Offshore high-power wind turbine variable pitch control system lithium titanate battery management method

Abstract

The application belongs to the technical field of wind power generation, and particularly discloses a lithium titanate battery management method for a variable pitch control system of an offshore high-power wind turbine generator set. The application collects battery pack data and battery monomer data of the lithium titanate battery, regularly detects the health condition of the lithium titanate battery of the variable pitch control system, judges the related faults of the lithium titanate battery, and takes corresponding system protection actions under the fault condition, so as to meet the quality management of the lithium titanate battery of the variable pitch control system and ensure the normal operation of the offshore high-power wind turbine generator set.

Description

Technical Field

[0001] This invention relates to the field of wind power generation technology, and in particular to a lithium titanate battery management method for a pitch control system of a high-power offshore wind turbine. Background Technology

[0002] With the decreasing availability of onshore land for wind farm construction, offshore wind turbines are gradually becoming the main trend in wind farm development. Compared to onshore wind turbines, offshore wind turbines generally have a larger single-unit generating capacity. As the generating power of the unit increases, the blade length and load of the wind turbine also increase, and the output power of the pitch control system and the backup power capacity also increase accordingly.

[0003] In the event of external grid voltage instability, the pitch control system utilizes its own backup power supply to provide emergency feathering to a safe position. This backup power supply can consist of lead-acid batteries, supercapacitors, or lithium-ion batteries. Lithium titanate batteries, a type of lithium-ion battery, offer advantages over other traditional lithium batteries, including high power output, support for high-current charging and discharging, high energy density, and good safety. Backup power supplies using lithium titanate batteries also occupy less space within the pitch control system cabinet. Furthermore, lithium titanate batteries exhibit excellent wide-temperature resistance. The harsh environment inside offshore wind turbine nacelles, with significant diurnal temperature variations, aligns well with the wide-temperature resistance characteristics of lithium titanate batteries for offshore wind turbine pitch control systems.

[0004] According to relevant national standards for pitch control systems, when using lithium titanate batteries as backup power, their capacity should be sufficient to allow the pitch motor to complete at least two feathering maneuvers within the entire pitch angle range at the user-required pitch speed under specified load conditions. To meet these national standards, the pitch control system needs to collect real-time data on the lithium titanate battery's voltage, temperature, charging current, and discharging current. The pitch control system should be able to determine lithium titanate battery faults based on the collected data and execute corresponding protective actions in case of a fault. The pitch control system must periodically perform health checks on the lithium titanate battery to ensure its health can support emergency feathering to a safe position.

[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to solve the technical problems existing in the background art. To this end, a method for managing lithium titanate batteries in the pitch control system of a high-power offshore wind turbine is provided, which can effectively determine the relevant faults of the backup power lithium titanate battery of the pitch control system and take corresponding fault protection actions.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] The lithium titanate battery management method for the pitch control system of high-power offshore wind turbines includes:

[0009] Data collection on lithium titanate battery packs and individual battery cells;

[0010] Regularly check the health status of the lithium titanate battery in the pitch control system;

[0011] Diagnose lithium titanate battery faults and take system protection actions in fault conditions;

[0012] The health status detection of the lithium titanate battery in the pitch control system includes the following steps:

[0013] Step 1: Consume the remaining capacity of the lithium titanate battery pack through the pitch control system;

[0014] Step 2: When the voltage of the lithium titanate battery pack drops to the middle value within the operating voltage range of the lithium titanate battery pack, stop consuming the capacity of the lithium titanate battery pack and wait for the voltage of the lithium titanate battery pack to stabilize.

[0015] Step 3: The pitch control system charger charges with a small rate of current I. c Charging the lithium titanate battery pack takes time t. c ;

[0016] Step 4: After the charging timer finishes, let the lithium titanate battery rest for t seconds. r Record the OCV voltage of the lithium titanate battery pack after it has been left to stand. C1 ;

[0017] Step 5: The charger restarts with a small current I C The lithium titanate battery pack is charged, and the charging time is t. c ;

[0018] Step 6: After the charging timer finishes, let the lithium titanate battery rest for t seconds. r Record the OCV voltage of the lithium titanate battery pack after it has been left to stand. C2 ;

[0019] Step 7: Determine the OCV based on the pre-calibrated correspondence between the open-circuit voltage (OCV) and the state of charge (SOC). C1 With OCV C2 The corresponding State of Charge (SOC) value for lithium titanate batteries;

[0020] Step 8: Calculate the state of health (SOH) of the lithium titanate battery pack;

[0021] Step 9: Determine whether the health status of the lithium titanate battery supports the pitch control system to urgently feather to a safe position.

[0022] The following is a further defined technical solution of the present invention: the battery pack data and individual cell data of the lithium titanate battery include: total battery pack voltage, battery pack charging current, battery pack discharging current, individual cell temperature and individual cell voltage within the battery pack.

[0023] The following is a further defined technical solution of the present invention: In step 8, the state of health (SOH) of the lithium titanate battery pack is obtained using the following formula:

[0024]

[0025] Among them I c For the charging current, t c C represents the charging time, C represents the rated capacity of the lithium titanate battery pack, and SOC represents the state of charge (SOC). c2 The open-circuit voltage OCV after the second settling period C2 The corresponding state of charge, SOC c1 The open-circuit voltage OCV after the first settling period C1 The corresponding state of charge.

[0026] The following is a further technical solution of the present invention: in the health status detection of lithium titanate batteries, the pitch control system periodically sends backup power health detection requests to the wind turbine main controller and performs the detection work when there is a command from the wind turbine main controller.

[0027] The following is a further defined technical solution of the present invention: In step 7, the relationship between the open circuit voltage OCV and the state of charge SOC of the lithium titanate battery is pre-calibrated through experiments.

[0028] The following is a further defined technical solution of the present invention: lithium titanate battery faults include serious faults and alarm faults. The serious faults include: excessively high total battery voltage, excessively high battery temperature, excessively low battery temperature, insulation leakage, and battery capacity decay. The alarm faults include: excessively high single-cell voltage, excessively low single-cell voltage, overcurrent during charging, overcurrent during discharging, and excessively large single-cell voltage difference.

[0029] The following is a further defined technical solution of the present invention, which includes system protection actions for lithium titanate battery faults:

[0030] When a serious fault is reported, the pitch control system disconnects the DC relay of the lithium titanate battery pack and the pitch control system urgently feathers to a safe position.

[0031] When an alarm fault is reported, the pitch control system immediately feathers the pitch to a safe position, and the alarm fault is automatically reset.

[0032] The following is a further defined technical solution of the present invention: when the driver bus voltage is unstable, the main controller of the pitch control system disconnects the DC relay of the lithium titanate battery pack to protect the lithium titanate battery pack from the influence of driver bus voltage fluctuations.

[0033] The following is a further defined technical solution of the present invention: when the SOH value of the lithium titanate battery is lower than the set threshold, the pitch control system reports a battery pack capacity decay fault and sends a battery pack replacement request to the wind turbine main controller.

[0034] Compared with the prior art, the present invention has the following technical effects:

[0035] This invention, based on wind power industry application scenarios, collects battery pack data and individual battery cell data of lithium titanate batteries, regularly detects the health status of lithium titanate batteries in pitch control systems, identifies related faults in lithium titanate batteries, and takes corresponding system protection actions in fault conditions. This satisfies the quality management of lithium titanate batteries in pitch control systems and ensures the normal operation of high-power offshore wind turbines.

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a flowchart of the method for detecting the health status of lithium titanate batteries in the pitch control system of the present invention;

[0039] Figure 2 yes Figure 1 An enlarged view of the first half of the process flow;

[0040] Figure 3 yes Figure 1 An enlarged view of the latter half of the process. Detailed Implementation

[0041] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0042] like Figure 1-3 The illustration shows an embodiment of a lithium titanate battery management method for a pitch control system of a high-power offshore wind turbine. In this embodiment, a lithium titanate battery pack with a rated capacity of 3Ah is selected as the backup power source for the pitch control system. The lithium titanate battery pack consists of three battery modules connected in series, with each module containing 50 individual battery cells.

[0043] The lithium titanate battery management method for the pitch control system of high-power offshore wind turbines includes:

[0044] Data collection for lithium titanate battery packs and individual cells; specifically, the data for lithium titanate battery packs and individual cells includes: total battery pack voltage, battery pack charging current, battery pack discharging current, individual cell temperature within the battery pack, and individual cell voltage within the battery pack.

[0045] Regularly check the health status of the lithium titanate battery in the pitch control system;

[0046] To diagnose lithium titanate battery faults and take system protection actions in the event of a fault.

[0047] Among them, the health status detection of the lithium titanate battery in the pitch control system, such as Figure 1-3 As shown, it includes the following steps:

[0048] Step 1: Consume the remaining capacity of the lithium titanate battery pack through the pitch control system.

[0049] Step 2: When the voltage of the lithium titanate battery pack drops to the middle value within the operating voltage range of the lithium titanate battery pack, stop consuming the capacity of the lithium titanate battery pack and wait for the voltage of the lithium titanate battery pack to stabilize.

[0050] Step 3: The pitch control system charger charges with a small rate of current I. c Charging the lithium titanate battery pack takes time t. c It should be noted that the charging current I... c and charging time t c The settings should be consistent with the I setting in the calibration procedure below. c and t c The values ​​are the same.

[0051] Step 4: After the charging timer finishes, let the lithium titanate battery rest for t seconds. r Record the OCV voltage of the lithium titanate battery pack after it has been left to stand. C1 Settling time t r It should be consistent with the calibration procedure described below. r same.

[0052] Step 5: The charger restarts with a small current I CCharging the lithium titanate battery pack, the charging time remains t. c .

[0053] Step 6: After the charging timer finishes, allow the lithium titanate battery to rest for the same duration (t). r Record the OCV voltage of the lithium titanate battery pack after it has been left to stand. C2 .

[0054] Step 7: Determine the OCV based on the pre-calibrated correspondence between the open-circuit voltage (OCV) and the state of charge (SOC). C1 With OCV C2 The corresponding State of Charge (SOC) values ​​for lithium titanate batteries. The relationship between the open-circuit voltage (OCV) and the SOC of lithium titanate batteries was pre-calibrated through experiments.

[0055] It should be noted that the calibration process for the correspondence between open-circuit voltage (OCV) and state of charge (SOC) includes:

[0056] The remaining capacity of the lithium titanate battery is consumed through the pitch control system; the lithium titanate battery is in the condition of a new battery before it is consumed.

[0057] When the voltage of the lithium titanate battery pack drops to the lowest value within the operating voltage range, the consumption of the lithium titanate battery pack capacity will stop.

[0058] Wait for the lithium titanate battery pack voltage to rise and stabilize; the pitch control system controller automatically records the stabilized lithium titanate battery pack voltage as the initial open circuit voltage OCV0, and calibrates its corresponding state of charge as SOC0.

[0059] The pitch control system charger uses a small current I C Charge the lithium titanate battery pack for a duration of t. c ;

[0060] After the lithium titanate battery is fully charged, let it stand for t time. r Record the open-circuit voltage OCV1 and the corresponding state of charge SOC1 value of the lithium titanate battery pack after it has been left to stand.

[0061] Repeat the first two steps to obtain different states of charge (SOC). 2…n and the corresponding open-circuit voltage OCV 2…n ;

[0062] The calibration process stops when the voltage of the lithium titanate battery pack reaches the maximum value within the operating voltage range.

[0063] It should be noted that the calibration process for the correspondence between open-circuit voltage (OCV) and state of charge (SOC) described above is not within the scope of this invention. Through the above calibration process, the correspondence between OCV and SOC can be determined. Therefore, for this invention, the correspondence between OCV and SOC is known and determined, thus allowing the determination of the SOC value of the lithium titanate battery in step 7 of this embodiment. In summary, the above calibration process is only for those skilled in the art to understand the SOC value of the lithium titanate battery obtained in this embodiment.

[0064] Step 8: Calculate the State of Health (SOH) of the lithium titanate battery pack using the following formula:

[0065]

[0066] Among them I c For the charging current, t c C represents the charging time, C represents the rated capacity of the lithium titanate battery pack, and SOC represents the state of charge (SOC). c2 The open-circuit voltage OCV after the second settling period C2 The corresponding state of charge, SOC c1 The open-circuit voltage OCV after the first settling period C1 The corresponding state of charge.

[0067] Step 9: Determine whether the health status of the lithium titanate battery supports the pitch control system to urgently feather to a safe position.

[0068] It should be noted that in the health status detection of lithium titanate batteries, the pitch control system periodically sends backup power health detection requests to the wind turbine main controller and performs the detection work when there is a command from the wind turbine main controller.

[0069] In this embodiment, the lithium titanate battery faults that need to be determined include serious faults and alarm faults. Serious faults include: excessively high total battery voltage, excessively high battery temperature, excessively low battery temperature, insulation leakage, and battery capacity decay. Alarm faults include: excessively high single-cell voltage, excessively low single-cell voltage, overcurrent during charging, overcurrent during discharging, and excessively large single-cell voltage difference.

[0070] System protection actions for lithium titanate battery faults include:

[0071] When a serious fault is reported, the pitch control system disconnects the DC relay of the lithium titanate battery pack and the pitch control system urgently feathers to a safe position.

[0072] When an alarm fault is reported, the pitch control system immediately feathers the pitch to a safe position, and the alarm fault is automatically reset.

[0073] When the driver bus voltage is unstable, the pitch control system decides whether to actively disconnect the lithium titanate battery pack from the system based on its own operating conditions. When it is necessary to disconnect from the system, the main controller disconnects the DC relay of the lithium titanate battery pack to protect the lithium titanate battery pack from the influence of driver bus voltage fluctuations.

[0074] When the SOH value of the lithium titanate battery is lower than the set threshold (i.e., when the SOH value is too low), the pitch control system reports a battery pack capacity decay fault and sends a battery pack replacement request to the wind turbine main controller, prompting the staff to replace the lithium titanate battery pack in time.

[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art can make many possible variations and modifications to the technical solution of the present invention, or modify it into equivalent embodiments, without departing from the scope of the present invention's technical solution. Therefore, all equivalent changes made based on the shape, structure, and principle of the present invention without departing from the scope of the present invention's technical solution should be covered within the protection scope of the present invention.

Claims

1. A lithium titanate battery management method for a pitch control system of a high-power offshore wind turbine, characterized in that, include: Data collection on lithium titanate battery packs and individual battery cells; Regularly check the health status of the lithium titanate battery in the pitch control system; Diagnose lithium titanate battery faults and take system protection actions in fault conditions; The health status detection of the lithium titanate battery in the pitch control system includes the following steps: Step 1: Consume the remaining capacity of the lithium titanate battery pack through the pitch control system; Step 2: When the voltage of the lithium titanate battery pack drops to the middle value within the operating voltage range of the lithium titanate battery pack, stop consuming the capacity of the lithium titanate battery pack and wait for the voltage of the lithium titanate battery pack to stabilize. Step 3: The pitch control system charger charges with a small rate of current. Charging the lithium titanate battery pack takes [time]. ; Step 4: After the charging timer finishes, let the lithium titanate battery rest for the specified time. Record the voltage of the lithium titanate battery pack after it has been left to stand. ; Step 5: The charger restarts with a smaller current rate. Charging the lithium titanate battery pack takes [time]. ; Step 6: After the charging timer finishes, let the lithium titanate battery rest for the specified time. Record the voltage of the lithium titanate battery pack after it has been left to stand. ; Step 7: Based on the pre-calibrated open-circuit voltage With state of charge Correspondence, determined and Corresponding state of charge of lithium titanate battery Numerical value; Step 8: Calculate the health status of the lithium titanate battery pack ; Step 9: Determine whether the health status of the lithium titanate battery supports the pitch control system's emergency feathering to a safe position; The battery pack data and individual cell data of lithium titanate batteries include: total battery pack voltage, battery pack charging current, battery pack discharging current, individual cell temperature and individual cell voltage within the battery pack; In step 8, the health status of the lithium titanate battery pack is assessed. Obtained using the following formula: ； in This is the charging current. For charging time, This refers to the rated capacity of the lithium titanate battery pack. Open circuit voltage after the second settling period The corresponding state of charge, Open circuit voltage after the first settling period The corresponding state of charge; In the health status detection of lithium titanate batteries, the pitch control system periodically sends backup power health detection requests to the wind turbine main controller and performs the detection work when there is a command from the wind turbine main controller. In step 7, the open-circuit voltage of the lithium titanate battery With state of charge The correspondence is pre-defined through experiments; Lithium titanate battery faults include serious faults and alarm faults. Serious faults include: excessively high total battery pack voltage, excessively high battery pack temperature, excessively low battery pack temperature, insulation leakage, and battery pack capacity decay. Alarm faults include: excessively high single cell voltage, excessively low single cell voltage, overcurrent during charging, overcurrent during discharging, and excessively large single cell voltage difference. System protection actions for lithium titanate battery faults include: When a serious fault is reported, the pitch control system disconnects the DC relay of the lithium titanate battery pack and the pitch control system urgently feathers to a safe position. When an alarm fault is reported, the pitch control system immediately feathers to a safe position, and the alarm fault is automatically reset. Health status of lithium titanate batteries When the value is lower than the set threshold, the pitch control system reports a battery pack capacity decay fault and sends a battery pack replacement request to the wind turbine main controller.

2. The lithium titanate battery management method for the pitch control system of a high-power offshore wind turbine as described in claim 1, characterized in that, When the driver bus voltage is unstable, the main controller of the pitch control system disconnects the DC relay of the lithium titanate battery pack to protect the lithium titanate battery pack from the influence of driver bus voltage fluctuations.

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