CN202215429U - Control system of differential gear box speed regulation type synchronous wind generating set - Google Patents

Abstract

The utility model discloses a control system of a differential gearbox speed regulating synchronous wind turbine generator set, comprising a wind wheel, a conventional three-stage transmission gearbox, a gearbox differential output stage, a servo motor output transmission gear pair, a servo motor, a frequency converter, a transformer, a conventional synchronous generator and a power grid, wherein the wind wheel is connected to the conventional three-stage transmission gearbox, the conventional three-stage transmission gearbox is respectively connected to the gearbox differential output stage and the servo motor output transmission gear pair, the servo motor output transmission gear pair, the servo motor, the frequency converter and the transformer are connected in sequence, the gearbox differential output stage is connected to the conventional synchronous generator, and the transformer and the conventional synchronous generator are respectively connected to the power grid. The technical solution of the utility model is adopted to enable the wind turbine generator set to operate at an optimal blade tip speed ratio within a widest possible operating wind speed range, so that the wind turbine generator set can capture more wind energy.

Description

A control system of a synchronous wind turbine generator with speed regulation by a differential gearbox

technical field

The utility model relates to the technical field of wind power generation, in particular to a control system of a synchronous wind power generating set with speed regulation by a differential gear box.

Background technique

At present, wind turbines use a gear box with a variable speed ratio in the transmission chain, that is, the speed ratio can be controlled according to requirements, so that the wind wheel can be operated at variable speeds as required, so that the gear box The dragged generator runs at a constant speed. This ability is achieved by adding a differential planetary stage to the output of the conventional gearbox, and the sun gear of this stage is driven by a servo motor to achieve a variable speed ratio. In this way, the wind turbine can use a conventional synchronous generator to realize variable-speed and constant-frequency operation of the wind turbine. With the increasing proportion of wind turbines in the grid, the grid has higher and higher requirements on the power generation performance of the wind turbines connected to the grid. These performances include low-voltage ride-through capability, the ability of the unit to support reactive power of the grid, and voltage waveform distortion.

Utility model content

The purpose of this utility model is to propose a control system of a synchronous wind power generating set with differential gear box speed regulation, so that the wind generating set can operate at the best blade tip speed ratio in the widest possible operating wind speed range, so that wind power can generate electricity The unit can capture more wind energy.

For this purpose, the utility model adopts the following technical solutions:

A control system for a synchronous wind power generating set with speed regulation by a differential gearbox, including a wind wheel, a conventional three-stage transmission gearbox, a differential output stage of a gearbox, a servo motor output transmission gear pair, a servo motor, a frequency converter, and a transformer , Conventional synchronous generator and power grid, the wind wheel is connected with the conventional three-stage transmission gearbox, the conventional three-stage transmission gearbox is respectively connected with the differential output stage of the gearbox and the output transmission gear pair of the servo motor, the output transmission gear pair of the servo motor, The servo motor, the frequency converter and the transformer are connected in sequence, the differential output stage of the gearbox is connected to the conventional synchronous generator, and the transformer and the conventional synchronous generator are respectively connected to the power grid.

It also includes a torque measuring mechanism and a torque differential controller, the torque measuring mechanism and the torque differential controller are respectively connected with the servo motor.

It also includes a power measuring unit and a generator power differentiator, which are respectively connected with the servo motor.

Also includes pitch controller.

Adopting the technical scheme of the utility model, by adopting different control strategies in three different areas, the generator set can be operated at the best blade tip speed ratio in the widest possible operating wind speed range, so that the generator set can Capture more wind energy.

Description of drawings

Fig. 1 is a structural schematic diagram of a control system of a differential gearbox speed-regulating type synchronous wind power generating set in a specific embodiment of the utility model.

Detailed ways

The technical scheme of the utility model will be further described below in conjunction with the accompanying drawings and through specific embodiments.

Fig. 1 is a structural schematic diagram of a control system of a differential gearbox speed-regulating type synchronous wind power generating set in a specific embodiment of the utility model. As shown in Figure 1, the control system of the differential gearbox speed-adjustable synchronous wind turbine includes a wind wheel 1, a conventional three-stage transmission gearbox 2, a differential output stage 3 of the gearbox, and a servo motor output transmission gear pair 4. Servo motor 5, frequency converter 6, transformer 7, conventional synchronous generator 8 and power grid 9.

Among them, the wind wheel is connected with the conventional three-stage transmission gearbox, and the conventional three-stage transmission gearbox is respectively connected with the differential output stage of the gearbox and the output transmission gear pair of the servo motor, the output transmission gear pair of the servo motor, the servo motor, the frequency converter and the transformer Connected in sequence, the differential output stage of the gearbox is connected with the conventional synchronous generator, and the transformer and the conventional synchronous generator are respectively connected to the power grid.

It may also include a torque measuring mechanism and a torque differential controller, and the torque measuring mechanism and the torque differential controller are respectively connected with the servo motor. It may also include a power measurement unit and a power differentiator of the generator, and the power measurement unit and the power differentiator of the generator are respectively connected with the servo motor.

It can also include a pitch controller, which is used to change the pitch angle of the blades and limit the operation of the generator set at the rated power.

As shown in Figure 1, the technical principle of the control system of the differential gearbox speed-adjustable synchronous wind turbine is that the servo motor is controlled by the frequency converter in order to achieve the purpose of changing the gearbox speed ratio as required. The basic purpose of control is to make the unit operate at the best tip speed ratio within the widest possible operating wind speed range (above the rated wind speed is another matter), so that the unit can capture more wind energy. To this end, the entire operating wind speed range is divided into three areas with reference to common doubly-fed units: Zone I, Zone II and Zone III, and different control strategies can be adopted in the three different zones. The ranges of wind speed V in the three regions are as follows:

Zone I: V _{cut in} < V < V _critical

Zone II: V _critical < V < V _rated

Zone III: V _rated < V < V _{cut out}

The above V _rated is the wind speed when the unit reaches the rated power, and V _critical is a certain wind speed lower than V _rated .

During normal operation, the speed of the wind rotor and the speed of the engine satisfy the following formula:

n _generator = i*n _{wind wheel} (1)

Among them: n _generator is the speed of conventional synchronous generator, i is the speed ratio of the gearbox, n _{wind wheel} is the speed of the wind wheel.

Since the unit adopts a conventional synchronous generator, the n _generator is always constant, so the control of the wind rotor speed has actually been transformed into the control of the gearbox speed ratio i, specifically, it has been transformed into the differential stage servo motor of the gearbox speed control. The control mode proposed by the technical solution of the utility model has the following three types: the basic control mode, the improved basic control mode, and the ideal control mode.

1. Basic control method

When the wind speed is greater than the cut-in wind speed and less than the critical wind speed, the following steps are included:

A1. According to the _optimal blade tip speed ratio λ of the wind turbine, calculate _the wind rotor speed n at different wind speeds;

A2. Calculate the gearbox speed ratio i corresponding to different wind rotor speeds according to the formula n _generator =i*n _{wind rotor} , wherein n _generator is the conventional synchronous generator speed;

A3. Calculate the speed of the servo motor according to the speed ratio i of the gearbox;

A4. Realize the speed-torque curve of the servo motor under different wind speeds;

A5. According to the measured torque of the servo motor, check the corresponding speed of the servo motor from the speed-torque curve;

A6. Perform PI control with the corresponding speed as the given value of speed control;

When the wind speed is equal to the critical wind speed, the brake is used to brake the servo motor, and the wind turbine operates at the _best tip speed ratio λ;

When the wind speed is greater than the critical wind speed and less than the rated wind speed, the brake is used to brake the servo motor, the gear box maintains a constant gear box speed ratio i, and the wind rotor speed n _{of the wind turbine} is in a constant speed operation state;

When the wind speed is greater than the rated wind speed and less than the cut-out wind speed, the brake is used to brake the servo motor, the gear box maintains a constant gear box speed ratio i, _{the wind} rotor speed n of the wind turbine is in a constant speed operation state, and the pitch control is performed , to ensure that the wind turbine operates at the rated power.

That is to say, according to the wind speed, it is divided into zone I, zone II and zone III and adopts different control methods respectively.

Firstly, according to different control methods, according to different requirements of blade tip speed ratio λ, calculate the rotor speed at different wind speeds. Calculated as follows:

n _{wind wheel} =30λV/πR , where R is the radius of the wind wheel.

1. Control mode of zone I

In this area, the rotor speed at various wind speeds can be _optimally calculated according to the optimal tip speed ratio λ, and then the gearbox speed ratio i corresponding to different rotor speeds can be calculated according to the formula (1), and the speed The ratio can be used to calculate the rotational speed of the servo motor, which can be used as the control target. In this way, the wind rotor of the unit can be guaranteed to operate at the highest Cp value in zone I. The specific method is: under the condition of ensuring the _best tip speed ratio λ, calculate the speed-torque curve of the servo motor under different wind speeds according to the transmission structure parameters of the differential gearbox, and measure it at any time during the actual control process. The obtained servo motor torque can be found from the existing speed-torque curve to find the proper speed of the servo motor, and the speed can be used as the given value of the speed control to perform PI control to achieve the control purpose. For the time being, this control method is called the method of checking the curve.

2. Critical point control

The critical point is the point where the wind speed is V _critical . When running at this point, the brake can be used to brake the servo motor without adjustment, and the unit will still run at the best tip speed ratio at this time.

3. Zone II control mode

In Zone II the servo motor is still under braking. Therefore, the gearbox will maintain a constant speed ratio, and the wind wheel of the unit will be in a constant speed operation state. At this time, as the wind speed increases, the unit will gradually deviate from the _optimal operation of the optimal tip speed ratio λ. When the wind speed increases to the rated wind speed, the difference between the actual λ and the _optimal λ will reach the maximum. That is, the Cp value will be reduced. But in fact, because the difference between V _critical and V _rated is not very large, the reduction of Cp value is not large. This point is the same as the commonly used control method of the conventional doubly-fed unit.

4. Control mode of Zone III

In Zone III, the servo motor is still under braking. Therefore, the gearbox will maintain a constant speed ratio, and the wind wheel of the unit will be in a constant speed operation state. At this time, the pitch controller will be put into operation to ensure that the unit operates at the rated power.

2. Improved basic control method

Compared with the basic control method, the improved basic control method adds that when the wind speed changes and the torque fluctuation reaches the preset value, the torque differential controller changes the gearbox speed ratio i, increases the wind rotor speed n _{wind rotor} , and instantly The wind energy is converted into the kinetic energy content of the wind rotor.

This is because the basic control method has the disadvantage that it causes relatively high dynamic loads in the drive train. This is due to the fact that during operation, when a sudden change in the wind forms a large torque fluctuation, the controller cannot react quickly to cut the peak value of the dynamic load in the transmission chain. For this reason, it is necessary to improve the above-mentioned basic control method. The specific method is: in addition to ensuring the control function of the original control system, add a controller with the torque differential of the transmission chain as the input signal to the speed of the servo motor. The input direction is: when the torque suddenly increases, the speed ratio of the differential gearbox is reduced. It can be known from formula (1) that when the speed ratio decreases, the speed of the wind rotor will increase. Therefore, when the torque differential controller is introduced, when the sudden change of the wind forms a large torque fluctuation, when the basic controller has no time to check the curve control, the torque differential controller has already acted to change the gearbox speed ratio, This causes the speed of the wind turbine to increase. In fact, it plays the role of converting the instantaneous wind energy into the kinetic energy of the wind wheel, thus reducing the peak value of the dynamic load in the transmission chain. In order to achieve the above-mentioned effect of reducing the peak value of the dynamic load in the transmission chain, the improved basic control mode is controlled in three areas:

Zone I: On the basis of the original basic control method, add a torque differential controller to the servo motor. The output direction of the torque differential controller is as mentioned above. The output of the torque differential controller can be expressed as:

D(t)=-K _d *dT _Servo /dt, wherein: T _Servo is the torque of the servo motor, and K _d is the differential gain.

Since the torque of each place in the transmission chain has a fixed proportional relationship, the above formula can be differentiated by the torque at any place. The negative sign in the formula indicates that the speed of the servo motor should decrease when it increases.

Critical point and Zone II: The servo motor keeps running at a lower speed in order to accept the output of the torque differential controller to reduce the peak value of the dynamic load in the transmission chain, and the wind wheel still runs at a constant speed statically .

Zone III: Speed control is the same as Zone II, and pitch control is added.

3. The ideal control method

Compared with the improved basic control method, the ideal control method adds the following:

When the wind speed is greater than the critical wind speed and less than the rated wind speed and when the wind speed is greater than the rated wind speed and less than the cut-out wind speed, the following steps are also included:

B1. According to the optimal blade tip speed ratio λ of the generator set _{, the} wind rotor speed n at different wind speeds is _optimally calculated;

B2. Calculate the gear box speed ratio i corresponding to different wind rotor speeds according to the formula n _generator =i*n _{wind rotor} , wherein n _generator is the generator speed;

B3. Calculate the rotational speed of the servo motor according to the gearbox speed ratio i;

B4. Realize the speed-torque curve of the servo motor under different wind speeds;

B5. According to the measured torque of the servo motor, check the corresponding speed of the servo motor from the speed-torque curve;

B6. Use the corresponding rotational speed as the given value of the rotational speed control to perform PI control, and the servo motor operates in reverse to generate electricity, and sends power to the grid through the frequency converter.

This is because the improved basic control method still has a shortcoming, that is, within the scope of II zone, since the servo motor runs at a constant speed, that is to say, the wind wheel runs at a constant speed, but the wind speed is still changing, so the unit cannot always Keep running at the _best tip speed ratio λ. The ideal control method is: within the scope of Zone II, according to the optimal tip speed ratio λ, the best calculation of the speed of the wind rotor under various wind speeds within the scope of Zone II, and then calculate the corresponding gearbox speed according to formula (1). Ratio i, and from this speed ratio, the speed corresponding to the differential stage servo motor can be calculated, which can be used as a given value for speed control. At this time, as long as the calculation is appropriate, the calculated speed of the servo motor can be changed in direction, that is, the servo motor will reverse and run as a generator, and the servo motor will send power to the grid through the frequency converter. The rotational speed and generating power of the servo motor will increase with the increase of the wind speed until reaching the maximum at the rated wind speed. The control strategy of the ideal control method in each area is as follows:

Zone I: Same as the improved basic controls.

Critical point: The servo motor runs at a speed close to zero (not equal to zero) in order to accept the output of the torque differential controller and achieve the purpose of reducing the peak value of the dynamic load in the transmission chain.

Zone II: Under the condition of ensuring the best blade tip speed ratio λ, calculate the speed-torque curve of the servo motor under different wind speeds according to the transmission structure parameters of the differential gearbox. In the actual control process, according to the torque of the servo motor measured at any time, the proper speed of the servo motor is found from the existing speed-torque curve, and the speed is used as the given value of the speed control to perform PI control; in fact, the servo motor Reverse to run in power generation mode. At the same time, the servo motor is controlled by the torque differential controller to achieve the purpose of reducing the peak value of the dynamic load in the transmission chain.

Zone III: The servo motor operates as a generator in the reverse direction at a certain speed, and the speed increases with the increase of wind speed. At the same time, the pitch controller is put into operation to ensure that the unit operates at rated load.

The above is only a preferred embodiment of the utility model, but the scope of protection of the utility model is not limited thereto, any person familiar with the technology can easily think of it within the technical scope disclosed in the utility model Changes or replacements should fall within the protection scope of the present utility model. Therefore, the protection scope of the present utility model should be based on the protection scope of the claims.

Claims (4)

1. the control system of a differential tooth case regulable speed type synchro wind generator group; It is characterized in that; Comprise wind wheel, conventional three grades of uni-drive gear boxes, gear-box differential type output level, actuating motor output drive gear pair, actuating motor, frequency variator, transformer, conventional synchronous generator and electrical network; Wind wheel is connected with conventional three grades of uni-drive gear boxes; Conventional three grades of uni-drive gear boxes are connected with the actuating motor output drive gear is secondary with gear-box differential type output level respectively; Actuating motor output drive gear pair, actuating motor, frequency variator are connected with transformer successively, and gear-box differential type output level is connected with conventional synchronous generator, and transformer is connected electrical network respectively with conventional synchronous generator.

2. the control system of a kind of differential tooth case regulable speed type synchro wind generator group according to claim 1; It is characterized in that; Also comprise torque measurement mechanism and torque derivative controller, torque measurement mechanism is connected with actuating motor respectively with the torque derivative controller.

3. the control system of a kind of differential tooth case regulable speed type synchro wind generator group according to claim 1; It is characterized in that; Also comprise power measurement unit and generator power derivative unit, power measurement unit is connected with actuating motor respectively with the generator power derivative unit.

4. the control system of a kind of differential tooth case regulable speed type synchro wind generator group according to claim 1 is characterized in that, also comprises becoming the oar controller.

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