Wind storage combined system for coordinated control of hybrid energy storage equipment and control method

Abstract

The invention belongs to the technical field of wind power generation, and particularly relates to a wind storage combined system for coordinated control of hybrid energy storage equipment and a control method. Wherein the wind generating set is used for converting wind energy into electric energy and outputting the electric energy to a power grid; the energy storage equipment comprises a battery energy storage system and a super capacitor; the direct current bus is used for being connected with the wind generating set, the battery energy storage system and the super capacitor through a control system and performing energy exchange with a power supply grid; and the control system is used for carrying out coordinated control on the energy storage equipment based on different power regulation requirements. According to the invention, the problems of power grid frequency fluctuation and power imbalance caused by wind speed fluctuation of the wind power generation system can be solved. Two different types of energy storage devices are integrated, cooperative regulation and control are carried out by utilizing respective characteristics of the energy storage devices, and power dispatching and frequency modulation control of different time scales are realized, so that the stability of a wind power generation system and the reliability of a power grid are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind power generation, and in particular relates to a wind-storage combined system for coordinated control of hybrid energy storage equipment and a control method. Background Art

[0002] With the growth of global energy demand and reliance on renewable energy, wind power generation, as an important component of clean energy, is gradually occupying an increasingly important position in the power system. However, wind power generation is volatile and unstable. In particular, with the change of wind speed, the wind power output will fluctuate frequently, affecting the frequency stability and energy balance of the power system. This fluctuation characteristic poses a challenge to the security and reliability of the power grid, especially when a high proportion of wind power is connected, the demand for grid frequency regulation and power balance is more prominent.

[0003] Energy storage technology is widely regarded as an effective means to solve the problem of volatility in wind power generation. Through the coordinated control of energy storage equipment, power regulation can be performed on different time scales to smooth wind power output. However, a single type of energy storage equipment is difficult to meet the regulation requirements of wind farms at different time scales and power demands. For example, traditional battery energy storage systems perform well in providing medium- and long-term energy balance, but their response speed is slow and they have difficulty coping with the instantaneous power demands of the power grid; and although supercapacitors have a fast response speed, their energy capacity is small and they are not suitable for long-term, large-capacity power regulation. Therefore, how to reasonably combine and coordinate the control of different energy storage devices to effectively respond to the different power demands of wind power systems is the focus of this invention that needs to be studied urgently. Summary of the invention

[0004] In view of this, the present invention provides a wind-storage combined system and control method for coordinated control of hybrid energy storage devices, aiming to solve the problems of grid frequency fluctuation and power imbalance caused by wind speed fluctuation in wind power generation systems. By integrating two different types of energy storage devices and using their respective characteristics for coordinated regulation, power dispatching and frequency modulation control at different time scales can be achieved, thereby improving the stability of the wind power generation system and the reliability of the grid.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: A wind-storage combined system for coordinated control of hybrid energy storage equipment, the system comprising: Wind turbines, which convert wind energy into electrical energy and export it to the grid; Energy storage equipment, including a battery energy storage system and a supercapacitor, wherein the battery energy storage system is used to handle power deviations of longer duration, and the supercapacitor is used to handle power fluctuations of shorter duration; A DC bus, used to connect the wind turbine generator set, the battery energy storage system and the supercapacitor through a control system, and to exchange energy with a power supply grid; The control system is used to monitor wind power output, grid status and the working conditions of energy storage equipment, and coordinate the control of energy storage equipment based on different power regulation requirements.

[0006] Furthermore, the control system comprises: An energy storage converter is connected to the DC bus, the battery energy storage system and the supercapacitor respectively, and is used to monitor the SOC state of the energy storage device in real time; A machine-side converter, connected between the wind turbine generator set and the DC bus, for real-time monitoring of wind power output to control wind power output power; The grid-side converter is connected between the DC bus and the power supply grid and is used to control the overall output power of the system.

[0007] A control method for a wind-storage combined system with coordinated control of a hybrid energy storage device, comprising a wind-storage combined system with coordinated control of a hybrid energy storage device, the control method comprising: S11, DC bus voltage monitoring and calculation of output current reference value The control system monitors the DC bus voltage monitoring value U of the wind turbine in real time DC and DC bus voltage reference value U* DC The difference between them is used to obtain the output current reference value I* of the energy storage device through proportional integral operation; S12, Comparison between output current reference value and measured value The control system monitors the actual output current I of the energy storage device and compares it with the output current reference value I ∗ The control system performs PI calculation again to generate a modulation duty cycle signal based on the difference between the two values ​​for subsequent modulation control. S13, modulation signal generation Based on the modulation duty cycle signal, the control system generates a modulation signal, and the modulation signal is used to control the energy storage converter so that the energy storage device performs charging or discharging operations according to current demand; S14. Energy storage equipment selection and switching The control system decides to start the battery energy storage system or supercapacitor in the energy storage system based on the output power monitoring of the wind turbine, the grid frequency monitoring and the SOC status of the energy storage device, as well as the dynamic allocation strategy of the energy storage device based on time scale hierarchical control, the control strategy based on real-time status monitoring and dynamic switching, and the protection mechanism of the energy storage device; S15, pulse width modulation control Based on the generated modulation signal, the control system controls the energy storage converter through pulse width modulation, and the energy storage converter adjusts the output current of the energy storage device so that the energy storage device responds to system requirements and provides rapid power regulation; S16. Output current regulation of energy storage equipment and closed-loop adjustment of control process The system continuously adjusts the output current according to the fluctuation of wind power, the SOC of the energy storage device and the changes in the grid frequency, and realizes precise energy regulation through closed-loop control; when the wind power returns to normal or the frequency deviation disappears, the system reduces the participation of the energy storage device and returns to normal operation.

[0008] Furthermore, in step S14, the energy storage device dynamic allocation strategy based on time scale hierarchical control includes the following steps: S21. Medium- and long-term energy scheduling of battery energy storage systems; S211, the control system monitors the wind turbine generator set in real time through sensors, and monitors the wind power P in real time wt , the fluctuation of the grid frequency f; S212: When the power output of the wind power system continues to deviate, and the control system detects that the power value or frequency value exceeds the medium- and long-term energy scheduling threshold, the process proceeds to step S213; otherwise, the process proceeds to step S221; S213, the system calculates the required energy compensation and determines whether the battery energy storage system needs to be mobilized. If yes, it proceeds to step S114, if not, it proceeds to step S211; S214. According to the magnitude of the power deviation, the battery energy storage system is gradually connected and started to provide energy output to ensure the long-term energy balance of the system; S215. When the wind power returns to normal or the load demand decreases, the battery energy storage system gradually exits; S22, instantaneous power regulation of supercapacitor; S221, determine the fluctuation amplitude, when the wind power P is detected wt When the fluctuation is severe and the power supply frequency f fluctuates beyond the instantaneous power regulation frequency deviation setting threshold, the system determines that instantaneous power regulation is required; S222, starting the supercapacitor. According to the amplitude of the frequency fluctuation, the system mobilizes the supercapacitor to respond quickly in milliseconds, releasing or absorbing energy to smooth the power fluctuation. S223, smooth power output, the supercapacitor continues to work until the grid frequency returns to the normal range, switches to battery energy storage, and enters step S214.

[0009] Furthermore, in step S212, the wind power P wtThe fluctuation deviation threshold is 10% or the grid frequency f deviation threshold is ±0.1 Hz, and the wind power fluctuation lasts for more than 10 seconds; In step S213, the energy demand calculation formula is E=P× , where E is the energy compensation required by the control system, P is the deviation value of wind power output power, that is, the difference between the actual output and the grid demand; Δt is the duration of the deviation; In step S214, the response time of the battery energy storage system is within the range of 1-10 seconds; in step S221, the instantaneous power regulation frequency deviation setting threshold is: the wind power P wt The fluctuation rate exceeds 10% / second or the grid frequency f deviation exceeds ±0.1 Hz / second; in step S222, the supercapacitor response time is less than 1 millisecond.

[0010] Furthermore, the control strategy based on real-time status monitoring and dynamic switching includes the following steps: S31, real-time monitoring of wind power output power, grid frequency and energy storage equipment SOC; monitoring the output power P of wind turbines through sensors wt , and calculate its fluctuation rate P wt / t; continuously monitor the grid frequency f, and when it deviates from ±0.1 Hz, the system enters the frequency regulation mode; the control system obtains the charge state of the supercapacitor and battery energy storage system in real time; S32, dynamically switching energy storage devices; S321, dynamic switching of supercapacitors: when the wind power fluctuation rate exceeds 10% / second or the grid frequency deviation exceeds ±0.1 Hz, and the supercapacitor SOC is between 30%–90%, the system will prioritize starting the supercapacitor to adjust power output; S322, battery energy storage switching: when the wind power fluctuation lasts for more than 10 seconds, or the supercapacitor SOC drops below 30%, the control system gradually reduces the use of supercapacitors and switches to the battery energy storage system; when the battery energy storage SOC is lower than 20%, the system will stop scheduling the battery energy storage to protect its life; S323, frequency recovery. When the grid frequency recovers to within the grid frequency deviation range, the control system stops using the energy storage device and resumes normal operation.

[0011] Furthermore, the protection mechanism of the energy storage device includes: S41. Protection mechanism of supercapacitor S411, real-time monitoring of voltage, the control system continuously monitors the charging voltage of the supercapacitor, when the voltage approaches the upper limit of 3.0V, the system automatically reduces the charging current or stops charging; S412, overcharge protection: when the supercapacitor SOC reaches 90%, the system limits its continued charging to ensure that the voltage does not exceed the design range to prevent damage; S413, over-discharge protection: when the supercapacitor SOC drops to 30%, the system reduces or stops its discharge load to prevent damage to the equipment caused by excessive discharge; S42. Protection mechanism of battery energy storage system S421, real-time monitoring of battery SOC. When the battery SOC approaches 95%, the system gradually reduces the charging current to avoid the impact of overcharging on battery life; S422, overcharge protection: when the battery SOC reaches 95%, the system stops charging the battery to prevent internal loss or overheating caused by overcharging; S423, over-discharge protection: when the battery SOC drops to 20%, the system stops the discharge task of the battery energy storage to prevent deep discharge from causing irreversible damage to the battery; S424, temperature protection: when the operating temperature of the battery or supercapacitor exceeds 40°C, the system starts cooling equipment or reduces the charging and discharging frequency of the energy storage device to ensure that the equipment operates within a safe temperature range.

[0012] The beneficial effects of the present invention are: The present invention proposes a wind-storage combined system with coordinated control of hybrid energy storage devices and a control method thereof, which realizes power regulation at different time scales by comprehensively utilizing the advantages of both battery energy storage systems and supercapacitors. Specifically, supercapacitors are mainly used for regulating instantaneous power changes due to their high power density and rapid response capabilities to cope with short-term fluctuations in wind farm output; while battery energy storage systems, relying on their larger energy density, are suitable for longer-term energy balance and frequency regulation.

[0013] This invention realizes intelligent and optimized power regulation under different operating conditions through coordinated control of two energy storage devices. It can not only quickly respond to instantaneous power changes, but also provide continuous energy balance, thereby improving the stability of wind power grid connection and the operating efficiency of the system.

[0014] In addition, the wind-storage combined system and control method of the hybrid energy storage device coordinated control of the present invention realizes intelligent coordinated control of energy storage devices, which can effectively deal with the power fluctuation problem in the wind power generation system, and specifically has the following advantages: (1) Fast response: Supercapacitors can quickly respond to instantaneous power demands and smooth out short-term power fluctuations.

[0015] (2) Continuous energy supply: The battery energy storage system can provide continuous energy balance when wind power output is insufficient or grid load increases.

[0016] (3) Improving system stability: Through the coordinated control of energy storage equipment, the stability of wind power grid connection can be significantly improved, reducing the impact on the power grid.

[0017] (4) Optimizing the utilization of energy storage resources: Rationally adjust the operating time and mode of energy storage equipment, optimize its performance and service life, and improve the overall economy and efficiency of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a block diagram of the wind-storage combined system for coordinated control of the hybrid energy storage device of the present invention.

[0019] Figure 2 It is a block diagram of the energy storage device dynamic allocation strategy based on time scale hierarchical control of the present invention.

[0020] Figure 3 It is a control strategy block diagram based on real-time status monitoring and dynamic switching of the present invention.

[0021] Figure 4 It is a flow chart of the wind-storage combined system for coordinated control of hybrid energy storage equipment and its control method of the present invention.

[0022] Figure 5 It is an example diagram of the wind-storage combined system for coordinated control of the hybrid energy storage device of the present invention and its control method.

[0023] The attached figure indicates: 1: wind turbine generator set, 2: machine-side converter, 3: grid-side converter, 4: power supply grid, 5: energy storage converter, 6: battery energy storage system, 7: supercapacitor, 8: DC bus. DETAILED DESCRIPTION

[0024] In order to better understand the present invention, the content of the present invention is further clearly described below in conjunction with the embodiments and the accompanying drawings, but the protection content of the present invention is not limited to the following embodiments. In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details.

[0025] Examples, such as Figure 1-5 As shown, in this embodiment, a wind-storage combined system and a control method thereof based on a hierarchical control strategy based on a time scale are described, aiming to solve short-term and long-term power fluctuations in a wind power generation system.

[0026] A wind-storage combined system for coordinated control of hybrid energy storage equipment, the system comprising the following main components: A wind turbine generator set 1, for converting wind energy into electrical energy and outputting it to a power grid; The energy storage device includes a battery energy storage system 6 and a supercapacitor 7. The battery energy storage system 6 has a large energy density and is mainly used to handle power deviations of longer duration, such as energy dispatch when wind power output is insufficient or load demand increases. The supercapacitor 7 has a high power density and fast response capability and is mainly used to handle short-term high power demand and cope with instantaneous fluctuations and frequency fluctuations of wind power output. A DC bus 8, used to connect the wind turbine generator set 1, the battery energy storage system 6 and the supercapacitor 7 through a control system, and to exchange energy with the power supply grid 4 through power electronic equipment; The control system is used to monitor the wind power output, the grid status and the working condition of the energy storage equipment, and coordinate the control of the energy storage equipment based on different power regulation requirements. The control system mainly includes the energy storage converter 5, the machine-side converter 2 and the grid-side converter 3; among them, the energy storage converter 5 is responsible for maintaining the DC voltage stability of the wind turbine, the machine-side converter 2 is responsible for controlling the wind power output power, and the grid-side converter 3 is responsible for controlling the overall output power of the system.

[0027] Specifically, the energy storage converter 5 is respectively connected to the DC bus 8, the battery energy storage system 6 and the supercapacitor 7, and is used for real-time monitoring of the SOC state of the energy storage device; the machine-side converter 2 is connected between the wind turbine 1 and the DC bus 8, and is used for real-time monitoring of wind power output to control wind power output power; the grid-side converter 3 is connected between the DC bus 8 and the power supply grid 4, and is used for controlling the overall output power of the system.

[0028] The present invention achieves efficient coordination of the battery energy storage system 6 and the supercapacitor 7 through the following coordinated control strategy: (1) Hierarchical control based on time scale: hierarchical control is performed based on the time scale of power demand. The supercapacitor 7 mainly responds to short-term power changes, while the battery energy storage system 6 handles long-term energy scheduling and frequency recovery.

[0029] (2) State monitoring and dynamic switching: The control system monitors the output power of wind turbine 1, grid frequency, and the state of charge (SOC) of the energy storage device in real time, and dynamically switches the working mode of the energy storage device according to actual conditions to ensure that the system is always in the optimal regulation state.

[0030] (3) Protection mechanism of energy storage device: In order to avoid overcharging or over-discharging of the supercapacitor 7 and the battery energy storage system 6, the present invention sets a corresponding protection mechanism to ensure that the energy storage device operates within a safe working range and prolong its service life.

[0031] Control strategy: Dynamic deployment strategy of energy storage equipment based on time scale hierarchical control The control method of the present invention dynamically allocates the battery energy storage system 6 and the supercapacitor 7 according to the power fluctuation of the wind power system and the frequency demand of the power grid. The specific control steps of the dynamic allocation strategy of the energy storage device based on time scale hierarchical control are as follows: S21. Medium- and long-term energy scheduling of battery energy storage system 6: S211, the control system monitors the wind turbine generator set 1 in real time through sensors, and monitors the wind power P in real time wt , the fluctuation of the grid frequency f; S212: When the power output of the wind power system continues to deviate, such as when the wind speed decreases or the grid load increases, and the control system detects that the power value or frequency value exceeds the medium- and long-term energy scheduling threshold, it proceeds to step S213; otherwise, it proceeds to step S221; S213, determine energy demand: the system calculates the required energy compensation and determines whether the battery energy storage system 6 needs to be mobilized. If yes, proceed to step S214, otherwise proceed to step S211; S214, starting the battery energy storage system 6: according to the size of the power deviation, the battery energy storage system 6 is gradually connected and started to provide energy output to ensure the long-term energy balance of the system; S215, restoring system balance: when the wind power returns to normal or the load demand decreases, the battery energy storage system 6 gradually exits; S22, instantaneous power regulation of supercapacitor 7; S221, determine the fluctuation amplitude, when the wind power P is detected wt When the fluctuation is severe and the power supply frequency f fluctuates beyond the instantaneous power regulation frequency deviation setting threshold, the system determines that instantaneous power regulation is required; S222, starting the supercapacitor 7, according to the amplitude of the frequency fluctuation, the system mobilizes the supercapacitor 7 to respond quickly in milliseconds, releases or absorbs energy to smooth the power fluctuation; S223, smooth power output, the supercapacitor 7 continues to work until the grid frequency returns to the normal range, switches to battery energy storage, and enters step S214.

[0032] In step S212, the wind power P wt The fluctuation deviation threshold is 10% or the grid frequency f deviation threshold is ±0.1 Hz, and the wind power fluctuation duration exceeds 10 seconds; in step S213, the energy demand calculation formula is E=P× , where E is the energy compensation required by the control system, P is the deviation value of the wind power output power, that is, the difference between the actual output and the grid demand; Δt is the duration of the deviation; in step S214, the response time of the battery energy storage system 6 is within the range of 1-10 seconds; in step S221, the instantaneous power regulation frequency deviation setting threshold is: wind power P wtThe fluctuation rate exceeds 10% / second or the grid frequency f deviation exceeds ±0.1 Hz / second; in step S222, the response time of the supercapacitor 7 is less than 1 millisecond.

[0033] The control flow in this embodiment is as follows: Real-time monitoring: The control system monitors the wind power P in real time through sensors. wt and grid frequency f to determine wind power output fluctuations and grid demand.

[0034] Short-term power regulation: When the wind power output power fluctuates violently and the frequency deviation f exceeds ±0.1 Hz, and the wind power fluctuation rate exceeds 10% / second, the control system determines that instantaneous power regulation is required and starts the supercapacitor 7. The supercapacitor 7 has a response time of less than 1 millisecond and quickly releases or absorbs energy to smooth power fluctuations.

[0035] Long-term energy dispatch: When the deviation of wind power output power is detected to last for more than 10 seconds and the deviation is greater than 10%, the system calculates the required energy compensation. If the cumulative energy demand of the deviation exceeds the minimum threshold of battery energy storage (such as 0.5MWh), the battery energy storage system 6 is gradually started for energy compensation. The response time of the battery energy storage system 6 is 1-10 seconds to ensure continuous power supply and energy balance.

[0036] Balance recovery: When the wind power returns to normal or the load demand decreases, the control system gradually reduces the output power of the battery energy storage, exits the supercapacitor 7 regulation, and returns to normal operation.

[0037] Through this method, the supercapacitor 7 is responsible for smoothing short-term fluctuations, while the battery energy storage system 6 is used for long-term energy balance, ensuring that the system operates efficiently on different time scales.

[0038] Control strategy: The control strategy based on real-time status monitoring and dynamic switching aims to achieve dynamic energy storage device switching according to the power fluctuation of the wind power system and the SOC status of the energy storage device to ensure system stability. It includes the following steps: S31, real-time monitoring of wind power output power, grid frequency and energy storage device SOC; monitoring the output power P of wind turbine generator set 1 through sensors wt , and calculate its fluctuation rate P wt / t; continuously monitor the grid frequency f, and when it deviates from ±0.1 Hz, the system enters the frequency regulation mode; the control system obtains the charge state of the supercapacitor 7 and the battery energy storage system 6 in real time; S32, dynamically switching energy storage devices; S321, dynamic switching of supercapacitor 7. When the wind power fluctuation rate exceeds 10% / second or the grid frequency deviation exceeds ±0.1 Hz, and the SOC of supercapacitor 7 is between 30% and 90%, the system will preferentially start supercapacitor 7 to adjust power output; S322, battery energy storage switching. When the wind power fluctuation lasts for more than 10 seconds, or the SOC of the supercapacitor 7 drops below 30%, the control system gradually reduces the use of the supercapacitor 7 and switches to the battery energy storage system 6. When the battery energy storage SOC is lower than 20%, the system will stop the scheduling of the battery energy storage to protect its life. S323, frequency recovery. When the grid frequency recovers to within the grid frequency deviation range, the control system stops using the energy storage device and resumes normal operation.

[0039] The battery energy storage system 6SOC range is: 20%-95%; the supercapacitor 7SOC range is: 30%-90%; the grid frequency deviation range is: ±0.1 Hz; the wind power fluctuation threshold: the power change rate exceeds 10% / second (when the power fluctuation amplitude exceeds this value, the system considers that rapid adjustment is required).

[0040] In this embodiment, the control process is as follows: Real-time monitoring: The control system monitors the wind power output power P in real time wt , grid frequency f and the SOC state of the energy storage device (supercapacitor 7 SOC range is 30%–90%, battery energy storage system 6 SOC range is 20%–95%).

[0041] Dynamic switching of energy storage devices: When the wind power fluctuation rate exceeds 10% / second or the grid frequency deviation exceeds ±0.1 Hz, and the SOC of supercapacitor 7 is between 30%–90%, the system prioritizes starting supercapacitor 7 for instantaneous power regulation.

[0042] If the wind power fluctuation lasts for more than 10 seconds, or the SOC of the supercapacitor 7 drops below 30%, the system gradually reduces the use of the supercapacitor 7 and switches to the battery energy storage system 6 to provide longer-term energy regulation.

[0043] SOC protection and optimization: When the battery energy storage SOC drops to 20%, the system stops using the battery energy storage to prevent excessive discharge from affecting battery life. At this time, the system gives priority to other adjustment measures (such as reducing load) according to the situation.

[0044] When the system status returns to the normal range (wind power fluctuation returns to normal, and the grid frequency deviation is less than ±0.1Hz), the control system stops using the energy storage equipment and returns to normal operation mode.

[0045] Temperature monitoring and protection: If the temperature of the energy storage device exceeds 40°C, the system starts cooling equipment or reduces the charging and discharging frequency of the energy storage device to ensure that the device operates within a safe temperature range.

[0046] Through this control strategy, the system can dynamically respond to different grid demands and intelligently switch energy storage devices according to wind power fluctuations and the status of energy storage devices, thereby optimizing the utilization efficiency and life of the energy storage devices.

[0047] Control strategy: Protection mechanism for energy storage equipment, including: S41, Protection mechanism of supercapacitor 7 S411, real-time monitoring of voltage, the control system continuously monitors the charging voltage of the supercapacitor 7, when the voltage approaches the upper limit of 3.0V, the system automatically reduces the charging current or stops charging; S412, overcharge protection: when the supercapacitor 7SOC reaches 90%, the system limits its continued charging to ensure that the voltage does not exceed the design range to prevent damage; S413, over-discharge protection: when the supercapacitor 7SOC drops to 30%, the system reduces or stops its discharge load to prevent damage to the equipment caused by excessive discharge; S42. Protection mechanism of battery energy storage system 6 S421, real-time monitoring of battery SOC. When the battery SOC approaches 95%, the system gradually reduces the charging current to avoid the impact of overcharging on battery life; S422, overcharge protection: when the battery SOC reaches 95%, the system stops charging the battery to prevent internal loss or overheating caused by overcharging; S423, over-discharge protection: when the battery SOC drops to 20%, the system stops the discharge task of the battery energy storage to prevent deep discharge from causing irreversible damage to the battery; S424, temperature protection, when the operating temperature of the battery or supercapacitor 7 exceeds 40°C, the system starts cooling equipment or reduces the charging and discharging frequency of the energy storage device to ensure that the equipment operates within a safe temperature range.

[0048] The supercapacitor 7 has a charging voltage range of 2.7V-3.0V (a typical single capacitor).

[0049] The battery energy storage system 6SOC lower limit: 20% (protection against deep discharge).

[0050] The battery energy storage system 6SOC upper limit: 95% (to protect against overcharging).

[0051] Described temperature monitoring range: 20°C–40°C (normal operating temperature range).

[0052] This embodiment describes a complete state monitoring and energy storage dynamic switching control process of a wind turbine generator set 1. By real-time monitoring of the DC bus 8 voltage of the wind turbine set, calculating the output current reference value of the energy storage device, combining multiple control strategies, and selecting appropriate energy storage devices for dynamic switching, the intelligent control of the wind and energy storage combined system is realized. The control steps are as follows: S11, DC bus 8 voltage monitoring and calculation of output current reference value The control system monitors the voltage monitoring value U of the DC bus 8 of the wind turbine generator set 1 in real time. DC and DC bus 8 voltage reference value U* DC The difference between them is used to obtain the output current reference value I* of the energy storage device through proportional-integral operation, and the operation of the energy storage device is controlled based on this output value.

[0053] The battery energy storage system 6 and the supercapacitor 7 devices are connected to the DC bus 8 via the energy storage converter 5 to respond to power fluctuations in real time.

[0054] S12, Comparison between output current reference value and measured value The control system monitors the actual output current I of the energy storage device and compares it with the output current reference value I ∗ The control system again uses PI operation to generate a modulation duty cycle signal based on the difference between the two for subsequent modulation control.

[0055] S13, modulation signal generation Based on the modulation duty cycle signal, the control system generates a modulation signal, and the modulation signal is used to control the energy storage converter 5 so that the energy storage device performs charging or discharging operations according to current demand.

[0056] S14. Energy storage equipment selection and switching The control system determines to start the battery energy storage system 6 or the supercapacitor 7 in the energy storage system according to the output power monitoring of the wind turbine 1, the grid frequency monitoring and the SOC status of the energy storage device, and according to the dynamic allocation strategy of the energy storage device based on the time scale hierarchical control, the control strategy based on the real-time status monitoring and dynamic switching, and the protection mechanism of the energy storage device; Short-term fluctuations: When the wind power fluctuates sharply for a short period of time and the frequency deviation exceeds ±0.1 Hz, the system starts the supercapacitor 7 to perform instantaneous power regulation, and the response time is less than 1 millisecond.

[0057] Long-term power imbalance: When power fluctuations last for more than 10 seconds and the deviation exceeds 10%, the system calculates the energy demand and activates the battery energy storage system 6 to ensure power balance.

[0058] S15, pulse width modulation control Based on the generated modulation signal, the control system controls the energy storage converter 5 through pulse width modulation, and the energy storage converter 5 adjusts the output current of the energy storage device so that the energy storage device responds to system requirements and provides rapid power regulation; S16. Output current regulation of energy storage equipment and closed-loop adjustment of control process The system continuously adjusts the output current according to the fluctuation of wind power, the SOC of the energy storage device and the changes in the grid frequency, and realizes precise energy regulation through closed-loop control; when the wind power returns to normal or the frequency deviation disappears, the system reduces the participation of the energy storage device and returns to normal operation.

[0059] The control process of this embodiment obtains the output current reference value through PI operation, and controls the output current of the energy storage device through pulse width modulation (PWM), so as to realize efficient dynamic switching of the energy storage device in the wind-storage combined system. Combining the hierarchical control of time scale, state monitoring and dynamic switching, and the protection mechanism of the energy storage device, the stable operation of the system is ensured under the condition of wind power fluctuation.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in the field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A wind-storage combined system with coordinated control of hybrid energy storage equipment, characterized in that: The system comprises: Wind turbines, which convert wind energy into electrical energy and export it to the grid; Energy storage equipment, including a battery energy storage system and a supercapacitor, wherein the battery energy storage system is used to handle power deviations of longer duration, and the supercapacitor is used to handle power fluctuations of shorter duration; A DC bus, used to connect the wind turbine generator set, the battery energy storage system and the supercapacitor through a control system, and to exchange energy with a power supply grid; The control system is used to monitor wind power output, grid status and the working conditions of energy storage equipment, and coordinate the control of energy storage equipment based on different power regulation requirements.

2. A wind-storage combined system for coordinated control of hybrid energy storage equipment according to claim 1, characterized in that: The control system comprises: An energy storage converter is connected to the DC bus, the battery energy storage system and the supercapacitor respectively, and is used to monitor the SOC state of the energy storage device in real time; A machine-side converter, connected between the wind turbine generator set and the DC bus, for real-time monitoring of wind power output to control wind power output power; The grid-side converter is connected between the DC bus and the power supply grid and is used to control the overall output power of the system.

3. A control method for a wind-storage combined system with coordinated control of a hybrid energy storage device, comprising a wind-storage combined system with coordinated control of a hybrid energy storage device as claimed in any one of claims 1 to 2, characterized in that: The control method comprises: S11, DC bus voltage monitoring and calculation of output current reference value The control system monitors the DC bus voltage monitoring value U of the wind turbine in real time DC and DC bus voltage reference value U* DC The difference between them is used to obtain the output current reference value I* of the energy storage device through proportional integral operation; S12, comparison between output current reference value and measured value The control system monitors the actual output current I of the energy storage device and compares it with the output current reference value I ∗ The control system performs PI calculation again to generate a modulation duty cycle signal based on the difference between the two values ​​for subsequent modulation control. S13, modulation signal generation Based on the modulation duty cycle signal, the control system generates a modulation signal, and the modulation signal is used to control the energy storage converter so that the energy storage device performs charging or discharging operations according to current demand; S14. Energy storage equipment selection and switching The control system decides to start the battery energy storage system or supercapacitor in the energy storage system based on the output power monitoring of the wind turbine, the grid frequency monitoring and the SOC status of the energy storage device, as well as the dynamic allocation strategy of the energy storage device based on time scale hierarchical control, the control strategy based on real-time status monitoring and dynamic switching, and the protection mechanism of the energy storage device; S15, pulse width modulation control Based on the generated modulation signal, the control system controls the energy storage converter through pulse width modulation, and the energy storage converter adjusts the output current of the energy storage device so that the energy storage device responds to system requirements and provides rapid power regulation; S16. Output current regulation of energy storage equipment and closed-loop adjustment of control process The system continuously adjusts the output current according to the fluctuation of wind power, the SOC of the energy storage device and the changes in the grid frequency, and realizes precise energy regulation through closed-loop control; when the wind power returns to normal or the frequency deviation disappears, the system reduces the participation of the energy storage device and returns to normal operation.

4. A control method for a wind-storage combined system with coordinated control of a hybrid energy storage device according to claim 3, characterized in that: In step S14, the energy storage device dynamic allocation strategy based on time scale hierarchical control includes the following steps: S21. Medium- and long-term energy scheduling of battery energy storage systems; S211, the control system monitors the wind turbine generator set in real time through sensors, and monitors the wind power P in real time wt , the fluctuation of the grid frequency f; S212: When the power output of the wind power system continues to deviate, and the control system detects that the power value or frequency value exceeds the medium- and long-term energy scheduling threshold, the process proceeds to step S213; otherwise, the process proceeds to step S221; S213, the system calculates the required energy compensation and determines whether the battery energy storage system needs to be mobilized. If yes, it proceeds to step S114, if not, it proceeds to step S211; S214. According to the magnitude of the power deviation, the battery energy storage system is gradually connected and started to provide energy output to ensure the long-term energy balance of the system; S215. When the wind power returns to normal or the load demand decreases, the battery energy storage system gradually exits; S22, instantaneous power regulation of supercapacitor; S221, determine the fluctuation amplitude, when the wind power P is detected wt When the fluctuation is severe and the power supply frequency f fluctuates beyond the instantaneous power regulation frequency deviation setting threshold, the system determines that instantaneous power regulation is required; S222, starting the supercapacitor. According to the amplitude of the frequency fluctuation, the system mobilizes the supercapacitor to respond quickly in milliseconds, releasing or absorbing energy to smooth the power fluctuation. S223, smooth power output, the supercapacitor continues to work until the grid frequency returns to the normal range, switches to battery energy storage, and enters step S214.

5. A control method for a wind-storage combined system with coordinated control of a hybrid energy storage device according to claim 4, characterized in that: In step S212, the wind power P wt The fluctuation deviation threshold is 10% or the grid frequency f deviation threshold is ±0.1Hz, and the wind power fluctuation lasts for more than 10 seconds; In step S213, the energy demand calculation formula is E=P× , where E is the energy compensation required by the control system, P is the deviation value of wind power output power, that is, the difference between the actual output and the grid demand; Δt is the duration of the deviation; In step S214, the response time of the battery energy storage system is within the range of 1-10 seconds; in step S221, the instantaneous power regulation frequency deviation setting threshold is: the wind power P wt The fluctuation rate exceeds 10% / second or the grid frequency f deviation exceeds ±0.1 Hz / second; in step S222, the supercapacitor response time is less than 1 millisecond.

6. A control method for a wind-storage combined system with coordinated control of a hybrid energy storage device according to claim 5, characterized in that: The control strategy based on real-time status monitoring and dynamic switching includes the following steps: S31, real-time monitoring of wind power output power, grid frequency and energy storage equipment SOC; monitoring the output power P of wind turbines through sensors wt , and calculate its fluctuation rate P wt / t; continuously monitor the grid frequency f, and when it deviates from ±0.1 Hz, the system enters the frequency regulation mode; the control system obtains the charge state of the supercapacitor and battery energy storage system in real time; S32, dynamically switching energy storage devices; S321, dynamic switching of supercapacitors: when the wind power fluctuation rate exceeds 10% / second or the grid frequency deviation exceeds ±0.1 Hz, and the supercapacitor SOC is between 30%–90%, the system will prioritize starting the supercapacitor to adjust power output; S322, battery energy storage switching: when the wind power fluctuation lasts for more than 10 seconds, or the supercapacitor SOC drops below 30%, the control system gradually reduces the use of supercapacitors and switches to the battery energy storage system; when the battery energy storage SOC is lower than 20%, the system will stop scheduling the battery energy storage to protect its life; S323, frequency recovery. When the grid frequency recovers to within the grid frequency deviation range, the control system stops using the energy storage device and resumes normal operation.

7. A control method for a wind-storage combined system with coordinated control of a hybrid energy storage device according to claim 6, characterized in that: The protection mechanisms of energy storage equipment include: S41. Protection mechanism of supercapacitor S411, real-time monitoring of voltage, the control system continuously monitors the charging voltage of the supercapacitor, when the voltage approaches the upper limit of 3.0V, the system automatically reduces the charging current or stops charging; S412, overcharge protection: when the supercapacitor SOC reaches 90%, the system limits its continued charging to ensure that the voltage does not exceed the design range to prevent damage; S413, over-discharge protection: when the supercapacitor SOC drops to 30%, the system reduces or stops its discharge load to prevent damage to the equipment caused by excessive discharge; S42. Protection mechanism of battery energy storage system S421, real-time monitoring of battery SOC. When the battery SOC approaches 95%, the system gradually reduces the charging current to avoid the impact of overcharging on battery life; S422, overcharge protection: when the battery SOC reaches 95%, the system stops charging the battery to prevent internal loss or overheating caused by overcharging; S423, over-discharge protection: when the battery SOC drops to 20%, the system stops the discharge task of the battery energy storage to prevent deep discharge from causing irreversible damage to the battery; S424, temperature protection: when the operating temperature of the battery or supercapacitor exceeds 40°C, the system starts cooling equipment or reduces the charging and discharging frequency of the energy storage device to ensure that the equipment operates within a safe temperature range.

Images