CN114301103A - Control method and system for direct-drive wind turbine with wind-storage coordination - Google Patents

Abstract

The invention proposes a direct-drive wind turbine control method and system for wind-storage coordination, which belongs to the technical field of wind-storage coordination control in power systems, and solves the technical problem that the prior art fails to comprehensively consider various related factors, and cannot control the wind turbine. Coordinate with the control of the energy storage unit, including: obtaining the frequency of the power system and comparing it with the set first threshold and the second threshold, respectively, and controlling according to the range; wherein, when the frequency of the power system is at the first threshold and the second threshold Between the thresholds, the state of charge of the DC side energy storage unit should be within the set interval; when the power system frequency is less than the first threshold, active power is provided for the frequency response of the wind turbine; when the power system frequency is greater than the second threshold, the Provide active power for the frequency response of the wind turbine, and at the same time control the pitch of the wind turbine. The invention can realize the grid operation of the voltage source of the wind turbine by configuring the energy storage system on the DC side of the wind turbine.

Description

Control method and system for direct-drive wind turbine with wind-storage coordination

technical field

The invention belongs to the technical field of wind-storage coordination control in a power system, and in particular relates to a direct-drive wind turbine control method and system for wind-storage coordination.

Background technique

The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

The new power system planning with new energy as the main body puts forward higher requirements for the grid-connected operation ability of wind turbines.

The voltage source grid-connected wind turbine has good weak grid adaptability and grid active support capability. It is a very promising technical route, but its specific implementation plan has not yet been clarified.

The existing technologies of wind-storage coordinated control include: wind-storage combined wind power converter and control method, including structure, control principle, and control sub-mode division of wind-storage combined wind power converter; wind-storage system frequency regulation method, including The system frequency change adjusts the charging and discharging power of the energy storage to realize the control method for the frequency regulation of the power grid, and the method based on the double-layer coordination technology to respectively control the wind turbine and the additional flywheel energy storage to realize the frequency modulation response to the power grid; and The frequency regulation and voltage regulation control method of the storage cluster, including determining the active power and reactive power regulation methods according to the wind condition and the real-time electrical state of the power system, etc.

The problems existing in the prior art mainly include:

On the one hand, the existing technologies are all proposed based on the conventional control method of wind turbines, that is, the current source type grid-connected control method. However, with the increase of wind power penetration rate, wind turbines using current source grid-connected control cannot guarantee the stable operation of the system, and voltage source grid-connected control is required.

On the other hand, the existing technology fails to comprehensively consider different working conditions such as the normal operation of the power grid and frequency deviation, as well as factors such as the state of charge of the energy storage unit, so as to coordinate the control of the wind turbine and the energy storage unit, so as to meet the requirements of wind-storage coordination. The stable voltage source network operation of direct-drive wind turbines under different operating conditions.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a wind-storage coordinated direct-drive wind turbine control method, which can realize the wind-storage coordinated direct-drive wind turbine voltage source network operation.

To achieve the above object, one or more embodiments of the present invention provide the following technical solutions:

In the first aspect, a direct-drive wind turbine control method with wind-storage coordination is disclosed, including:

Obtain the frequency of the power system and compare it with the set first threshold and the second threshold, respectively, and control according to the range;

Among them, when the frequency of the power system is between the first threshold and the second threshold, the state of charge of the DC side energy storage unit should be within the set interval, and when the state of charge of the energy storage unit deviates from the above interval, the power Control the output power of the side converter to restore the state of charge;

When the power system frequency is less than the first threshold, by controlling the DC bus voltage to be constant, the DC side energy storage unit discharges spontaneously to provide active power for the frequency response of the wind turbine. Discharge is stopped through grid-side converter control;

When the frequency of the power system is greater than the second threshold, by controlling the DC bus voltage to be constant, the energy storage system will charge itself to provide active power for the frequency response of the wind turbine. The side energy storage unit is overcharged.

In a further technical solution, when the frequency of the power system is between the first threshold and the second threshold, the state of charge of the DC side energy storage unit should be within the set interval, the grid side converter adjusts the active power reference value, and outputs the wind power. The maximum wind power captured by the generator is used to track the maximum power of the wind turbine.

In a further technical solution, the grid-side converter adjusts the active power reference value, and then the main controller of the wind turbine unit controls the motor-side converter so that the output wind turbine captures the maximum wind power.

In a further technical solution, when the state of charge of the energy storage unit deviates from the above interval, the output power of the grid-side converter is controlled to restore the state of charge, specifically:

When the state of charge of the energy storage unit is not in the set range, the grid-side converter adjusts the active power reference value to make it less than or greater than the maximum wind energy capture power, so that some wind turbines capture wind energy into the energy storage unit or make the storage The energy unit is discharged, and the state of charge of the energy storage unit is adjusted to restore to the required set interval.

In a further technical solution, when the frequency of the power system is less than the first threshold, the motor-side converter is adjusted so that the active power output is

为风电机组主控制器向电机侧变流器下发的有功功率控制指令，

为风电机组所能捕获的最大风功率，

为电压源组网控制的虚拟惯量参数，

为电压源组网控制的额定角速度参数，

为电压源组网控制的角速度，

为角速度对时间的微分量；

It is the active power control command issued by the main controller of the wind turbine to the motor-side converter,

is the maximum wind power that the wind turbine can capture,

is the virtual inertia parameter controlled by the voltage source network,

is the rated angular velocity parameter controlled by the voltage source network,

is the angular velocity controlled by the voltage source network,

is the derivative of the angular velocity with respect to time;

While performing the maximum power tracking control, part of the rotor inertia is released for power support, and the main controller of the wind turbine unit cooperates to monitor and control the speed of the wind turbine.

In a further technical solution, when the power system frequency is less than the first threshold, and when the state of charge of the DC side energy storage unit is greater than the allowable minimum value, the grid side converter sets the reference active power to be the maximum wind energy capture power, and the active power The power is provided by the DC side energy storage discharge and the kinetic energy of the wind turbine rotor.

In a further technical solution, when the frequency of the power system is less than the first threshold value, and when the state of charge of the DC side energy storage unit is reduced to the allowable minimum value, the grid side converter is adjusted to set the reference active power, so that it is no longer available to the outside world. Provides additional active power, the maximum wind power captured by the wind turbine output.

In a further technical solution, when the power system frequency is greater than the second threshold, the grid-side converter sets the reference active power as the maximum wind energy capture power, and the active power is provided by the DC-side energy storage charging and wind turbine pitch control.

A further technical solution is to increase the pitch angle of the wind turbine when the power system frequency is greater than the second threshold, so that the active power output of the motor-side converter is

Reduce the output power of the wind turbine for frequency support.

In the second aspect, a wind-storage coordinated direct-drive wind turbine control system is disclosed, including:

Energy storage side converter, grid side converter, motor side converter and main controller of wind turbine;

The DC link between the motor side converter and the grid side converter is connected with the energy storage side converter;

The wind turbine main controller obtains the frequency of the power system and compares it with the set first threshold value and the second threshold value respectively, and controls respectively according to the range;

Among them, when the frequency of the power system is between the first threshold and the second threshold, the state of charge of the DC side energy storage unit should be within the set interval, and when the state of charge of the energy storage unit deviates from the above interval, the power Control the output power of the side converter to restore the state of charge;

When the power system frequency is less than the first threshold, by controlling the DC bus voltage to be constant, the DC side energy storage unit discharges spontaneously to provide active power for the frequency response of the wind turbine. Discharge is stopped through grid-side converter control;

When the frequency of the power system is greater than the second threshold, by controlling the DC bus voltage to be constant, the energy storage system will charge itself to provide active power for the frequency response of the wind turbine. The side energy storage unit is overcharged.

One or more of the above technical solutions have the following beneficial effects:

The invention realizes the integrated design and coordinated operation of wind-storage integration by configuring the energy storage system on the DC side of the wind turbine, and provides stable DC voltage support and power backup by means of the energy storage, so that the voltage source network operation of the wind turbine can be realized.

The present invention is controlled by the DC side energy storage system to stabilize the DC link voltage, and provides energy charging and discharging during the frequency response process.

In the invention, the grid-side converter realizes the network operation of the voltage source, establishes the voltage externally, and provides active frequency support.

In the invention, the motor-side converter cooperates with the main controller of the wind turbine to realize the maximum energy tracking control in the normal operation state, and uses the rotor speed adjustment and the pitch angle adjustment in the frequency response process to provide partial energy support.

Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will become apparent from the description which follows, or may be learned by practice of the invention.

Description of drawings

The accompanying drawings forming a part of the present invention are used to provide further understanding of the present invention, and the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, and do not constitute an improper limitation of the present invention.

1 is a schematic diagram of a direct-drive wind turbine with coordinated wind storage according to an embodiment of the present invention;

2 is a block diagram of a voltage source networking control block diagram of a grid-side converter according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a voltage control flow of a DC link by a DC side energy storage system according to an embodiment of the present invention.

Detailed ways

It should be noted that the following detailed description is exemplary and intended to provide further explanation of the invention. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It should be noted that the terminology used herein is for the purpose of describing specific embodiments only, and is not intended to limit the exemplary embodiments according to the present invention.

Embodiments of the invention and features of the embodiments may be combined with each other without conflict.

Example 1

The present embodiment discloses a direct-drive wind turbine control method with wind-storage coordination, including:

In order to realize the control of the wind turbine, the data to be collected include: the three-phase voltage V _abc of the grid-connected point, the three-phase current I _abc of the grid-connected point, the state of charge (SOC) of the energy storage unit, and the wind turbine and energy storage. Other routine acquisition data required for normal operational control of the unit.

The collected data is used in the following ways:

According to the collected three-phase voltage V _abc and the three-phase current I _abc of the grid-connected point, the output active power P _e , reactive power Q _e and voltage measurement value V _m of the wind turbine can be obtained by calculation, and then use Fig. 2 The method shown is for voltage source networking control.

According to the collected three-phase voltage V _abc of the grid connection point, the grid frequency is obtained by calculation, and according to the calculated grid frequency and the collected state of charge of the energy storage unit, the direct-drive wind turbine with wind-storage coordination is controlled according to the control method.

The control flow is:

(1) According to the collected three-phase voltage V _abc of the grid connection point, the grid frequency is obtained by calculation;

(2) Determine the state of the power grid and the wind turbine based on the calculated power grid frequency and the collected state of charge of the energy storage unit, and use the following methods for the grid-side converter, DC-side energy storage system, and motor respectively. The side converter and the main controller of the wind turbine are controlled to realize the voltage source network operation of the direct-drive wind turbine with coordinated wind and storage.

The present invention is connected to the additional energy storage unit through the energy storage side converter on the DC link between the motor side converter and the grid side converter of the direct-drive wind turbine;

The energy storage side converter and energy storage unit are used to control the DC link voltage stability, and provide energy charging and discharging during the frequency response process.

The grid-side converter adopts the voltage source networking control method:

The motor-side converter cooperates with the main controller of the wind turbine to realize the maximum energy tracking control under normal operation, and adjust the rotor speed and pitch angle during the frequency response process.

Specifically, the grid-side converter of the wind turbine adopts the method shown in Figure 2 to control the voltage source network, including:

1) In normal operation state, that is, when the system frequency is detected to be [50-D f _db , 50+D f _db ] (where D f _db is the frequency response control dead zone), the active power control reference value of the grid-side converter Select as follows:

Among them, D P is the power deviation value determined by the manufacturer or the operation dispatcher, which can be determined according to the captured wind power and the charging and discharging power requirements of the energy storage unit. The purpose is to generate the deviation between the output power of the unit and the captured wind power, The energy storage unit is charged or discharged by the deviation power D P.

When the SOC of the DC side energy storage unit is in the range of [60%, 70%], the grid-side converter adjusts the active power reference value, outputs the maximum wind power P _MPPT captured by the wind turbine, and realizes the maximum power tracking of the wind turbine. Operation (maximum power point tracking, MPPT); when the SOC of the energy storage unit is less than 60% (or greater than 70%), the grid-side converter adjusts the active power reference value P _ref to make it less than (or greater than) the maximum wind energy capture power P _MPPT , so that part of the wind turbine captures wind energy into the energy storage unit (or discharges the energy storage unit), so that the SOC of the energy storage unit can be adjusted to recover to the required [60%, 70%] range.

2) When it is detected that the system frequency is less than 50-D f _db , the active power control reference value of the grid-side converter is selected as follows:

When the SOC of the DC-side energy storage unit is greater than the allowable minimum value SOC _min , the grid-side converter sets the reference active power P _ref as the maximum wind energy capture power P _MPPT . At this time, according to the voltage source networking control strategy , the specific control process is shown in Figure 2, which can provide active power support spontaneously, and the active power is provided by the DC side energy storage discharge and the kinetic energy of the wind turbine rotor; when the SOC of the DC side energy storage unit is reduced to the allowable minimum value When the SOC is _min , the DC-side energy storage unit cannot continue to support power. At this time, the active power reference P _ref is set by adjusting the grid-side converter, so that it no longer provides additional active power to the outside world, and the maximum wind energy captured by the wind turbine output is Power P _MPPT .

3) When it is detected that the system frequency is greater than 50+D f _db , the active power control reference value of the grid-side converter is selected as follows:

The grid-side converter sets the reference active power P _ref as the maximum wind energy capture power P _MPPT , and spontaneously provides active power support according to the voltage source networking control group strategy. At this time, the active power supported by the DC side Energy storage charging and wind turbine pitch control are provided.

In a more specific example, referring to Fig. 2 again, the specific control process of the voltage source networking control: in the active power-phase angle control loop, firstly, the active power command P _ref and the active power calculation value P _e are determined by Deviation, through the rotor dynamic simulation link, the angular velocity deviation D w = w - w ₀ is generated, and the characteristics represented by the rotor dynamic simulation link can be described as Jw ₀ ( dw / dt ) = P _ref - P _e - K _p ( w - w ₀ ); and then the angular velocity deviation D w and the angular velocity rated value w ₀ are added to obtain the angular velocity control reference w _ref , and through the integral link, the phase angle control reference q _ref is obtained.

In the reactive power-voltage control loop, the deviation between the reactive power command Q _ref and the reactive power calculated value Q _e , and the deviation between the voltage command V _ref and the voltage measurement value V _m are first calculated through the proportional links K _q and K _v , the control signals K _q ×D Q and K _v × DV are obtained; then the control signals K _q × D Q and K _v × DV are added together, and through the integration link, the output voltage control deviation DE is generated, and the The output voltage ratings E ₀ are added to obtain the output voltage control reference E _ref .

Then, from the phase angle control reference q _ref and the output voltage control reference E _ref , through the reference voltage generation and dq coordinate transformation, the output voltage control reference E _d,ref and E _q,ref of the dq axis are obtained, and the phase angle control reference E d,ref and E q,ref are obtained. The reference q _ref is passed to the voltage loop control together; next, through the PI (proportional-integral) link in the voltage loop control, the current control reference I _d,ref and I _q,ref of the dq axis are generated, and the phase angle control reference q _ref is transmitted to the current loop control together; finally, through the PI (proportional-integral) link in the current loop control, the bridge arm three-phase AC voltage control reference e _ref is generated for the PWM modulation link to generate the power electronic switch trigger signal.

Specifically, the DC side energy storage system uses the method shown in Figure 3 to control the DC link voltage, including:

1) In normal operation state, that is, when the system frequency is detected to be [50-D f _db , 50+D f _db ], the SOC of the DC side energy storage unit should be in the [60%, 70%] interval. When the SOC deviates from the above range, the output power of the grid-side converter is controlled to restore the SOC state.

2) When it is detected that the system frequency is less than 50-D f _db , by controlling the DC bus voltage to be constant, the energy storage system discharges _{spontaneously} , providing active power support for the frequency response of the wind turbine. The grid-side converter control can stop the discharge.

3) When it is detected that the system frequency is greater than 50+D f _db , by controlling the DC bus voltage to be constant, the energy storage system is charged spontaneously to provide active power support for the frequency response of the wind turbine. At the same time, through the wind turbine pitch control, the overall Wind turbines run at reduced power and avoid overcharging of energy storage units.

The working process of the motor-side converter and the main controller of the wind turbine is as follows:

1) 1) Normal operation state, that is, when it is detected that the system frequency is at [50 - D f _db , 50 + D f _db ], MPPT control is adopted to make its active power output as

At this time, output the maximum wind power P _MPPT that can be captured by the wind turbine;

2) When it is detected that the system frequency is less than 50 - D f _db , adjust the motor side converter to make its active power output as

Among them, P _wt is the active power control command issued by the wind turbine main controller to the motor-side converter, P _MPPT is the maximum wind power that the wind turbine can capture, and J is the voltage source network control (as shown in Figure 2). ) virtual inertia parameter, w ₀ is the rated angular velocity parameter controlled by the voltage source network, w is the angular velocity controlled by the voltage source network, dw/dt is the differential component of the angular velocity to time.

At the same time of MPPT control, part of the rotor inertia is released for power support, and the main controller of the wind turbine unit cooperates to monitor and control the speed of the wind turbine.

，使电机侧变流器有功功率输出为：3) When it is detected that the system frequency is greater than 50+D f _db , increase the pitch angle of the wind turbine

, so that the active power output of the motor-side converter is:

Reduce the output power of the wind turbine for frequency support.

The invention proposes a wind-storage coordinated voltage source networking type direct-drive wind turbine operation control method, which can realize the voltage source networking operation of the direct-drive wind turbine, and through the coordination of the wind turbine and the DC side energy storage system, Realize the active frequency response of the wind turbine to the grid.

Embodiment 2

The purpose of this embodiment is to provide a wind-storage coordinated direct-drive wind turbine control system, as shown in FIG. 1 , including:

Energy storage side converter, grid side converter, motor side converter and main controller of wind turbine;

The DC link between the motor side converter and the grid side converter is connected with the energy storage side converter;

The wind turbine main controller obtains the frequency of the power system and compares it with the set first threshold value and the second threshold value respectively, and controls respectively according to the range;

Among them, when the frequency of the power system is between the first threshold and the second threshold, the state of charge of the DC side energy storage unit should be within the set interval, and when the state of charge of the energy storage unit deviates from the above interval, the power Control the output power of the side converter to restore the state of charge;

When the power system frequency is less than the first threshold, by controlling the DC bus voltage to be constant, the DC side energy storage unit discharges spontaneously to provide active power for the frequency response of the wind turbine. Discharge is stopped through grid-side converter control;

When the frequency of the power system is greater than the second threshold, by controlling the DC bus voltage to be constant, the energy storage system will charge itself to provide active power for the frequency response of the wind turbine. The side energy storage unit is overcharged.

The invention utilizes the DC side energy storage system to provide the voltage stability control of the DC link and the power backup during frequency response, and realizes the voltage source network operation of the wind turbine. The scheme proposed by the present invention cooperates with the energy storage side converter, the grid side converter, the motor side converter and the main controller of the wind turbine to operate, so as to realize the coordination of wind storage.

Among them, the main controller of the wind turbine and the converter controller are the actual hardware controllers of the wind turbine. The main controller can be regarded as the highest level controller in the wind turbine, which captures the wind power of the mechanical part of the wind turbine and controls the electrical part of the wind turbine. The power output of the power grid is uniformly regulated by the upper level. Converter control According to the control instructions of the main control, for the power electronic grid-connected converter, it mainly controls the grid-connected power, voltage, and current.

The invention connects the additional energy storage unit through the energy storage side converter on the direct current link between the motor side converter and the grid side converter of the conventional direct-drive wind turbine, so as to constitute the integrated design and coordinated operation of wind energy storage. , for the specific control process or working principle of the above system, refer to the method in the first embodiment.

The steps involved in the apparatus of the above embodiment correspond to the method embodiment 1, and the specific implementation can refer to the relevant description part of the embodiment 1.

Although the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, they do not limit the scope of protection of the present invention. Those skilled in the art should understand that on the basis of the technical solutions of the present invention, those skilled in the art do not need to pay creative work. Various modifications or deformations that can be made are still within the protection scope of the present invention.

Claims (10)

1. The direct-drive wind turbine control method of wind-storage coordination, is characterized in that, comprises: Obtain the frequency of the power system and compare it with the set first threshold and the second threshold, respectively, and control according to the range; Among them, when the frequency of the power system is between the first threshold and the second threshold, the state of charge of the DC side energy storage unit should be within the set interval, and when the state of charge of the energy storage unit deviates from the above interval, the power Control the output power of the side converter to restore the state of charge; When the power system frequency is less than the first threshold, by controlling the DC bus voltage to be constant, the DC side energy storage unit discharges spontaneously to provide active power for the frequency response of the wind turbine. Discharge is stopped through grid-side converter control; When the frequency of the power system is greater than the second threshold, by controlling the DC bus voltage to be constant, the energy storage system will charge itself to provide active power for the frequency response of the wind turbine. The side energy storage unit is overcharged. 2 . The direct-drive wind turbine control method of wind-storage coordination according to claim 1 , wherein when the power system frequency is between the first threshold and the second threshold, the state of charge of the DC-side energy storage unit should be Within the set interval, the grid-side converter adjusts the active power reference value, outputs the maximum wind power captured by the wind turbine, and performs the maximum power tracking operation of the wind turbine. 3. The direct-drive wind turbine control method of wind-storage coordination according to claim 2, wherein the grid-side converter adjusts the active power reference value, and then the main controller of the wind turbine group controls the motor-side converter to output the output. Wind turbines capture maximum wind power. 4. The wind-storage coordinated direct-drive wind turbine control method according to claim 2, wherein when the state of charge of the energy storage unit deviates from the above interval, the output power of the grid-side converter is controlled to make It restores the state of charge, specifically: When the state of charge of the energy storage unit is not in the set range, the grid-side converter adjusts the active power reference value to make it less than or greater than the maximum wind energy capture power, so that some wind turbines capture wind energy into the energy storage unit or make the storage The energy unit is discharged, and the state of charge of the energy storage unit is adjusted to restore to the required set interval. 5. The wind-storage coordinated direct-drive wind turbine control method according to claim 1, wherein when the power system frequency is less than the first threshold, the motor-side converter is adjusted to make its active power output as

P _wt is the active power control command issued by the main controller of the wind turbine to the motor-side converter, P _MPPT is the maximum wind power that the wind turbine can capture, J is the virtual inertia parameter controlled by the voltage source network, w ₀ is The rated angular velocity parameter controlled by the voltage source network, w is the angular velocity controlled by the voltage source network, dw/dt is the differential component of the angular velocity to time; While performing the maximum power tracking control, part of the rotor inertia is released for power support, and the main controller of the wind turbine unit cooperates to monitor and control the speed of the wind turbine. 6. The wind-storage coordinated direct-drive wind turbine control method according to claim 1, wherein when the power system frequency is less than the first threshold, when the state of charge of the DC side energy storage unit is greater than the allowable minimum value , the grid-side converter sets the reference active power as the maximum wind energy capture power, which is provided by the DC side energy storage discharge and the kinetic energy of the wind turbine rotor. 7. The wind-storage coordinated direct-drive wind turbine control method according to claim 6, wherein when the power system frequency is less than the first threshold, when the state of charge of the DC side energy storage unit is reduced to the allowable minimum value When the grid-side converter is adjusted to set the reference active power, it will no longer provide additional active power to the outside, and the wind turbine will output the maximum wind energy power captured. 8. The direct-drive wind turbine control method for wind-storage coordination according to claim 1, wherein when the power system frequency is greater than the second threshold, the grid-side converter sets the reference active power to be the maximum wind energy capture power, Active power is provided by DC side energy storage charging and wind turbine pitch control. 9 . The direct-drive wind turbine control method of wind storage coordination according to claim 1 , wherein when the frequency of the power system is greater than the second threshold, the pitch angle of the wind turbine is increased to make the motor-side converter active. 10 . The power output is

P _wt is the active power control command issued by the main controller of the wind turbine to the motor-side converter, P _MPPT is the maximum wind power that the wind turbine can capture, J is the virtual inertia parameter controlled by the voltage source network, w ₀ is Rated angular velocity parameter controlled by voltage source network, w is the angular velocity controlled by voltage source network, dw/dt is the differential component of angular velocity to time,

is the angular velocity deviation; Reduce the output power of the wind turbine for frequency support. 10. The control system for realizing the control method for the direct-drive wind turbine generator set according to any one of claims 1-9, characterized in that it comprises: Energy storage side converter, grid side converter, motor side converter and main controller of wind turbine; The DC link between the motor side converter and the grid side converter is connected with the energy storage side converter The wind turbine main controller obtains the frequency of the power system and compares it with the set first threshold value and the second threshold value respectively, and controls respectively according to the range; Among them, when the frequency of the power system is between the first threshold and the second threshold, the state of charge of the DC side energy storage unit should be within the set interval, and when the state of charge of the energy storage unit deviates from the above interval, the power Control the output power of the side converter to restore the state of charge; When the power system frequency is less than the first threshold, by controlling the DC bus voltage to be constant, the DC side energy storage unit discharges spontaneously to provide active power for the frequency response of the wind turbine. Discharge is stopped through grid-side converter control; When the frequency of the power system is greater than the second threshold, by controlling the DC bus voltage to be constant, the energy storage system will charge itself to provide active power for the frequency response of the wind turbine. The side energy storage unit is overcharged.

Images