency modulation target power based on the secondary frequency modulation command signal and the maximum frequency modulation bid capacity includes:

[0047] The secondary frequency modulation target power is determined by multiplying the secondary frequency modulation command signal and the maximum frequency modulation bid capacity.

[0048] In this embodiment, the value range of the secondary frequency modulation command signal is [-1, 1]. The secondary frequency modulation target power is determined based on the product of the secondary frequency modulation command signal and the maximum frequency modulation bid capacity. Specifically, if r t If r represents the secondary frequency modulation command signal, then t ∈[-1,1],PAGC =r t C bid This ensures that the target power for secondary frequency modulation is within a suitable range, thereby improving the accuracy of secondary frequency modulation.

[0049] In some embodiments of this application, the first controller includes:

[0050] A power-to-voltage module is used to convert the first reference power into a reference voltage based on the mapping relationship between the output power and output voltage of the photovoltaic power generation unit.

[0051] The voltage closed-loop control module is used to perform closed-loop control on the output voltage of the photovoltaic power generation unit based on the first reference voltage using a voltage closed-loop circuit.

[0052] In this embodiment, after the first controller obtains the first reference power, it converts the first reference power into a reference voltage through a power-to-voltage conversion module based on the mapping relationship between the output power and output voltage of the photovoltaic power generation unit. Then, the power-to-voltage conversion module outputs the reference voltage to the voltage closed-loop control module. The voltage closed-loop control module uses the voltage closed-loop circuit to perform closed-loop control on the output voltage of the photovoltaic power generation unit according to the first reference voltage, so that the output voltage reaches the first reference voltage, thereby achieving a voltage that matches the output of the photovoltaic power generation unit with the first reference power and improving the accuracy of secondary frequency regulation.

[0053] In some embodiments of this application, the transfer function corresponding to the voltage closed-loop circuit includes a photovoltaic proportional-integral transfer function, a photovoltaic pulse width modulation transfer function, and a photovoltaic output voltage transfer function with respect to the duty cycle, connected in sequence.

[0054] The photovoltaic proportional-integral transfer function is expressed as:

[0055] The photovoltaic pulse width modulation transfer function is expressed as follows:

[0056] The transfer function of the photovoltaic output voltage with respect to the duty cycle is expressed as:

[0057]

[0058] Where, k p1 and k i1 These are the proportional and integral parameters of the proportional-integral controller, respectively, where s is the independent variable of the Laplace transform, and V... PWM It is a pulse width modulation voltage. The photovoltaic power generation unit uses a 4-channel interleaved parallel DC-DC converter for power output. L is the inductance in the DC-DC converter, C is the input-side capacitor in the DC-DC converter, R is the load resistance of the photovoltaic power generation unit, and I...L Let L be the current, D be the duty cycle of the photovoltaic power generation unit during operation, and U be the current. PV The output voltage of the photovoltaic power generation unit located on the input side of the DC converter is denoted as .

[0059] In this embodiment, as Figure 4 The diagram shown is a structural schematic of the first controller according to an embodiment of this application. Figure 4 In this process, based on the mapping relationship f between the output power and output voltage of the photovoltaic power generation unit, the first reference power is... Convert to reference voltage Then the reference voltage Input photovoltaic proportional-integral transfer function G PI (s), and then the photovoltaic proportional-integral transfer function G PI The output of (s) is input to the photovoltaic pulse width modulation transfer function G. pwm (s) will be the photovoltaic pulse width modulation transfer function G pwm (s) After limiting the duty cycle d(s) of the output result to between 0 and 1, the transfer function G of the input photovoltaic output voltage with respect to the duty cycle is... ud (s), obtain the output voltage U of the photovoltaic power generation unit. PV Then output voltage U PV Returning to the photovoltaic proportional-integral transfer function G PI The input terminal of (s) is connected to the reference voltage. Comparison, forming a comparison with the output voltage U PV The closed-loop control improves the accuracy of the output voltage of the photovoltaic power generation unit.

[0060] The photovoltaic power generation unit uses four interleaved parallel DC-DC converters for power output, such as... Figure 5 The diagram shown is a schematic of the DC-DC converter interface model of a photovoltaic power generation unit according to an embodiment of this application. In this embodiment, the transfer function of the DC-DC converter is derived using the state-space averaging method, which approximates the transfer function by averaging the inductor current and capacitor voltage over one switching cycle. ud (s) is also the frequency domain dynamic model of the DC-DC converter, As a frequency domain variation of the input voltage, As a frequency domain change quantity representing the duty cycle, then:

[0061]

[0062] In some embodiments of this application, the output power of the photovoltaic power generation unit is expressed as: P = I PV U PV ;

[0063] I PVIt is the output current of the photovoltaic power generation unit, wherein,

[0064]

[0065] I sc U is the short-circuit current of the photovoltaic power generation unit. oc U is the open-circuit voltage of the photovoltaic power generation unit. m S is the maximum power point voltage of the photovoltaic power generation unit. pv T represents light intensity. ref The reference temperature is used during photovoltaic cell testing, and ΔT is the difference between the actual temperature and the reference temperature.

[0066] S ref ΔS serves as the reference light intensity for photovoltaic cell testing. pv Let be the difference between the actual light intensity and the reference light intensity, where a, b, and c are the current temperature coefficient, voltage light intensity coefficient, and voltage temperature coefficient, respectively, and e is a constant.

[0067] In this embodiment, the equivalent circuit of the photovoltaic power generation unit generally adopts a single diode equivalent circuit, such as... Figure 6 As shown. Figure 6 middle,

[0068]

[0069] I PV It is the output current of the photovoltaic cell, I ph It is photocurrent, I d It is the current flowing through the diode, I sh It flows through the internal parallel resistor R sh The current, I0 is the saturation current of the diode, U PV It is the output voltage of the photovoltaic cell, K is the Boltzmann constant, and R is the output voltage of the photovoltaic cell. s This is the equivalent series resistance, T is the absolute temperature, A is the ideality factor of the PN junction (2.8 when the absolute temperature is 300 K), and q is the electron charge (1.6 × 10⁻¹⁹ C). In practical applications, theoretical models are affected by manufacturing processes and environmental conditions, making analysis difficult. Therefore, simplifications are needed, based on the open-circuit voltage U provided by the photovoltaic module manufacturer. oc Short-circuit current I sc Maximum power point voltage U m Maximum power point current I m By performing mathematical fitting, we obtain:

[0070]

[0071] The output current I of the photovoltaic power generation unit is determined using a simplified model.PV This reduces the amount of computation, thus enabling a more efficient determination of the mapping relationship f between the output power and output voltage of the photovoltaic power generation unit based on the formula for the output power of the photovoltaic power generation unit.

[0072] In some embodiments of this application, the second controller includes:

[0073] A power-to-current module is used to convert the second reference power into a reference current based on a power-to-current transfer function.

[0074] A current closed-loop control module is used to perform closed-loop control of the operating current of the alkaline electrolysis hydrogen production unit based on the reference current using a current closed-loop circuit.

[0075] In this embodiment, after receiving the second reference power, the second controller uses a power-to-current module to convert the second reference power into a reference current based on the power-to-current transfer function. Then, the power-to-current module outputs the reference current to the current closed-loop control module. The current closed-loop circuit performs closed-loop control on the operating current of the alkaline electrolysis hydrogen production unit according to the reference current, so that the operating current reaches the reference current. This achieves the matching of the current of the alkaline electrolysis hydrogen production unit with the second reference power, improving the accuracy of the secondary frequency modulation.

[0076] In some embodiments of this application, the power-to-current transfer function is expressed as:

[0077]

[0078] Among them, I o R represents the current at the linearization point of the alkaline electrolysis hydrogen production unit. act Representative in I o The linearization resistance at point R ohm U represents the equivalent resistance under overvoltage conditions in the alkaline electrolysis hydrogen production unit. rev For reversible voltage, C dl This represents the double-layer effect of the electrodes, where s is the independent variable of the Laplace transform.

[0079] In this embodiment, the port voltage U of the alkaline electrolysis hydrogen production unit is... o Mainly composed of reversible voltage U rev Activation overvoltage U act and ohmic overvoltage U ohm It consists of three parts, namely U o =U rev +U act +U ohm In alkaline electrolysis (AEL) systems, the overvoltage caused by reactant diffusion is negligible due to the low current density.

[0080] Reversible voltage Urev This refers to the process of converting electrical energy into chemical energy in a product gas. Under stable conditions of temperature, pressure, and electrolyte flow rate, U rev It is fixed. Activation overvoltage U act This refers to the voltage lost when a chemical reaction overcomes the activation energy barrier. U act and stack current I o This nonlinear relationship can be described by the improved Tafel equation, where a and b are constants R. act Representative in I o Linearization resistance at:

[0081]

[0082] Ohmic overvoltage U ohm This represents the overvoltage caused by current flowing through the stack and wires, where R ohm Represents equivalent resistance:

[0083] U ohm =I o R ohm .

[0084] The double-layer effect of the counter electrode is represented by C dl It represents the dynamic process of charge accumulation at the electrode-electrolyte interface. The stack voltage U... o This cannot be changed immediately, which would result in a slow dynamic response of the fuel cell power.

[0085] like Figure 7 The diagram shown is a structural schematic of the second controller according to an embodiment of this application. Figure 7 As shown, It is the reference current. It is the second reference power, G PI,2 (s) is the transfer function of the proportional-integral controller in the alkaline electrolysis hydrogen production unit, α is the thyristor conduction angle, and G iα (s) is the dynamic model of the transfer function of the alkaline electrolysis hydrogen production unit.

[0086] The second controller receives the second reference power. Then, based on the power-to-current transfer function G... pi (s) will use the second reference power Convert to reference current Then the reference current The transfer function G of the proportional-integral controller of the alkaline electrolysis hydrogen production unit is passed sequentially. PI,2 (s), the dynamic model of the transfer function G of the thyristor rectifier circuit (thyristor conduction angle α) and the alkaline electrolysis hydrogen production unit. iα After (s), the operating current I of the alkaline electrolysis hydrogen production unit is obtained. oThen change the operating current I o Returning to the transfer function G of the proportional-integral controller of the alkaline electrolysis hydrogen production unit PI,2 The input terminal of (s) is connected to the reference current. Comparison, forming a comparison with the operating current I o The closed-loop control improves the accuracy of the operating current of the alkaline electrolysis hydrogen production unit.

[0087] It should be noted that the power-to-current transfer function G pi I in (s) o The current at the linearization point of the alkaline electrolysis hydrogen production unit can be selected for design based on the rated current, and it differs from... Figure 7 The operating current I shown o as well as Figure 6 Diode saturation current I o .

[0088] In some embodiments of this application, the simplified form of the power-to-current transfer function is expressed as follows:

[0089] G pi (s)≈2(R act +R ohm )I o +U rev .

[0090] In this embodiment, G pi (s) has one zero and one pole. The frequency difference between the zero p and the pole z is:

[0091]

[0092] Due to U rev Much larger than U ohm and U act And C dl The frequency difference is typically very large (on the order of farads), so it is almost zero. Therefore, it approximates a proportional element, resulting in:

[0093] G pi (s)≈2(R act +R ohm )I o +U rev .

[0094] Because the power-to-current transfer function has been simplified, the second reference power can be converted into a reference current based on a proportional controller, thereby achieving a more efficient acquisition of the reference current.

[0095] To further illustrate the technical concept of this application, the technical solution will now be explained in conjunction with specific application scenarios.

[0096] This application provides a control method for secondary frequency regulation based on a photovoltaic hydrogen production system. The photovoltaic hydrogen production system includes a photovoltaic power generation unit equipped with a first controller and an alkaline electrolysis hydrogen production unit equipped with a second controller. The photovoltaic power generation unit is connected to the power grid via a DC / DC converter and a first rectifier, and the alkaline electrolysis hydrogen production unit is connected to the power grid via a second rectifier. The method includes the following processes:

[0097] Initialization: The first controller enables the photovoltaic power generation unit to operate at its maximum power point. The second controller enables the alkaline electrolysis hydrogen production unit to operate at its rated power point. Determine the maximum frequency modulation bidding capacity

[0098] Step S1, Receive AGC signal r t ∈[-1,1].

[0099] Step S2, calculate the secondary frequency modulation target power P AGC =r t C bid Perform step S3 or step S4.

[0100] Step S3, if P AGC >0 then

[0101] Step S4, if P AGC ≤0, then

[0102] Step S5, End.

[0103] Step S6: Return to step S1 to wait for the next AGC signal.

[0104] This application also provides a computer device, such as... Figure 8 As shown, it includes a processor and a memory, wherein the memory stores an executable program, and the processor executes the executable program to perform a control method for secondary frequency modulation based on a photovoltaic hydrogen production system as described in the various embodiments of this application.

[0105] The computer device in this application embodiment can be a terminal or other devices besides a terminal. For example, the computer device can be a mobile phone, tablet computer, laptop computer, handheld computer, in-vehicle electronic device, mobile internet device (MID), augmented reality (AR) / virtual reality (VR) device, robot, wearable device, ultra-mobile personal computer (UMPC), netbook, or personal digital assistant (PDA), etc. It can also be a server, network attached storage (NAS), personal computer (PC), television (TV), ATM, or self-service machine, etc. The embodiments disclosed in this disclosure do not impose specific limitations.

[0106] The memory may include RAM (Random Access Memory) or non-volatile memory, such as at least one disk storage device. Optionally, the memory may also be at least one storage device located remotely from the aforementioned processor.

[0107] The processors mentioned above can be general-purpose processors, including CPUs, NPs (Network Processors), etc.; they can also be DSPs (Digital Signal Processors), ASICs (Application Specific Integrated Circuits), FPGAs (Field Programmable Gate Arrays), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0108] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state drive), etc.

[0109] The above embodiments are merely exemplary embodiments of this application and are not intended to limit this application. The scope of protection of this application is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to this application within its substance and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of this application.

Claims

1. A control method for secondary frequency regulation based on a photovoltaic hydrogen production system, characterized in that, The photovoltaic hydrogen production system includes a photovoltaic power generation unit equipped with a first controller and an alkaline electrolysis hydrogen production unit equipped with a second controller. The photovoltaic power generation unit is connected to the power grid via a DC / DC converter and a first rectifier, and the alkaline electrolysis hydrogen production unit is connected to the power grid via a second rectifier. The control method includes: The photovoltaic power generation unit is operated at its maximum power point based on the first controller, and the alkaline electrolysis hydrogen production unit is operated at its rated power point based on the second controller. In response to receiving a secondary frequency modulation command signal, the secondary frequency modulation target power is determined based on the secondary frequency modulation command signal and the maximum frequency modulation bid capacity, wherein the maximum frequency modulation bid capacity is less than the smaller of the maximum power point and the rated power point; Based on the secondary frequency modulation target power, the maximum power point, and the rated power point, determine the first reference power corresponding to the photovoltaic power generation unit and the second reference power corresponding to the alkaline electrolysis hydrogen production unit; The photovoltaic power generation unit is controlled by the first controller according to the first reference power, and the alkaline electrolysis hydrogen production unit is controlled by the second controller according to the second reference power.

2. The control method for secondary frequency regulation based on a photovoltaic hydrogen production system as described in claim 1, characterized in that, Based on the secondary frequency modulation target power, the maximum power point, and the rated power point, determine the first reference power corresponding to the photovoltaic power generation unit and the second reference power corresponding to the alkaline electrolysis hydrogen production unit, including: If the secondary frequency modulation target power is greater than zero, the maximum power point is determined as the first reference power, and the difference between the rated power point and the secondary frequency modulation target power is determined as the second reference power. If the secondary frequency modulation target power is not greater than zero, the sum of the maximum power point and the secondary frequency modulation target power is determined as the first reference power, and the rated power point is determined as the second reference power.

3. The control method for secondary frequency regulation based on a photovoltaic hydrogen production system as described in claim 1, characterized in that, The value range of the secondary frequency modulation command signal is [-1, 1]. Determining the secondary frequency modulation target power based on the secondary frequency modulation command signal and the maximum frequency modulation bid capacity includes: The secondary frequency modulation target power is determined by multiplying the secondary frequency modulation command signal and the maximum frequency modulation bid capacity.

4. The control method for secondary frequency regulation based on a photovoltaic hydrogen production system as described in claim 1, characterized in that, The first controller includes: A power-to-voltage module is used to convert the first reference power into a reference voltage based on the mapping relationship between the output power and output voltage of the photovoltaic power generation unit. The voltage closed-loop control module is used to perform closed-loop control on the output voltage of the photovoltaic power generation unit based on the first reference voltage using a voltage closed-loop circuit.

5. The control method for secondary frequency regulation based on a photovoltaic hydrogen production system as described in claim 4, characterized in that, The transfer function corresponding to the voltage closed-loop circuit includes, in sequence, the photovoltaic proportional-integral transfer function, the photovoltaic pulse width modulation transfer function, and the photovoltaic output voltage transfer function with respect to the duty cycle. The photovoltaic proportional-integral transfer function is expressed as: The photovoltaic pulse width modulation transfer function is expressed as follows: The transfer function of the photovoltaic output voltage with respect to the duty cycle is expressed as: Where, k p1 and k i1 These are the proportional and integral parameters of the proportional-integral controller, respectively, where s is the independent variable of the Laplace transform, and V... PWM It is a pulse width modulation voltage. The photovoltaic power generation unit uses a 4-channel interleaved parallel DC-DC converter for power output. L is the inductance in the DC-DC converter, C is the input-side capacitor in the DC-DC converter, R is the load resistance of the photovoltaic power generation unit, and I... L Let L be the current, D be the duty cycle of the photovoltaic power generation unit during operation, and U be the current. PV The output voltage of the photovoltaic power generation unit located on the input side of the DC converter is denoted as .

6. The control method for secondary frequency regulation based on a photovoltaic hydrogen production system as described in claim 4, characterized in that, The output power of the photovoltaic power generation unit is expressed as: P = I PV U PV ; I PV It is the output current of the photovoltaic power generation unit, wherein, I sc U is the short-circuit current of the photovoltaic power generation unit. oc U is the open-circuit voltage of the photovoltaic power generation unit. m S is the maximum power point voltage of the photovoltaic power generation unit. pv T represents light intensity. ref The reference temperature for photovoltaic cell testing is ΔT, where ΔT is the difference between the actual temperature and the reference temperature, and S is the reference temperature. ref ΔS serves as the reference light intensity for photovoltaic cell testing. pv Let be the difference between the actual light intensity and the reference light intensity, where a, b, and c are the current temperature coefficient, voltage light intensity coefficient, and voltage temperature coefficient, respectively, and e is a constant.

7. The control method for secondary frequency regulation based on a photovoltaic hydrogen production system as described in claim 1, characterized in that, The second controller includes: A power-to-current module is used to convert the second reference power into a reference current based on a power-to-current transfer function. A current closed-loop control module is used to perform closed-loop control of the operating current of the alkaline electrolysis hydrogen production unit based on the reference current using a current closed-loop circuit.

8. The control method for secondary frequency regulation based on a photovoltaic hydrogen production system as described in claim 7, characterized in that, The power-to-current transfer function is expressed as: Among them, I o R represents the current at the linearization point of the alkaline electrolysis hydrogen production unit. act Representative in I o The linearization resistance at point R ohm U represents the equivalent resistance under overvoltage conditions in the alkaline electrolysis hydrogen production unit. rev For reversible voltage, C dl This represents the double-layer effect of the electrodes, where s is the independent variable of the Laplace transform.

9. The control method for secondary frequency regulation based on a photovoltaic hydrogen production system as described in claim 8, characterized in that, The simplified form of the power-to-current transfer function is expressed as: Gpi(s)≈2(Ract+Rohm)Io+Urev.

10. A computer device comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the control method for secondary frequency modulation based on a photovoltaic hydrogen production system as described in any one of claims 1-9.

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