Method for detecting super capacitor capacitance value, controller and wind turbine generator system

Abstract

Disclosed are a super capacitor capacitance detection method, a controller and a wind turbine generator unit. The super capacitor capacitance detection method comprises: detecting whether the wind turbine generator unit restarts after power failure; in response to the wind turbine generator unit restarting after power failure, detecting whether the voltage of a super capacitor of a variable pitch system and the working state of a charger both satisfy super capacitor capacitance detection conditions; in response to the voltage of the super capacitor and the working state of the charger both satisfying the super capacitor capacitance detection conditions, calculating the capacitance of the super capacitor according to the rated current of the charger and / or the output current of the charger and the voltage of the super capacitor. The super capacitor capacitance detection method is not limited by the length of power failure of the variable pitch cabinet, and the capacitance detection function can be realized even in the case of short-time power failure of the variable pitch cabinet.

Description

Technical Field

[0001] This disclosure generally relates to the field of wind power generation technology, and more specifically, to a method for detecting the capacitance value of a supercapacitor, a controller, and a wind turbine generator set. Background Technology

[0002] Under normal operating conditions, when the wind speed exceeds the rated wind speed, the pitch system of the wind turbine controls the blade pitch angle to maintain a constant rotor speed in order to control the power output. In the event of a fault, the pitch system will execute an emergency pitch retraction function, achieving aerodynamic braking and ensuring the safety of the wind turbine. The pitch system operates under normal grid power supply. When a grid fault occurs (e.g., a power outage or low-voltage ride-through), the pitch system requires backup power for pitch retraction. To prevent major accidents, strict monitoring of the backup power supply performance is crucial.

[0003] Supercapacitors are highly suitable for the harsh working environment of pitch systems in wind turbine generators due to their advantages such as high power density (up to 300W / KG~5000W / KG, equivalent to 5 to 10 times that of ordinary batteries), fast charging speed (charging for 10 seconds to 10 minutes can reach more than 95% of its rated capacity), long cycle life (more than 500,000 cycles), and wide operating temperature range (-40℃ to +70℃). Therefore, they are widely used as backup power for pitch systems.

[0004] Factors such as single-cell breakdown, open circuit, changes in electrical parameters (including capacitance deviation, increased loss tangent, decreased insulation performance, or fluctuating leakage current), environmental humidity, and duration of use can all lead to a decrease in the capacitance value of supercapacitors, resulting in reduced effective energy or even failure, seriously jeopardizing the safety and reliability of wind turbine generators. Therefore, the detection of supercapacitor capacitance values ​​is crucial and necessary. Inaccurate capacitance detection may trigger false alarms in the generator set, causing unnecessary shutdowns or wasting supercapacitors. Therefore, improving the accuracy of supercapacitor capacitance detection is a pressing issue that needs to be addressed in current technology. Summary of the Invention

[0005] The embodiments of this disclosure provide a method, controller, and wind turbine generator set for detecting the capacitance value of a supercapacitor, which can realize the detection of the supercapacitor capacitance value in the event of a short-term power outage in the wind turbine generator set (especially the pitch control unit).

[0006] In one general aspect, a method for detecting the capacitance value of a supercapacitor is provided. The method includes: detecting whether a wind turbine generator restarts after a power outage; in response to the restart of the wind turbine generator after a power outage, detecting whether the voltage of the supercapacitor in the pitch system and the operating state of the charger both meet the supercapacitor capacitance value detection conditions; and in response to the supercapacitor voltage and the charger operating state both meeting the supercapacitor capacitance value detection conditions, calculating the capacitance value of the supercapacitor based on the rated current of the charger and / or the output current of the charger, and the voltage of the supercapacitor.

[0007] Optionally, the supercapacitor capacitance detection conditions include: the voltage of the supercapacitor changes from less than a first threshold voltage to greater than the first threshold voltage, and the charger is in normal charging state, wherein the first threshold voltage is set based on the supercapacitor voltage and bias voltage at the time of restart after power failure.

[0008] Optionally, in response to the power-on operation flag being set in the pitch controller of the pitch system and the pitch system being in normal condition, it is determined that the wind turbine generator set will restart after a power outage.

[0009] Optionally, in response to receiving a predetermined enable signal from the main controller of the wind turbine generator and the blade pitch angle being within a predetermined angle range, the pitch system is determined to be in normal condition.

[0010] Optionally, the step of calculating the capacitance value of the supercapacitor includes: calculating the capacitance value of the supercapacitor in each capacitance detection cycle based on the charging current of the charger at each sampling moment in each capacitance detection cycle and the voltage of the supercapacitor at each sampling moment in each capacitance detection cycle, wherein, at each sampling moment, the rated current of the charger or the output current of the charger is used as the charging current of the charger based on the magnitude of the output current of the charger.

[0011] Optionally, at each sampling time, in response to the charger's output current being zero, the charger's rated current is used as the charger's charging current; in response to the charger's output current being non-zero, the charger's output current is used as the charger's charging current.

[0012] Optionally, the step of calculating the capacitance of the supercapacitor in each capacitance detection cycle includes: for any capacitance detection cycle, calculating the average value of the charging current of the charger within that capacitance detection cycle; calculating the voltage difference between the start and end times of the supercapacitor in that capacitance detection cycle; and calculating the capacitance of the supercapacitor in that capacitance detection cycle based on the average value of the charging current, the voltage difference, and the duration of the capacitance detection cycle.

[0013] Optionally, the step of calculating the capacitance of the supercapacitor in each capacitance detection cycle includes: for any capacitance detection cycle, calculating the value of the charging current of the charger at the intermediate sampling moment within the capacitance detection cycle; calculating the voltage difference between the start and end moments of the supercapacitor in the capacitance detection cycle; and calculating the capacitance of the supercapacitor in the capacitance detection cycle based on the value of the charging current at the intermediate sampling moment, the voltage difference, and the duration of the capacitance detection cycle.

[0014] Optionally, the supercapacitor capacitance detection method further includes: in response to the supercapacitor's voltage being greater than a second threshold voltage, calculating the final capacitance value of the supercapacitor based on the capacitance values ​​of the supercapacitor in each capacitance detection cycle before the moment when the supercapacitor's voltage is greater than the second threshold voltage, wherein the second threshold voltage is set based on the supercapacitor's rated voltage and is greater than the first threshold voltage.

[0015] Optionally, the step of calculating the final capacitance value of the supercapacitor includes: calculating the average value of the capacitance value of each capacitance detection cycle as the final capacitance value of the supercapacitor, or using the capacitance value of the intermediate capacitance detection cycle of each capacitance detection cycle as the final capacitance value of the supercapacitor.

[0016] Optionally, the supercapacitor capacitance detection method further includes: in response to the output current of the charger being zero at each sampling moment within a predetermined number of capacitance detection cycles, stopping the calculation of the supercapacitor capacitance value, and outputting a charger fault indication signal.

[0017] Optionally, in response to receiving a specific digital feedback signal from the charger, the charger's operating state is determined to be a normal charging state.

[0018] In another general aspect, a computer-readable storage medium is provided that stores a computer program, which, when executed by a processor, implements the supercapacitor capacitance detection method as described above.

[0019] In another general aspect, a controller is provided, the controller comprising: a processor; and a memory storing a computer program that, when executed by the processor, implements the supercapacitor capacitance detection method as described above.

[0020] In another general aspect, a wind turbine generator set is provided, the wind turbine generator set including the controller as described above.

[0021] According to the embodiments of the present disclosure, the supercapacitor capacitance detection method, controller, and wind turbine generator set expand the supercapacitor capacitance detection conditions by adopting a self-matching algorithm for the capacitance detection lower limit when the wind turbine generator set is restarted after a power outage. This expands the supercapacitor capacitance detection conditions and is not limited by the length of the power outage of the wind turbine generator set (especially the pitch control unit). It enables supercapacitor capacitance detection even when the wind turbine generator set (especially the pitch control unit) is powered out for a short period of time.

[0022] Furthermore, the supercapacitor capacitance detection method, controller, and wind turbine generator set according to the embodiments of this disclosure can effectively solve the problem that the signal (e.g., charging current) acquisition time lags behind the power-on time of the wind turbine generator set by realizing communication establishment time crossing, thus avoiding the inability to perform supercapacitor capacitance detection due to the reduction of supercapacitor capacitance detection conditions caused by the above-mentioned problem. Attached Figure Description

[0023] The above and other objects and features of the embodiments of this disclosure will become clearer from the following description taken in conjunction with the accompanying drawings illustrating the embodiments, wherein:

[0024] Figure 1 This is a schematic block diagram illustrating a pitch system according to an embodiment of the present invention;

[0025] Figure 2 This is a flowchart illustrating a method for detecting the capacitance value of a supercapacitor according to an embodiment of the present disclosure;

[0026] Figure 3 It is a diagram showing the voltage change curve of the supercapacitor and the blade pitch angle change curve after the wind turbine generator is powered off;

[0027] Figure 4 This is a block diagram illustrating a controller according to an embodiment of the present disclosure;

[0028] Figure 5 This is a control topology diagram illustrating the pitch system of a wind turbine generator set according to an embodiment of the present disclosure. Detailed Implementation

[0029] The following detailed embodiments are provided to aid the reader in gaining a comprehensive understanding of the methods, apparatus, and / or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatus, and / or systems described herein will become apparent upon understanding this disclosure. For example, the order of operations described herein is merely illustrative and is not limited to those orders set forth herein, but may be changed as will become clear upon understanding this disclosure, except for operations that must occur in a specific order. Furthermore, for clarity and conciseness, descriptions of features known in the art may be omitted.

[0030] The shortcomings of existing supercapacitor capacitance testing methods are described below, along with the working principle of the supercapacitor capacitance testing method according to embodiments of this disclosure.

[0031] Existing capacitance measurement methods are mostly offline discharge methods and internal resistance measurement methods. Offline measurement methods cannot achieve online capacitance measurement, and for existing wind turbine generators, this method is inconvenient to implement and involves a large workload. Using external timers and voltmeters for capacitance measurement increases the complexity of the measurement system, and there is a risk of inaccurate timing and asynchronous timing and voltage value acquisition, leading to a decrease in measurement accuracy. Moreover, this method is also offline and cannot achieve online capacitance measurement. While using Kalman filtering for capacitance measurement can achieve online capacitance measurement and noise reduction, Kalman filtering is only an optimal estimate and cannot be used as a basis for determining the true value. Capacitance measurement methods using individual capacitors increase the complexity of the capacitor module structure. Existing capacitor modules need to be modified to perform capacitance measurement, which is also inconvenient to implement for existing wind turbine generators and cannot achieve online capacitance measurement.

[0032] The capacitance testing of supercapacitors, which serve as backup power for the pitch system of wind turbine generators, presents certain unique challenges. Currently, several methods are commonly used for supercapacitor capacitance testing. One method involves disconnecting the output of the pitch system's charger while the wind turbine is in shutdown mode. The supercapacitor's energy is then dissipated through energy-consuming devices such as the pitch motor, and the charger is reconnected to charge the supercapacitor. The capacitance value is tested during this charging process. Because this method requires disconnecting the charger's output, testing must be performed in shutdown mode and cannot be conducted online (i.e., while the wind turbine is running). Another method involves directly disconnecting the charger's output for a period during wind turbine operation, waiting for the supercapacitor's capacitance value to drop to a certain level, and then reconnecting the charger to charge it. The disadvantage of this method is that since the purpose of testing the supercapacitor's capacitance is to monitor its performance, abruptly disconnecting the charger without knowing the supercapacitor's performance poses a safety hazard to the wind turbine. Finally, another method involves manually discharging the supercapacitor using a discharge device. This method requires the wind turbine to be shut down and requires testing personnel to climb onto the turbine, resulting in high labor and time costs.

[0033] Furthermore, power outage detection (i.e., power restoration after a power outage) has the following problems. The duration of grid outages or wind turbine maintenance is uncertain, ranging from 2 to 4 hours. Therefore, if a fixed voltage detection range (e.g., 50-70V) is set, the supercapacitor voltage may only drop to 55V due to the short power outage time of the wind turbine (especially the pitch control unit), making capacitance detection impossible. Therefore, it is necessary to expand the capacitance detection conditions to overcome the limitation imposed by the duration of wind turbine power outages.

[0034] Figure 1 This is a schematic block diagram illustrating a pitch system according to an embodiment of the present invention. (Refer to...) Figure 1 The pitch system includes a charger 101, a supercapacitor 102, a frequency converter 103, a pitch motor 104, and a pitch controller 105.

[0035] The input terminal of charger 101 is connected to the power grid. The positive output terminal "+" of charger 101 is connected to the positive terminal of supercapacitor 102 and the positive terminal of inverter 103, respectively. The negative output terminal "-" of charger 101 is connected to the negative terminal of supercapacitor 102 and the negative terminal of inverter 103, respectively. Charger 101 is used to charge supercapacitor 102 and supply power to inverter 103. The control terminal of charger 101 is connected to pitch controller 105. Pitch controller 105 can interact with charger 101 via, for example, the CANOpen protocol. For example, pitch controller 105 can output a switch control command to charger 101, which charger 101 can then turn on or off according to the switch control command. Furthermore, pitch controller 105 can also interact with the main controller of the wind turbine generator. The positive and negative terminals of supercapacitor 102 are connected to the positive and negative terminals of inverter 103, respectively, to supply power to inverter 103. The output terminal of the frequency converter 103 is connected to the pitch motor 104 and is used to drive the pitch motor 104 to run.

[0036] When the power grid supply is normal, the charger 101 monitors the voltage of the supercapacitor 102 in real time and compares it with a preset charging threshold voltage. When the voltage of the supercapacitor 102 drops below the preset charging threshold voltage due to the energy consumption of the pitch motor 104, the charger 101 begins charging the supercapacitor 102. In one example, PID control can be used to control the charging process of the supercapacitor 102 to improve the charging rate and ensure safety during the charging process. In PID control, the input is the preset voltage value of the supercapacitor, the feedback is the actual voltage value of the supercapacitor, and the output is the charging current of the charger 101.

[0037] When the power grid supply is abnormal, the supercapacitor 102 continues to supply power to the frequency converter 103, driving the pitch motor 104 to operate. Since the capacitance of the supercapacitor 102 will gradually decrease or even fail during use, affecting the safe operation of the wind turbine generator, it is necessary to test the capacitance of the supercapacitor in the actual operation of the pitch system.

[0038] To ensure the safe operation of wind turbine generators, regular inspections are necessary. For example, monthly inspections are conducted within the first year after commissioning, and annual or semi-annual inspections are performed thereafter. The main tasks of these regular inspections include: adding lubricating oil, checking torque values, inspecting bolts and wiring for looseness, and checking for abnormal connections in various components. This is similar to the maintenance of a car, and the wind turbine generators need to be actively disconnected from the power grid during inspections. In addition, wind farms may experience occasional power outages from the grid.

[0039] After a power outage, charger 101 can no longer charge supercapacitor 102, and supercapacitor 102 will experience self-discharge. Self-discharge refers to the loss of battery capacity caused by internal spontaneous reactions when the battery and supercapacitor are not connected to an external circuit.

[0040] Based on such Figure 1 The pitch system structure shown has the following problem with power-down detection (i.e., power restoration after a power outage): The supercapacitor capacitance detection is initiated when the current in charger 101 is greater than 0. However, there is a communication delay between the power-on time of the pitch system and the time it takes for the pitch controller 105 to read the current value of charger 101. By the time the pitch controller 105 reads the current value of charger 101, the capacitor voltage may have already risen beyond the voltage detection range, preventing the capacitance detection from being completed.

[0041] Therefore, the embodiments of this disclosure provide a method for detecting the capacitance value of a supercapacitor. By adaptively adjusting the lower limit of capacitance detection when the wind turbine generator is restarted after a power outage, the method can detect the capacitance value of the supercapacitor even when the wind turbine generator is powered off for a short period of time. Furthermore, by enabling communication establishment time to be crossed, the method can effectively solve the problem that the signal acquisition time lags behind the power-on time of the wind turbine generator.

[0042] Figure 2 This is a flowchart illustrating a method for detecting the capacitance value of a supercapacitor according to an embodiment of the present disclosure.

[0043] The supercapacitor capacitance detection method according to embodiments of this disclosure can be executed by the pitch controller of a wind turbine generator set, or by the main controller or other dedicated controller of the wind turbine generator set. It should be noted that if the supercapacitor capacitance detection method is executed by the main controller or other dedicated controller of the wind turbine generator set, the following problems may occur. The acquisition of pitch system data (e.g., charger output current, capacitor voltage, etc.) by the main controller or other dedicated controller is affected by the stability of DP communication. For example, the rated charging current of the charger for a low-voltage pitch system is 90A, and the time to charge the capacitor voltage to the rated voltage is approximately 1 minute. However, the main controller has a slow power-on startup, and coupled with the DP communication establishment time, the main controller may be unable to effectively acquire pitch system data.

[0044] Reference Figure 2 In step S201, it is detected whether the wind turbine generator set has restarted after the power outage.

[0045] Typically, power outages for wind turbine generators include scheduled maintenance or grid outages. However, this disclosure is not limited to these. Power outages can also include short-term outages due to other reasons. When a wind turbine generator experiences a power outage, a fan typically operates in the pitch control cabinet where the charger is located, causing the supercapacitor's voltage to drop rapidly.

[0046] According to embodiments of this disclosure, a power-on operation flag can be set within the pitch controller. When the power-on operation flag is set (e.g., a rising edge occurs) and the pitch system is in normal condition, it can be determined that the wind turbine has restarted after a power outage. Typically, after the pitch controller is powered on, a built-in counter starts counting, and when the count value reaches a predetermined value, the power-on operation flag is set. This ensures that the pitch controller operates normally after power-on. Furthermore, the power-on operation flag can be reset when the wind turbine (or pitch system) loses power. Alternatively, when a predetermined enable signal (e.g., but not limited to 0) is received from the wind turbine's main controller and the blade pitch angle is within a predetermined angle range (e.g., but not limited to, a pitch angle greater than 86 degrees when triggered by an 87-degree proximity switch), it is determined that the pitch system is in normal condition.

[0047] In step S202, in response to the wind turbine restarting after a power outage, it is checked whether the voltage of the supercapacitor in the pitch system and the operating status of the charger both meet the supercapacitor capacitance detection conditions. However, if the wind turbine does not restart after a power outage, the process can return to step S201.

[0048] According to embodiments of this disclosure, the supercapacitor capacitance detection conditions include: the supercapacitor voltage changes from less than a first threshold voltage to greater than a first threshold voltage, and the charger is in normal charging mode. Here, the first threshold voltage can be set based on the supercapacitor voltage and bias voltage at the time of restart after a power outage. For example, assuming the supercapacitor voltage at the time of restart after a power outage is U0 and the bias voltage is ΔU1, then the first threshold voltage U1 = U0 + ΔU1. In this way, the first threshold voltage U1, which serves as the lower limit for capacitance detection, can be dynamically and adaptively adjusted, thereby expanding the capacitance detection conditions (i.e., the voltage detection range), so that capacitance detection is no longer limited by the duration of the wind turbine generator power outage; that is, capacitance detection can be achieved even with a short power outage. Optionally, the bias voltage ΔU1 can be taken in the range of 3V to 5V, but this disclosure is not limited thereto.

[0049] On the other hand, when a specific digital feedback signal is received from the charger, it can be determined that the charger is in a normal charging state. Specifically, when the digital feedback signal received from the charger is "True", it can be determined that the charger is in a normal charging state. Here, the transmission time of the digital feedback signal is almost zero compared to the time required to acquire pitch system data (e.g., charger output current, capacitor voltage, etc.).

[0050] Optionally, in step S202, the capacitance value of the supercapacitor obtained from the previous supercapacitor capacitance value detection method, the capacitance value of the supercapacitor in each capacitance value detection cycle, and various temporary variables (such as various counters and timers) to be used in executing the supercapacitor capacitance value detection method can be reset, and the termination voltage of capacitance value detection (the second threshold voltage U2 as described below) can be set. Furthermore, determining whether the supercapacitor voltage changes from less than the first threshold voltage to greater than the first threshold voltage can begin after the power-on operation flag is set and remains so for a predetermined time (e.g., but not limited to 80ms). Simultaneously, when setting the first threshold voltage by reading the supercapacitor voltage at the time of power-off restart, the preparation detection flag can be set. Then, when the supercapacitor voltage changes to greater than the first threshold voltage while the preparation detection flag is set, it can be determined that the supercapacitor voltage has changed from less than the first threshold voltage to greater than the first threshold voltage.

[0051] In step S203, in response to the fact that both the voltage of the supercapacitor and the operating state of the charger meet the supercapacitor capacitance value detection conditions, the capacitance value of the supercapacitor is calculated based on the rated current and / or output current of the charger, and the voltage of the supercapacitor. However, if at least one of the voltage of the supercapacitor in the pitch system and the operating state of the charger does not meet the supercapacitor capacitance value detection conditions, the supercapacitor capacitance value detection method can be terminated.

[0052] In existing methods for supercapacitor capacitance testing, capacitance measurement is only performed when the charger's output current is greater than 0. However, due to the lag between signal acquisition and wind turbine power-on time, the following situations may occur: For example, the supercapacitor voltage may be 40V when the wind turbine is powered on, but by the time the pitch controller reads the charger's output current, the supercapacitor voltage may have increased to over 60V, leading to a decrease in the accuracy of capacitance measurement; or, conversely, the supercapacitor voltage may be 60V when the wind turbine is powered on, but by the time the pitch controller reads the charger's output current, the supercapacitor voltage may have increased beyond the voltage detection range, making capacitance measurement impossible. Furthermore, directly using the charger's output current of 0 value to calculate the capacitance value will result in an underestimation of the capacitance, affecting the accuracy of the capacitance measurement.

[0053] However, according to embodiments of this disclosure, the capacitance value of the supercapacitor in each capacitance detection cycle can be calculated based on the charging current of the charger at each sampling moment within each capacitance detection cycle and the voltage of the supercapacitor at each sampling moment within each capacitance detection cycle. Here, at each sampling moment, the charger's rated current or the charger's output current can be used as the charger's charging current based on the magnitude of the charger's output current. For example, at each sampling moment, if the charger's output current is zero, the charger's rated current can be used as the charger's charging current; if the charger's output current is not zero, the charger's output current can be used as the charger's charging current. This effectively solves the problem of signal acquisition time lagging behind the wind turbine generator's power-on time while ensuring the accuracy of capacitance detection. The duration of the capacitance detection cycle can be, for example, 500ms, 1s, 2s, etc., and the sampling interval between each sampling moment can be, for example, 20ms, 40ms, etc., but this disclosure is not limited to these; the duration of the capacitance detection cycle and the sampling interval between each sampling moment can be set differently.

[0054] The following describes the method for calculating the capacitance of a supercapacitor in each capacitance detection cycle.

[0055] The capacitance C of a supercapacitor can be calculated using the following equation (1).

[0056] C = I × t / △U (1)

[0057] Where I is the charging current, t is the charging time, and ΔU is the voltage change of the supercapacitor during the time period t.

[0058] According to equation (1), for any capacitance detection cycle, the average value of the charging current of the charger during the capacitance detection cycle (I in equation (1)) can be calculated first, then the voltage difference between the start and end times of the supercapacitor during the capacitance detection cycle (U in equation (1)) can be calculated, and finally the capacitance value of the supercapacitor during the capacitance detection cycle can be calculated based on the average value of the charging current, the voltage difference, and the duration of the capacitance detection cycle (t in equation (1)). Alternatively, for any capacitance detection cycle, the value of the charging current of the charger at the intermediate sampling time during the capacitance detection cycle can be calculated first (I in equation (1)), then the voltage difference between the start and end times of the supercapacitor during the capacitance detection cycle (U in equation (1)) can be calculated, and finally the capacitance value of the supercapacitor during the capacitance detection cycle can be calculated based on the average value of the charging current, the voltage difference, and the duration of the capacitance detection cycle (t in equation (1)). If the capacitance detection period includes N sampling times, then when N is odd, the intermediate sampling time can be the (N+1) / 2th sampling time, and when N is even, the intermediate sampling time can be the N / 2th sampling time or the N / 2+1th sampling time.

[0059] According to embodiments of this disclosure, the supercapacitor capacitance detection method may further include the following steps: in response to a supercapacitor voltage exceeding a second threshold voltage, calculating the final capacitance value of the supercapacitor based on the capacitance values ​​of the supercapacitor in each capacitance detection cycle prior to the moment when its voltage exceeds the second threshold voltage. Here, the second threshold voltage may be set based on the rated voltage of the supercapacitor, and the second threshold voltage is greater than a first threshold voltage. For example, the second threshold voltage U2 may be set to 80% of the rated voltage of the supercapacitor, but is not limited thereto. On the other hand, the final capacitance value of the supercapacitor may represent the capacitance value of the supercapacitor ultimately output by the supercapacitor capacitance detection method, i.e., the capacitance detection result. Specifically, the average value of the capacitance values ​​in each capacitance detection cycle may be calculated as the final capacitance value of the supercapacitor, or the capacitance value in the intermediate capacitance detection cycle of each capacitance detection cycle may be used as the final capacitance value of the supercapacitor. If there are a total of M capacitance detection cycles, then when M is odd, the intermediate capacitance detection cycle can be the (M+1) / 2th capacitance detection cycle; when M is even, the intermediate capacitance detection cycle can be the M / 2th or M / 2+1th capacitance detection cycle. Optionally, while outputting the final capacitance value of the supercapacitor, a capacitance detection completion flag can also be set to indicate that the supercapacitor capacitance detection method is complete.

[0060] According to embodiments of this disclosure, the supercapacitor capacitance detection method may further include the following steps: in response to the output current of the charger being zero at each sampling moment within a predetermined number of capacitance detection cycles, stopping the calculation of the supercapacitor capacitance value and outputting a charger fault indication signal. For example, if the output current is zero at each sampling moment within 8 seconds, the calculation of the supercapacitor capacitance value can be stopped, and a charger fault indication signal can be output. Here, 8 seconds is merely an example, and this disclosure is not limited thereto. In other words, if the charger's output current remains at 0 for 8 seconds, even if the digital feedback signal received from the charger is "True," it can be determined that the charger has actually malfunctioned and cannot output charging current. In this case, even if the capacitance value of the supercapacitor is calculated using the charger's rated current, the accuracy of the capacitance detection cannot be guaranteed, therefore the supercapacitor capacitance detection method will terminate.

[0061] Figure 3 This is a diagram showing the voltage change curve of the supercapacitor and the blade pitch angle change curve after the wind turbine generator is powered off.

[0062] Reference Figure 3 The horizontal axis represents time, the left vertical axis represents the voltage value of the supercapacitor, and the right vertical axis represents the blade pitch angle. Curves 301, 302, and 303 represent the voltage variation curves of the supercapacitor in the pitch system corresponding to the three blades, respectively, while curve 311 represents the blade pitch angle variation curve. Figure 3 As shown, at around 9:53:48, the wind turbine generator stopped and feathered. During the feathering process, the voltage of the supercapacitor dropped rapidly because the charger could no longer charge the supercapacitor.

[0063] Assuming the wind turbine is a 2.XMW type, and the supercapacitor's rated voltage is 85V, the supercapacitor's voltage drops from 78V to 62V in just 20 minutes. If the supercapacitor's voltage starts to drop from 85V, it takes approximately 1 hour. That is, a 1-hour power outage of the pitch control unit is sufficient for supercapacitor capacitance testing. Existing supercapacitor capacitance testing methods require setting the lower limit voltage for capacitance testing very low (i.e., requiring a pitch control unit power outage of more than 3-4 hours) to achieve capacitance testing. However, in actual wind turbine maintenance, the power outage time and maintenance duration are uncertain. If maintenance is completed in 2 hours, but a 3-hour power outage is required for capacitance testing, it will inevitably affect the wind turbine's start-up time, reduce power generation, and increase labor costs. Using the supercapacitor capacitance testing method according to the embodiments of this disclosure, accurate capacitance testing can be performed with a minimum pitch control unit power outage of 1 hour (or even 40 minutes or less).

[0064] Figure 4 This is a block diagram illustrating a controller according to an embodiment of the present disclosure. The controller may be a pitch controller for a wind turbine generator, a main controller for a wind turbine generator, or other dedicated controller.

[0065] Reference Figure 4 The controller 400 according to embodiments of the present disclosure may include a processor 410 and a memory 420. The processor 410 may include (but is not limited to) a central processing unit (CPU), a digital signal processor (DSP), a microcomputer, a field-programmable gate array (FPGA), a system-on-a-chip (SoC), a microprocessor, an application-specific integrated circuit (ASIC), etc. The memory 420 may store a computer program to be executed by the processor 410. The memory 420 may include high-speed random access memory and / or a non-volatile computer-readable storage medium. When the processor 410 executes the computer program stored in the memory 420, the supercapacitor capacitance detection method described above can be implemented.

[0066] Alternatively, the controller 400 can communicate with various other components in the wind turbine generator set via wired or wireless communication, and can also communicate with other devices in the wind farm via wired or wireless communication. Furthermore, the controller 400 can communicate with devices outside the wind farm via wired or wireless communication.

[0067] According to embodiments of this disclosure, a wind turbine generator set including a controller 400 can be provided.

[0068] Figure 5 This is a control topology diagram of the pitch system of a wind turbine generator set according to an embodiment of the present disclosure.

[0069] Reference Figure 5 The three blades of the wind turbine (blades 501, 502, and another one not in) Figure 5 The blades shown are mounted on hub 503. Pitch controller 105 and pitch drive 506 are mounted in pitch control cabinet 504. Pitch controller 105 receives pitch commands from main controller 508 installed in nacelle 509 via communication line 510 (e.g., but not limited to DP communication circuit) and sends pitch speed setpoints to pitch drive 506. Pitch drive 506 drives pitch motor 507 according to the pitch speed setpoints, thereby realizing pitch operation. In addition to communication line 510, power supply lines, safety chain lines, and other hardware control lines may also be provided between main controller 508 and pitch controller 105. Main controller 508 and pitch controller 105 can communicate via, for example... Figure 4 The controller 400 shown is used to implement this.

[0070] According to the embodiments of the present disclosure, the supercapacitor capacitance detection method, controller, and wind turbine generator set expand the supercapacitor capacitance detection conditions by adopting a self-matching algorithm for the capacitance detection lower limit when the wind turbine generator set is restarted after a power outage. This expands the supercapacitor capacitance detection conditions and is not limited by the length of the power outage of the wind turbine generator set (especially the pitch control unit). It enables supercapacitor capacitance detection even when the wind turbine generator set (especially the pitch control unit) is powered out for a short period of time.

[0071] Furthermore, the supercapacitor capacitance detection method, controller, and wind turbine generator set according to the embodiments of this disclosure can effectively solve the problem that the signal (e.g., charging current) acquisition time lags behind the power-on time of the wind turbine generator set by realizing communication establishment time crossing, thus avoiding the inability to perform supercapacitor capacitance detection due to the reduction of supercapacitor capacitance detection conditions caused by the above-mentioned problem.

[0072] While some embodiments of this disclosure have been shown and described, those skilled in the art will understand that modifications may be made to these embodiments without departing from the principles and spirit of this disclosure, which are defined by the claims and their equivalents.

Claims

1. A method for detecting the capacitance value of a supercapacitor, characterized in that, The method for detecting the capacitance value of a supercapacitor includes: Check whether the wind turbine generator restarts after a power outage; In response to the restart of the wind turbine generator after a power outage, the voltage of the supercapacitor in the pitch system and the operating status of the charger are checked to see if they both meet the supercapacitor capacitance value detection conditions. The supercapacitor capacitance value detection conditions include: the charger is in a normal charging state. In response to the fact that both the voltage of the supercapacitor and the operating state of the charger meet the supercapacitor capacitance detection conditions, the capacitance value of the supercapacitor is calculated based on the rated current of the charger and / or the output current of the charger, and the voltage of the supercapacitor. At each sampling moment, in response to the output current of the charger being zero, the rated current of the charger is used as the charging current of the charger.

2. The method for detecting the capacitance value of a supercapacitor as described in claim 1, characterized in that, The supercapacitor capacitance detection condition further includes: the voltage of the supercapacitor changes from less than a first threshold voltage to greater than the first threshold voltage, wherein the first threshold voltage is set based on the voltage and bias voltage of the supercapacitor at the time of restart after power failure.

3. The method for detecting the capacitance value of a supercapacitor as described in claim 1 or 2, characterized in that, In response to the power-on operation flag being set in the pitch controller of the pitch system and the pitch system being in normal condition, it is determined that the wind turbine generator set has restarted after a power outage.

4. The method for detecting the capacitance value of a supercapacitor as described in claim 3, characterized in that, In response to receiving a predetermined enable signal from the main controller of the wind turbine generator and the blade pitch angle being within a predetermined angle range, the pitch system is determined to be in normal condition.

5. The method for detecting the capacitance value of a supercapacitor as described in claim 1 or 2, characterized in that, The steps for calculating the capacitance value of the supercapacitor include: The capacitance of the supercapacitor in each capacitance detection cycle is calculated based on the charging current of the charger at each sampling time in each capacitance detection cycle and the voltage of the supercapacitor at each sampling time in each capacitance detection cycle.

6. The method for detecting the capacitance value of a supercapacitor as described in claim 5, characterized in that, The steps for calculating the capacitance value of the supercapacitor in each capacitance detection cycle include: For any given capacitance detection cycle, calculate the average value of the charging current of the charger within that capacitance detection cycle; Calculate the voltage difference between the start and end times of the supercapacitor during the capacitance detection cycle; The capacitance of the supercapacitor in the capacitance detection period is calculated based on the average value of the charging current, the voltage difference, and the duration of the capacitance detection period.

7. The method for detecting the capacitance value of a supercapacitor as described in claim 5, characterized in that, The steps for calculating the capacitance value of the supercapacitor in each capacitance detection cycle include: For any capacitance detection cycle, calculate the charging current value of the charger at the intermediate sampling time within that capacitance detection cycle; Calculate the voltage difference between the start and end times of the supercapacitor during the capacitance detection cycle; Based on the value of the charging current at the intermediate sampling moment, the voltage difference, and the duration of the capacitance detection period, the capacitance value of the supercapacitor in that capacitance detection period is calculated.

8. The method for detecting the capacitance value of a supercapacitor as described in claim 2, characterized in that, The supercapacitor capacitance detection method also includes: In response to the supercapacitor's voltage exceeding a second threshold voltage, the final capacitance value of the supercapacitor is calculated based on the capacitance values ​​of the supercapacitor during each capacitance detection period prior to the moment when the supercapacitor's voltage exceeds the second threshold voltage. The second threshold voltage is set based on the rated voltage of the supercapacitor, and the second threshold voltage is greater than the first threshold voltage.

9. The method for detecting the capacitance value of a supercapacitor as described in claim 8, characterized in that, The steps for calculating the final capacitance value of the supercapacitor include: The average value of the capacitance value in each capacitance detection cycle is calculated as the final capacitance value of the supercapacitor, or the capacitance value in the middle capacitance detection cycle of each capacitance detection cycle is used as the final capacitance value of the supercapacitor.

10. The method for detecting the capacitance value of a supercapacitor as described in claim 5, characterized in that, The supercapacitor capacitance detection method also includes: In response to the fact that the output current of the charger is zero at each sampling moment within a predetermined number of capacitance detection cycles, the calculation of the capacitance value of the supercapacitor is stopped, and a charger fault indication signal is output.

11. The method for detecting the capacitance value of a supercapacitor as described in claim 1, characterized in that, The charger is determined to be in normal charging state in response to a specific digital feedback signal received from the charger.

12. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the supercapacitor capacitance detection method as described in any one of claims 1 to 11.

13. A controller, characterized in that, The controller includes: processor; and A memory storing a computer program that, when executed by a processor, implements the supercapacitor capacitance detection method as described in any one of claims 1 to 11.

14. A wind turbine generator set, characterized in that, The wind turbine generator set includes the controller as described in claim 13.

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