Double-fed gravity energy storage system cooperative control method and system based on virtual torque feedforward

Abstract

The invention relates to the field of energy storage, in particular to a virtual torque feedforward-based double-fed gravity energy storage system cooperative control method and system, and the method comprises the steps: obtaining a basic electromagnetic torque reference value based on a proportional integral controller according to the real-time rotor speed of a DFIG; obtaining an electromagnetic torque standard value by using the basic electromagnetic torque reference value and a corresponding mechanical torque ideal value; reactive power feed-forward calculation is performed by using the electromagnetic torque standard value to obtain a cooperative control result of the double-fed gravity energy storage system, predictive compensation of instructions is realized by optimizing a control algorithm, the burden of a feedback controller is significantly reduced, and the dependence of the system on high feedback gain is reduced, so that overshoot or oscillation is effectively weakened, and the cooperative control effect of the double-fed gravity energy storage system is improved. The dynamic response capability of the system is optimized, rotating speed fluctuation caused by heavy object switching can be effectively inhibited, and meanwhile reactive power fed into a power grid is compensated to be stabilized at a designed reference value instruction.

Description

Technical Field

[0001] This invention relates to the field of energy storage, specifically to a collaborative control method and system for a doubly-fed gravity energy storage system based on virtual torque feedforward. Background Technology

[0002] The penetration rate of intermittent and fluctuating renewable energy sources such as wind and solar power in power systems is continuously increasing. Their inherent randomness and intermittency pose significant challenges to the frequency stability, power balance, and safe operation of the power grid. Therefore, developing large-scale, long-duration, and efficient new energy storage technologies has become a crucial link in solving the problem of renewable energy consumption and enhancing grid resilience.

[0003] Among numerous energy storage technologies, gravity energy storage has received widespread attention in recent years due to its advantages such as simple principle, long lifespan, environmental friendliness, and independence from specific geographical conditions. Among these, gravity energy storage systems based on doubly-fed induction generators (DFIGs) represent a novel technological approach. By lifting / lowering heavy blocks, it achieves the storage and release of electrical energy, simulating the inertial response and primary frequency regulation function of synchronous generators, providing valuable ancillary services to the power grid, and showing broad application prospects.

[0004] The core of this system lies in the DFIG's rotor, which is connected to the power grid via a converter, while its stator is directly connected to the grid. During operation, the electromagnetic torque of the motor is adjusted by controlling the rotor-side converter, thereby controlling the lifting and lowering speed of the load and achieving precise control of the charging and discharging power. Its unique advantage lies in its ability to not only continuously adjust the load's translational speed but also to incrementally change the system's potential power through discrete "load and unload" operations. Rapidly loading the load instantly increases potential energy, thus feeding a large amount of active power into the grid; unloading the load has the opposite effect. This mode enables it to respond effectively to the grid's frequency regulation commands.

[0005] However, this "thick load dropping" operation mode introduces severe technical challenges: First, the system lacks inherent damping: compared to the massive steam turbine generator sets of traditional thermal power generating units, the mechanical transmission parts of gravity energy storage systems are relatively "light" and lack natural mechanical damping. Simultaneously, the rotational inertia of the DFIG rotor itself is also relatively small. Second, power surges and speed fluctuations: when the load is suddenly added or removed, it is equivalent to applying a huge step-like mechanical torque disturbance to the motor shaft system. In a low-damping, low-inertia system, such severe disturbances will induce strong electromechanical oscillations, leading to significant fluctuations and overshoot in motor speed. Third, it jeopardizes system stability: this speed fluctuation, through the electromagnetic coupling relationship of the DFIG, further leads to fluctuations in grid-connected power, not only failing to provide stable power support but also injecting new power disturbances into the grid, endangering the operational safety of the system itself and the stability of the grid. Traditional PI feedback-based controllers, due to their lag response, struggle to effectively suppress such rapid and severe disturbances.

[0006] Therefore, effectively suppressing the speed and power fluctuations caused by the dropping of heavy blocks has become a key technical challenge for improving the dynamic performance of doubly-fed gravity energy storage systems, ensuring their safe and reliable grid connection, and fully leveraging their grid support function. Existing control strategies have significant shortcomings in this regard, and a new control algorithm capable of proactively suppressing disturbances and enhancing the system's equivalent damping is urgently needed. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a cooperative control method for doubly-fed gravity energy storage systems based on virtual torque feedforward. By optimizing the control algorithm, predictive compensation for commands is achieved, significantly reducing the burden on the feedback controller and lowering the system's dependence on high feedback gain.

[0008] To achieve the above objectives, this invention provides a cooperative control method for a doubly-fed gravity energy storage system based on virtual torque feedforward, comprising:

[0009] Based on the real-time rotor speed of the DFIG using a proportional-integral controller, the basic electromagnetic torque reference value is obtained.

[0010] The standard value of electromagnetic torque is obtained by using the basic electromagnetic torque reference value and the corresponding ideal mechanical torque value;

[0011] The reactive power feedforward calculation is performed using the electromagnetic torque standard value to obtain the collaborative control results of the doubly-fed gravity energy storage system.

[0012] Preferably, obtaining the basic electromagnetic torque reference value based on the DFIG real-time rotor speed using a proportional-integral controller includes:

[0013] Collect real-time rotor speed of DFIG;

[0014] The rotor speed error signal is calculated based on the real-time rotor speed of the DFIG and the corresponding preset rotor speed.

[0015] The basic electromagnetic torque reference value is obtained based on the rotor speed error signal using a proportional-integral controller.

[0016] Furthermore, the calculation formula for the rotor speed error signal, obtained from the real-time rotor speed of the DFIG and the corresponding preset rotor speed, is as follows:

[0017]

[0018] Where, ω r_error The rotor speed error signal, ω r_ref ω is the preset rotor speed. r This represents the real-time rotor speed of the DFIG.

[0019] Furthermore, the basic electromagnetic torque reference value obtained based on the rotor speed error signal using a proportional-integral controller includes:

[0020]

[0021] Among them, T e_ref The basic electromagnetic torque reference value, ω r_error This is the rotor speed error signal.

[0022] Furthermore, by using the aforementioned basic electromagnetic torque reference value and the corresponding ideal mechanical torque value, the standard value of the electromagnetic torque is obtained, including:

[0023] The ideal value of mechanical torque is obtained by feedforward calculation based on the mass of the heavy object and the switching information of the doubly fed gravity energy storage system.

[0024] The standard value of electromagnetic torque is obtained based on the ideal value of mechanical torque.

[0025] Furthermore, based on the mass of the load and the switching information of the doubly-fed gravity energy storage system, the formula for calculating the ideal value of the mechanical torque is as follows:

[0026]

[0027] Where k is the pulley system ratio, N is the gear ratio of the gearbox, m is the mass of the load, g is the acceleration due to gravity, and T is the acceleration due to gravity. L This is the ideal value of the mechanical torque.

[0028] Furthermore, the formula for calculating the standard value of electromagnetic torque based on the ideal value of mechanical torque is as follows:

[0029]

[0030] Among them, T e ， _ref The electromagnetic torque reference value is given by K1, where K1 is the feedforward coefficient and T is the reference value. L T is the ideal value of the mechanical torque. e_ref This is the basic electromagnetic torque reference value.

[0031] Furthermore, by using the aforementioned electromagnetic torque standard value to perform reactive power feedforward calculations, the collaborative control results of the doubly-fed gravity energy storage system are obtained, including:

[0032] When there is a sudden change in the amplitude of the ideal mechanical torque, the slope signal variable value is obtained by designing the input amount based on the ideal mechanical torque and the corresponding heavy object throwing command.

[0033] The reactive power reference value is obtained based on the slope signal variable value;

[0034] The formula for calculating the actual reactive power value as the collaborative control result of the doubly-fed gravity energy storage system using the aforementioned reactive power reference value is as follows:

[0035]

[0036] Among them, Q s ， _ref K2 is the actual value of reactive power, T is the feedforward coefficient, and T is the actual value of reactive power. L T is the ideal value of the mechanical torque. L0 For casting information, Q s_ref This is a reference value for reactive power.

[0037] Furthermore, obtaining the reactive power reference value based on the slope signal variable value includes:

[0038] Obtain the corresponding steady-state value of the ramp signal based on the ramp signal variable value;

[0039] The steady-state value of the slope signal is used as a compensation input to the doubly-fed gravity energy storage system;

[0040] When the output power of the doubly-fed gravity energy storage system is stable, obtain the corresponding reactive power reference value.

[0041] A system based on the cooperative control method for a doubly-fed gravity energy storage system based on virtual torque feedforward as described in any one of claims 1-9, comprising:

[0042] The electromagnetic torque processing module is used to obtain the basic electromagnetic torque reference value based on the real-time rotor speed of the DFIG using a proportional-integral controller.

[0043] The electromagnetic torque optimization module is used to obtain the standard value of electromagnetic torque by using the basic electromagnetic torque reference value and the corresponding ideal value of mechanical torque;

[0044] The collaborative control processing module uses the electromagnetic torque standard value to perform reactive power feedforward calculation and obtains the collaborative control results of the doubly-fed gravity energy storage system.

[0045] Compared with the closest existing technology, the present invention has the following advantages:

[0046] By introducing virtual mechanical torque feedforward into the machine-grid coordinated control algorithm and optimizing the control algorithm, predictive compensation for commands is achieved, significantly reducing the burden on the feedback controller and lowering the system's dependence on high feedback gain. This effectively weakens overshoot or oscillation, optimizes the system's dynamic response capability, effectively suppresses speed fluctuations caused by loading and unloading heavy objects, and compensates for reactive power fed into the grid to stabilize it at the designed reference value command. This provides reliable technical support for adjusting the active power fed into the grid by loading and unloading heavy objects in doubly-fed gravity energy storage systems, improves the safety and operability of the method, and promotes the sustainable and healthy development of the new energy industry. Attached Figure Description

[0047] Figure 1 This is a flowchart of the collaborative control method for a doubly-fed gravity energy storage system based on virtual torque feedforward provided by the present invention;

[0048] Figure 2 The present invention provides a doubly-fed gravity energy storage system architecture based on machine-grid collaborative control, which is a collaborative control method for doubly-fed gravity energy storage systems based on virtual torque feedforward.

[0049] Figure 3 This invention relates to the internal mechanical structure of a mechanical device for a cooperative control method of a doubly-fed gravity energy storage system based on virtual torque feedforward, as provided by the present invention.

[0050] Figure 4 This is a block diagram of the virtual mechanical torque feedforward control of the cooperative control method for doubly-fed gravity energy storage systems based on virtual torque feedforward provided by the present invention.

[0051] Figure 5 The waveforms of system torque, rotor speed, active power, and reactive power before optimization of the cooperative control method for a doubly fed gravity energy storage system based on virtual torque feedforward provided by this invention are shown.

[0052] Figure 6 The rotor speed waveform diagram after introducing virtual mechanical torque feedforward into the machine-grid collaborative control of the doubly-fed gravity energy storage system based on virtual torque feedforward provided by this invention;

[0053] Figure 7 The reactive power waveform of the doubly fed gravity energy storage system based on virtual torque feedforward, provided by this invention, is shown in the machine-grid collaborative control diagram after introducing virtual mechanical torque feedforward into the system reactive power waveform.

[0054] Figure 8 This invention provides a method for coordinated control of doubly-fed gravity energy storage systems based on virtual torque feedforward. The waveform diagram shows the torque change after introducing virtual mechanical torque feedforward into the machine-grid coordinated control. Detailed Implementation

[0055] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] Example 1:

[0058] This invention provides a cooperative control method for a doubly-fed gravity energy storage system based on virtual torque feedforward, such as... Figure 1 As shown, it includes:

[0059] S1. Based on the real-time rotor speed of the DFIG using a proportional-integral controller, obtain the basic electromagnetic torque reference value;

[0060] S2. Obtain the standard value of electromagnetic torque by using the basic electromagnetic torque reference value and the corresponding ideal value of mechanical torque;

[0061] S3. Using the electromagnetic torque standard value, perform reactive power feedforward calculation to obtain the collaborative control results of the doubly fed gravity energy storage system.

[0062] S1 specifically includes:

[0063] S1-1. Collect the real-time rotor speed of the DFIG;

[0064] S1-2. Calculate the rotor speed error signal based on the real-time rotor speed of the DFIG and the corresponding preset rotor speed.

[0065] S1-3. Based on the rotor speed error signal, obtain the basic electromagnetic torque reference value using a proportional-integral controller.

[0066] The formula for calculating S1-2 is as follows:

[0067]

[0068] Where, ω r_error The rotor speed error signal, ω r_ref ω is the preset rotor speed. r This represents the real-time rotor speed of the DFIG.

[0069] S1-3 specifically includes:

[0070]

[0071] Among them, Te_ref The basic electromagnetic torque reference value, ω r_error This is the rotor speed error signal.

[0072] S2 specifically includes:

[0073] S2-1. The ideal value of mechanical torque is obtained by feedforward calculation based on the mass of the heavy object and the switching information of the doubly fed gravity energy storage system.

[0074] S2-2. Obtain the standard value of electromagnetic torque based on the ideal value of mechanical torque.

[0075] The formula for calculating S2-1 is as follows:

[0076]

[0077] Where k is the pulley system ratio, N is the gear ratio of the gearbox, m is the mass of the load, g is the acceleration due to gravity, and T is the acceleration due to gravity. L This is the ideal value of the mechanical torque.

[0078] The formula for calculating S2-2 is as follows:

[0079]

[0080] Among them, T e ， _ref The electromagnetic torque reference value is given by K1, where K1 is the feedforward coefficient and T is the reference value. L T is the ideal value of the mechanical torque. e_ref This is the basic electromagnetic torque reference value.

[0081] S3 specifically includes:

[0082] S3-1. When there is a sudden change in the amplitude of the ideal value of the mechanical torque, the slope signal variable value is obtained by designing the input amount based on the ideal value of the mechanical torque and the corresponding heavy object throwing command.

[0083] S3-2. Obtain the reactive power reference value based on the slope signal variable value;

[0084] S3-3, The calculation formula for obtaining the actual reactive power value as the collaborative control result of the doubly-fed gravity energy storage system using the aforementioned reactive power reference value is as follows:

[0085]

[0086] Among them, Q s ， _ref K2 is the actual value of reactive power, T is the feedforward coefficient, and T is the actual value of reactive power. L T is the ideal value of the mechanical torque. L0 For casting information, Q s_ref This is a reference value for reactive power.

[0087] S3-2 specifically includes:

[0088] S3-2-1. Obtain the corresponding steady-state value of the ramp signal based on the ramp signal variable value;

[0089] S3-2-2, The steady-state value of the slope signal is used as a compensation input to the doubly fed gravity energy storage system;

[0090] S3-2-3. When the output power of the doubly-fed gravity energy storage system is stable, obtain the corresponding reactive power reference value.

[0091] In this embodiment, the collaborative control method for the doubly-fed gravity energy storage system based on virtual torque feedforward is implemented in the following real-time manner:

[0092] like Figure 2 As shown, the overall architecture of a doubly-fed gravity energy storage system is presented. The system consists of a weight, mechanical components, a DFIG (Double-Induced Gravity Induction Generator), a rotor-side converter (RSC), a grid-side converter (GSC), and a filter. The weight is mechanically connected to the doubly-fed motor rotor via the mechanical components, utilizing gravity to drive the mechanical components and generate a mechanical torque T. L This drives the rotor to rotate. U gABC I gABC These are the three-phase voltage at the point of common coupling (PCC), the three-phase current on the AC side of the GSC, and U. sABC I sABC The three-phase output voltage and current are respectively located on the stator side. The GSC is connected to the PCC through a low-pass filter. The three-phase power supply from the grid is inverted into DC voltage through the GSC control system and space vector pulsed width modulation (SVPWM), providing a stable DC bus voltage V for the RSC. DC RSC controls the operation of the doubly-fed induction generator (DFIG) based on the stable DC bus voltage. RSC control and GSC control together constitute the machine-grid coordinated control. When the voltages across the circuit breaker are synchronized, i.e., the amplitude, frequency, and phase are the same, the circuit breaker closes, and the output power of the DFIG stator side is fed into the PCC through the circuit breaker.

[0093] The RSC controller is optimized by introducing virtual mechanical torque feedforwards in both the electromagnetic torque and reactive power stages. In the electromagnetic torque stage, the calculated virtual mechanical torque feedforward is superimposed with the speed closed-loop output to obtain T. e ， _refIn the reactive power stage, Q is obtained by adding the calculated virtual mechanical torque feedforward to the reactive power command. s ， _ref The specific process of feeding these components into the pre-optimized rotor-side converter control system is as follows:

[0094] First, the speed closed-loop: measuring the actual rotor speed ω of the DFIG. r Its value is related to the preset rotor speed setting ω. r_ref The rotor speed error signal ω is obtained by subtraction. r_error The electromagnetic torque reference value T is obtained by passing it through a proportional-integral controller (PI). e_ref :

[0095]

[0096]

[0097] Next is the feedforward calculation in the electromagnetic torque stage, which calculates the mechanical torque T under ideal conditions using the known mass of the load and the cutting information. L :

[0098]

[0099] In the formula, k is the pulley system ratio; N is the gear ratio of the gearbox; m is the mass of the object; g is the acceleration due to gravity; and T is the acceleration due to gravity. L It is a stepped wave with time as the independent variable. The specific structure of the mechanical device is as follows: Figure 3 As shown.

[0100] T L T is obtained by scaling the feedforward coefficient K1 and superimposing it with the closed-loop output of the rotational speed. e ， _ref :

[0101]

[0102] Next is the feedforward calculation in the reactive power stage: such as Figure 4 As shown, T L ， The input quantity designed according to the command to drop heavy objects, so that T L When the amplitude of a stepped wave changes abruptly, it is converted into a ramp signal. The input, along with its steady-state value, serves as a compensation quantity, stabilizing the system's output reactive power at the set reference value command Q. s_ref T L With T L ， The difference between the two values ​​is fed forward by the feedforward coefficient K2 to obtain the virtual mechanical torque feedforward of the reactive power link, which is then compared with the reactive power command Q.s_ref Q is obtained by superposition. s ， _ref :

[0103]

[0104] Finally, the obtained virtual mechanical torque feedforward calculation results are fed into the RSC control system as part of the machine-network coordinated control to optimize the system control and achieve the effects of suppressing speed fluctuations and compensating for reactive power.

[0105] A simulation model of a doubly-fed gravity energy storage system based on machine-grid coordinated control was built in Simulink. The virtual mechanical torque feedforward proposed in this patent was used for optimization. Its control block diagram is shown below. Figure 4 As shown. The verification of suppressing speed fluctuations and compensating for reactive power is as follows: The initial load is set to 0.8 pu at the per unit value. At 15s, a load of 0.2 pu is loaded. At 20s and 25s, loads of 0.5 pu are loaded again. At the same time, the reference value set for reactive power is always 0. Figure 5 The waveforms of system torque, rotor speed, active power, and reactive power before optimization are presented. The changes in rotor speed, reactive power, and torque waveforms after introducing virtual mechanical torque feedforward are observed, as shown below. Figure 6 , 7 As shown in Figure 8. Figure 6 In the middle, ω r (Blue line) represents the rotor speed under virtual mechanical torque feedforward with only electromagnetic torque input, ω. r Optimized (yellow line) refers to the rotor speed under the condition that virtual mechanical torque feedforward is introduced into both electromagnetic torque and reactive power components. Figure 7 In the middle, Q s (Blue line) represents the stator-side reactive power, Q, under the condition of virtual mechanical torque feedforward with only electromagnetic torque element introduced. s Optimized (yellow line) represents the stator-side reactive power under conditions where virtual mechanical torque feedforward is introduced into both the electromagnetic torque and reactive power components. (Comparison) Figure 5 It can be seen that introducing virtual mechanical torque feedforward into the electromagnetic torque stage can significantly suppress speed fluctuations. On this basis, introducing virtual mechanical torque feedforward into the reactive power stage can further suppress speed fluctuations, while also effectively compensating for reactive power and stabilizing it at the set reference value.

[0106] Figure 8 The waveforms of torque variation at each stage of loading the heavy object are given, T L (Blue line) represents the actual mechanical torque; T e (Red line) represents the actual electromagnetic torque before optimization; T eOptimized (purple line) represents the actual electromagnetic torque after introducing a virtual mechanical torque load. The red line shows a larger overshoot, while the purple line shows a smaller overshoot. This demonstrates that the essence of this patent's suppression of speed fluctuations is to suppress electromagnetic torque fluctuations through optimized control algorithms.

[0107] Example 2:

[0108] A collaborative control system for a doubly-fed gravity energy storage system based on virtual torque feedforward includes:

[0109] The electromagnetic torque processing module is used to obtain the basic electromagnetic torque reference value based on the real-time rotor speed of the DFIG using a proportional-integral controller.

[0110] The electromagnetic torque optimization module is used to obtain the standard value of electromagnetic torque by using the basic electromagnetic torque reference value and the corresponding ideal value of mechanical torque;

[0111] The collaborative control processing module uses the electromagnetic torque standard value to perform reactive power feedforward calculation and obtains the collaborative control results of the doubly-fed gravity energy storage system.

[0112] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied 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.

[0113] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0114] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0115] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0116] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A virtual torque feedforward based coordinated control method for doubly-fed gravity energy storage system, characterized in that, The method comprises the steps of: obtaining a basic electromagnetic torque reference value based on a proportional-integral controller according to a real-time rotor speed of a DFIG; obtaining an electromagnetic torque standard value by using the basic electromagnetic torque reference value and a corresponding mechanical torque ideal value; performing reactive power feedforward calculation by using the electromagnetic torque standard value to obtain a cooperative control result of a doubly-fed gravity energy storage system.

2. The virtual torque feedforward based coordinated control method of a doubly-fed gravity energy storage system according to claim 1, wherein, The step of obtaining the basic electromagnetic torque reference value based on the proportional-integral controller according to the real-time rotor speed of the DFIG comprises the steps of: collecting the real-time rotor speed of the DFIG; calculating a rotor speed error signal according to the real-time rotor speed of the DFIG and a corresponding preset rotor speed; obtaining the basic electromagnetic torque reference value based on the proportional-integral controller according to the rotor speed error signal.

3. The virtual torque feedforward based coordinated control method of a doubly-fed gravity energy storage system according to claim 2, wherein, The calculation formula for calculating the rotor speed error signal according to the real-time rotor speed of the DFIG and the corresponding preset rotor speed is as follows: where ω r_error is the rotor speed error signal, ω r_ref is the preset rotor speed, and ω r is the real-time rotor speed of the DFIG.

4. The virtual torque feedforward based coordinated control method of a doubly-fed gravity energy storage system according to claim 3, wherein, The step of obtaining the basic electromagnetic torque reference value based on the proportional-integral controller according to the rotor speed error signal comprises the steps of: wherein T e_ref is the base electromagnetic torque reference value, ω r_error is the rotor speed error signal.

5. The virtual torque feed forward based coordinated control method of a doubly-fed gravity energy storage system according to claim 2, wherein, The step of obtaining the electromagnetic torque standard value by using the basic electromagnetic torque reference value and the corresponding mechanical torque ideal value comprises the steps of: performing feedforward calculation according to the mass of the gravity of the doubly-fed gravity energy storage system and switching information to obtain the mechanical torque ideal value; obtaining the electromagnetic torque standard value according to the mechanical torque ideal value.

6. The virtual torque feed forward based coordinated control method of a doubly-fed gravity energy storage system according to claim 5, wherein, The calculation formula for performing the feedforward calculation according to the mass of the gravity of the doubly-fed gravity energy storage system and the switching information to obtain the mechanical torque ideal value is as follows: where k is the pulley ratio, N is the gear box gear ratio, m is the mass of the weight, g is the acceleration due to gravity, T L is the ideal mechanical torque.

7. The virtual torque feed forward based coordinated control method of a doubly-fed gravity energy storage system according to claim 6, wherein, The calculation formula for obtaining the electromagnetic torque standard value according to the mechanical torque ideal value is as follows: where T e ， _ref is the electromagnetic torque reference value, K1 is a feedforward coefficient, T L is the mechanical torque ideal value, T e_ref is the base electromagnetic torque reference value.

8. The virtual torque feed forward based coordinated control method of a doubly-fed gravity energy storage system according to claim 5, wherein, The step of performing the reactive power feedforward calculation by using the electromagnetic torque standard value to obtain the cooperative control result of the doubly-fed gravity energy storage system comprises the steps of: when there is an amplitude mutation in the mechanical torque ideal value, obtaining a ramp signal variable value according to the mechanical torque ideal value and a corresponding switching gravity instruction design input; obtaining a reactive power reference value according to the ramp signal variable value; The calculation formula for obtaining the reactive power actual value by using the reactive power reference value as the cooperative control result of the doubly-fed gravity energy storage system is as follows: Wherein, Q s ， _ref is the actual value of reactive power, K2 is the feedforward coefficient, T L is the ideal value of mechanical torque, T L0 is the switching information, Q s_ref is the reference value of reactive power.

9. The virtual torque feed forward based coordinated control method of a doubly-fed gravity energy storage system according to claim 8, wherein, The step of obtaining the reactive power reference value according to the ramp signal variable value comprises the steps of: obtaining a corresponding ramp signal steady-state value according to the ramp signal variable value; using the ramp signal steady-state value as a compensation input of the doubly-fed gravity energy storage system; when the output power of the doubly-fed gravity energy storage system is stable, obtaining the corresponding reactive power reference value.

10. A system based on the virtual torque feed forward based coordinated control method of a doubly-fed gravity energy storage system according to any one of the preceding claims 1-9, characterized in that, The method comprises the steps of: an electromagnetic torque processing module, configured to obtain a basic electromagnetic torque reference value based on a proportional-integral controller according to a real-time rotor speed of a DFIG; an electromagnetic torque optimization module, configured to obtain an electromagnetic torque standard value by using the basic electromagnetic torque reference value and a corresponding mechanical torque ideal value; a cooperative control processing module, configured to perform reactive power feedforward calculation by using the electromagnetic torque standard value to obtain a cooperative control result of a doubly-fed gravity energy storage system.

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