Method and device for detecting a leak in an accumulator of a wind turbine generator

Abstract

The present disclosure provides a leakage detection method and device for an accumulator of a wind turbine. The leakage detection method comprises: in a starting stage of the wind turbine, acquiring in real time a loop hydraulic parameter of an accumulator of a hydraulic variable pitch system, an environmental temperature parameter of the accumulator, and a liquid volume parameter of a hydraulic pump of the hydraulic variable pitch system discharged since starting; estimating a gas mass parameter of the accumulator based on the real-time acquired loop hydraulic parameter, the environmental temperature parameter, and the liquid volume parameter; and determining that the accumulator leaks in a case where the gas mass parameter is lower than a first preset threshold.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of wind power generation in general, and more particularly, to a method and device for detecting leakage of an accumulator of a wind turbine. BACKGROUND

[0002] Energy is the main material basis of social economy and human life, and is the driving force of social development. However, the reserves of non-renewable energy such as oil, coal, and natural gas, which are the main pillars of the world's energy, are decreasing day by day. Therefore, all countries in the world are developing wind power generation. As a new energy source, wind power has formed a mature scale. A wind turbine (hereinafter, also referred to as a turbine) is a device that converts wind energy into electrical energy. The safety of the standby energy of a hydraulic variable pitch system, which is a widely used variable pitch system in large wind turbines, is crucial to the safety and power generation performance of the entire machine.

[0003] A detection device of a wind turbine is of great significance to the performance, reliability, and economy of the turbine. Existing detection devices cannot accurately diagnose the leakage of the accumulator of the hydraulic variable pitch system. If a device (e.g., a sensor) is added to directly detect the position of the accumulator piston, the cost will increase and the possibility of gas leakage will be higher. SUMMARY

[0004] An exemplary embodiment of the present disclosure provides a method and device for detecting leakage of an accumulator of a wind turbine, which can achieve high-accuracy diagnosis of the leakage of the accumulator without additional sensors.

[0005] According to a first aspect of an embodiment of the present disclosure, a method for detecting leakage of an accumulator of a wind turbine is provided, comprising: in a starting phase of the wind turbine, acquiring in real time a loop hydraulic parameter of an accumulator of a hydraulic variable pitch system, an environmental temperature parameter of the accumulator, and a liquid volume parameter of a hydraulic pump of the hydraulic variable pitch system that has been discharged since the start; based on the real-time acquired loop hydraulic parameter, environmental temperature parameter, and liquid volume parameter, estimating a gas mass parameter of the accumulator; and in the case that the gas mass parameter is lower than a first preset threshold, determining that the accumulator is leaking.

[0006] Optionally, the step of estimating the gas mass parameter of the accumulator based on the real-time acquired loop hydraulic parameter, environmental temperature parameter, and liquid volume parameter comprises: estimating a gas temperature parameter of the accumulator based on the real-time acquired environmental temperature parameter; estimating a gas volume parameter of the accumulator based on the real-time acquired liquid volume parameter; and estimating the gas mass parameter of the accumulator based on the real-time acquired loop hydraulic parameter, estimated gas temperature parameter, and gas volume parameter.

[0007] Optionally, the step of estimating the gas mass parameter of the accumulator based on the real-time acquired circuit hydraulic pressure parameter, the real-time estimated gas temperature parameter and the gas volume parameter comprises: estimating the gas mass parameter of the accumulator in real time by a Kalman filter based on the real-time acquired circuit hydraulic pressure parameter, the real-time estimated gas temperature parameter and the gas volume parameter.

[0008] Optionally, the Kalman filter is constructed based on the Benedict-Webb-Rubin equation of the circuit hydraulic pressure parameter, the gas temperature parameter and the gas volume parameter of the accumulator.

[0009] Optionally, the Kalman filter is an extended Kalman filter; and the step of estimating the gas mass parameter of the accumulator in real time by the Kalman filter based on the real-time acquired circuit hydraulic pressure parameter, the real-time estimated gas temperature parameter and the gas volume parameter comprises: obtaining the gas mass parameter estimated this time by the extended Kalman filter based on the gas mass parameter estimated last time by the extended Kalman filter, the currently acquired circuit hydraulic pressure parameter, the currently estimated gas volume parameter and the gas temperature parameter.

[0010] Optionally, the step of estimating the gas temperature parameter of the accumulator based on the real-time acquired ambient temperature parameter comprises: obtaining the gas temperature parameter estimated this time based on the volume and the pre-charge pressure of the accumulator, the gas temperature parameter estimated last time and the currently acquired ambient temperature parameter; and / or, the step of estimating the gas volume parameter of the accumulator based on the real-time acquired liquid volume parameter comprises: obtaining the gas volume parameter estimated this time based on the volume of the accumulator and the currently acquired liquid volume parameter.

[0011] Optionally, the leakage detection method further comprises: acquiring the circuit hydraulic pressure parameter of the accumulator in real time in the operation stage of the wind turbine generator set; and determining whether the accumulator leaks based on the amplitude-frequency characteristic of the real-time acquired circuit hydraulic pressure parameter.

[0012] Optionally, the amplitude-frequency characteristic comprises: an amplitude of a frequency segment lower than a preset frequency threshold.

[0013] Optionally, the step of determining whether the accumulator leaks based on the amplitude-frequency characteristic of the real-time acquired circuit hydraulic pressure parameter comprises: performing wavelet transform on the real-time acquired circuit hydraulic pressure parameter to obtain an approximation coefficient corresponding to a detail coefficient lower than the preset frequency threshold; and determining that the accumulator leaks in the case that the approximation coefficient is higher than a second preset threshold.

[0014] Optionally, the hydraulic variable pitch system comprises: an oil tank, a hydraulic pump, a hydraulic cylinder, a hydraulic valve group and an accumulator; and a piston of the hydraulic cylinder is connected to a blade bearing of the wind turbine generator set.

[0015] Optionally, the step of acquiring the circuit hydraulic parameter of the accumulator of the hydraulic variable pitch system, the environmental temperature parameter of the accumulator, and the liquid volume parameter of the hydraulic pump of the hydraulic variable pitch system discharged since starting in real time comprises: acquiring the circuit hydraulic parameter in real time through a pressure sensor installed on the accumulator circuit of the hydraulic variable pitch system; acquiring the environmental temperature parameter in real time through a temperature sensor installed in the wind turbine generator system; and acquiring the liquid volume parameter in real time based on the liquid flow rate delivered by the hydraulic pump.

[0016] According to a second aspect of the embodiments of the present disclosure, a leakage detection device for an accumulator of a wind turbine generator system is provided, comprising: a data acquisition unit configured to acquire, in a starting phase of the wind turbine generator system, a circuit hydraulic parameter of an accumulator of a hydraulic variable pitch system, an environmental temperature parameter of the accumulator, and a liquid volume parameter of a hydraulic pump of the hydraulic variable pitch system discharged since starting in real time; a gas mass estimation unit configured to estimate a gas mass parameter of the accumulator based on the circuit hydraulic parameter, the environmental temperature parameter, and the liquid volume parameter acquired in real time; and a leakage determination unit configured to determine that the accumulator leaks if the gas mass parameter is lower than a first preset threshold.

[0017] Optionally, the gas mass estimation unit is configured to estimate a gas temperature parameter of the accumulator based on the environmental temperature parameter acquired in real time, estimate a gas volume parameter of the accumulator based on the liquid volume parameter acquired in real time, and estimate the gas mass parameter of the accumulator based on the circuit hydraulic parameter acquired in real time, the estimated gas temperature parameter, and the estimated gas volume parameter.

[0018] Optionally, the gas mass estimation unit is configured to estimate the gas mass parameter of the accumulator in real time through a Kalman filter based on the circuit hydraulic parameter acquired in real time, the estimated gas temperature parameter, and the estimated gas volume parameter.

[0019] Optionally, the Kalman filter is constructed based on the Benedict-Rubin-Rubin equation about the circuit hydraulic parameter, the gas temperature parameter, and the gas volume parameter of the accumulator.

[0020] Optionally, the Kalman filter is an extended Kalman filter; and the gas mass estimation unit is configured to obtain the gas mass parameter estimated this time through the extended Kalman filter based on the gas mass parameter estimated last time through the extended Kalman filter, the circuit hydraulic parameter acquired currently, and the estimated gas volume parameter and gas temperature parameter currently.

[0021] Optionally, the gas mass estimation unit is configured to obtain the current estimated gas temperature parameter based on the volume and pre-charge pressure of the accumulator, the last estimated gas temperature parameter, and the current acquired ambient temperature parameter; and / or the gas mass estimation unit is configured to obtain the current estimated gas volume parameter based on the volume of the accumulator and the current acquired liquid volume parameter.

[0022] Optionally, the data acquisition unit is further configured to acquire the loop hydraulic parameter of the accumulator in real time in the operation phase of the wind turbine generator set; and the leakage determination unit is further configured to determine whether the accumulator leaks based on the amplitude-frequency characteristic of the loop hydraulic parameter acquired in real time.

[0023] Optionally, the amplitude-frequency characteristic includes an amplitude of a frequency segment lower than a preset frequency threshold.

[0024] Optionally, the leakage determination unit is configured to perform wavelet transform on the loop hydraulic parameter acquired in real time to obtain an approximation coefficient corresponding to a detail coefficient lower than the preset frequency threshold; and determine that the accumulator leaks when the approximation coefficient is higher than a second preset threshold.

[0025] Optionally, the hydraulic variable pitch system includes an oil tank, a hydraulic pump, a hydraulic cylinder, a hydraulic valve group, and an accumulator; and a piston of the hydraulic cylinder is connected to a blade bearing of the wind turbine generator set.

[0026] Optionally, the data acquisition unit is configured to acquire the loop hydraulic parameter in real time by a pressure sensor installed on the accumulator loop of the hydraulic variable pitch system, acquire the ambient temperature parameter in real time by a temperature sensor installed in the wind turbine generator set, and acquire the liquid volume parameter in real time based on the liquid flow delivered by the hydraulic pump.

[0027] According to a third aspect of the embodiments of the present disclosure, a computer readable storage medium storing instructions is provided, when the instructions are executed by a processor of an electronic device, the electronic device is enabled to perform the leakage detection method as described above.

[0028] According to a fourth aspect of the embodiments of the present disclosure, an electronic device is provided, which includes a processor and a memory storing computer executable instructions, when the computer executable instructions are executed by the processor, the processor is caused to perform the leakage detection method as described above.

[0029] The leakage detection method and device of the accumulator of the wind turbine generator set according to the exemplary embodiments of the present disclosure can realize high-accuracy diagnosis of the leakage of the accumulator without additional sensors. In addition, the leakage detection of the accumulator of the hydraulic variable pitch system can be realized in the starting stage and the running stage of the unit, that is, the leakage of the accumulator can be diagnosed in all working conditions with high accuracy.

[0030] In the following description, some aspects and / or advantages of the general inventive concept will be set forth and / or made apparent in combination with the accompanying drawings, and further aspects and / or advantages will be rendered obvious by consideration of the described embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0031] These and / or other aspects and advantages of the application will become apparent and more readily appreciated from the following detailed description, taken in conjunction with the accompanying drawings, in which:

[0032] Figure 1 A flow chart of a leakage detection method of an accumulator of a wind turbine generator set according to exemplary embodiments of the present disclosure is shown;

[0033] Figure 2 A structural schematic diagram of a hydraulic variable pitch system according to exemplary embodiments of the present disclosure is shown;

[0034] Figure 3 A flow chart of a method for estimating the gas mass parameter of an accumulator according to exemplary embodiments of the present disclosure is shown;

[0035] Figure 4 A flow chart of a leakage detection method of an accumulator of a wind turbine generator set in a running stage according to exemplary embodiments of the present disclosure is shown;

[0036] Figure 5 and Figure 6 A Bode plot of a transfer function at different pre-charging pressures of an accumulator according to exemplary embodiments of the present disclosure is shown;

[0037] Figure 7 A wavelet transform schematic diagram according to exemplary embodiments of the present disclosure is shown;

[0038] Figure 8 A structural block diagram of a leakage detection device of an accumulator of a wind turbine generator set according to exemplary embodiments of the present disclosure is shown. DETAILED DESCRIPTION

[0039] Reference will now be made in detail embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments will be explained by referring to the drawings in detail.

[0040] It should be noted that the terms "first", "second", and the like in the description and claims of the present disclosure and the foregoing drawings are used only to distinguish similar objects and do not necessarily have a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present disclosure described herein can be implemented in an order other than that illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0041] It should be noted herein that "at least one of a plurality" appearing in the present disclosure means that three types of alternatives are included, i.e., "any one of the plurality", "a combination of any multiple of the plurality", and "all of the plurality". For example, "including at least one of A and B" includes the following three alternatives: (1) including A; (2) including B; (3) including A and B. For another example, "performing at least one of step one and step two" means the following three alternatives: (1) performing step one; (2) performing step two; (3) performing step one and step two.

[0042] Figure 1 A flowchart of a leakage detection method of an accumulator of a wind turbine generator set according to an exemplary embodiment of the present disclosure is shown.

[0043] As an example, the leakage detection method of the accumulator of the wind turbine generator set according to the exemplary embodiment of the present disclosure can be performed by an electronic device with data processing capability, for example, the electronic device can be a hydraulic variable pitch system controller, a wind turbine generator set controller, a wind farm controller, and the present disclosure does not limit the embodiments.

[0044] The hydraulic variable pitch system mainly consists of an oil tank, a hydraulic pump, a hydraulic cylinder, a hydraulic valve group, and an accumulator. Figure 2 A structural schematic diagram of a hydraulic variable pitch system according to an exemplary embodiment of the present disclosure is shown. Exemplarily, the piston of the hydraulic cylinder is connected to the blade bearing to convert the linear motion made by the piston of the hydraulic cylinder when it is extended or retracted into the rotary motion of the blade bearing, and the blades of the wind turbine generator set are rotated under the driving of the blade bearing to realize variable pitch.

[0045] Referring to Figure 1 In step S101, during the starting stage (i.e., the starting stage) of the wind turbine generator set, the loop hydraulic parameter Ps of the accumulator of the hydraulic variable pitch system, the environmental temperature parameter Ta of the accumulator, and the liquid volume parameter Vp discharged by the hydraulic pump of the hydraulic variable pitch system since the start are acquired in real time.

[0046] As an example, the loop hydraulic parameter Ps of the accumulator of the hydraulic variable pitch system, the environmental temperature parameter Ta of the accumulator, and the liquid volume parameter Vp discharged by the hydraulic pump of the hydraulic variable pitch system since the start can be acquired by Figure 2The circuit hydraulic parameter Ps of the accumulator is acquired by the pressure sensor PI in the wind turbine generator set.

[0047] As an example, the ambient temperature parameter Ta of the accumulator can be acquired by a temperature sensor. For example, the temperature sensor can be arranged in the wind turbine generator set to detect the temperature in the wind turbine generator set.

[0048] As an example, at the start-up stage of the wind turbine generator set, as the hydraulic pump starts, the hydraulic pump starts to discharge liquid (e.g., hydraulic oil) from the oil tank to the circuit of the accumulator, i.e., the volume of the liquid discharged by the hydraulic pump starts to increase from 0 over time, and the amount of increase is proportional to the liquid flow rate q Figure 2 The liquid flow rate q p As an example, the volume of the liquid discharged by the hydraulic pump can be obtained by time integration of the liquid flow rate q p .

[0049] In step S102, the gas mass parameter mg of the accumulator is estimated based on the real-time acquired circuit hydraulic parameter, ambient temperature parameter, and liquid volume parameter.

[0050] Specifically, the gas mass parameter (i.e., the mass of the gas in the accumulator) of the accumulator is estimated in real time based on the real-time acquired circuit hydraulic parameter, ambient temperature parameter, and liquid volume parameter.

[0051] As an example, the unit of the gas mass parameter mg can be kg.

[0052] In step S103, if the gas mass parameter is lower than a first preset threshold, it is determined that the accumulator leaks.

[0053] As an example, the value of the first preset threshold can be set according to the gas mass of the accumulator when the actual accumulator leaks.

[0054] The present disclosure considers that the gas mass parameter mg does not change when the accumulator does not leak, and if the accumulator leaks, the gas mass parameter decreases, therefore, it is proposed to estimate the gas mass of the accumulator at the start-up stage of the wind turbine generator set to determine whether the accumulator leaks. Thus, the accumulator can be detected for leakage at the start-up of the wind turbine generator set, and no additional tools, fixtures, and processes are needed for detection.

[0055] Figure 3 A flow chart of a method for estimating the gas mass parameter of the accumulator according to an example embodiment of the present disclosure is shown.

[0056] Referring to Figure 3In step S201, the gas temperature parameter Tg of the accumulator is estimated based on the real-time acquired ambient temperature parameter.

[0057] Specifically, the gas temperature parameter (i.e., the temperature of the gas inside the accumulator) of the accumulator can be estimated in real time based on the real-time acquired ambient temperature parameter. As an example, the gas temperature parameter can be obtained based on the volume Va and the pre-charge pressure Ppc of the accumulator, the last estimated gas temperature parameter, and the currently acquired ambient temperature parameter.

[0058] As an example, the differential of the gas temperature parameter with respect to time can be estimated by formula (1)

[0059]

[0060] wherein the time constant C v represents the heat capacity parameter corresponding to the gas volume; h represents the heat conduction coefficient of the gas container, which is related to the material of the outer wall of the accumulator; and A represents the outer wall area of the gas container.

[0061] As an example, the time constant τ can be estimated based on the pre-charge pressure Ppc and the volume Va of the accumulator by formula (2):

[0062] τ≈0.3·10 -5 ·p pc V a 0.33 +86.2·V a 0.49 (2)

[0063] As an example, since the detection in the start-up stage is mainly for long-term detection, the change period of mg is generally in units of months, the relative temperature change can be considered as a constant, and the partial derivative of ps with respect to Tg is almost 0, so when the differential of the gas temperature parameter with respect to time is estimated by formula (1) , the part before the minus sign can be mainly considered, and the part after the minus sign can be ignored.

[0064] As an example, the gas temperature parameter Tg k-1 of the last estimation and the integral result of the time integration of calculated by formula (1) can be used to obtain the gas temperature parameter Tg k of the current estimation.

[0065] In step S202, the gas volume parameter Vg of the accumulator is estimated based on the real-time acquired liquid volume parameter.

[0066] Specifically, the gas volume parameter of the accumulator (i.e., the volume of the gas inside the accumulator, the volume of the accumulator gas chamber) can be estimated in real time based on the real-time acquired liquid volume parameter. As an example, the gas volume parameter Vg of the current estimation can be obtained based on the volume Va of the accumulator and the current acquired liquid volume parameter Vp.

[0067] Before the hydraulic pump is started, there is no hydraulic oil in the accumulator, and the initial value Vg0 of the gas volume parameter is equal to the volume Va of the accumulator. As the pump is started, the gas volume parameter starts to decrease from Va, and the amount of decrease is related to the liquid flow rate q delivered by the pump. p For example, the liquid flow rate q delivered by the pump can be determined based on the pump speed n and the pump displacement Vp, i.e., q = n * Vp. The differential of the gas volume parameter with respect to time is denoted as. Accordingly, the difference between the volume of the accumulator and the current acquired liquid volume parameter can be taken as the gas volume parameter of the current estimation, i.e., Vg = Va-Vp.

[0068] In step S203, the gas mass parameter of the accumulator is estimated based on the real-time acquired circuit hydraulic parameter, the estimated gas temperature parameter, and the gas volume parameter.

[0069] Specifically, the gas mass parameter of the accumulator can be estimated in real time based on the real-time acquired circuit hydraulic parameter, the estimated gas temperature parameter, and the gas volume parameter.

[0070] As an example, the gas mass parameter of the accumulator can be estimated in real time by a Kalman Filter (KF) based on the real-time acquired circuit hydraulic parameter, the real-time estimated gas temperature parameter, and the gas volume parameter. For example, the Kalman Filter used can be specifically an Extended Kalman Filter (EKF).

[0071] The Kalman Filter is an efficient optimal estimator (a set of mathematical equations) that provides a recursive computational method to obtain the gas mass parameter (i.e., the target variable) from the circuit hydraulic parameter, the gas temperature parameter, and the gas volume parameter (i.e., the intermediate variable) with noise.

[0072] As an example, the Kalman Filter can be constructed based on the Benedict-Webb-Rubin equation (BWR equation) about the circuit hydraulic parameter, the gas temperature parameter, and the gas volume parameter of the accumulator. In other words, the Kalman Filter obtains the estimated value of the gas mass parameter by filtering the BWR equation.

[0073] As an example, the form of the Benedict-Webb-Rubin equation can be as shown in equation (3):

[0074]

[0075] wherein A0, B0, C0, a, b, c, a, g, R represent characteristic constants of nitrogen, e represents the base of natural logarithm, Vg represents a gas volume parameter, mg represents a gas mass parameter, Tg represents a gas temperature parameter, and ps represents a circuit hydraulic parameter (i.e., a gas pressure parameter).

[0076] As an example, the step S203 can include: estimating the gas mass parameter this time by an extended Kalman filter based on the gas mass parameter estimated last time by the extended Kalman filter, the circuit hydraulic parameter currently acquired, the gas volume parameter and the gas temperature parameter currently estimated.

[0077] As an example, the EKF equation of the extended Kalman filter can be as shown in formula (4), and the mg can be iterated by formula (4).

[0078] Initialization (k = 0)

[0079]

[0080]

[0081] R = cov (V k ) = (10 5 [Pa]) 2

[0082] P0= 100 · Q

[0083] Prediction

[0084]

[0085]

[0086] Update

[0087]

[0088]

[0089]

[0090] P k|k = (I-K k C k )P k|k-1 (4)

[0091] As an example, represents a predicted state vector; represents the difference between the observed value y and the predicted value; P represents the state covariance matrix; Q represents the process noise matrix; A represents the state transition matrix; K represents the filter gain; R represents the measurement noise matrix; C represents the measurement matrix; I represents the identity matrix of the same dimension as the state vector; k represents the kth time.

[0092] As an example, Vg0represents the initial value of the gas volume parameter, which is generally the accumulator volume; Tg0represents the initial value of the gas temperature parameter, which is generally the initial ambient temperature of the accumulator; mg0represents the initial value of the gas mass parameter.

[0093] As an example, the specific form of the function f and the function g can be as shown in equation (5):

[0094]

[0095]

[0096] x(0)=x0 (5)

[0097] As an example,

[0098] The above exemplary embodiments are mainly used for accumulator leakage detection in the starting phase of the unit, in addition to this, the present disclosure also provides accumulator leakage detection in the operation of the unit, Figure 4 A flow chart of a leakage detection method for an accumulator in the operation phase of a wind turbine generator unit according to an exemplary embodiment of the present disclosure is shown.

[0099] Referring to Figure 4 In step S301, in the operation phase of the wind turbine generator unit, the loop hydraulic parameters of the accumulator are acquired in real time.

[0100] In step S302, based on the amplitude-frequency characteristics of the loop hydraulic parameters acquired in real time, it is determined whether the accumulator is leaking.

[0101] As an example, the amplitude-frequency characteristics can include but are not limited to: the amplitude of the frequency band below the preset frequency threshold. For example, the preset frequency threshold can be 0.1 MHz. It should be understood that the value of the preset frequency threshold can be set according to the actual situation and specific needs.

[0102] In fact, the expressions of δpsand δTgobtained by taking the partial derivative of equation (3) are as shown in equations (6) and (7).

[0103] Δp s =K pv ΔV g +K pt ΔT g (6)

[0104]

[0105] wherein,

[0106] Based on formula (6) and formula (7), a transfer function between the gas pressure parameter and the liquid flow is obtained as shown in formula (8).

[0107]

[0108] wherein,

[0109] It can be obtained by analysis that the amplitude-frequency characteristics of the transfer function are related to the pre-charge pressure Ppc, and the lower the pre-charge pressure is, the higher the amplitude-frequency gain of the transfer function is, as shown in formula (9). Figure 5 The present disclosure considers that the gas leakage of the accumulator is equivalent to a change in the pre-charge pressure, and this feature is mainly reflected in the amplitude-frequency gain change before 0.1 MHz, as shown in formula (10). Figure 6 Therefore, the present disclosure proposes to determine whether the accumulator is leaking based on the amplitude before 0.1 MHz of the gas pressure signal (i.e., the real-time obtained loop hydraulic parameter signal).

[0110] As an example, in order to obtain the amplitude-frequency characteristics of the gas pressure signal, the wavelet transform can be used to process the gas pressure signal, as shown in formula (9).

[0111]

[0112] wherein, ψ represents a scale function, φ represents a mother wavelet, a l represents the approximation coefficient of the lth level, which represents the low-frequency characteristics, i.e., the assignment feature, d j represents the detail coefficient of the jth level, i.e., the frequency feature, a l and d j can be obtained by using high-pass filters and low-pass filters with different cutoff frequencies on the measured signal, as shown in formula (9). Figure 7

[0113] As an example, step S302 can include: performing wavelet transform on the real-time obtained loop hydraulic parameter to obtain an approximation coefficient corresponding to a detail coefficient below a preset frequency threshold; and determining that the accumulator is leaking if the approximation coefficient is higher than a second preset threshold.

[0114] Specifically, the real-time obtained loop hydraulic parameter (i.e., the gas pressure signal) is subjected to wavelet transform to obtain each level of detail coefficient and each level of approximation coefficient, and if the ith level of detail coefficient d i is below a preset frequency threshold, then the approximation coefficient corresponding to the detail coefficient below the preset frequency threshold is the ith level of approximation coefficient a i , wherein i is an integer greater than 0.​

[0115] The disclosure proposes to determine the leakage of the accumulator according to the d i The corresponding a i The change of the amplitude of the gas pressure signal is determined, and if the value of ai is obviously increased, it represents that the pre-charging pressure is lowered, that is, the gas leaks (whether it is internal leakage or external leakage), so that the leakage of the accumulator can be determined.

[0116] According to the exemplary embodiments of the disclosure, the leakage of the accumulator is diagnosed by the existing hydraulic variable pitch sensor and operating information, the high-accuracy diagnosis of the leakage of the accumulator can be realized without additional sensors, and the leakage of the accumulator of the hydraulic variable pitch system can be detected in the starting stage and the running stage of the unit.

[0117] According to the exemplary embodiments of the disclosure, the following technical effects can be achieved: (1) the accumulator can be detected without changing the hydraulic system design; (2) the accumulator can be detected without additional actions of the variable pitch system; (3) the external leakage and the internal leakage can be detected at the same time; (4) the false alarm and false alarm probability of the detection is greatly reduced compared with the original pure pressure judgment.

[0118] Figure 8 A structural block diagram of a leakage detection device of an accumulator of a wind turbine generator set according to an exemplary embodiment of the disclosure is shown. As an example, the leakage detection device can be arranged in a hydraulic variable pitch system controller, a wind turbine generator set controller, and a wind farm controller, and the disclosure does not limit this.

[0119] As Figure 8 shown, the leakage detection device of the accumulator of the wind turbine generator set according to the exemplary embodiments of the disclosure includes a data acquisition unit 101, a gas quality estimation unit 102, and a leakage determination unit 103.

[0120] Specifically, the data acquisition unit 101 is configured to acquire, in real time, a loop hydraulic parameter of an accumulator of a hydraulic variable pitch system, an environmental temperature parameter of the accumulator, and a liquid volume parameter of a hydraulic pump of the hydraulic variable pitch system discharged from the start in the starting stage of the wind turbine generator set.

[0121] The gas quality estimation unit 102 is configured to estimate a gas quality parameter of the accumulator based on the real-time acquired loop hydraulic parameter, the environmental temperature parameter, and the liquid volume parameter.

[0122] The leakage determination unit 103 is configured to determine that the accumulator leaks when the gas quality parameter is lower than a first preset threshold.

[0123] As an example, the gas mass estimation unit 102 can be configured to estimate a gas temperature parameter of the accumulator based on a real-time acquired ambient temperature parameter; estimate a gas volume parameter of the accumulator based on a real-time acquired liquid volume parameter; and estimate a gas mass parameter of the accumulator based on a real-time acquired circuit hydraulic parameter, the estimated gas temperature parameter and the gas volume parameter.

[0124] Optionally, the gas mass estimation unit 102 can be configured to estimate a gas mass parameter of the accumulator in real time by a Kalman filter based on a real-time acquired circuit hydraulic parameter, a real-time estimated gas temperature parameter and a gas volume parameter.

[0125] Optionally, the Kalman filter can be constructed based on a Benedict-Webb-Rubin equation about the circuit hydraulic parameter, the gas temperature parameter and the gas volume parameter of the accumulator.

[0126] Optionally, the Kalman filter is an extended Kalman filter; and the gas mass estimation unit 102 can be configured to obtain a current estimated gas mass parameter by the extended Kalman filter based on a last estimated gas mass parameter obtained by the extended Kalman filter, a current acquired circuit hydraulic parameter, a current estimated gas volume parameter and a gas temperature parameter.

[0127] Optionally, the gas mass estimation unit 102 can be configured to obtain a current estimated gas temperature parameter based on a volume of the accumulator and a pre-charging pressure, a last estimated gas temperature parameter and a current acquired ambient temperature parameter.

[0128] As an example, the gas mass estimation unit 102 can be configured to obtain a current estimated gas volume parameter based on a volume of the accumulator and a current acquired liquid volume parameter.

[0129] As an example, the data acquisition unit 101 can be further configured to acquire a circuit hydraulic parameter of the accumulator in real time in an operation stage of the wind turbine generator; and the leakage determination unit 103 can be further configured to determine whether the accumulator leaks based on a magnitude-frequency characteristic of the real-time acquired circuit hydraulic parameter.

[0130] As an example, the magnitude-frequency characteristic can include a magnitude of a frequency segment lower than a preset frequency threshold.

[0131] As an example, the leakage determination unit 103 can be configured to perform wavelet transform on the real-time acquired circuit hydraulic parameter to obtain an approximation coefficient corresponding to a detail coefficient lower than the preset frequency threshold; and determine that the accumulator leaks in a case where the approximation coefficient is higher than a second preset threshold.

[0132] As an example, the hydraulic pitch system can include, but is not limited to, an oil tank, a hydraulic pump, a hydraulic cylinder, a hydraulic valve group, and an accumulator; wherein a piston of the hydraulic cylinder is connected to a blade bearing of the wind turbine generator system.

[0133] As an example, the data acquisition unit 101 can be configured to acquire, in real time, a circuit hydraulic parameter through a pressure sensor installed on an accumulator circuit of the hydraulic pitch system; acquire, in real time, an environmental temperature parameter through a temperature sensor installed in the wind turbine generator system; and acquire, in real time, a liquid volume parameter based on a liquid flow delivered by the hydraulic pump.

[0134] It should be understood that the specific processes performed by the leakage detection device of the accumulator of the wind turbine generator system according to the exemplary embodiments of the present disclosure have been described in detail with reference to the accompanying drawings, and related details will not be repeated here. Figures 1 to 7 The detailed description has been made, and related details will not be repeated here.

[0135] It should be understood that each unit in the leakage detection device of the accumulator of the wind turbine generator system according to the exemplary embodiments of the present disclosure can be implemented by hardware components and / or software components. Those skilled in the art can implement each unit, for example, using a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC), according to the processes performed by each unit as defined.

[0136] The exemplary embodiments of the present disclosure provide a computer-readable storage medium storing instructions, which, when executed by a processor of an electronic device, enable the electronic device to perform the leakage detection method of the accumulator of the wind turbine generator system as described in the above exemplary embodiments. The computer-readable storage medium is any data storage device that can store data readable by a computer system. Examples of the computer-readable storage medium include a read-only memory, a random access memory, a read-only optical disc, a magnetic tape, a floppy disc, an optical data storage device, and a carrier wave such as data transmission through an internet via a wired or wireless transmission path.

[0137] The electronic device according to the exemplary embodiments of the present disclosure includes at least one processor; at least one memory storing computer executable instructions, wherein the computer executable instructions, when executed by the at least one processor, cause the at least one processor to perform the leakage detection method of the accumulator of the wind turbine generator system as described in the above exemplary embodiments. As an example, the electronic device can be a hydraulic pitch system controller, a wind turbine generator system controller, a wind farm controller, and the present disclosure embodiments are not limited thereto.

[0138] While certain example embodiments of the disclosure have been described and shown, it is understood that modifications will occur to those skilled in the art, without departing from the spirit and scope of the disclosure as defined by the following claims and their equivalents.

Claims

1. A method of detecting a leak of an accumulator of a wind turbine, characterized in that, The method comprises: During a starting phase of a wind turbine generator set, real-time acquisition of a loop hydraulic parameter of an accumulator of a hydraulic variable pitch system, an environmental temperature parameter of the accumulator, and a liquid volume parameter of a hydraulic pump of the hydraulic variable pitch system discharged since starting; Based on the real-time acquired loop hydraulic parameter, environmental temperature parameter, and liquid volume parameter, estimation of a gas mass parameter of the accumulator; In a case where the gas mass parameter is lower than a first preset threshold value, determination of a leak of the accumulator.

2. The leak detection method of claim 1, wherein, The step of estimating the gas mass parameter of the accumulator based on the real-time acquired loop hydraulic parameter, environmental temperature parameter, and liquid volume parameter comprises: Based on the real-time acquired environmental temperature parameter, estimation of a gas temperature parameter of the accumulator; Based on the real-time acquired liquid volume parameter, estimation of a gas volume parameter of the accumulator; Based on the real-time acquired loop hydraulic parameter, estimated gas temperature parameter, and gas volume parameter, estimation of the gas mass parameter of the accumulator.

3. The leak detection method of claim 2, wherein, The step of estimating the gas mass parameter of the accumulator based on the real-time acquired loop hydraulic parameter, estimated gas temperature parameter, and gas volume parameter comprises: Based on the real-time acquired loop hydraulic parameter, real-time estimated gas temperature parameter, and gas volume parameter, real-time estimation of the gas mass parameter of the accumulator by a Kalman filter.

4. The leak detection method of claim 3, wherein, The Kalman filter is constructed based on a Benedict-Ruth-Lewis equation about the loop hydraulic parameter, gas temperature parameter, and gas volume parameter of the accumulator.

5. The leak detection method of claim 3 or 4, wherein, The Kalman filter is an extended Kalman filter. The step of estimating the gas mass parameter of the accumulator based on the real-time acquired loop hydraulic parameter, real-time estimated gas temperature parameter, and gas volume parameter by the Kalman filter comprises: Based on the gas mass parameter estimated by the extended Kalman filter last time, the current acquired loop hydraulic parameter, the current estimated gas volume parameter, and the current estimated gas temperature parameter, the gas mass parameter estimated this time is obtained by the extended Kalman filter.

6. The leak detection method of claim 2, wherein, The step of estimating the gas temperature parameter of the accumulator based on the real-time acquired environmental temperature parameter comprises: based on the volume and pre-charge pressure of the accumulator, the gas temperature parameter estimated last time, and the current acquired environmental temperature parameter, the gas temperature parameter estimated this time is obtained. And / or, the step of estimating the gas volume parameter of the accumulator based on the real-time acquired liquid volume parameter comprises: based on the volume of the accumulator and the current acquired liquid volume parameter, the gas volume parameter estimated this time is obtained.

7. The leak detection method of claim 1, wherein, The hydraulic variable pitch system comprises: an oil tank, a hydraulic pump, a hydraulic cylinder, a hydraulic valve group, and an accumulator. The piston of the hydraulic cylinder is connected to a blade bearing of the wind turbine generator set.

8. The leak detection method of claim 1 or 7, wherein, The step of real-time acquisition of the loop hydraulic parameter of the accumulator of the hydraulic variable pitch system, the environmental temperature parameter of the accumulator, and the liquid volume parameter of the hydraulic pump of the hydraulic variable pitch system discharged since starting comprises: Real-time acquisition of the loop hydraulic parameter by a pressure sensor installed on the accumulator loop of the hydraulic variable pitch system; An environmental temperature parameter is acquired in real time by a temperature sensor installed in the wind turbine generator system; A liquid volume parameter is acquired in real time based on the liquid flow delivered by the hydraulic pump.

9. A leak detection device for an accumulator of a wind turbine generator system, characterized in that, Comprise: A data acquisition unit configured to acquire in real time, during a start-up phase of the wind turbine generator system, a circuit hydraulic parameter of an accumulator of a hydraulic variable pitch system, an environmental temperature parameter of the accumulator, a liquid volume parameter of a hydraulic pump of the hydraulic variable pitch system having been discharged since the start-up; A gas mass estimation unit configured to estimate a gas mass parameter of the accumulator based on the circuit hydraulic parameter, the environmental temperature parameter, and the liquid volume parameter acquired in real time; A leakage determination unit configured to determine that the accumulator leaks if the gas mass parameter is lower than a first preset threshold.

10. A computer-readable storage medium storing instructions, wherein, When the instructions are executed by a processor of an electronic device, the electronic device is enabled to perform the leakage detection method as claimed in any one of claims 1 to 8.

11. An electronic device, comprising: The electronic device comprises: A processor; A memory storing computer-executable instructions, Wherein the computer-executable instructions, when executed by the processor, cause the processor to perform the leakage detection method as claimed in any one of claims 1 to 8.

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