Wind power PEM hydrogen production island system black-start strategy optimization method

Abstract

The invention discloses a black-start strategy optimization method for a wind power PEM hydrogen production island system. The method comprises the steps that the connection state of a micro-grid system and a main power grid is detected to enter an island mode; detecting the SOC of the energy storage unit and judging whether the output power of the energy storage unit meets the power supply requirement of the auxiliary equipment, and if not, starting the fan unit to supply power to the energy storage unit; establishing and maintaining a direct-current bus voltage by adopting a direct-current voltage droop control strategy; recovering the power supply of the wind power unit and the PEM hydrogen production unit auxiliary unit; the starting sequence of the fan unit and the PEM hydrogen production unit is judged based on the optimized objective function, and all the units are started in sequence; starting the wind power unit and adjusting the output power according to the wind speed to match the system requirement; starting the PEM hydrogen production system and judging whether the temperature of the electrolytic bath reaches a hot standby condition or not, and if not, keeping standby; and after the system is recovered, key parameters are monitored and adjusted to maintain long-term stable operation. The adaptability and the energy utilization efficiency of the system in the island mode are improved.

Description

Technical Field

[0001] This invention belongs to the field of power technology, and in particular relates to an optimization method for black start strategy of wind power PEM hydrogen production islanding system. Background Technology

[0002] Hydrogen energy, as a widely available, green, and low-carbon secondary energy source, is an integral part of the future national energy system and plays a crucial role in achieving carbon peaking and carbon neutrality goals. Promoting research into cutting-edge low-carbon technologies such as hydrogen production from renewable energy sources, and strengthening the research, demonstration, and large-scale application of key technologies for hydrogen production, storage, and utilization are of great significance.

[0003] With the integration of distributed renewable energy into the power grid, the penetration rate of the power system continues to rise. As of March 2024, the total installed capacity of renewable energy accounted for 52.9% of the total installed capacity in China. However, due to the strong volatility of new energy sources, such as wind power, and the unbalanced output power of new energy power generation devices, the grid's capacity to absorb them is very limited, resulting in serious energy waste. By connecting a PEM hydrogen production unit to a wind power DC islanded system and using it as a load, the system's utilization rate of new energy sources, such as wind power, can be effectively improved, while reducing hydrogen production costs, which will help promote the development of the hydrogen energy industry.

[0004] The structure of a typical wind power DC islanded PEM hydrogen production system is as follows: Figure 1 As shown, compared to PEM hydrogen production systems connected to the main power grid, wind power DC islanded PEM hydrogen production systems exhibit poor stability. To address the fluctuating characteristics of wind energy, energy storage units in the islanded grid play a crucial role in continuously supplying power to the load. During islanded operation, the energy storage units act as balancing nodes to construct the DC bus voltage and maintain system voltage stability. Currently, related research, based on renewable energy microgrid hydrogen production systems, considering the dynamic characteristics of hydrogen production loads and incorporating new energy output forecast data, has proposed a black-start optimization method for renewable energy DC microgrid hydrogen production, achieving safe, reliable, and efficient operation of the hydrogen production system under the microgrid system. However, this method fails to consider the islanded operation state of the microgrid hydrogen production system. During islanded operation, due to the lack of voltage support from the main power grid, the fluctuations are stronger, and the original black-start scheme cannot adapt to the new operating state of the system. Therefore, it is necessary to optimize the black-start scheme to enhance its adaptability to different situations. Summary of the Invention

[0005] To address the aforementioned technical issues, this invention proposes an optimization method for the black start strategy of a wind power PEM hydrogen production islanding system, which can ensure the system can safely, reliably, and quickly resume normal operation when a microgrid system fails.

[0006] To achieve the above objectives, this invention provides an optimization method for black start strategy of wind power PEM hydrogen production islanding system, comprising: S1. Detect the connection status between the microgrid system and the main power grid. When the connection is disconnected, enter the islanding operation mode. S2. Detect the state of charge (SOC) of the energy storage unit and determine whether its output power meets the power supply requirements of the system's auxiliary equipment. S3. If the conditions in S2 are not met, the fan unit is started to supply power to the energy storage unit until the power supply requirement is met. S4. Use the energy storage unit to establish and maintain a stable DC bus voltage using a DC voltage droop control strategy. S5. Restore power supply to the auxiliary units of the wind power unit and the PEM hydrogen production unit; S6. Determine the startup order of the fan unit and the PEM hydrogen production unit based on the optimization objective function, and start each unit in the order stated. S7. Start the wind power unit and adjust the output power according to the wind speed to match the system load requirements; S8. After the DC bus voltage stabilizes, start the PEM hydrogen production system and determine whether the temperature of the hydrogen electrolyzer has reached the hot standby condition. If it has not reached the condition, keep it on standby until the condition is met. S9. After system recovery, monitor key parameters and make adjustments to maintain long-term stable operation.

[0007] Optionally, in S2, the process of determining whether its output power meets the power supply requirements of the system's auxiliary equipment includes: comparing the output power of the energy storage unit at the initial moment with the total power required by the auxiliary equipment to ensure the normal operation of the wind turbine and the hydrogen electrolyzer.

[0008] Optionally, in S3, the process of starting the wind turbine unit to supply power to the energy storage unit includes: using the wind turbine unit's own uninterruptible power supply (UPS) to start the auxiliary devices of the wind turbine unit, thereby starting the wind turbine unit to supply power to the energy storage device, until the sum of the predicted output of the wind turbine unit and the output of the energy storage unit minus the power required by the wind turbine auxiliary equipment meets the power supply requirements of the system auxiliary equipment.

[0009] Optionally, in S4, the process of establishing and maintaining a stable DC bus voltage using a DC voltage droop control strategy with the energy storage unit includes: setting the expected value of the bus voltage, detecting the current bus voltage, and adjusting the output power of the energy storage unit through the droop control equation to stabilize the bus voltage.

[0010] Optionally, in S6, the process of determining the start-up order of the wind turbine unit and the PEM hydrogen production unit based on the optimization objective function includes: taking minimizing the system recovery time and maximizing the system efficiency as the objectives, and combining the SOC state of the energy storage unit and the hot standby time of the hydrogen production unit, calculating the optimal start-up order through the objective function.

[0011] Optionally, in S7, the process of starting the wind power unit and adjusting the output power according to the wind speed includes: calculating the mechanical power of the wind turbine according to the wind speed, and controlling the wind turbine output power to a reference value through the upper-level coordination control system to match the system load demand.

[0012] Optionally, in S8, the process of determining whether the temperature of the hydrogen electrolyzer has reached the hot standby condition includes: comparing the current electrolyzer temperature with the temperature required to reach the hot standby condition; if it has not been reached, the system remains in standby mode.

[0013] Optionally, in S9, the process of monitoring and adjusting key parameters includes: monitoring the DC bus voltage and the SOC of the energy storage unit, and dynamically adjusting the system operating parameters based on the monitoring results to maintain stability.

[0014] Technical Effects of this Invention: This invention discloses an optimization method for black start strategy of wind power PEM hydrogen production islanding system. It considers multiple initial states of the energy storage unit and proposes a complete and targeted black start scheme, ensuring the safety and effectiveness of the black start scheme for wind power DC islanding PEM hydrogen production system. This invention optimizes the control objective, considering the hot standby time of the PEM hydrogen production equipment. With the goal of the PEM hydrogen production unit recovering to normal operation as quickly as possible, it proposes a comprehensive and effective control objective function based on wind power forecast data and the current state of the energy storage unit. This function determines the equipment deployment scheme that allows the PEM hydrogen production unit to recover to normal operation as quickly as possible, improving the flexibility and effectiveness of black start of the wind power DC islanding PEM hydrogen production system. 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 an optimization method for a black start strategy in a wind power PEM hydrogen production islanding system 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 Figure 2 As shown, this embodiment provides a black start strategy optimization method for a wind power PEM hydrogen production islanding system, including: S1. Detect the connection status between the microgrid system and the main power grid. When the connection is disconnected, enter the islanding operation mode. S2. Detect the state of charge (SOC) of the energy storage unit and determine whether its output power meets the power supply requirements of the system's auxiliary equipment. S3. If the conditions in S2 are not met, the fan unit is started to supply power to the energy storage unit until the power supply requirement is met. S4. Use the energy storage unit to establish and maintain a stable DC bus voltage using a DC voltage droop control strategy. S5. Restore power supply to the auxiliary units of the wind power unit and the PEM hydrogen production unit; S6. Determine the startup order of the fan unit and the PEM hydrogen production unit based on the optimization objective function, and start each unit in the order stated. S7. Start the wind power unit and adjust the output power according to the wind speed to match the system load requirements; S8. After the DC bus voltage stabilizes, start the PEM hydrogen production system and determine whether the temperature of the hydrogen electrolyzer has reached the hot standby condition. If it has not reached the condition, keep it on standby until the condition is met. S9. After system recovery, monitor key parameters and make adjustments to maintain long-term stable operation.

[0019] Furthermore, in S2, the process of determining whether its output power meets the power supply requirements of the system's auxiliary equipment includes: comparing the output power of the energy storage unit at the initial moment with the total power required by the auxiliary equipment to ensure the normal operation of the wind turbine and the hydrogen electrolyzer.

[0020] Furthermore, in S3, the process of starting the wind turbine unit to supply power to the energy storage unit includes: using the wind turbine unit's own uninterruptible power supply (UPS) to start the auxiliary devices of the wind turbine unit, thereby starting the wind turbine unit to supply power to the energy storage device, until the sum of the predicted output of the wind turbine unit and the output of the energy storage unit minus the power required by the wind turbine auxiliary equipment meets the power supply requirements of the system auxiliary equipment.

[0021] Furthermore, in S4, the process of establishing and maintaining a stable DC bus voltage using the DC voltage droop control strategy of the energy storage unit includes: setting the expected value of the bus voltage, detecting the current bus voltage, and adjusting the output power of the energy storage unit through the droop control equation to stabilize the bus voltage.

[0022] Furthermore, in S6, the process of determining the start-up order of the wind turbine unit and the PEM hydrogen production unit based on the optimization objective function includes: taking minimizing the system recovery time and maximizing the system efficiency as the objectives, and combining the SOC state of the energy storage unit and the hot standby time of the hydrogen production unit, calculating the optimal start-up order through the objective function.

[0023] Furthermore, in S7, the process of starting the wind power unit and adjusting the output power according to the wind speed includes: calculating the mechanical power of the wind turbine according to the wind speed, and controlling the wind turbine output power to a reference value through the upper-level coordination control system to match the system load demand.

[0024] Furthermore, in S8, the process of determining whether the temperature of the hydrogen electrolyzer has reached the hot standby condition includes: comparing the current electrolyzer temperature with the temperature required to reach the hot standby condition; if it has not been reached, the system remains in standby mode.

[0025] Furthermore, in S9, the process of monitoring and adjusting key parameters includes: monitoring the DC bus voltage and the SOC of the energy storage unit, and dynamically adjusting the system operating parameters based on the monitoring results to maintain stability.

[0026] Specifically, the implementation process of this embodiment includes: (1) System status detection: In the early stage of black start, the microgrid system detects that the connection with the main grid has been disconnected and enters the islanding operation mode, and adopts the black start strategy of wind power DC islanding system.

[0027] (2) Energy storage unit SOC detection: The SOC of the energy storage units in the microgrid system is detected at time t0 to assess their remaining energy level. That is, the SOC(t0) of the energy storage unit at time t0 should satisfy: ; in, The output power of the energy storage unit at time t0. P fud The total power required to power auxiliary equipment to ensure the normal operation of equipment within the system is specifically expressed as follows: ; in, P fud_wind and P fud_pem These are the power supplies required to power the auxiliary equipment that ensures the normal operation of the wind turbine and the hydrogen electrolyzer.

[0028] If the SOC of the energy storage unit meets the conditions, use it as the initial power source for black start and proceed to step (4). Otherwise, proceed to step (3).

[0029] (3) Start the fan unit to supply power to the energy storage unit: Use the UPS power supply of the fan unit itself to start the auxiliary device of the fan unit, and then start the fan unit to supply power to the energy storage device until the following conditions are met, and proceed to step (4). ; in, P wind (t) and P out (t) represents the predicted output of the wind turbine unit and the output of the energy storage unit at time t.

[0030] (4) DC bus voltage establishment: The energy storage unit acts as a balancing node to establish the DC bus voltage. This is achieved by setting an appropriate expected value for the bus voltage. V ref The system detects the current bus voltage R and applies a DC voltage droop control strategy to the energy storage units. The energy storage system adopts a modular structure. Assuming the system contains n energy storage units, its droop control equation is: ; in, P outn , P refn K Pn The first n The output power, reference power, and droop factor of the energy storage unit.

[0031] if V < V ref The energy storage unit will increase its output power to improve the bus voltage. If V > V ref The energy storage unit will reduce its output power to lower the bus voltage.

[0032] (5) Power supply restoration for auxiliary units: Power supply restoration for auxiliary units of wind power unit and PEM hydrogen production unit.

[0033] (6) Determine the order in which the wind turbine unit and the PEM hydrogen production unit are connected to the power grid: Before executing the optimization objective function, determine the operating status of the t0 wind turbine unit. If the wind turbine unit is already in operation, then record it as... .

[0034] in m Defined as a binary variable to represent the boot sequence. m =1 indicates that the fan unit starts first. m =0 indicates that the PEM hydrogen production unit starts first.

[0035] If the fan unit is in operation at this time, start each unit in the following order: fan unit - voltage balancer - PEM hydrogen production unit.

[0036] If the wind turbine unit is in a shutdown state at this time, the optimization objective function is executed to determine the order in which the wind turbine unit and the PEM hydrogen production unit are connected to the power grid.

[0037] The objective function aims to minimize the system recovery time T. restore And maximizing system efficiency η sys The objective function is expressed as follows: (This is a partial translation of the original text, which is incomplete and requires further context.) ; Among them, w1, w2, w3, w4, and w5 are weighting coefficients. T restore It is the time it takes for the system to go from a black boot to a full recovery. or sys It refers to system operating efficiency. (SOC) final This refers to the SOC state of the energy storage unit after a black start, t hot_pem It is the average time required for the PEM hydrogen production unit to reach hot standby status.

[0038] w1 represents the weighted value indicating the time required for the system to fully recover from a black boot, and is used to describe the importance of the recovery time.

[0039] This indicates a weighted underestimation of system operating efficiency. System operating efficiency is defined as the ratio of useful output energy to total input energy. Where 1- or sys This indicates inefficiency, and its importance in optimization is adjusted using weight w2. Satisfy the following formula: ; in, The hydrogen production power of the PEM hydrogen production unit. , These represent the output power of the wind power unit and the energy storage unit, respectively.

[0040] This indicates the inadequacy of the ratio of the energy storage unit's State of Charge (SOC) to its maximum SOC after a black start. w3 measures the importance of maintaining a high SOC level for the energy storage unit after a black start. To ensure the energy storage unit's SOC remains within a safe range, the following constraints must be met: ; This represents the weighted value for the hot standby time of the PEM hydrogen production unit. w4 can be used to describe the optimization strategy's requirements for adjusting the PEM hot standby time.

[0041] w5 is a weighting coefficient related to the power-on sequence preference. If the system prefers the PEM hydrogen production unit to start first, then w5 should be a positive number.

[0042] T restore The formula is shown below: ; Among them, t start_pem The time when the PEM hydrogen production unit receives the start-up command and begins to start up is the waiting time for startup.

[0043] The hot standby time of the PEM hydrogen production unit is affected by power. The hot standby time of the hydrogen production unit can be assumed to satisfy the following formula: It should be noted that, It concerns the overall system recovery time, t hot_pem Hot standby time for the PEM hydrogen production unit. Includes t hot_pem The reason for assigning separate weights to these two items is that, in the actual optimization process, these two items may require different strategies and control methods to minimize, as they represent different aspects of the system's performance. The former represents the effectiveness of the overall black-start strategy, while the latter focuses more on the efficiency of the hydrogen production process. By assigning different weights to these two items, their contributions to the overall optimization objective can be balanced.

[0044] To ensure the execution of logical constraints, a large number M is introduced such that: ; ; Among them, t start_wind This represents the point in time when the wind turbine unit begins supplying power to the isolated grid. Here, M is a sufficiently large number to ensure that when... m When the value is 0 or 1, the corresponding inequality constraint becomes an equality constraint.

[0045] The power balance constraints of the system during operation are known to be: m =1 ; m =0 ; in, P wind (t) represents the predicted output of the wind turbine unit at time t. P pem (t), P ch (t) represents the power consumed by the PEM hydrogen production unit and the charging power of the energy storage unit at time t.

[0046] The output power of the wind turbine unit, the output power of the energy storage unit, the power consumption of the PEM hydrogen production unit, and the charging power of the energy storage unit should all be within safe limits, i.e., satisfy the following: ; Solving the objective function yields the following results: m , , The results are used to start each unit.

[0047] (7) Start-up and power adjustment of wind power units: Start the wind power units and adjust the output power of the wind turbines according to the current wind speed and system requirements. Ensure that the output of the wind power units matches the load requirements of the microgrid system to support the stable operation of the system.

[0048] wind turbine output power P wind_mec With wind speed v The relationship between them can be approximated by a cube function of wind speed, that is: ; in, r It is the air density. A is the swept area of ​​the wind turbine (the square of the blade length). C p ( v () is wind speed v The power factor depends on the design of the wind turbine and the wind speed.

[0049] Based on the actual operational needs of the microgrid system, the wind turbine output power at time t can be controlled to [value] through the upper-level coordination control system and the wind turbine control system. P wind_ref (t), thereby ensuring that the output of the wind power unit matches the power demand of the PEM hydrogen production unit in the microgrid system, so as to support the stable operation of the system.

[0050] (8) Start-up of the PEM hydrogen production system: After confirming that the DC bus voltage is stable, start the PEM hydrogen production system. Determine whether the temperature of the hydrogen electrolyzer at time t has reached the hot standby operating condition, i.e.: ; in, T pem This is the current temperature of the electrolytic cell. T hot_pem The temperature required for the electrolytic cell to reach the hot standby condition.

[0051] If the conditions are not met as expected, the system will remain in standby mode until the conditions for a warm start are met.

[0052] (9) Monitoring and Continuous Operation: As the PEM hydrogen production system stabilizes and fully returns to normal operation, continue to monitor all key parameters, such as voltage and SOC. Based on the monitoring results, make necessary adjustments and optimizations to maintain the long-term stable operation of the system.

[0053] This invention discloses an optimization method for black start strategy of wind power PEM hydrogen production islanding system. It considers multiple initial states of the energy storage unit and proposes a complete and targeted black start scheme to ensure the safety and effectiveness of the black start scheme for wind power DC islanding PEM hydrogen production system. This invention optimizes the control objective, considering the hot standby time of the PEM hydrogen production equipment. With the goal of the PEM hydrogen production unit recovering to normal operation as quickly as possible, it proposes a comprehensive and effective control objective function based on wind power forecast data and the current state of the energy storage unit. This function determines the equipment deployment scheme that allows the PEM hydrogen production unit to recover to normal operation as quickly as possible, improving the flexibility and effectiveness of black start for wind power DC islanding PEM hydrogen production system.

[0054] 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. An optimization method for black start strategy of a wind power PEM hydrogen production islanding system, characterized in that, include: S1. Detect the connection status between the microgrid system and the main power grid. When the connection is disconnected, enter the islanding operation mode. S2. Detect the state of charge (SOC) of the energy storage unit and determine whether its output power meets the power supply requirements of the system's auxiliary equipment. S3. If the conditions in S2 are not met, the fan unit is started to supply power to the energy storage unit until the power supply requirement is met. S4. Use the energy storage unit to establish and maintain a stable DC bus voltage using a DC voltage droop control strategy. S5. Restore power supply to the auxiliary units of the wind power unit and the PEM hydrogen production unit; S6. Determine the startup order of the fan unit and the PEM hydrogen production unit based on the optimization objective function, and start each unit in the order stated. S7. Start the wind power unit and adjust the output power according to the wind speed to match the system load requirements; S8. After the DC bus voltage stabilizes, start the PEM hydrogen production system and determine whether the temperature of the hydrogen electrolyzer has reached the hot standby condition. If it has not reached the condition, keep it on standby until the condition is met. S9. After system recovery, monitor key parameters and make adjustments to maintain long-term stable operation.

2. The black start strategy optimization method for wind power PEM hydrogen production islanding system as described in claim 1, characterized in that, In S2, the process of determining whether its output power meets the power supply requirements of the system's auxiliary equipment includes: comparing the output power of the energy storage unit at the initial moment with the total power required by the auxiliary equipment to ensure the normal operation of the wind turbine and the hydrogen electrolyzer.

3. The black start strategy optimization method for wind power PEM hydrogen production islanding system as described in claim 1, characterized in that, In S3, the process of starting the wind turbine unit to supply power to the energy storage unit includes: using the wind turbine unit's own uninterruptible power supply (UPS) to start the auxiliary devices of the wind turbine unit, thereby starting the wind turbine unit to supply power to the energy storage device, until the sum of the predicted output of the wind turbine unit and the output of the energy storage unit, minus the power required by the wind turbine auxiliary equipment, meets the power supply requirements of the system auxiliary equipment.

4. The black start strategy optimization method for wind power PEM hydrogen production islanding system as described in claim 1, characterized in that, In S4, the process of establishing and maintaining a stable DC bus voltage using the DC voltage droop control strategy of the energy storage unit includes: setting the expected value of the bus voltage, detecting the current bus voltage, and adjusting the output power of the energy storage unit through the droop control equation to stabilize the bus voltage.

5. The black start strategy optimization method for wind power PEM hydrogen production islanding system as described in claim 1, characterized in that, In S6, the process of determining the start-up order of the wind turbine unit and the PEM hydrogen production unit based on the optimization objective function includes: taking minimizing the system recovery time and maximizing the system efficiency as the objectives, and combining the SOC state of the energy storage unit and the hot standby time of the hydrogen production unit, the optimal start-up order is calculated through the objective function.

6. The black start strategy optimization method for wind power PEM hydrogen production islanding system as described in claim 1, characterized in that, In S7, the process of starting the wind power unit and adjusting the output power according to the wind speed includes: calculating the mechanical power of the wind turbine according to the wind speed, and controlling the wind turbine output power to a reference value through the upper-level coordination control system to match the system load demand.

7. The black start strategy optimization method for wind power PEM hydrogen production islanding system as described in claim 1, characterized in that, In S8, the process of determining whether the temperature of the hydrogen electrolyzer has reached the hot standby condition includes: comparing the current electrolyzer temperature with the temperature required to reach the hot standby condition; if it has not been reached, the system remains in standby mode.

8. The black start strategy optimization method for wind power PEM hydrogen production islanding system as described in claim 1, characterized in that, In S9, the process of monitoring and adjusting key parameters includes: monitoring the DC bus voltage and the SOC of the energy storage unit, and dynamically adjusting the system operating parameters based on the monitoring results to maintain stability.

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