A control method and device for inertia response of a wind turbine generator system and a storage medium

Abstract

The application discloses a kind of wind power generator set inertia response control method, device and storage medium, belong to wind power generation technical field.The inertia response process of wind turbine is divided into three stages, the first stage reduces active power output and makes wind wheel speed rise, so that the kinetic energy of wind wheel increases for subsequent use, the second stage increases active power output and makes wind wheel speed reduce, converts the kinetic energy of last stage into electric energy to suppress grid frequency drop, the third stage makes impeller speed to return to normal operation curve.The application can reduce impeller kinetic energy recovery as far as possible in the process of impeller speed recovery, and fastest the wind energy absorbed by wind wheel is converted into electric energy, while completing inertia response, increases the power generation efficiency of wind power generator set.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of wind power generation, and particularly relates to a control method and device for inertia response of a wind turbine generator system and a storage medium. BACKGROUND

[0002] The frequency of a traditional synchronous generator is relatively controllable, while wind power presents random fluctuation characteristics on the supply side. A variable-speed constant-frequency wind turbine generator is connected to a power grid through a back-back converter, and the generator is decoupled from the power grid system, so that the system frequency cannot be inhibited. High proportion of renewable energy access and high proportion of power electronic equipment application make the power system present low inertia and weak damping. The frequency stability problem of the power electronic new power system is highlighted, and the new energy station needs to be connected to the power grid frequency modulation.

[0003] The existing technical solutions for this problem include detecting the change amount and rate of the power grid frequency, calculating the active power change amount of the wind turbine generator according to the change, and responding to the change of the power grid frequency in combination with the current active power value of the wind turbine generator. Since the inertia of the impeller system of the wind turbine generator is large during rotation, the kinetic energy of the impeller during rotation can be converted into active power to temporarily inhibit the drop of the power grid frequency. However, the impeller speed is reduced due to the sacrifice of the kinetic energy. When the inertia response ends, the impeller speed gradually recovers during the frequency recovery process. At this time, the wind energy absorbed by the impeller is converted into the kinetic energy of the recovered impeller and into electric energy output. The recovery process depends on the wind condition time, and the wind energy absorbed by the impeller cannot be completely converted into electric energy. In addition, the longer the recovery process, the greater the impact on the inertia response. SUMMARY

[0004] In order to solve the above problems, the purpose of the present application is to provide a control method and device for inertia response of a wind turbine generator system, which can minimize the recovery of the kinetic energy of the impeller during the recovery process of the impeller speed, and convert the wind energy absorbed by the wind wheel into electric energy as quickly as possible, thereby increasing the power generation efficiency of the wind turbine generator while completing the inertia response.

[0005] The present application is achieved by the following technical solutions:

[0006] A control method for inertia response of a wind turbine generator system divides the inertia response process of the wind turbine generator system into the following three stages, and achieves inertia response control by sending active power instructions to the control system of the wind turbine generator in each stage.

[0007] In the first stage, the active power output is reduced and the wind wheel speed is increased, so that the kinetic energy of the wind wheel is increased and accumulated.

[0008] In the second stage, the active power output is increased and the wind wheel speed is reduced, so that the kinetic energy accumulated in the first stage is converted into electric energy to inhibit the drop of the power grid frequency.

[0009] The third stage is to restore the impeller speed to the normal operation curve.

[0010] Preferably, the regulation of active power in the three stages is realized by the following logic:

[0011] S1: detect whether the function flag is 1 in the current detection period, if not, the logic ends, if yes, go to S2;

[0012] S2: detect the grid frequency change rate and compare it with the set dead zone, if the grid frequency change rate is less than the dead zone, the logic ends, if the grid frequency change rate is greater than the dead zone, go to S3;

[0013] S3: obtain the inertia time constant TJ and the power system rated frequency fN and divide them to get TJ / fN; then multiply it with the detected grid frequency change rate df / dt to get (TJ / fN)*(df / dt);

[0014] S4: obtain the wind turbine single-machine rated capacity PN, and multiply it with the result obtained in S3 and take the inverse to get -PN*(TJ / fN)*(df / dt);

[0015] S5: obtain the current active power value P of the wind turbine and add it with the result obtained in S4 to get P-PN*(TJ / fN)*(df / dt), which is sent to the wind turbine control system as the active power instruction value to execute the active power instruction.

[0016] Further preferably, in S2, the dead zone is 0.5 Hz / s.

[0017] Further preferably, the grid frequency change rate is detected by a high-precision frequency measuring device.

[0018] Further preferably, in S3, the inertia time constant TJ is 4-12 s.

[0019] Further preferably, in S3, the power system rated frequency fN is 50 Hz.

[0020] Preferably, in the third stage, when the rotating speed is below the rated rotating speed, the active power is controlled according to the instruction of Pact=Kopt*omega*omega*omega, or above the rated rotating speed, the rated active power output is kept; here, the rotating speed of the wind turbine is omega, the optimal wind energy coefficient of the wind turbine is CPmax, CPmax is a function of the tip speed ratio lamda, lamda=omega*R / w, w is the wind speed, and R is the radius of the impeller; at a specified wind speed w, the tip speed ratio lamda corresponding to the maximum power Pmax at a specific rotating speed omega of the wind turbine is CPmax; Kopt=rou*pi*R*R*R*R*R*CPmax / (2*lamda*lamda*lamda*G*G*G), wherein rou is the air density, R is the radius of the impeller, and G is the gear box speed ratio.

[0021] Preferably, the first stage is from achieving the inertia response trigger condition to 100-400 ms, the second stage is from 100-400 ms to the grid frequency no longer further decreasing, and the third stage is from the frequency no longer further decreasing to the rotating speed of the impeller recovering to the normal operation curve.

[0022] The application discloses a computer device, which comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the wind turbine inertia response control method when executing the computer program.

[0023] The application discloses a computer readable storage medium, which stores a computer program, and the computer program implements the steps of the wind turbine inertia response control method when executed by a processor.

[0024] Compared with the prior art, the application has the following beneficial technical effects:

[0025] The wind turbine inertia response control method disclosed by the application innovatively divides the inertia response process into three stages, i.e., the first stage reduces active power output and increases the wind wheel speed, the wind wheel kinetic energy is increased for subsequent use, the second stage increases the active power output to reduce the wind wheel speed, the kinetic energy in the previous stage is converted into electric energy to suppress the power grid frequency drop, and the third stage restores the impeller speed to the normal operation curve. In the first stage, the impeller speed is greatly reduced due to the rapid conversion of impeller kinetic energy into electric energy, which may cause problems such as blade stall, unstable unit control, etc. In the process of restoring the impeller speed, the wind energy absorbed by the impeller is converted into impeller kinetic energy and electric energy according to the wind condition, and the restoration process may affect the secondary inertia response if it is too long. In the application, the impeller kinetic energy is accumulated in the first stage, and the impeller kinetic energy is released in the second stage, so that the impeller speed can be restored to the wind turbine operation control curve as soon as possible. Compared with the traditional method, the application reduces the impeller kinetic energy recovery as much as possible in the process of restoring the impeller speed, and converts the wind energy absorbed by the wind wheel into electric energy as soon as possible, thereby increasing the power generation efficiency of the wind turbine while completing the inertia response. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The method flowchart of the embodiment of the application is shown in the following. DETAILED DESCRIPTION

[0027] The application will be further described in detail below with the drawings and specific embodiments, which are an explanation of the application rather than a limitation.

[0028] The wind turbine inertia response control method of the application divides the wind turbine inertia response process into the following three stages, and inertia response control is achieved by sending active power instructions to the wind turbine control system in each stage.

[0029] In the first stage, the active power output is reduced and the wind wheel speed is increased, so that the kinetic energy of the wind wheel is increased and accumulated.

[0030] In the second stage, the active power output is increased and the wind wheel speed is reduced, the kinetic energy accumulated in the first stage is converted into electric energy, and the power grid frequency drop is suppressed.

[0031] The third stage is to restore the impeller speed to the normal operation curve. If the speed is below the rated speed, the active power is given a command according to Pact=Kopt*omega*omega*omega, and if the speed is above the rated speed, the rated active power output is maintained for control. Here, the wind turbine impeller speed is omega, the wind turbine optimal wind energy coefficient is CPmax, CPmax is a function of the tip speed ratio lamda, lamda=omega*R / w, w is the wind speed, and R is the impeller radius. At a specified wind speed w, the tip speed ratio lamda corresponding to the maximum power Pmax at a specific wind turbine impeller speed omega is CPmax. Kopt=rou*pi*R*R*R*R*R*CPmax / (2*lamda*lamda*lamda*G*G*G), where rou is the air density, R is the impeller radius, and G is the gear ratio.

[0032] Generally, the three stages are divided as follows:

[0033] The first stage is from achieving the inertia response trigger condition to 100-400 ms, the second stage is from 100-400 ms to the grid frequency no longer further decreasing, and the third stage is from the frequency no longer further decreasing to the impeller speed restoring to the normal operation curve.

[0034] In the three stages, the active power adjustment is achieved through the following logic: Figure 1

[0035] In the current detection period, it is detected whether the function flag Fenable is 1. If it is 1, it indicates that the control function is turned on, and if it is not 1, the logic ends. The function flag Fenable can be set to be manually turned on or set to be automatically turned on by the system according to the parameter value. After being turned on, it means that the wind turbine enters the inertia response control mode.

[0036] Next, the grid frequency change rate df / dt is detected, a dead zone delatF_deadband is set, which can be generally set to 0.5 Hz / s, and it is judged whether the grid frequency change rate df / dt is greater than delatF_deadband. If it is greater than the dead zone, the inertia response is performed, and if it is less than the dead zone, the logic ends.

[0037] ​Get the inertia time constant TJ, generally set to 4~12s. Divide it by the rated frequency of the power system fN=50Hz, so that TJ / fN is obtained. Multiply it with the detected grid frequency change rate df / dt to obtain (TJ / fN)*(df / dt). Get the single-machine rated capacity PN of the wind turbine, multiply it to obtain PN*(TJ / fN)*(df / dt), and take the negative to obtain -PN*(TJ / fN)*(df / dt). Get the current active power value P of the wind turbine, and add it to obtain P-PN*(TJ / fN)*(df / dt).

[0038] Take P-PN*(TJ / fN)*(df / dt) as the active power instruction value of the wind turbine for response inertia control, and deliver it to the wind turbine control system to execute the active power instruction.

[0039] The following points need to be noted about the present application:

[0040] The present application adopts inertia response control for a single wind turbine, which can also be used in wind farm level control, that is, to calculate the active power instruction for full-field inertia response control, and deliver it to a single wind turbine through an energy management platform or other means for active power instruction execution.

[0041] The present application adopts a fixed dead zone method, but is not limited to this method, such as a variable dead zone method that sets different dead zones to correspond to different conditions for entering inertia response.

[0042] The present application adopts a method of directly delivering the active power instruction value of the wind turbine for response inertia control to the main control system for execution, but is not limited to this method, and other methods such as directly transmitting it to the pitch actuator and current actuator through the power control module.

[0043] The present application adopts a method of calculating the inertia response active power instruction based on the grid frequency change rate df / dt, the rated capacity PN of the wind turbine, the inertia time constant TJ, and the rated frequency fN of the power system, but is not limited to this method, such as considering the grid frequency change amount to calculate the inertia response active power instruction.

[0044] The present application adopts a method of calculating the active power instruction of the wind turbine for response inertia control, but is not limited to this method, and other methods such as calculating the speed control instruction and torque control instruction of the wind turbine for response inertia control.

[0045] The present application also provides a computer device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the wind turbine inertia response control method of the present application when executing the computer program.

[0046] The wind turbine inertia response control method of the present application can be in the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can be in the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The wind turbine inertia response control method of the present application, if implemented in the form of a software function unit and sold or used as an independent product, can be stored in a computer-readable storage medium.

[0047] Based on such understanding, in the exemplary embodiments, a computer-readable storage medium is also provided, and the present application implements all or part of the processes of the above-mentioned embodiments, which can also be completed by a computer program instructing related hardware. The computer program can be stored in the computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by a processor. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or some intermediate forms, etc. The computer-readable storage medium includes permanent and non-permanent, removable and non-removable media, which can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules, or other data. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction, for example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electrical carrier signals and telecommunication signals. The computer storage medium can be any available medium or data storage device that can be accessed by a computer, including but not limited to magnetic storage (such as floppy disks, hard disks, magnetic tapes, magneto-optical disks (MO), etc.), optical storage (such as CD, DVD, BD, HVD, etc.), and semiconductor storage (such as ROM, EPROM, EEPROM, non-volatile memory (NAND FLASH), solid state disk (SSD), etc.).

[0048] In the example embodiment, a computer device is also provided, which comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the control method for the inertia response of the wind turbine generator system when executing the computer program. The processor can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0049] It should be noted that the above description is only part of the embodiments of the present application, and equivalent changes made to the system described in the present application are included in the protection scope of the present application. Those skilled in the art can make similar substitutions to the specific examples described, as long as they do not deviate from the structure of the present application or exceed the scope defined by the present claims, and are within the protection scope of the present application.

Claims

1. A method for controlling the inertia response of a wind turbine generator set, characterized in that: The inertia response process of a wind turbine generator set is divided into the following three stages. In each stage, the inertia response control is achieved by sending active power commands to the wind turbine generator set control system: In the first stage, the active power output is reduced and the rotor speed is increased, so that the kinetic energy of the rotor is increased and accumulated; In the second stage, the active power output is increased and the rotor speed is reduced, converting the kinetic energy accumulated in the first stage into electrical energy and suppressing the drop in grid frequency. In the third stage, the impeller speed is restored to the normal operating curve. The regulation of active power in the three phases is achieved through the following logic: S1: Check whether the function flag is 1 in the current detection cycle. If not, the logic ends. If it is 1, go to S2. S2: Detect the grid frequency change rate and compare it with the set dead zone. If the grid frequency change rate is less than the dead zone, the logic ends; if the grid frequency change rate is greater than the dead zone, go to S3; S3: Obtain the inertia time constant TJ and the rated frequency fN of the power system and divide them to obtain TJ / fN. Then multiply this by the detected grid frequency change rate df / dt to obtain (TJ / fN)*(df / dt). S4: Obtain the rated capacity PN of a single wind turbine, multiply it by the result obtained in S3, and then invert it to obtain -PN*(TJ / fN)*(df / dt); S5: Obtain the current active power value P of the wind turbine and add it to the result obtained in S4 to obtain P-PN*(TJ / fN)*(df / dt), and send this value as the active power command value to the wind turbine control system to execute the active power command.

2. The method for controlling the inertia response of a wind turbine generator set according to claim 1, wherein: In S2, the dead zone is 0.5 Hz / s.

3. The method for controlling the inertia response of a wind turbine generator set according to claim 1, wherein: The grid frequency change rate is detected by a high-precision frequency measuring device.

4. The method for controlling the inertia response of a wind turbine generator set according to claim 1, wherein: In S3, the inertia time constant TJ is 4~12s.

5. The method for controlling the inertia response of a wind turbine generator set according to claim 1, wherein: In S3, the rated frequency fN of the power system is 50Hz.

6. The method for controlling the inertia response of a wind turbine generator set according to claim 1, wherein: In the third stage, if the speed is below the rated speed, the active power is instructed according to Pact=Kopt*omega*omega*omega. If it is above the rated speed, the rated active power output is maintained for control. Here, the wind turbine rotor speed is omega, and the wind turbine has the optimal wind energy coefficient CPmax. CPmax is a function of the tip speed ratio lamda, lamda=omega*R / w, where w is the wind speed and R is the impeller radius. Under a specified wind speed w, the tip speed ratio lamda that can generate the maximum power Pmax at the specific wind turbine rotor speed omega is CPmax. Kopt=rou*pi*R*R*R*R*R*R*CPmax / (2*lamda*lamda*lamda*G*G*G), where rou is the air density, R is the impeller radius, and G is the gearbox speed ratio.

7. The method for controlling the inertia response of a wind turbine generator set according to claim 1, wherein: The first stage is from the time when the inertia response trigger condition is met to 100~400ms, the second stage is from 100~400ms to the time when the grid frequency stops decreasing further; the third stage is from the time when the frequency stops decreasing further to the time when the impeller speed returns to the normal operating curve.

8. A computer device, characterized in that: The method comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the method for controlling the inertia response of a wind turbine generator set according to any one of claims 1 to 7 are implemented.

9. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method for controlling the inertia response of a wind turbine generator set according to any one of claims 1 to 7 are implemented.

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