CN111237127A - A pitch control method for the black-start start-up process of an offshore wind turbine - Google Patents

Abstract

The invention discloses a variable pitch control method for a black start startup process of an offshore wind generating set, wherein in the process of increasing the rotating speed of a generator, the rotating speed Vz of a resonance generator is set, a region of Vz (1 +/-A%) is set as a resonance region, in order to ensure that the resonance region is passed through as soon as possible in the black start process, the resonance region is set as Vz (1 +/-B%), when the rotating speed VG of the generator is less than Vz x (1-B%), a given value VG1 of the rotating speed of the generator is a smaller value between the actual rotating speed VG + C and Vz x (1-B%) of the generator, and the obtained rotating speed VG1 of the generator sequentially passes through a rotating speed controller and a pitch angle controller to obtain a final pitch angle which is; when Vz (1-B%) < generator rotation speed VG < Vz (1+ B%), the given value VG2 of the generator rotation speed is a small value between the actual rotation speed VG + D of the generator and the actual rotation speed Vz (1+ B%), and the obtained generator rotation speed VG2 is sequentially obtained through a rotation speed controller and a pitch angle controller, and is input to a pitch system to execute the propeller opening. The invention can safely start the propeller and start the machine on the basis of meeting the requirement of black start control.

Description

A pitch control method for the black-start start-up process of an offshore wind turbine

technical field

The invention relates to the technical field of black start of offshore wind turbines, in particular to a pitch control method for the black start process of offshore wind turbines, which can safely start the paddles on the basis of satisfying the black start control requirements.

Background technique

Offshore wind resources are abundant. With the development of offshore wind power generation technology, more and more offshore wind farms will be built in the future. During the construction of the offshore wind farm or during the grid failure of the wind farm, the offshore wind turbine will be in an island state, and the unit's own uninterruptible power supply cannot guarantee the long-term power supply inside the wind turbine. Self-dehumidification, anti-salt spray and mechanical lubrication will cause irreversible damage to electrical equipment and mechanical components.

The existing patent 201910154245.2 proposes a method for controlling the start-up process of an offshore wind turbine black-start unit. However, the patent does not mention in detail how the pitch control is performed during the start-up process.

In addition, wind speed changes, impeller overspeed, tower resonance area and power loss factors during black start need to be considered during black start to ensure that wind turbines quickly reach a self-sufficient state of power supply in a safe state.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art, and proposes a pitch control method for the black-start start-up process of the offshore wind power generating set, which can make the wind power generating set run out under the safe condition of the wind power generating set during the black-starting process. In a short period of time, the generator speed can cross the resonance area as soon as possible to reach the target speed required by the black start, and realize the self-sufficiency of the power supply of the wind turbine.

In order to achieve the above purpose, the technical solution provided by the present invention is: a pitch control method for the black start-up process of an offshore wind turbine, the method is to set a resonant generator in the process of increasing the rotational speed of the generator of the wind turbine. Speed Vz, set the area of Vz (1±A%) as the resonance area, where A is 10; in order to ensure that the resonance area is crossed as soon as possible during the black start, take the resonance area as Vz (1±B%), that is, the resonance area The lower limit is Vz×(1-B%), and the upper limit is Vz×(1+B%), where A<B, the specific value of B is based on the pitch system of the wind turbine when it starts black-start. Open paddle test confirmed;

When the generator speed VG<Vz×(1-B%), the generator speed given value VG1 is the smaller value between the actual generator speed VG+C and Vz×(1-B%), that is, VG1= min(VG+C, Vz×(1-B%)), the obtained generator speed VG1 is passed through the speed controller to obtain the pitch angle given value θ ₁ , and then the pitch angle given value θ ₁ is passed through the pitch angle The angle controller obtains the final pitch angle, and inputs it to the pitch system of the wind turbine to perform pitch opening;

When Vz×(1-B%)<generator speed VG<Vz×(1+B%), the generator speed given value VG2 is the sum of the generator actual speed VG+D and Vz×(1+B%) The smaller value between the two, namely VG2=min(VG+D, Vz×(1+B%)), the obtained generator speed VG2 is obtained through the speed controller to obtain the pitch angle given value θ ₂ , and then the pitch angle The angle given value θ ₂ is obtained through the pitch angle controller to obtain the final pitch angle, and is input to the pitch system of the wind turbine to perform propeller opening;

In the formula, C and D are two reference quantities and C < D. The values of C and D should be taken into account during the black start period to bring the pitch system to the open state as soon as possible and not to retreat. The specific values are determined by the pitch system test.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. By controlling the speed of the generator, it is ensured that the speed of the generator passes through the resonance zone as soon as possible during the black start.

2. In the case of limited electric energy of the wind turbine, control the pitch to only open the propeller or not to operate, so as to reduce the power loss and start the machine safely.

3. It can effectively prevent the damage of offshore wind turbines under power grid failure, and improve the reliability of offshore wind turbines.

Description of drawings

Fig. 1 is the principle block diagram of pitch control.

Figure 2 is a schematic diagram of the resonance region.

Fig. 3 is the flow chart of generator set value calculation.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments.

The main components of wind turbines include permanent magnet generators, gearboxes, blades, impellers, towers, main control systems, pitch systems, full power converters, step-up transformers, low-voltage cabinets, and high-voltage ring network cabinets. When the wind turbine is in the shutdown state, the pitch angle is generally at 89 degrees or 90 degrees, and the airflow does not produce torque on the blades; when the wind turbine is in the shutdown state, the pitch angle is 89 degrees or 90 degrees is reduced to the standby angle at a certain speed. The main control system of the wind turbine will perform pitch control according to the rotational speed of the generator. As can be seen from Figure 1, the pitch control can be indirectly performed by controlling the rotational speed of the generator.

Secondly, the following factors need to be paid attention to in the process of opening the propeller and speeding up:

1. In the case of using uninterruptible power supply and limited electric energy, the actions of each actuator of the unit should minimize unnecessary actions and reduce electric energy loss while ensuring the safety of the whole machine.

For the pitch system, in order to reduce the power loss, only open the propeller should be performed or no action should be performed during the speed-up process of the propeller, and the propeller should be retracted only when it is judged that the impeller is overspeeding or the unit is faulty.

2. For the 3P coupling between the first-order natural frequency of the tower and the blade passing frequency during the start-up process of the wind turbine, the resonant speed zone of the generator should be set according to the natural frequency of the tower during the speed-up process. In the speed zone, the propellers should be controlled to open the propeller to increase the generator speed so that the generator speed quickly crosses the upper limit of the resonance zone, so as to avoid the risk of tower collapse caused by the resonance of the tower caused by frequency coupling.

3. In the process of increasing the speed, the wind speed change should be considered to reasonably control the propeller opening, to ensure that the control of the generator speed and the generator speed acceleration is within a safe range, and to avoid the impeller speed overspeeding or running out of control.

Therefore, to sum up, the specific conditions of the pitch control method for the black start process of the offshore wind turbine generator set provided by the present invention are as follows:

In the process of increasing the generator speed, the resonant generator speed Vz is set, and the region of Vz (1±A%) is set as the resonance region, and the value of A is usually 10. In order to ensure that the resonance region is crossed as soon as possible during the black start, the resonance region is taken as Vz (1±B%), that is, the lower limit of the resonance region is Vz×(1-B%), and the upper limit is Vz×(1+B%) , where A<B, the specific value of B is determined according to the pitch-opening test of the pitch system of the wind turbine when it is black-started, and the resonance area is set as shown in Figure 2.

As shown in Figure 3, when the generator speed VG<Vz×(1-B%), the generator speed given value VG1 is the smaller between the actual generator speed VG+C and Vz×(1-B%) , namely VG1=min(VG+C, Vz×(1-B%)), the obtained generator speed VG1 is passed through the speed controller to obtain the pitch angle given value θ ₁ , and then the pitch angle given The value θ ₁ is obtained through the pitch angle controller to obtain the final pitch angle, and is input to the pitch system to perform pitch opening. When Vz×(1-B%)<generator speed VG<Vz×(1+B%), the generator speed given value VG2 is the sum of the generator actual speed VG+D and Vz×(1+B%) The smaller value between the two, namely VG2=min(VG+D, Vz×(1+B%)), the obtained generator speed VG2 is obtained through the speed controller to obtain the pitch angle given value θ ₂ , and then the pitch angle The angle given value θ ₂ is obtained through the pitch angle controller to obtain the final pitch angle, and is input to the pitch system to perform pitch opening.

In the formula, C and D are two reference quantities and C<D. The values of C and D should be taken into account during the black start period to bring the pitch system to the open state as soon as possible and not to retreat. The specific value is determined by the pitch system test.

The above-mentioned embodiments are only preferred embodiments of the present invention, and are not intended to limit the scope of implementation of the present invention. Therefore, any changes made according to the shape and principle of the present invention should be included within the protection scope of the present invention.

Claims (1)

1. a pitch control method for a black start start-up process of an offshore wind turbine, it is characterized in that: the method is in the generator rotational speed rising process of the wind turbine, setting the resonant generator rotational speed Vz, setting Vz (1 The area of ±A%) is the resonance area, where A is 10; in order to ensure that the black start period passes through the resonance area as soon as possible, the resonance area is taken as Vz (1±B%), that is, the lower limit of the resonance area is Vz×(1 -B%), the upper limit is Vz×(1+B%), where A<B, the specific value of B is determined according to the pitch-opening test of the pitch system of the wind turbine when it is black-started; When the generator speed VG<Vz×(1-B%), the generator speed given value VG1 is the smaller value between the actual generator speed VG+C and Vz×(1-B%), that is, VG1= min(VG+C, Vz×(1-B%)), the obtained generator speed VG1 is passed through the speed controller to obtain the pitch angle given value θ ₁ , and then the pitch angle given value θ ₁ is passed through the pitch angle The angle controller obtains the final pitch angle and inputs it to the pitch system to open the pitch; When Vz×(1-B%)<generator speed VG<Vz×(1+B%), the generator speed given value VG2 is the sum of the generator actual speed VG+D and Vz×(1+B%) The smaller value between the two, namely VG2=min(VG+D, Vz×(1+B%)), the obtained generator speed VG2 is obtained through the speed controller to obtain the pitch angle given value θ ₂ , and then the pitch angle The angle given value θ ₂ is obtained through the pitch angle controller to obtain the final pitch angle, and is input to the pitch system of the wind turbine to perform propeller opening; In the formula, C and D are two reference quantities and C < D. The values of C and D should be taken into account during the black start period to bring the pitch system to the open state as soon as possible and not to retreat. The specific values are determined by the pitch system test.

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