Impact stabilizing method and system for gravity energy storage system of doubly-fed motor

Abstract

The invention discloses a doubly-fed motor gravity energy storage system impact stabilizing method and system, and relates to the technical field of gravity energy storage, and the method comprises the steps: collecting the three-phase voltage and current of the stator side of a doubly-fed motor; calculating a power error signal based on the acquired three-phase voltage and current; designing a sliding mode controller based on the power error signal; the change rate of power is calculated through a sliding mode controller, and a control signal is generated; the rotor voltage is calculated through the generated control signal, a PWM voltage signal is generated, feedback is formed for motor power generation, and power closed-loop control of the doubly-fed motor is achieved; according to the invention, the problem of system impact caused by a mass block entering and exiting a track or power step change is effectively solved; and the stability and the response speed of the motor are improved. By the adoption of the control method, the adjustment time of the motor is remarkably shortened, overshoot is eliminated, stator current, rotating speed and power fluctuation are effectively restrained, and the operation stability and safety of the energy storage system are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of gravity energy storage, and particularly to a method and system for suppressing the impact of a doubly-fed motor gravity energy storage system. Background Art

[0002] Gravity energy storage technology utilizes the potential energy of heavy objects for the storage and release of electrical energy, and has unique advantages, such as not relying on water resources and strong adaptability. Traditional gravity energy storage systems usually use motors as power sources. However, due to the discreteness of the energy storage medium (such as mass blocks), when adding or removing mass blocks in the gravity energy storage system, it will cause a step change in the system power, resulting in a large impact current and mechanical fluctuation in the motor, affecting the system stability and service life.

[0003] In the prior art, especially in the gravity energy storage system, traditional power regulation methods mainly rely on proportional-integral (PI) control. However, this control method shows obvious deficiencies when facing the addition or removal of mass blocks of the energy storage medium. Specifically: Impact during the power change process: Since the mass blocks of the energy storage medium change discretely, this leads to a step change in the system power, and the traditional PI control method cannot effectively smooth this change, thus causing a large impact current and mechanical fluctuation in the motor. System stability problem: In the process of high-power change, the robustness of traditional PI control is poor, and it is easy to cause system instability. Especially in the case of rapid response requirements and high-dynamic environments, PI control is difficult to meet the dual requirements of system stability and response speed. Influence on the motor life: Frequent impact currents and mechanical fluctuations will significantly shorten the service life of the motor, increasing the system maintenance cost and failure risk. Slow response speed: Traditional PI control is slow in dynamically adjusting the power output and cannot meet the high requirements of modern power grids for rapid response and precise control. Summary of the Invention

[0004] In view of the above existing problems, the present invention is proposed.

[0005] Therefore, the technical problem to be solved by the present invention is: how to provide a more rapid and stable control strategy to suppress the system impact.

[0006] To solve the above technical problem, the present invention provides the following technical solutions:

[0007] In a first aspect, an embodiment of the present invention provides a method for suppressing the impact of a doubly-fed motor gravity energy storage system, including:

[0008] Collect the three-phase voltage and current on the stator side of the doubly-fed motor;

[0009] Calculate the power error signal based on the collected three-phase voltage and current;

[0010] Design a sliding mode controller based on the power error signal;

[0011] The rate of change of power is calculated by a sliding mode controller to generate a control signal;

[0012] The rotor voltage is calculated by the generated control signal to generate a PWM voltage signal, which forms a feedback on the motor power to achieve the power closed-loop control of the doubly-fed motor.

[0013] As a preferred solution of the impact suppression method for the doubly-fed motor gravity energy storage system, wherein:

[0014] The acquisition of the three-phase voltage and current on the stator side of the doubly-fed motor includes:

[0015] The voltage and current on the stator side of the doubly-fed motor are acquired, converted to a specified coordinate system, and the active power and reactive power are calculated.

[0016] As a preferred solution of the impact suppression method for the doubly-fed motor gravity energy storage system, wherein:

[0017] The calculation of the power error signal based on the acquired three-phase voltage and current includes:

[0018] Based on the acquired three-phase voltage and current, an error comparison is made with a preset target power to obtain a power error signal; the target power is dynamically set according to the power regulation requirements of the power grid and the load requirements of the gravity energy storage system.

[0019] As a preferred solution of the impact suppression method for the doubly-fed motor gravity energy storage system, wherein:

[0020] The design of the sliding mode controller based on the power error signal includes:

[0021] The sliding mode surface of the sliding mode controller is defined as:

[0022]

[0023] In the formula, s P and s Q are the sliding mode surface functions of the active and reactive powers, e P (t), e Q (t) are the errors between the set values and the actual values of the active and reactive powers respectively, k P and k Q are the integral sliding mode surface coefficients.

[0024] As a preferred solution of the impact suppression method for the doubly-fed motor gravity energy storage system, wherein:

[0025] The design of the sliding mode controller based on the power error signal further includes:

[0026] The sliding mode reaching law adopts the exponential reaching law control method:

[0027]

[0028] Among them, represents the rate of change of the sliding mode surface with time, reflecting the approaching speed and direction of the system state towards the sliding mode surface. s is the sliding mode surface function, which defines the combination of the error of the system deviating from the desired state and its derivative. c is the approaching rate parameter, and ε is the sliding mode gain to achieve the fast convergence of the sliding mode surface s and ensure the stability of the system dynamic response. sgn(s) is the sign function used to maintain the stability of the system and control the direction of approaching the sliding mode surface, and its expression is:

[0029]

[0030] The approaching rates of active and reactive powers are expressed as:

[0031]

[0032] Among them, and are the rates of change of the sliding mode surface functions of active and reactive powers with time, ε P and ε Q are the sliding mode gains of active and reactive powers, sgn(s P ) and sgn(s Q ) are the sign functions of active and reactive powers, c P and c Q are the approaching rate parameters of active and reactive powers, s P and s Q are the sliding mode surface functions of active and reactive powers.

[0033] As an optimal scheme of the impact suppression method for the doubly-fed motor gravity energy storage system, where:

[0034] The rate of change of power calculated by the sliding mode controller to generate the control signal includes:

[0035] The formula is expressed as:

[0036]

[0037] Among them, P s and Q s are the stator active and reactive powers, and are the rates of change of the stator active and reactive powers with time.

[0038] As an optimal scheme of the impact suppression method for the doubly-fed motor gravity energy storage system, where:

[0039] Calculating the rotor voltage through the generated control signal, generating a PWM voltage signal, and forming a feedback on the motor power generation to achieve the power closed-loop control of the doubly-fed motor includes:

[0040] According to the power error value of the doubly-fed motor, the rate of change of power is calculated through a sliding mode controller, the rotor voltage value is obtained to generate a PWM voltage, and a feedback is formed on the motor power generation to achieve the power closed-loop control of the doubly-fed motor.

[0041] In a second aspect, an impact suppression system for a doubly-fed motor gravity energy storage system according to an embodiment of the present invention includes:

[0042] A data acquisition module for acquiring three-phase voltages and currents on the stator side of the doubly-fed motor;

[0043] A power calculation module for calculating a power error signal based on the acquired three-phase voltages and currents;

[0044] A controller design module for designing a sliding mode controller based on the power error signal;

[0045] A control signal generation module for calculating the rate of change of power through the sliding mode controller and generating a control signal;

[0046] A feedback control module for calculating the rotor voltage through the generated control signal, generating a PWM voltage signal, and forming a feedback on the motor power generation to achieve the power closed-loop control of the doubly-fed motor.

[0047] In a third aspect, an embodiment of the present invention provides a computing device, including:

[0048] A memory and a processor;

[0049] The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the one or more programs are executed by the one or more processors, the one or more processors implement the impact suppression method for a doubly-fed motor gravity energy storage system according to any embodiment of the present invention.

[0050] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium that stores computer-executable instructions, and when the computer-executable instructions are executed by a processor, the impact suppression method for a doubly-fed motor gravity energy storage system is implemented.

[0051] Advantages of the present invention: By applying sliding mode control in the DFIG gravity energy storage system, the present invention effectively solves the problem of system shock caused by the mass block entering and exiting the track or power step change. Compared with the traditional PI control, the sliding mode control can significantly reduce the shock current and speed fluctuation of the system, improving the stability and response speed of the motor. By adopting the control method of the present invention, the adjustment time of the motor is significantly shortened, the overshoot is eliminated, and the stator current, speed and power fluctuations are effectively suppressed, significantly improving the operation stability and safety of the energy storage system. Description of the Drawings

[0052] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0053] Figure 1 is the overall flowchart of the shock suppression method for the double-fed induction generator (DFIG) gravity energy storage system of the present invention;

[0054] Figure 2 is the simulation schematic diagram of the sudden load active power of the speed control system with traditional PI control in the simulation example of the shock suppression method for the DFIG gravity energy storage system of the present invention;

[0055] Figure 3 is the simulation result schematic diagram of the DFIG reactive power with traditional PI control in the simulation example of the shock suppression method for the DFIG gravity energy storage system of the present invention;

[0056] Figure 4 is the simulation result schematic diagram of the DFIG speed with traditional PI control in the simulation example of the shock suppression method for the DFIG gravity energy storage system of the present invention;

[0057] Figure 5 is the simulation result schematic diagram of the DFIG stator current with traditional PI control in the simulation example of the shock suppression method for the DFIG gravity energy storage system of the present invention;

[0058] Figure 6 is the simulation result schematic diagram of the DFIG active power with sliding mode control in the simulation example of the shock suppression method for the DFIG gravity energy storage system of the present invention;

[0059] Figure 7 is the simulation result schematic diagram of the DFIG reactive power with sliding mode control in the simulation example of the shock suppression method for the DFIG gravity energy storage system of the present invention;

[0060] Figure 8It is a schematic diagram of the simulation result of the DFIG speed in the sliding mode control in the simulation example of the impact suppression method of the doubly-fed motor gravity energy storage system described in the present invention;

[0061] Figure 9 It is a schematic diagram of the simulation result of the stator current of the DFIG in the sliding mode control in the simulation example of the impact suppression method of the doubly-fed motor gravity energy storage system described in the present invention. Specific embodiments

[0062] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following will describe the specific embodiments of the present invention in detail with reference to the accompanying drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0063] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0064] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that can be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it an individual or alternative embodiment that mutually excludes other embodiments.

[0065] Embodiment 1

[0066] Refer to Figure 1 , which is the first embodiment of the present invention. This embodiment provides a method for suppressing the impact of a doubly-fed motor gravity energy storage system, including:

[0067] S1: Collect the three-phase voltage and current on the stator side of the doubly-fed motor;

[0068] S2: Calculate the power error signal based on the collected three-phase voltage and current;

[0069] S3: Design a sliding mode controller based on the power error signal;

[0070] S4: Calculate the change rate of power through the sliding mode controller to generate a control signal;

[0071] S5: Calculate the rotor voltage through the generated control signal to generate a PWM voltage signal, which forms a feedback on the motor power generation to achieve the power closed-loop control of the doubly-fed motor.

[0072] It should be noted that through the above steps, in this embodiment, a doubly-fed motor is used as the power conditioning device of the gravity energy storage system. By combining the sliding mode control method with the direct power control, the power output and speed of the doubly-fed motor are adjusted to suppress the power step change caused by the movement of the mass block, reduce the system impact and improve the stability.

[0073] Embodiment 2

[0074] Referring to Figure 1 , an embodiment of the present invention provides a method for suppressing the impact of a doubly-fed motor gravity energy storage system based on the previous embodiment, including:

[0075] In the embodiment of the present application, the acquisition of the three-phase voltage and current on the stator side of the doubly-fed motor in step S1 includes:

[0076] Acquire the three-phase voltage and current on the stator side of the doubly-fed motor, and convert the three-phase voltage and current to the α, β coordinate system through Clark transformation to obtain the voltage and current u α , u β , i α , i β on the stator side, and then calculate the active power P s and the reactive power Q s .

[0077] Specifically, the calculation formula is:

[0078]

[0079] In another possible implementation manner, the three-phase voltage and current can also be converted to the rotating dq coordinate system through Park transformation (also known as dq transformation). The dq coordinate system is a coordinate system that rotates synchronously with the motor rotor and can better reflect the dynamic characteristics of the motor.

[0080] Steps: Acquire the three-phase voltage and current: The same as Clark transformation, first acquire the three-phase voltage and current on the stator side of the doubly-fed motor.

[0081] Park transformation: Convert the three-phase voltage and current to the dq coordinate system through Park transformation.

[0082] Calculate the active power and reactive power: In the dq coordinate system, the d-axis components (u d , i d ) and q-axis components (u q , i q ) of the voltage and current can be directly used to calculate the active power and reactive power.

[0083] In the embodiments of the present application, calculating the power error signal based on the collected three-phase voltage and current in the above step S2 includes:

[0084] Comparing the error between the collected three-phase voltage and current with a preset target power to obtain a power error signal:

[0085] e P (t) = P set -P s

[0086] e Q (t) = Q set -Q s

[0087] Wherein, e P (t) and e Q (t) are the errors between the set values and the actual values of the active and reactive powers, P set and Q set are the set values of the active and reactive powers, and P s and Q s are the actual powers.

[0088] The set values of the active and reactive powers are dynamically set according to the power regulation requirements of the power grid and the load requirements of the gravity energy storage system. The dynamic setting rule is:

[0089] P ref (t) = f(t)

[0090] Q ref (t) = g(t)

[0091] Wherein, P ref (t) and Q ref (t) are the set values of the active and reactive powers, and f(t) and g(t) are power reference functions that change with time.

[0092] In the embodiments of the present application, designing a sliding mode controller based on the power error signal in the above step S3 includes:

[0093] Defining the sliding mode surface of the sliding mode controller as:

[0094]

[0095] In the formula, s P and s Q are the sliding mode surface functions of the active and reactive powers, e P (t), e Q (t) are respectively the errors between the set values and the actual values of the active and reactive powers, and k P 、k Q are the integral sliding mode surface coefficients.

[0096] The sliding mode reaching law adopts the exponential reaching law control method:

[0097]

[0098] Wherein, represents the rate of change of the sliding mode surface with time, reflecting the approaching speed and direction of the system state towards the sliding mode surface. s is the sliding mode surface function, which defines the combination of the error of the system deviating from the desired state and its derivative. c is the reaching rate parameter, and ε is the sliding mode gain to achieve the rapid convergence of the sliding mode surface s and ensure the stability of the system dynamic response. sgn(s) is the sign function, which is used to maintain the stability of the system and control the direction of approaching the sliding mode surface. Its expression is:

[0099]

[0100] The reaching rates of active and reactive powers are expressed as:

[0101]

[0102] Wherein, and are the rates of change of the sliding mode surface functions of active and reactive powers with time. ε P and ε Q are the sliding mode gains of active and reactive powers. sgn(s P ) and sgn(s Q ) are the sign functions of active and reactive powers. c P and c Q are the reaching rate parameters of active and reactive powers. s P and s Q are the sliding mode surface functions of active and reactive powers.

[0103] In the embodiment of the present application, the rate of change of power calculated by the sliding mode controller in the above step S4 to generate a control signal includes:

[0104]

[0105] Wherein, P s and Q s are the stator active and reactive powers, and are the rates of change of the stator active and reactive powers with time.

[0106] In the embodiment of the present application, the rotor voltage is calculated by the generated control signal in the above step S5 to generate a PWM voltage signal, which forms a feedback on the motor power to achieve the power closed-loop control of the doubly-fed motor, including:

[0107] According to the power error value of the doubly-fed induction generator (DFIG), the rate of change of power is calculated through a sliding mode controller, and the rotor voltage value is obtained to generate a PWM voltage, which forms a feedback on the motor power to achieve the power closed-loop control of the DFIG.

[0108] Specifically, the rotor voltage is obtained through the following formula to generate a PWM voltage:

[0109]

[0110] Among them, u rd and u rq are the d-axis component and q-axis component of the rotor voltage, R r is the rotor resistance, i rd and i rq are the d-axis component and q-axis component of the rotor current, L s is the self-inductance of the stator winding, L s is the self-inductance of the stator winding, L m is the mutual inductance between the stator and rotor windings, ω 1 and ω r are the synchronous angular velocity and rotor electrical angular velocity, Ψ s is the stator magnetic flux.

[0111] Embodiment 3

[0112] The above is a schematic solution of the impact suppression method for the doubly-fed induction generator gravity energy storage system in this embodiment. It should be noted that the technical solution of the impact suppression system for the doubly-fed induction generator gravity energy storage system belongs to the same concept as the above-mentioned impact suppression method for the doubly-fed induction generator gravity energy storage system. For the details not described in detail in the technical solution of the impact suppression system for the doubly-fed induction generator gravity energy storage system in this embodiment, reference can be made to the description of the technical solution of the impact suppression method for the doubly-fed induction generator gravity energy storage system.

[0113] This embodiment also provides a system based on the impact suppression method for the doubly-fed induction generator gravity energy storage system, including:

[0114] A data acquisition module for acquiring the three-phase voltage and current on the stator side of the doubly-fed induction generator;

[0115] A power calculation module for calculating a power error signal based on the acquired three-phase voltage and current;

[0116] A controller design module for designing a sliding mode controller based on the power error signal;

[0117] A control signal generation module for calculating the rate of change of power through the sliding mode controller and generating a control signal;

[0118] A feedback control module is used to calculate the rotor voltage through the generated control signal, generate a PWM voltage signal, and form a feedback on the motor power generation to achieve the power closed-loop control of the doubly-fed motor.

[0119] This embodiment also provides a computing device applicable to the case of the impact suppression method of the doubly-fed motor gravity energy storage system, including:

[0120] A memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the impact suppression method of the doubly-fed motor gravity energy storage system as proposed in the above embodiment.

[0121] This embodiment also provides a storage medium, on which a computer program is stored, and when the program is executed by a processor, it implements the impact suppression method of the doubly-fed motor gravity energy storage system as proposed in the above embodiment.

[0122] The storage medium proposed in this embodiment and the impact suppression method of the doubly-fed motor gravity energy storage system proposed in the above embodiment belong to the same inventive concept. The technical details not described in detail in this embodiment can be referred to the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0123] Embodiment 4

[0124] Refer to Figures 2 - 9 , which is an embodiment of the present invention, provides an impact suppression method for a doubly-fed motor gravity energy storage system. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through simulation experiments.

[0125] Based on the power loop of the DFIG, a simulation model of the typical power change scenario of gravity energy storage using a power closed-loop controller with sliding mode control and a controller with traditional PI control is built in Simulink, where the motor parameters are: P N = 1.5 MW, f = 50 HZ, U N = 690 v, R s = 0.0055 Ω, L s = 1.56×10 -4 H, L r = 2.26×10 -4 H, L m = 0.01101 H.

[0126] Traditional PI control and sliding mode control are respectively adopted to compare their active power, reactive power, stator current and speed changes in the typical power change scenario of gravity energy storage, and to compare the static and dynamic performances of the two and the impact on the system.

[0127] The initial mechanical torque of the system is 5000 N·M, the initial reference value of the active power is set to 0.5 MW, and the reference value of the reactive power is set to 0 Mvar. At 3 s, a power increase command is received from the dispatching center, the on-orbit mass block is increased, the mechanical torque suddenly changes to 10000 N·M, and the power reference values are set to 1 MW and 0 Mvar respectively.

[0128] From Figures 2 to 5 It can be seen that under the traditional PI control method, when the mechanical torque suddenly changes at 3 s, the reference value of the active power also changes accordingly. The system adjustment time is about 0.5 s, and the overshoot of the active power can reach 25%, with obvious overshoot. There are large fluctuations in the reactive power. The maximum overshoot value of the speed exceeds the steady-state value by 2.8 rad / s, and the impact current can exceed the steady-state value by 300 A. When the mechanical torque suddenly decreases at 4 s and returns to the original value after 0.1 s, the reference value of the active power remains unchanged at 1 MW. It can be seen that the fluctuation value of the active power can reach 1.078 MW, there are fluctuations in the reactive power, the maximum value is 0.1 MW, the fluctuation value of the speed can reach 5.345 rad / s, and the impact current exceeds the steady-state value by 390 A.

[0129] From Figures 6 to 9 It can be seen that under the sliding mode control method, the system adjustment time at 3 s is extremely small, reaching 1 ms. The active power changes very quickly without overshoot, the fluctuations in the reactive power are small, and the maximum value is 0.05 MW. There is no overshoot in both the speed and the stator current. At 4 s, the active power, reactive power, speed, and stator current all maintain a steady state. However, in the system with sliding mode control, the steady-state fluctuations are large, and there are chattering in the active power, reactive power, and speed. The chattering of the active power is ±0.04 MW, the chattering of the reactive power is ±0.04 MW, and the chattering of the speed is about ±0.5 rad / s.

[0130] It can be seen from this that in the PI control system, the steady-state value can be accurately tracked, but the adjustment speed is slow and the overshoot is large, which is not conducive to the stability of the system. In the sliding mode control system, the dynamic performance is excellent, and the impact on the system can be greatly reduced, but there is steady-state chattering.

[0131] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A method for smoothing impact of a doubly-fed generator gravity energy storage system, characterized in that: include: Collect the three-phase voltage and current on the stator side of the doubly-fed generator; Calculate the power error signal based on the collected three-phase voltage and current; Design a sliding mode controller based on the power error signal; The power change rate is calculated by the sliding mode controller to generate a control signal; The rotor voltage is calculated through the generated control signal, and a PWM voltage signal is generated to form feedback on the motor power generation, thereby realizing power closed-loop control of the doubly-fed motor.

2. The method for smoothing the impact of the doubly-fed generator gravity energy storage system according to claim 1, characterized in that: The collecting of three-phase voltage and current on the stator side of the doubly-fed generator comprises: The voltage and current on the stator side of the doubly-fed generator are collected, converted to the specified coordinate system, and the active power and reactive power are calculated.

3. The method for smoothing the impact of a doubly-fed electric machine gravity energy storage system according to claim 2, characterized in that: The calculation of the power error signal based on the collected three-phase voltage and current includes: Based on the collected three-phase voltage and current, an error comparison is performed with the preset target power to obtain a power error signal; the target power is dynamically set according to the power regulation requirements of the power grid and the load requirements of the gravity energy storage system.

4. The method for smoothing the impact of a doubly-fed electric machine gravity energy storage system according to claim 3, characterized in that: The designing of a sliding mode controller based on a power error signal comprises: The sliding surface of the sliding mode controller is defined as: In the formula, s P and Q is the sliding surface function of active and reactive power, e P (t), e Q (t) are the errors between the set value and the actual value of active and reactive power, respectively, k P , k Q is the integral sliding surface coefficient.

5. The method for smoothing the impact of the doubly-fed generator gravity energy storage system according to claim 4, characterized in that: The designing of a sliding mode controller based on a power error signal further comprises: The sliding mode reaching law adopts the exponential reaching rate control method: in, It represents the rate of change of the sliding surface over time, reflecting the speed and direction of the system's state approaching the sliding surface. s is the sliding surface function, which defines the combination of the system's error from the desired state and its derivative. c is the approach rate parameter. ε is the sliding gain, which is used to achieve rapid convergence of the sliding surface s and ensure the stability of the system's dynamic response. sgn(s) is a sign function used to maintain the stability of the system and control the direction of approaching the sliding surface. Its expression is: The approach rate of active and reactive power is expressed as: in, and is the rate of change of active and reactive power sliding mode surface function over time, ε P and ε Q is the active and reactive power sliding film gain, sgn(s P ) and sgn(s Q ) is the sign function of active and reactive power, c P and c Q is the active and reactive power approach rate parameter, s P and Q is the sliding mode surface function of active and reactive power.

6. The method for smoothing the impact of a doubly-fed electric machine gravity energy storage system according to claim 5, characterized in that: The power change rate is calculated by the sliding mode controller to generate a control signal, which includes: The formula is: Among them, P s and Q s is the stator active and reactive power, and is the rate of change of stator active and reactive power with time.

7. The method for smoothing the impact of a doubly-fed electric machine gravity energy storage system according to claim 6, characterized in that: The method of calculating the rotor voltage through the generated control signal, generating a PWM voltage signal, and generating feedback on the motor power to realize the power closed-loop control of the doubly-fed motor includes: According to the power error value of the doubly-fed motor, the power change rate is calculated through the sliding mode controller, and the rotor voltage value is obtained to generate PWM voltage, which forms feedback on the motor power generation and realizes the power closed-loop control of the doubly-fed motor.

8. A system using the method for smoothing the impact of a doubly-fed electric machine gravity energy storage system as claimed in any one of claims 1 to 7, characterized in that: include: A data acquisition module is used to collect the three-phase voltage and current on the stator side of the doubly-fed generator; A power calculation module, used for calculating a power error signal based on the collected three-phase voltage and current; A controller design module for designing a sliding mode controller based on a power error signal; A control signal generating module, used for calculating the rate of change of power through a sliding mode controller and generating a control signal; The feedback control module is used to calculate the rotor voltage through the generated control signal, generate a PWM voltage signal, form feedback on the motor power generation, and realize the power closed-loop control of the doubly-fed motor.

9. A computing device comprising: Memory and processor; The memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions. When the computer executable instructions are executed by the processor, the steps of the impact smoothing method of the doubly-fed motor gravity energy storage system described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the steps of the method for impact smoothing of a doubly-fed electric machine gravity energy storage system according to any one of claims 1 to 7.

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