A direct-current bus voltage construction method of a wind power island hydrogen production system based on energy storage units

Abstract

The application discloses a direct-current bus voltage construction method of a wind power island hydrogen production system based on an energy storage unit, and comprises the following steps: distributed optimization control of the energy storage unit is adopted to minimize voltage and power deviation; a dynamic adjustment of droop coefficients is performed to respond to voltage changes through adaptive droop control; output power, charging and discharging current and state of charge change rate of the energy storage unit are monitored in real time and constraints are applied; and state information is exchanged between the energy storage units through a communication system to dynamically adjust reference power. The application can effectively construct and maintain the stability of the direct-current bus voltage, enhance the adaptability of the system to wind energy fluctuation, improve energy utilization efficiency, and guarantee safe operation of the hydrogen production system.

Description

Technical Field

[0001] This invention belongs to the field of voltage construction technology, and particularly relates to a method for constructing the DC bus voltage of a wind power island hydrogen production system based on an energy storage unit. Background Technology

[0002] Hydrogen energy is an important component of the national energy system. The medium- and long-term development plan for the hydrogen energy industry, jointly formulated by the National Development and Reform Commission and the National Energy Administration, explicitly proposes to promote research and development of cutting-edge low-carbon technologies such as hydrogen production from renewable energy sources and strengthen demonstration applications. Currently, the total installed capacity of renewable energy sources exceeds half of the total installed capacity in China, making the production of hydrogen energy from renewable energy sources such as wind power of significant practical importance. However, in wind-powered DC islanded hydrogen production systems, due to the inherent volatility and intermittency of wind power, the system lacks the support of a large power grid, making it difficult to maintain stable DC bus voltage. This voltage instability manifests as frequent changes in the operating status of the hydrogen production system in actual operation, directly affecting hydrogen production efficiency and system reliability, and severely restricting the large-scale application of this technology.

[0003] In existing technologies, energy storage units, as key components for balancing loads and maintaining voltage stability, typically employ fixed control strategies. For example, traditional droop control adjusts the output power of the energy storage unit by setting a fixed droop coefficient. This method exhibits slow response and insufficient adjustment accuracy when wind power or hydrogen production loads change rapidly. Due to the randomness and suddenness of wind energy fluctuations and load changes, fixed control parameters cannot adapt to dynamic operating conditions, easily leading to continuous deviations of the DC bus voltage from its rated value, thereby triggering system protection actions or even shutdowns. Furthermore, the lack of an effective coordination mechanism among multiple energy storage units means that each unit often operates independently, making it difficult to achieve reasonable power distribution and coordinated voltage control, further reducing the overall stability of the system.

[0004] Meanwhile, the existing system's monitoring and protection mechanisms for the operating status of energy storage units are insufficient. If key parameters such as the output, current, and state of charge of the energy storage units are not monitored and effectively constrained in real time, an imbalance can easily occur during actual operation, where some units operate under overload while others are underutilized. This not only affects system efficiency but may also prematurely damage the energy storage equipment due to overcharging or over-discharging, shortening its lifespan. This problem is particularly prominent in islanded operation environments where maintenance is difficult and equipment reliability requirements are higher. Therefore, a comprehensive control strategy is urgently needed to effectively construct and stabilize the DC bus voltage and coordinate the efficient operation of multiple energy storage units under safe constraints, thereby improving the overall performance and application feasibility of wind power islanded hydrogen production systems. Summary of the Invention

[0005] To address the aforementioned technical issues, this invention proposes a method for constructing the DC bus voltage of a wind power islanded hydrogen production system based on energy storage units. This method monitors and constrains the output, current, and rate of change of state of charge of the energy storage units in real time, ensuring that the energy storage units operate within a safe range and improving the overall safety of the system.

[0006] To achieve the above objectives, this invention provides a method for constructing the DC bus voltage of a wind power islanded hydrogen production system based on an energy storage unit, comprising: Distributed optimization control is performed on multiple energy storage units in the system to minimize the DC bus voltage deviation and the energy storage unit output power deviation, and a reference power is generated for each energy storage unit. Based on the reference power, an adaptive droop control strategy is adopted for each energy storage unit. The droop coefficient is dynamically adjusted according to the deviation between the DC bus voltage and the reference voltage, and the output power of each energy storage unit is calculated. Establish and maintain DC bus voltage based on the output power of all energy storage units and hydrogen production load requirements; The status parameters of each energy storage unit are monitored in real time, and constraints are imposed on the status parameters to ensure that the energy storage unit operates within a safe range; The energy storage units exchange status information through a communication system, and the reference power of each energy storage unit is dynamically adjusted based on the status information.

[0007] Optionally, the distributed optimization control process includes: minimizing the deviation between the DC bus voltage and the reference voltage and the deviation between the output power of each energy storage unit and the reference power as the optimization objective, and minimizing the objective function by independently adjusting the reference power of each energy storage unit, wherein the weighting coefficient is used to adjust the contribution of each energy storage unit to the system stability.

[0008] Optionally, the adaptive droop control strategy includes the following steps: for each energy storage unit, the deviation between the DC bus voltage and the reference voltage is converted into an output power adjustment using a droop coefficient, wherein the droop coefficient is dynamically updated according to the voltage deviation using an adaptive parameter algorithm, and the updated droop coefficient is used to calculate the output power of the energy storage unit.

[0009] Optionally, the process of establishing and maintaining the DC bus voltage includes: determining the DC bus voltage value based on the balance between the total output power of all energy storage units and the hydrogen production load power and system loss power, wherein the DC bus voltage is jointly determined by the reference voltage and the deviation between the output power of the energy storage units and the reference power.

[0010] Optionally, the process of real-time monitoring of the state parameters of each energy storage unit includes: monitoring the output power, charge and discharge current and the rate of change of state of charge of each energy storage unit, and imposing minimum and maximum constraints on the output power, a safe range constraint on the charge and discharge current, and a rate of change limit on the rate of change of state of charge.

[0011] Optionally, the process of imposing constraints on the state parameters includes ensuring that the output power of each energy storage unit is between its minimum and maximum output power, the charge / discharge current is between its minimum and maximum current, and the rate of change of state of charge is between its minimum and maximum rate of change.

[0012] Optionally, the process of exchanging status information through the communication system includes: transmitting DC bus voltage, reference voltage, total load power and output power of each energy storage unit between energy storage units, and dynamically adjusting the reference power of each energy storage unit using a control algorithm based on the communication information.

[0013] Optionally, the process of dynamically adjusting the reference power based on state information includes: calculating the reference power of each energy storage unit through a control function based on the DC bus voltage, reference voltage, total load power, and output power of each energy storage unit, so as to achieve system power distribution and voltage stability.

[0014] Technical Effects of this Invention: This invention discloses a method for constructing the DC bus voltage of a wind power islanded hydrogen production system based on energy storage units. Through distributed optimization control and adaptive droop control strategies of the energy storage units, the DC bus voltage of the wind power islanded hydrogen production system is effectively constructed and stabilized. This method significantly improves the system's adaptability to wind energy fluctuations and enhances operational stability and reliability. By real-time monitoring and constraint of the energy storage unit's output, current, and rate of change of state of charge, the system ensures that the energy storage units operate within a safe range, improving the overall safety of the system. The communication and coordination mechanism between energy storage units further optimizes power distribution and improves energy utilization efficiency. This invention responds to the national policy requirements for promoting renewable energy hydrogen production and energy structure transformation, providing a highly efficient and stable solution for wind power DC islanded hydrogen production systems, and has significant application value. Attached Figure Description

[0015] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a topology diagram of the PEM hydrogen production system in a wind power DC islanded system according to an embodiment of the present invention; Figure 2 This is a flowchart illustrating a method for constructing the DC bus voltage of a wind power islanded hydrogen production system based on an energy storage unit, according to an embodiment of the present invention. Detailed Implementation

[0016] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0017] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0018] like Figures 1-2 As shown, this embodiment provides a method for constructing the DC bus voltage of a wind power islanded hydrogen production system based on an energy storage unit, including: Distributed optimization control is performed on multiple energy storage units in the system to minimize the DC bus voltage deviation and the energy storage unit output power deviation, and a reference power is generated for each energy storage unit. Based on the reference power, an adaptive droop control strategy is adopted for each energy storage unit. The droop coefficient is dynamically adjusted according to the deviation between the DC bus voltage and the reference voltage, and the output power of each energy storage unit is calculated. Establish and maintain DC bus voltage based on the output power of all energy storage units and hydrogen production load requirements; The status parameters of each energy storage unit are monitored in real time, and constraints are imposed on the status parameters to ensure that the energy storage unit operates within a safe range; The energy storage units exchange status information through a communication system, and the reference power of each energy storage unit is dynamically adjusted based on the status information.

[0019] Furthermore, the distributed optimization control process includes: minimizing the deviation between the DC bus voltage and the reference voltage, and the deviation between the output power of each energy storage unit and the reference power, as the optimization objective. The objective function is minimized by independently adjusting the reference power of each energy storage unit, where the weighting coefficient is used to adjust the contribution of each energy storage unit to the system stability.

[0020] Furthermore, the adaptive droop control strategy includes the following steps: for each energy storage unit, the deviation between the DC bus voltage and the reference voltage is converted into an output power adjustment using a droop coefficient. The droop coefficient is dynamically updated based on the voltage deviation using an adaptive parameter algorithm, and the updated droop coefficient is used to calculate the output power of the energy storage unit.

[0021] Furthermore, the process of establishing and maintaining the DC bus voltage includes: determining the DC bus voltage value based on the balance between the total output power of all energy storage units, the hydrogen production load power, and the system loss power, wherein the DC bus voltage is jointly determined by the reference voltage and the deviation between the output power of the energy storage units and the reference power.

[0022] Furthermore, the process of real-time monitoring of the state parameters of each energy storage unit includes: monitoring the output power, charge and discharge current and the rate of change of state of charge of each energy storage unit, and imposing minimum and maximum value constraints on the output power, safety range constraints on the charge and discharge current, and rate of change limits on the rate of change of state of charge.

[0023] Furthermore, the process of imposing constraints on the state parameters includes ensuring that the output power of each energy storage unit is between its minimum and maximum output power, the charging and discharging current is between its minimum and maximum current, and the rate of change of state of charge is between its minimum and maximum rate of change.

[0024] Furthermore, the process of exchanging status information through the communication system includes: transmitting DC bus voltage, reference voltage, total load power and output power of each energy storage unit between energy storage units, and dynamically adjusting the reference power of each energy storage unit using a control algorithm based on communication information.

[0025] Furthermore, the process of dynamically adjusting the reference power based on state information includes: calculating the reference power of each energy storage unit through a control function based on the DC bus voltage, reference voltage, total load power, and output power of each energy storage unit, so as to achieve system power distribution and voltage stability.

[0026] Specifically, the implementation process of this embodiment includes: In a wind power DC islanded system with n energy storage units, the establishment of the DC bus voltage can be achieved by coordinating the outputs of these energy storage units, specifically including: Distributed optimization control of energy storage units: To ensure DC bus voltage stability and make the energy storage unit's output as close to the ideal state as possible, the energy storage unit is optimized with the goal of minimizing voltage and output power deviations. The optimization objective function is as follows: ; Among them, w i It is a weighting coefficient that can be adjusted based on the contribution of the energy storage unit to the system stability. V bus It is the DC bus voltage. V ref It is the reference voltage of the DC bus. P refiIt is the reference power of the i-th energy storage unit. P outi It is the output power of the i-th energy storage unit.

[0027] The goal of this optimization problem is to find a reference power. P refi Make the above functions f Minimum, by independently adjusting the reference power of each energy storage unit. P refi This will optimize the operation of the entire system. Furthermore, this result will serve as the starting point for droop control.

[0028] Adaptive droop control strategy for energy storage units: The energy storage unit in the system is controlled using droop control, a commonly used method. Its core idea is to make the output power of the energy storage unit inversely proportional to its voltage. The process is as follows: Assume that each energy storage unit i has a droop control coefficient K pi And it can output power P outi Its relationship with bus voltage V bus The relationship can be represented as: ; Among them, K pi is the droop factor of the i-th energy storage unit, which reflects the degree of response to voltage deviation. Each energy storage unit adjusts its output power according to the deviation between the DC bus voltage and the preset expected value.

[0029] if V bus < V ref The energy storage unit will increase its output power to improve the bus voltage. If V bus > V ref The energy storage unit will reduce its output power to lower the bus voltage.

[0030] Regarding the droop coefficient K Pi An adaptive parameter algorithm is designed to dynamically adjust the droop coefficient based on changes in the DC bus voltage, enabling the system to more flexibly cope with different operating conditions and improve the overall performance and stability of the system.

[0031] ; Among them, the adjustment coefficient αThe sign of the adjustment coefficient determines the direction of the droop coefficient adjustment, which is related to the system design objectives and the specific voltage deviation. If the objective is to enhance the responsiveness of the energy storage unit to voltage changes and enable the system to recover voltage stability more quickly, a positive adjustment coefficient is selected. If it is necessary to reduce the sensitivity of the energy storage unit to voltage changes and reduce the fluctuation of output power, a negative adjustment coefficient is selected.

[0032] Update the control equations for droop control using the new droop coefficient: ; Evaluate the adjusted system response to ensure effective voltage deviation control and system stability. Continuously monitor the DC bus voltage and periodically apply an adaptive control parameter adjustment algorithm to update the droop coefficient.

[0033] When adjusting the droop coefficient, the boundary conditions need to be considered to ensure that K p_new Within a reasonable range, that is, satisfying: .

[0034] Establishment of DC bus voltage: DC bus voltage V bus The stability of the bus voltage is determined by the combined output power of all energy storage units and the hydrogen production load demand. This requires the output power of all energy storage units to remain consistent with the system's hydrogen production load and the desired voltage, as expressed in: .

[0035] Real-time monitoring and state constraints of energy storage unit status: During operation, the status of the energy storage units is monitored in real time, and the real-time status of the hydrogen production system is fed back to each energy storage unit in a timely manner through the communication system, so as to adjust the output of each energy storage unit in a timely manner and ensure the high efficiency of the system operation.

[0036] According to the law of conservation of energy, the total output power of the energy storage unit and the power consumed by the hydrogen production unit satisfy the following condition: ; in, P load This represents the power consumed by the hydrogen production unit in a wind-powered DC islanded hydrogen production system, as well as the total power of the wind power and auxiliary equipment of the hydrogen production unit. P loss Power representing system losses.

[0037] When the hydrogen production system consumes power P load When changes occur, the output power of the energy storage unit P outIt should be adjusted in a timely manner to ensure the stability of the system voltage.

[0038] During the adjustment process, the energy storage unit i outputs power. P outi Limited by maximum and minimum power, the following constraints must be met: ; The charging and discharging current R of energy storage unit i outi Its output power outi and bus voltage V bus It is related to the following formula: ; Energy storage unit i charging and discharging current R outi Limited by its safety range, it meets the following constraints: ; Using charging and discharging current I outi The rate of change of SOC of energy storage unit i can be calculated, i.e.: ; Among them, E cap This refers to the rated capacity of the energy storage unit.

[0039] The rate of change of SOC should be kept within a safe range, and its magnitude is constrained by its maximum and minimum values. .

[0040] Communication and coordination between energy storage units: Through the real-time communication system in the energy storage unit, each energy storage unit can effectively respond to changes in the operating status of the above system in order to maintain the stability and efficiency of the entire system.

[0041] Each energy storage unit exchanges the current DC bus voltage. V bus Bus voltage reference value V ref Total load power P load Output power of each energy storage unit P outi And state, using a control algorithm based on communication information, dynamically adjust its own reference power P refi This improves system stability. The control algorithm is shown below: ; in, mes For communication information.

[0042] This invention discloses a method for constructing the DC bus voltage of a wind power islanded hydrogen production system based on energy storage units. Through distributed optimization control and adaptive droop control strategies of the energy storage units, the DC bus voltage of the wind power islanded hydrogen production system is effectively constructed and stabilized. This method significantly improves the system's adaptability to wind energy fluctuations and enhances operational stability and reliability. By real-time monitoring and constraint of the energy storage unit's output, current, and rate of change of state of charge, the method ensures that the energy storage units operate within a safe range, improving the overall system safety. The communication and coordination mechanism between energy storage units further optimizes power distribution and improves energy utilization efficiency. This invention responds to the national policy requirements for promoting renewable energy hydrogen production and energy structure transformation, providing a highly efficient and stable solution for wind power DC islanded hydrogen production systems, and has significant application value.

[0043] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for constructing the DC bus voltage of a wind power islanded hydrogen production system based on energy storage units, characterized in that, include: Distributed optimization control is performed on multiple energy storage units in the system to minimize the weighted sum of DC bus voltage deviation and energy storage unit output power deviation, and a reference power is generated for each energy storage unit. The distributed optimization control process includes: minimizing the weighted sum of the deviation between the DC bus voltage and the reference voltage and the deviation between the output power of each energy storage unit and the reference power as the optimization objective; minimizing the objective function by independently adjusting the reference power of each energy storage unit; where the weighting coefficient is used to adjust the contribution of each energy storage unit to the system stability. Based on the reference power, an adaptive droop control strategy is adopted for each energy storage unit. The droop coefficient is dynamically adjusted according to the deviation between the DC bus voltage and the reference voltage, and the output power of each energy storage unit is calculated. Establish and maintain DC bus voltage based on the output power of all energy storage units and hydrogen production load requirements; The status parameters of each energy storage unit are monitored in real time, and constraints are imposed on the status parameters to ensure that the energy storage unit operates within a safe range; The energy storage units exchange status information through a communication system, and the reference power of each energy storage unit is dynamically adjusted based on the status information.

2. The method for constructing the DC bus voltage of a wind power islanded hydrogen production system based on energy storage units as described in claim 1, characterized in that, The adaptive droop control strategy involves the following steps: For each energy storage unit, the deviation between the DC bus voltage and the reference voltage is converted into an output power adjustment using a droop coefficient. The droop coefficient is dynamically updated based on the voltage deviation using an adaptive parameter algorithm, and the updated droop coefficient is used to calculate the output power of the energy storage unit.

3. The method for constructing the DC bus voltage of a wind power islanded hydrogen production system based on energy storage units as described in claim 1, characterized in that, The process of establishing and maintaining the DC bus voltage includes: determining the DC bus voltage value based on the balance between the total output power of all energy storage units, the hydrogen production load power, and the system loss power, wherein the DC bus voltage is jointly determined by the reference voltage and the deviation between the output power of the energy storage units and the reference power.

4. The method for constructing the DC bus voltage of a wind power islanded hydrogen production system based on energy storage units as described in claim 1, characterized in that, The process of real-time monitoring of the state parameters of each energy storage unit includes: monitoring the output power, charge and discharge current and the rate of change of state of charge of each energy storage unit, and imposing minimum and maximum constraints on the output power, safety range constraints on the charge and discharge current, and rate of change limits on the rate of change of state of charge.

5. The method for constructing the DC bus voltage of a wind power islanded hydrogen production system based on energy storage units as described in claim 1, characterized in that, The process of imposing constraints on the state parameters includes ensuring that the output power of each energy storage unit is between its minimum and maximum output power, the charge and discharge current is between its minimum and maximum current, and the rate of change of state of charge is between its minimum and maximum rate of change.

6. The method for constructing the DC bus voltage of a wind power islanded hydrogen production system based on energy storage units as described in claim 1, characterized in that, The process of exchanging status information through a communication system includes: transmitting DC bus voltage, reference voltage, total load power, and output power of each energy storage unit between energy storage units, and dynamically adjusting the reference power of each energy storage unit using a control algorithm based on the communication information.

7. The method for constructing the DC bus voltage of a wind power islanded hydrogen production system based on energy storage units as described in claim 1, characterized in that, The process of dynamically adjusting the reference power based on state information includes: calculating the reference power of each energy storage unit through a control function based on the DC bus voltage, reference voltage, total load power, and output power of each energy storage unit, so as to achieve system power distribution and voltage stability.

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