A method for monitoring and protecting the rotation speed of a wind turbine generator set

Abstract

The present invention relates to the technical field of rotational speed monitoring of wind turbines, and specifically discloses a method for monitoring and protecting the rotational speed of a wind turbine, which specifically includes the following steps: obtaining the maximum allowable rotational speed ω before the unit is connected to the grid max , the protection action rotational speed ω pro , the protection action delay t pro ; according to the parameters of the unit, obtaining the relational expression θ = g(v), and obtaining the minimum wind speed v min for protection action; collecting the wind speed v act , and converting it to the wind speed v sta under the standard air density; obtaining the corresponding minimum pitch angle θ act at the wind speed v min ; setting that when starting the machine, the pitch angle is restricted to be not less than the minimum pitch angle θ min ; monitoring and comparison: comparing v sta with the minimum wind speed v min for protection action; according to the wind speed comparison situation, comparing the actually measured rotational speed ω rot with the protection action rotational speed ω pro ; according to the rotational speed comparison situation, judging whether the actually measured rotational speed ω rot is abnormal, and if so, triggering protection shutdown. The present invention can ensure that there is no overspeed risk before the unit is connected to the grid, and can timely detect the abnormalities existing in the rotational speed acquisition system, ensuring the safety of the unit.

Description

Technical Field

[0001] The present invention relates to the technical field of wind generator rotation monitoring and protection, and more specifically, to a wind generator set rotation speed monitoring and protection method. Background Art

[0002] For wind turbines, the rotor speed is one of the most important state variables. The grid connection control, blade angle control, overspeed protection, etc. of the unit are all based on the measured speed. In particular, the overspeed protection of the unit is directly related to the safety of the unit.

[0003] For direct-drive wind turbines, two speed measurement systems are generally configured, one is a direct speed measurement system based on a slip ring encoder installed on the central axis of the wind rotor, and the other is a speed measurement system based on the calculation of the electromagnetic characteristics of the stator side of the permanent magnet generator by the converter. Although the speed calculated by the converter is very accurate after the generator is connected to the grid, the speed error calculated by the converter is very large at low speeds before the grid is connected. Therefore, the current mainstream control speed usage method is: use the speed directly measured by the encoder before the grid is connected, and use the speed calculated by the converter after the grid is connected, or use one of the two.

[0004] After grid connection, if there is a problem with the speed calculation of the converter, it means that there is a problem with the grid-related variables collected by the converter, which will cause problems in the converter's use of these variables for grid control, and ultimately will inevitably lead to converter errors and unit protection shutdown. However, before grid connection, if there is a significant deviation in the speed measurement at this time or the speed is not detected for some reason, such as the slip ring encoder is damaged or broken, since the speed detected by the main control system = 0rpm or is too low, the main control system will continue to control the variable pitch system to open the propeller to increase the speed until the actual speed has exceeded the speed, but the unit's overspeed protection cannot be protected because it cannot receive the actual speed, which eventually leads to a runaway accident. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a wind turbine generator speed monitoring and protection method, which can ensure that the unit has no overspeed risk before grid connection, and can promptly detect abnormalities in the speed acquisition system to ensure the safety of the unit operation.

[0006] The solution adopted by the present invention to solve the technical problem is:

[0007] A method for monitoring and protecting the rotation speed of a wind turbine generator set comprises the following steps:

[0008] Step A: Obtain the maximum allowable speed ω before the unit is connected to the grid max , protection action speed ω pro , protection action delay t pro ;

[0009] Step B: According to the parameters of the unit, the relationship θ = g(v) is obtained, and the minimum wind speed v for protection action is obtained min ;

[0010] Step C: Collect wind speed v act , convert it to the wind speed v under standard air density sta ;

[0011] Step D: Find the wind speed v act The corresponding minimum blade angle θ min ; When setting the start-up, the limited variable pitch angle is not less than the minimum pitch angle θ min ;

[0012] Step E: monitoring and comparison;

[0013] The wind speed v under standard air density sta Minimum wind speed v for protection action min Compare; according to the wind speed comparison, the actual measured speed ω rot And protection action speed ω pro Compare; according to the speed comparison, determine the actual measured speed ω rot Check whether there is any abnormality. If so, a protection shutdown is triggered.

[0014] In some possible implementations, the maximum allowable speed ω before grid connection in step B is max The corresponding blade angle θ is calculated as follows:

[0015]

[0016] Among them, ρ0 is the standard air density;

[0017] S is the wind swept area of ​​the wind wheel;

[0018] v is the wind speed under standard air density;

[0019] C p is the wind energy absorption coefficient;

[0020] λ is the tip speed ratio;

[0021] Mω max Drag the unit to idle for wind energy max Power required;

[0022] R is the wind swept radius of the wind wheel.

[0023] In some possible implementations, the specific calculation method of step C is:

[0024]

[0025] Where ρ is the current air density.

[0026] In some possible implementations, the maximum allowable speed before grid connection ω max Set to 0.9-1.0 times the hardware overspeed of the unit.

[0027] In some possible implementations, the protection action speed ω of the unit before grid connection pro Set to 0.5-1.0 times the grid-connected speed of the unit.

[0028] In some possible implementations, the wind speed v at standard air density is sta Use the 30s average value and multiply it by the safety factor for calculation. The safety factor is between 1.0 and 1.2.

[0029] In some possible implementations, the step E specifically refers to:

[0030] If v sta <v min , does not trigger protection shutdown;

[0031] If v sta ≥v min , but does not satisfy the actual speed ω rot <Protection action speedω pro , and the duration exceeds the protection action delay t pro When , the protection shutdown is not triggered;

[0032] If v sta ≥v min , and at the same time satisfy the actual speed ω rot <Protection action speedω pro , and the duration exceeds the protection action delay t pro When the protection shutdown is triggered.

[0033] In some possible implementations, in step E:

[0034] When v sta <v min When , execute step E1:

[0035] If the unit is not connected to the grid, repeat steps B to E and continue monitoring;

[0036] Otherwise, exit monitoring and protection;

[0037] When v sta ≥v min When , execute step E2:

[0038] If the actual speed ω rot <Protection action speedω pro, and the duration exceeds the protection action delay t pro , triggering protection shutdown;

[0039] Otherwise, continue to step E1.

[0040] In some possible implementations, in step D, the wind speed v is obtained. act The corresponding minimum blade angle θ min , specifically refers to the wind speed v converted to the standard air density sta Substituting into formula (3), the calculated speed is the maximum allowable speed before grid connection ω max The minimum blade angle θ corresponding to min When multiple values ​​are obtained, the minimum blade angle θ min Take the maximum value.

[0041] In some possible implementations, in step B, when the relationship θ=g(v) is solved to obtain a unique value, the corresponding wind speed is the minimum wind speed v for the protection action. min .

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The present invention can ensure that there is no risk of overspeeding of the unit before grid connection, and can timely discover abnormalities in the speed acquisition system to ensure the safety of the unit;

[0044] The present invention can ensure that when a problem occurs in the wind wheel speed measurement system of the unit, the unit has no risk of overspeed, thereby ensuring the safety of the unit and being able to detect problems in advance and trigger a protective shutdown;

[0045] Compared with the prior art, the present invention is easier to implement and can be implemented in a main controller without increasing hardware costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a flowchart of the workflow of the present invention; DETAILED DESCRIPTION

[0047] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral body; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. The "first", "second" and similar words mentioned in this application do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, "one" or "one" and other similar words do not indicate a quantity restriction, but indicate the existence of at least one. In the implementation of this application, "and / or" describes the association relationship of the associated objects, indicating that there can be three relationships, for example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In the description of the embodiments of the present application, unless otherwise specified, the meaning of "multiple" refers to two or more. For example, multiple positioning columns refer to two or more positioning columns. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] The present invention is described in detail below.

[0049] like Figure 1 As shown:

[0050] A method for monitoring and protecting the rotation speed of a wind turbine generator set comprises the following steps:

[0051] Step A: Obtain the maximum allowable speed ω before the unit is connected to the grid max , protection action speed ω pro , protection action delay t pro ;

[0052] Step B: According to the parameters of the unit, the relationship θ = g(v) is obtained, and the minimum wind speed v for protection action is obtained min In step B, when the relationship θ=g(v) is solved to obtain a unique value, the corresponding wind speed is the minimum wind speed v for protection action. min .

[0053] The maximum permissible speed ω before grid connection in step B max The corresponding blade angle θ is the wind energy used to drag the unit to ω when idling. max Required power, tip speed ratio, wind speed v act The minimum blade angle θ is calculated, and the specific calculation method is:

[0054]

[0055] Among them, ρ0 is the standard air density;

[0056] S is the wind swept area of ​​the wind wheel;

[0057] v is the wind speed under standard air density;

[0058] C p is the wind energy absorption coefficient;

[0059] λ is the tip speed ratio;

[0060] Mω max Drag the unit to idle for wind energy max Power required;

[0061] R is the wind swept radius of the wind wheel.

[0062] Step C: Collect wind speed v act , convert it to the wind speed v under standard air density sta , the specific calculation method is:

[0063]

[0064] Where ρ is the current air density.

[0065] Step D: Find the wind speed v act The corresponding minimum blade angle θ min ; When setting the start-up, the limited variable pitch angle is not less than the minimum pitch angle θ min ;

[0066] In step D, find the wind speed v act The corresponding minimum blade angle θ min , specifically refers to the collected wind speed v act Wind speed v converted to standard air density sta Substituting into formula (3), the calculated speed is the maximum allowable speed before grid connection ω max The minimum blade angle θ corresponding to min When multiple values ​​are obtained, the minimum blade angle θ min Take the maximum value.

[0067] Step E: Monitoring and comparison:

[0068] The wind speed v under standard air density sta Minimum wind speed v for protection action min Compare; according to the wind speed comparison, the actual measured speed ω rot And protection action speed ω pro Compare; according to the speed comparison, determine the actual measured speed ω rot Check whether there is any abnormality. If so, a protection shutdown is triggered.

[0069] The step E specifically refers to:

[0070] If v sta <v min , does not trigger protection shutdown;

[0071] If v sta ≥v min , but does not satisfy the actual speed ω rot <Protection action speedω pro , and the duration exceeds the protection action delay t pro When , the protection shutdown is not triggered;

[0072] If v sta ≥v min , and at the same time satisfy the actual speed ω rot <Protection action speedω pro , and the duration exceeds the protection action delay t pro When the protection shutdown is triggered.

[0073] In step E:

[0074] When v sta <v min When , execute step E1:

[0075] If the unit is not connected to the grid, repeat steps B to E and continue monitoring;

[0076] Otherwise, exit monitoring and protection;

[0077] When v sta ≥v min When , execute step E2:

[0078] If the actual speed ω rot <Protection action speedω pro , and the duration exceeds the protection action delay t pro , triggering protection shutdown;

[0079] Otherwise, continue to step E1.

[0080] That is, in step E: when v sta <v min When , execute step E1;

[0081] Step E1: If the unit is not connected to the grid, repeat steps B to D and continue monitoring;

[0082] Otherwise: When the unit is connected to the grid, exit monitoring and protection.

[0083] In some possible implementations, in step E, when v sta ≥v min When , execute step E2;

[0084] Step E2: If the actual speed ω rot <Protection action speedω pro , and the duration exceeds the protection action delay t pro , triggering protection shutdown;

[0085] otherwise:

[0086] When the actual speed ω rot >Protection action speedω pro ;

[0087] Or the actual speed ω rot <Protection action speedω pro , but the delay does not exceed the protection action delay t pro hour;

[0088] Continue to execute step E1.

[0089] For example, the actual parameter settings are as follows: The maximum allowable speed of the unit before grid connection ω max =10rpm, protection action speed before the unit is connected to the grid ω pro =3rpm, the protection action wind speed v is calculated min =5m / s;

[0090] When the actual collected wind speed is converted to v under standard air density sta =4m / s. At this time, no matter where the blade angle is, because the wind energy is not enough, the actual speed of the wind wheel ω rot It is impossible to reach 10rpm, so there is no risk of overspeed and no need to limit the propeller angle (that is, there is no minimum propeller angle θ min , and no need to limit the blade angle), and no need to activate the protection logic;

[0091] When the actual collected wind speed is converted to v under standard air density sta =8m / s, due to the minimum blade angle θ min Restrictions are imposed, such as the minimum blade angle θ min =20°, the main control no longer allows the variable pitch angle to be smaller, which is equivalent to limiting the wind energy. The energy corresponding to this pitch angle is at most the actual speed of the wind wheel ω rot The maximum permissible speed before the unit is connected to the grid is 10 rpm, thus avoiding the risk of overspeed. rot The protection action delay time t pro , actual speed ω rot If it still cannot reach 3m / s, it indicates that there is a problem with the speed acquisition, triggering a protection shutdown.

[0092] In some possible implementations, the maximum allowable speed before grid connection ω maxSet to 0.9-1.0 times the hardware overspeed of the unit;

[0093] In some possible implementations, the protection action speed ω of the unit before grid connection pro Set to 0.5-1.0 times the grid-connected speed of the unit;

[0094] In some possible implementations, the wind speed v at standard air density is sta The above calculation is performed by using the 30s average value multiplied by the safety factor, and the safety factor is between 1.0 and 1.2. The reason why the 30s average value is used for calculation is that, on the one hand, the influence of turbulence on wind speed causes large fluctuations in instantaneous wind speed, and on the other hand, because the wind rotor has a large moment of inertia, the instantaneous wind speed cannot instantly increase the speed. Therefore, using the 30s average value can better represent the energy of the wind in the short term, and it is more reasonable to use it for calculation;

[0095] For the above maximum allowable speed before grid connection ω max 、Protection action speed before unit is connected to the gridω pro , wind speed v under standard air density sta The purpose of this setting is to prevent the protection from being too sensitive and causing false triggering, resulting in inaccurate monitoring.

[0096] By using the present invention, it can be ensured that when a problem occurs in the wind wheel speed measurement system of the unit, the unit has no risk of overspeed, thereby ensuring the safety of the unit and being able to discover problems in advance to trigger a protective shutdown; the monitoring is relatively convenient using the present invention, and it can be achieved by adding the method of the present invention to the main controller without increasing hardware costs.

[0097] The method of the present application can also be extended to all operating conditions of wind turbines. However, considering that if there is a problem with the converter calculating the rotational speed after grid connection, it will inevitably lead to a converter error and trigger the unit protection shutdown. Therefore, the method of the present application may not be extended.

[0098] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A method for monitoring and protecting the rotation speed of a wind turbine generator set, characterized in that: The specific steps include: Step A: Obtain the maximum allowable speed ω before the unit is connected to the grid max , protection action speed ω pro , protection action delay t pro ; Step B: According to the parameters of the unit, the relationship θ = g(v) is obtained, and the minimum wind speed v for protection action is obtained min ; The maximum permissible speed ω before grid connection in step B max The corresponding blade angle θ is calculated as follows: Among them, ρ0 is the standard air density; S is the wind swept area of ​​the wind wheel; v is the wind speed under standard air density; C p is the wind energy absorption coefficient; λ is the tip speed ratio; Mω max Drag the unit to idle for wind energy max Power required; R is the wind sweep radius of the wind wheel; When the relationship θ=g(v) is solved to obtain a unique value, the corresponding wind speed is the minimum wind speed v for protection action. min ; Step C: Collect wind speed v act , convert it to the wind speed v under standard air density sta ; Step D: Find the wind speed v act The corresponding minimum blade angle θ min ; When setting the start-up, the limited variable pitch angle is not less than the minimum pitch angle θ min ; Step E: Monitoring and comparison: The wind speed v under standard air density sta Minimum wind speed v for protection action min Compare; according to the wind speed comparison, the actual measured speed ω rot And protection action speed ω pro Compare; according to the speed comparison, determine the actual measured speed ω rot Whether there is an abnormality, if so, triggering a protection shutdown; the step E specifically refers to: If v sta <v min , does not trigger protection shutdown; If v sta ≥v min , but does not satisfy the actual speed ω rot <Protection action speedω pro , and the duration exceeds the protection action delay t pro When , the protection shutdown is not triggered; If v sta ≥v min , and at the same time satisfy the actual speed ω rot <Protection action speedω pro , and the duration exceeds the protection action delay t pro When the protection shutdown is triggered.

2. A method for monitoring and protecting the speed of a wind turbine generator set according to claim 1, characterized in that: The specific calculation method of step C is: Where ρ is the current air density.

3. A method for monitoring and protecting the rotation speed of a wind turbine generator set according to claim 1, characterized in that: The maximum permissible speed before grid connection ω max Set to 0.9-1.0 times the hardware overspeed of the unit.

4. A method for monitoring and protecting the rotation speed of a wind turbine generator set according to claim 3, characterized in that: The protection action speed ω of the unit before grid connection pro Set to 0.5-1.0 times the grid-connected speed of the unit.

5. A method for monitoring and protecting the rotation speed of a wind turbine generator set according to claim 4, characterized in that: Wind speed v at standard air density sta Use the 30s average value and multiply it by the safety factor for calculation. The safety factor is between 1.0 and 1.

2.

6. A method for monitoring and protecting the rotation speed of a wind turbine generator set according to claim 1, characterized in that: In step E: When v sta <v min When , execute step E1: If the unit is not connected to the grid, repeat steps B to E and continue monitoring; Otherwise, exit monitoring and protection; When v sta ≥v min When , execute step E2: If the actual speed ω rot <Protection action speedω pro , and the duration exceeds the protection action delay t pro , triggering protection shutdown; Otherwise, continue to step E1.

7. A method for monitoring and protecting the rotation speed of a wind turbine generator set according to claim 1, characterized in that: In step D, the wind speed v act The corresponding minimum blade angle θ min , specifically refers to the wind speed v under standard air density sta Substituting into formula (3), the calculated speed is the maximum allowable speed before grid connection ω max The minimum blade angle θ corresponding to min When multiple values ​​are obtained, the minimum blade angle θ min Take the maximum value.

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