Cooperative control method and device for doubly-fed gravity energy storage system with grid-connected characteristics

Abstract

This invention discloses a collaborative control method and device for a doubly-fed gravity energy storage system with grid-connection characteristics. The method includes: determining the stator-side output voltage phase based on the stator-side voltage frequency obtained from a phase-locked loop; performing coordinate transformation on the pre-acquired two-phase stationary stator-side voltages to obtain the d-axis voltage in a two-phase rotating coordinate system based on the voltage phase; determining the stator-side electromagnetic active power feedforward based on a stator-side output voltage frequency reference value and the stator-side voltage frequency; simultaneously, determining the stator-side electromagnetic reactive power feedforward based on a stator-side output voltage amplitude reference value and the d-axis voltage; and determining the rotor-side converter state based on the stator-side electromagnetic active power feedforward and the stator-side electromagnetic reactive power feedforward. This invention can provide support for the grid connection point frequency and amplitude.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, and in particular to a collaborative control method and device for a doubly-fed gravity energy storage system with grid-connected characteristics. Background Technology

[0002] In the process of transitioning to clean and low-carbon energy, how to efficiently develop and scale up gravity energy storage systems has become an urgent technical problem to be solved. Based on differences in control strategies, the control strategies for gravity energy storage systems can be divided into two main technical routes: grid-following control and grid-connected control. Grid-following control uses high-precision phase-locked loop (PLL) technology to achieve real-time tracking of grid connection parameters, ensuring that the device maintains strict synchronization with the grid. Grid-connected control, on the other hand, is based on droop characteristic control and virtual synchronous machine control, establishing stable voltage amplitude and frequency references to provide continuous and reliable support to grid-connected nodes even under abnormal conditions such as grid faults.

[0003] Existing technologies generally only perform grid-connected control of gravity energy storage systems, without coordinating the processing of grid data on the stator and rotor sides. The general grid-connected control has the drawback of changing with the grid and being unable to provide active support to the grid connection point during sudden disturbances, such as sudden changes in grid frequency or amplitude. Summary of the Invention

[0004] Based on this, the purpose of the present invention is to provide a collaborative control method and device for a doubly fed gravity energy storage system with grid-connection characteristics, so as to achieve active support for the grid connection point.

[0005] In a first aspect, embodiments of the present invention provide a cooperative control method for a doubly-fed gravity energy storage system with grid-connected characteristics. The method includes: S102: based on the stator-side voltage frequency f obtained by the phase-locked loop... s_pll Determine the stator-side output voltage phase θ; S104: Based on the voltage phase θ, calculate the pre-acquired stator-side stationary two-phase voltage U sαβ Perform coordinate transformation to obtain the d-axis voltage U in the rotating coordinate system. sd_pll S106: Based on the preset stator-side output voltage frequency reference value f s_ref and the voltage frequency f on the stator side s_pll Determine the feedforward ΔP for the stator-side electromagnetic active power. s Based on the stator-side output voltage amplitude reference value U sd_ref The d-axis voltage U in the rotating coordinate system sd_pll Determine the feedforward ΔQ of the stator-side electromagnetic reactive power. s S108: Feedforward ΔP based on stator-side electromagnetic active power s Feedforward ΔQ of stator-side electromagnetic reactive power s Determine the status of the rotor-side converter.

[0006] Furthermore, S106 includes: ΔP s =K f (f s_ref -f s_pll ); where K f The frequency coefficient constant is obtained in advance; ΔQ s =K U (U sd_ref -U sd_pll ); where K U This is a pre-acquired amplitude coefficient constant.

[0007] Furthermore, S102 includes: Where s is the differential operator.

[0008] Furthermore, S104 includes: Among them, U sdq_pll Overall, U represents the d-axis voltage in a rotating coordinate system. sd_pll and q-axis voltage U sq_pll .

[0009] Furthermore, S108 includes: S1082: based on the feedforward ΔP of the stator-side electromagnetic active power. s Feedforward ΔQ of stator-side electromagnetic reactive power s Determine the current reference value in the rotating coordinate system on the rotor side. S1084: Determine the double closed-loop feedforward Δu for voltage and current. rdq S1086: Based on the current reference value in the rotating coordinate system on the rotor side. and dual closed-loop feedforward Δu rdq Determine the conduction state of the rotor-side converter.

[0010] Furthermore, S1082 includes: Among them, G PI_U (s) is a preset proportional-integral controller, P s_error For the pre-obtained active power error, Q s_error For the pre-acquired reactive power error, U sd_pll Let ω be the d-axis voltage in the rotating coordinate system. grid The voltage frequency f on the stator side s_pll The corresponding rotational speed, L m It refers to the mutual inductance between the coaxial equivalent windings of the stator and rotor in a rotating coordinate system.

[0011] Furthermore, S1084 includes: Among them, R r ω slip , σ, ψ sd, , and respectively represent the pre-obtained rotor resistance, speed slip, leakage inductance coefficient, and stator flux linkage along the d-axis in a two-phase rotating coordinate system; L m L s L r I rq I rd These represent the mutual inductance between the coaxial equivalent windings of the stator and rotor in the rotating coordinate system, the self-inductance of the equivalent two-phase winding of the stator in the rotating coordinate system, the self-inductance of the equivalent two-phase winding of the rotor in the rotating coordinate system, the q-axis current on the rotor side in the rotating coordinate system, and the d-axis current on the rotor side in the rotating coordinate system, respectively.

[0012] Furthermore, S102 also includes: information from the phase-locked loop based on closed-loop acquisition.

[0013] Secondly, embodiments of the present invention provide a cooperative control device for a doubly-fed gravity energy storage system with grid-connected characteristics. The device includes: a first control module, configured to control the stator-side voltage frequency f obtained by a phase-locked loop. s_pll The first module determines the voltage phase θ of the stator-side output; the second module is used to adjust the pre-acquired stator-side stationary two-phase voltage U based on the voltage phase θ. sαβ Perform coordinate transformation to obtain the d-axis voltage U in the rotating coordinate system. sd_pll The third control module is used to control the stator-side output voltage frequency reference value f based on a pre-set value. s_ref and the voltage frequency f on the stator side s_pll Determine the feedforward ΔP for the stator-side electromagnetic active power. s Based on the stator-side output voltage amplitude reference value U sd_ref The d-axis voltage U in the rotating coordinate system sd_pll Determine the feedforward ΔQ of the stator-side electromagnetic reactive power. s The fourth control module is used to feed forward ΔP based on the stator-side electromagnetic active power. s Feedforward ΔQ of stator-side electromagnetic reactive power s Determine the status of the rotor-side converter.

[0014] Thirdly, embodiments of the present invention provide a computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the steps of the above-described cooperative control method for a doubly-fed gravity energy storage system with grid-like characteristics.

[0015] The beneficial effects of the embodiments of the present invention are as follows:

[0016] The present invention provides a cooperative control method and transposition for a doubly-fed gravity energy storage system with grid-connected characteristics, which adds a grid-connected characteristic feedforward ΔP to the grid-following control. s ΔQ sThis enables active support for the grid connection point, specifically by obtaining the stator-side output voltage frequency fs_pll and voltage amplitude U through a phase-locked loop. sd_pll Compared with reference value f s_ref U sd_ref Compared to confirming feedforward, this approach applies the corresponding feedforward to the active and reactive power control loops at the grid connection point, thereby achieving active support for the voltage frequency and amplitude at the grid connection point. Simultaneously, the rotor speed can be calculated based on the feedforward, thus controlling the speed of the load. Applying a control strategy that combines grid-connected characteristic feedforward with grid-fed control to a doubly-fed gravity energy storage system enables both precise control of the load's speed and active support for the grid connection point. Attached Figure Description

[0017] Figure 1 A flowchart illustrating a collaborative control method for a doubly-fed gravity energy storage system with grid-connected characteristics, provided for the implementation of this invention;

[0018] Figure 2 A schematic diagram of a closed-loop phase-locked loop provided for the implementation of this invention;

[0019] Figure 3 A flowchart illustrating a collaborative control method for a doubly-fed gravity energy storage system with grid-connected characteristics, provided for the implementation of this invention;

[0020] Figure 4 A control block diagram of feedforward and grid-following control for grid-connected characteristics of a doubly-fed gravity energy storage system is provided for the implementation of this invention.

[0021] Figure 5 A waveform diagram of the grid end and the grid-connected end frequency under grid-connected control is provided for the implementation of this invention.

[0022] Figure 6 A waveform diagram of the grid end and the grid-connected end frequency under feedforward coordinated grid-following control for grid characteristics is provided for the implementation of this invention.

[0023] Figure 7 An active power diagram of power flowing from the power grid into a doubly fed gravity energy storage system is provided for the implementation of this invention;

[0024] Figure 8 A voltage waveform diagram of the grid terminal and the grid-connected terminal under grid-connected control for implementing the present invention, showing the voltage change of the grid d-axis under grid-connected control.

[0025] Figure 9 A voltage waveform diagram of the grid end and the grid-connected end under the grid-connected control of feedforward coordinated grid-following control with grid-connected characteristics is provided for the implementation of this invention.

[0026] Figure 10A reactive power diagram of the power flowing from the power grid into a doubly fed gravity energy storage system is provided for the implementation of this invention;

[0027] Figure 11 A schematic diagram of a storage medium provided for the implementation of the present invention. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] Gravity energy storage technology, as a novel physical energy storage solution, achieves the spatiotemporal transfer of energy by constructing a gravity potential energy conversion system. During the energy storage phase, the system utilizes surplus electrical energy to drive a lifting mechanism, raising a high-density object to a predetermined height to complete potential energy storage. During the energy release phase, the system controls the descent of the object to drive a power generation device, efficiently converting the potential energy into high-quality electrical energy. This technology boasts outstanding advantages such as zero performance degradation throughout its entire lifecycle, inherent safety, and zero pollution, and it exhibits broad adaptability to various geographical environments, opening up new pathways for large-scale energy storage applications.

[0030] In the construction of new power systems, gravity energy storage and wind and solar power generation have natural synergistic advantages. By constructing a gravity energy storage-new energy power generation composite system, not only can fluctuations in new energy output be effectively mitigated, but the overall energy efficiency of the system can also be significantly improved. It is worth noting that the unique mechanical rotational inertia characteristics of gravity energy storage systems provide the power system with additional disturbance resistance reserves, demonstrating excellent stability improvement effects when dealing with abnormal operating conditions such as grid frequency fluctuations.

[0031] Doubly-fed induction generators (DFIGs) feature bidirectional energy flow. The stator is directly connected to the power grid, while the rotor interacts with the grid via a bidirectional frequency converter, significantly improving the flexibility of renewable energy integration. Furthermore, by adjusting the rotor excitation current phase, reactive power output can be dynamically adjusted, improving the power factor of the power grid. As a core component of next-generation power electronic devices, DFIGs demonstrate significant technological advantages in renewable energy grid-connected control, and their innovative control modes provide crucial support for renewable energy integration.

[0032] The evolution of doubly-fed induction generator (DFIG) control technology has provided crucial support for renewable energy grid connection. Based on differences in control strategies, it can be divided into two main technical routes: grid-following control and grid-connecting control. Grid-following control uses high-precision phase-locked loop (PLL) technology to achieve real-time tracking of grid connection parameters, ensuring strict synchronization between the device and the grid. Grid-connecting control, on the other hand, is based on droop characteristic control and virtual synchronous machine control, establishing stable voltage amplitude and frequency references. Even under abnormal conditions such as grid faults, it can still provide continuous and reliable support to the grid connection nodes, significantly enhancing the robustness of the renewable energy grid connection system.

[0033] This invention proposes a collaborative control strategy for a doubly fed gravity energy storage system with grid-building characteristics. It incorporates feedforward with grid-building characteristics into grid-following control, enabling grid-following control to provide active support to the grid connection point to a certain extent.

[0034] Example 1

[0035] like Figure 1 The diagram shows a flowchart of a collaborative control method for a doubly-fed gravity energy storage system with grid-connected characteristics. The method includes:

[0036] S102: The stator-side voltage frequency f obtained from the phase-locked loop. s_pll Determine the phase θ of the output voltage on the stator side.

[0037] Specifically, such as Figure 2 The diagram shown illustrates a phase-locked loop (PLL) closure, which is a schematic diagram of a signal processing procedure. The acquired signal is a three-phase AC voltage signal. After being updated and processed by the PLL, the updated data is returned, and the voltage frequency f can be output. s_pll .

[0038] A phase-locked loop (PLL) typically consists of a phase detector (PD), a loop filter (LF), and a voltage-controlled oscillator (VCO). Its control structure is as follows: Figure 2 As shown, the signal processing procedure is as follows:

[0039] First, the three-phase AC voltage V is collected. a v b v c Signal;

[0040] Then, the virtual orthogonal components are reconstructed to build a two-phase rotating coordinate system;

[0041] Then, the phase difference between the input signal and the internal synchronization signal is calculated in real time based on two rotating coordinate systems. This phase difference is then processed by a filter and used to adjust the voltage-controlled oscillator parameters.

[0042] Finally, the oscillator will output a reference signal, namely f. s_pll ; where f s_pll With input voltage v a v b v c The fundamental frequency and phase of the signal are precisely synchronized.

[0043] Figure 2 The closed-loop feedback mechanism of a phase-locked loop can be used to control f. s_pll Dynamic tracking and real-time acquisition of f s_pll This is also one of the innovative aspects of this application.

[0044] S104: Based on the voltage phase θ, the pre-acquired stator-side stationary two-phase voltage Usαβ Perform coordinate transformation to obtain the d-axis voltage U in the rotating coordinate system. sd_pll .

[0045] S106: Based on the pre-set stator-side output voltage frequency reference value f s_ref and the voltage frequency f on the stator side s_pll Determine the feedforward ΔP for the stator-side electromagnetic active power. s Based on the stator-side output voltage amplitude reference value U sd_ref d-axis voltage U in rotating coordinate system sd_pll Determine the feedforward ΔQ of the stator-side electromagnetic reactive power. s .

[0046] Specifically, frequency and voltage regulation can be achieved through S106, which is not present in existing grid-connected control. It is similar to feedforward in grid-connected control, but there is a fundamental difference. In grid-connected control, the frequency fs and voltage Us being compared are constructed by the control algorithm, while in this step, the frequency fs and voltage Us being compared are the actual values ​​sampled by the phase-locked loop. Applying feedforward with grid-connected characteristics to grid-connected control is one of the innovations of this invention, which enables active support for the grid connection point.

[0047] S108: Feedforward ΔP based on stator-side electromagnetic active power s Feedforward ΔQ of stator-side electromagnetic reactive power s Determine the status of the rotor-side converter.

[0048] Specifically, based on the calculated feedforward ΔP s ΔQ s The pre-processed data, such as current and stator flux linkage, can be used to adjust the state of the converter on the rotor side (on or off), thereby adjusting the speed of the rotor in the gravity energy storage system.

[0049] The cooperative control method for a doubly-fed gravity energy storage system with grid-connected characteristics in this embodiment adds a grid-connected characteristic feedforward ΔP to the grid-following control. s ΔQ s This enables active support for the grid connection point, specifically by obtaining the stator-side output voltage frequency fs_pll and voltage amplitude U through a phase-locked loop. sd_pll Compared with reference value f s_ref U sd_refCompared to confirming feedforward, this approach applies the corresponding feedforward to the active and reactive power control loops at the grid connection point, thereby achieving active support for the voltage frequency and amplitude at the grid connection point. Simultaneously, the rotor speed can be calculated based on the feedforward, thus controlling the speed of the load. Applying a control strategy that combines grid-connected characteristic feedforward with grid-fed control to a doubly-fed gravity energy storage system enables both precise control of the load's speed and active support for the grid connection point.

[0050] Example 2

[0051] like Figure 3 As shown in the figure, this embodiment provides a flowchart of another collaborative control method for a doubly-fed gravity energy storage system with grid-building characteristics. This embodiment is a detailed explanation of the previous embodiment.

[0052] In this embodiment, the data that needs to be acquired in advance includes: various reference values, constants, and the stator-side voltage frequency f obtained based on the phase-locked loop. s_pll Stator side three-phase voltage U sABC Stator side three-phase current I sABC Rotor-side three-phase current I rabc The rotor speed ω of the doubly fed motor r R r ω slip , σ, ψ sd L m L s L r I rq I rd R s Stator side instantaneous line voltage u sABC Stator side instantaneous line current i sABC .

[0053] S102: Based on the stator-side voltage frequency f obtained from the phase-locked loop. s_pll Determine the phase θ of the output voltage on the stator side.

[0054] S102 includes: the stator-side voltage frequency f output by the phase-locked loop. s_pll The stator-side output voltage phase θ is obtained by integration:

[0055]

[0056] Where s is the differential operator.

[0057] S104: Based on the voltage phase θ, the pre-acquired stator-side stationary two-phase voltage U sαβ The d-axis voltage U is obtained by conversion. sd_pll .

[0058] S1042: This phase reference value θ serves as the feedback quantity of the phase-locked loop (PLL) for stator-side coordinate transformation, converting the two-phase stationary coordinate system into a rotating two-phase coordinate system to obtain the stator-side stationary two-phase voltage U. sαβ ,include:

[0059]

[0060] S1044: Calculate U sd_pll ,include:

[0061]

[0062] Among them, U sdq_pll Overall, U represents the d-axis voltage in a rotating coordinate system. sd_pll and q-axis voltage U sq_pll .

[0063] S106: Based on the pre-set stator-side output voltage frequency reference value f s_ref and the voltage frequency f on the stator side s_pll Determine the feedforward ΔP for the stator-side electromagnetic active power. s Simultaneously, based on the stator-side output voltage amplitude reference value U sd_ref The d-axis voltage U in the rotating coordinate system sd_pll Determine the feedforward ΔQ of the stator-side electromagnetic reactive power. s .

[0064] S106 includes:

[0065] ΔP s =K f (f s_ref -f s_pll ) Formula 4;

[0066] Among them, K f These are pre-acquired frequency coefficient constants;

[0067] ΔQ s =K U (U sd_ref -U sd_pll ) Formula 5;

[0068] Among them, K U This is a pre-acquired amplitude coefficient constant.

[0069] S108: Feedforward ΔP based on stator-side electromagnetic active power s Feedforward ΔQ of stator-side electromagnetic reactive power s Determine the status of the rotor-side converter.

[0070] S1082: Feedforward ΔP based on stator-side electromagnetic active power sFeedforward ΔQ of stator-side electromagnetic reactive power s Determine the current reference value in the rotating coordinate system on the rotor side.

[0071] S1082 includes:

[0072]

[0073] Among them, G PI_U (s) is a preset proportional-integral controller, P s_error For the pre-obtained active power error, Q s_error For the pre-acquired reactive power error, U sd_pll Let ω be the d-axis voltage in the rotating coordinate system on the stator side. grid The voltage frequency f on the stator side s_pll The corresponding rotational speed, L m This refers to the mutual inductance between the coaxial equivalent windings of the stator and rotor in a pre-obtained rotating coordinate system.

[0074] The steps for calculating the power error include:

[0075] Stator side active and reactive power reference values ​​P s_ref Q s_ref Subtract the actual measured values ​​P of active and reactive power on the stator side respectively. s_rea Q s_rea The power error P is obtained. s_error Q s_error :

[0076] S10822: P s_rea =u sA i sA +u sB i sB +u sC i sC Formula 8;

[0077]

[0078] Among them, u sABC i is the instantaneous line voltage on the stator side. sABC This refers to the instantaneous line current on the stator side.

[0079] S10824: P s_error =P s_ref -P s_rea Formula 10;

[0080] Q s_error =Q s_ref -Q s_rea Formula 11.

[0081] Where, ωgrid =2πf s_pll Formula 12.

[0082] S10826: Calculate the current reference value in the rotating coordinate system on the rotor side based on Equations 6 and 7.

[0083] S1084: Determine the double closed-loop feedforward Δu for voltage and current. rdq .

[0084] S1084 includes:

[0085]

[0086] Among them, R r ω slip , σ, ψ sd , , and respectively represent the pre-obtained rotor resistance, speed slip, leakage inductance coefficient, and stator flux linkage along the d-axis in a two-phase rotating coordinate system; L m L s L r I rq I rd These represent the mutual inductance between the coaxial equivalent windings of the stator and rotor in the rotating coordinate system, the self-inductance of the equivalent two-phase winding of the stator in the rotating coordinate system, the self-inductance of the equivalent two-phase winding of the rotor in the rotating coordinate system, the q-axis current on the rotor side in the rotating coordinate system, and the d-axis current on the rotor side in the rotating coordinate system, respectively.

[0087] S10842: Stator side voltage frequency f s_pll Corresponding rotational speed ω grid (From Formula 12) Subtract the rotor speed ω r The speed slip ω is obtained. slip After integration, the phase slip θ is obtained. slip :

[0088]

[0089] S10844: Convert the rotor-side three-phase current into a stationary coordinate two-phase current, and then based on the phase slip θ slip Confirm the current I in the rotating coordinate system on the rotor side. rdq :

[0090]

[0091] Among them, the rotor-side three-phase current I rABC It was obtained in advance.

[0092] S10846: The process of calculating the stator flux linkage along the d-axis in a two-phase rotating coordinate system is as follows:

[0093] First, the pre-acquired stator-side three-phase current I... sABC By performing coordinate transformation and integration, we obtain its expression in a stationary two-phase coordinate system:

[0094]

[0095] Among them, R s For the pre-obtained stator resistance, U sαβ The result of formula 2, I sABC The three-phase current on the stator side is obtained in advance.

[0096] Finally, the stator flux linkage is subjected to a rotational coordinate transformation:

[0097]

[0098] Where, ψ sdq To obtain the stator flux linkage in the two-phase rotating coordinate system, θ is the result calculated by Formula 1.

[0099] S10848: Calculate Δu based on Formula 13 rdq .

[0100] Δu rdq It is a voltage and current dual closed-loop feedforward used for decoupling and is part of the control.

[0101] Among them, leakage inductance coefficient

[0102] S1086: Based on the current reference value in the rotating coordinate system on the rotor side. and dual closed-loop feedforward Δu rdq Determine the conduction state of the rotor-side converter.

[0103] S10862: In current closed-loop control, the rotor current reference value and the rotor current I in the actual rotating coordinate system... rdq The difference is processed by a proportional-integral controller, plus a feedforward Δu rdq That is, the rotor voltage reference value in the rotating coordinate system is obtained.

[0104] in, This is confirmed based on Formulas 6 and 7, I rdq It is determined based on Formula 16, G PI_I (s) is a proportional-integral controller, K p_I k is a pre-obtained scaling factor. i_I These are the pre-acquired integral coefficients.

[0105] S10864: Obtain the rotor voltage reference value Coordinated control of the doubly-fed gravity energy storage system is achieved by controlling the turn-on and turn-off of the rotor-side converter through space vector pulsed voltage modulation (SVPWM).

[0106] The prerequisites for implementing this embodiment are as follows:

[0107] 1) According to the formula:

[0108] in, For grid voltage phasors, Let P be the voltage phasor at the grid connection point, and Q be the active and reactive power flowing from the grid connection point to the grid, respectively. R and X be the line resistance and line impedance between the grid connection point and the grid, respectively, and j be the imaginary unit. This formula shows the relationship between the voltage changes at the output terminal (grid connection point) of the energy storage system and the voltage changes at the grid terminal, and the transmitted active and reactive power.

[0109] 2) ΔU represents the change in amplitude between the grid connection point voltage and the grid voltage, and δU represents the change in phase between the grid connection point voltage and the grid voltage. Therefore:

[0110]

[0111] Typically, power lines are inductive, meaning the line impedance X is much greater than the line resistance R. Therefore, the grid connection point voltage can be supported by adjusting the reactive power fed into the grid from the stator side of the doubly-fed gravity energy storage system. Conversely, the grid connection point frequency can be supported by adjusting the active power fed into the grid from the stator side. The formulas provide specific expressions for the amplitude and phase of voltage changes. Generally, power lines are inductive, and active and reactive power are decoupled; that is, changes in voltage phase (the integral of frequency) are only related to active power, and changes in voltage amplitude are only related to reactive power. Therefore, when the grid frequency changes abruptly, the abrupt change in grid connection point frequency can be delayed by adjusting active power; when the grid voltage amplitude changes abruptly, the grid connection point voltage can be raised by adjusting reactive power. This is how grid connection point voltage support is achieved through feedforward, and its specific implementation is expressed in the following two expressions.

[0112] 3) The active-frequency network characteristics feedforward are shown in the following formula:

[0113] ΔP s =K f (f s_ref -f s_pll ) Formula 4;

[0114] Where ΔP s K is the feedforward in the stator electromagnetic active power circuit. f f is the frequency coefficient. s_reff is the reference value for the stator-side output voltage frequency, i.e., the ideal grid frequency during normal operation. s_pll This refers to the frequency of the stator-side output voltage actually measured through a phase-locked loop (PLL). When the actual frequency f... s_pll Less than the reference value f s_ref At the same time, the active power fed into the grid from the stator side is increased.

[0115] 4) The reactive power-amplitude grid characteristic feedforward is shown in the following formula:

[0116] ΔQ s =K U (U sd_ref -U sd_pll ) Formula 5;

[0117] Where ΔQ s K is the feedforward in the stator electromagnetic reactive power circuit. U U is the voltage amplitude coefficient. sd_ref U is the reference value for the d-axis amplitude of the stator-side output voltage, i.e., the d-axis voltage amplitude of the ideal power grid during normal operation. sd_pll This refers to the frequency of the stator-side output voltage actually measured through a phase-locked loop. When the actual frequency U... sd_pll Less than the reference value U sd_ref At the same time, the reactive power fed into the grid from the stator side is increased.

[0118] Furthermore, in gravitational potential energy storage systems, traditional solutions often use synchronous motors as the core energy conversion device. Their operating characteristics are strictly coupled with the grid frequency, meaning that the rotor speed of the synchronous motor must be precisely matched to the synchronous speed corresponding to the grid frequency. This results in the lifting rate of the heavy object being locked at a fixed value determined by the grid frequency. Therefore, the energy storage system can only change the power fed into the grid by adjusting the load torque in a single dimension.

[0119] In this embodiment, the introduction of a doubly-fed asynchronous motor gives the system more flexible operation and control capabilities. By independently controlling the rotor excitation frequency, the mechanical speed and grid frequency are decoupled. This gives the gravity energy storage system a dual advantage in power regulation: power output can be adjusted by changing the mechanical torque of the weight, and energy conversion efficiency can be optimized by adjusting the rotor speed (i.e., the speed of the weight), significantly enriching power regulation methods. This is one of the innovations of this invention. The specific implementation process is as follows:

[0120] This embodiment uses a mechanical torque input model (in which the mechanical torque changes follow a given reference value, and the rotor speed is controlled through a speed loop), and the implementation process is as follows:

[0121] Rotor speed ω r Reference value ω r_ref Compared with the actual value ωr_rea Using physical quantities as model inputs, the reference value T of the electromagnetic torque is obtained through the rotational speed loop in the model. e (i.e., the process from S202 to S208):

[0122] S202: Calculate the electromagnetic power P output on the stator side. es :

[0123]

[0124] In the formula L m ω1 represents the mutual inductance between the coaxial equivalent windings of the stator and rotor in the dq coordinate system; ird and irq are the d-axis and q-axis components of the rotor-side current in the rotating dq coordinate system, respectively; isd and isq are the d-axis and q-axis components of the stator-side current in the rotating dq coordinate system, respectively; and ω1 is the pre-acquired synchronous speed.

[0125] S204: Calculate the rotor-side output electromagnetic power P er :

[0126]

[0127] In the formula ω slip For speed slip, the stator side voltage frequency f s_pll Corresponding rotational speed ω grid (From Formula 12) Subtract the rotor speed ω r Obtain the speed slip ω slip .

[0128] S206: Calculate the total electromagnetic power P output by the DFIG unit. e :

[0129]

[0130] S208: Calculate the electromagnetic torque T in the dq coordinate system e :

[0131] T e =n p L m (i sq i rd -i sd i rq ) Formula 28;

[0132] In the formula n p This represents the number of pole pairs of the motor.

[0133] S210: Electromagnetic torque T e Multiplying this value by the pre-acquired synchronous speed ω1 yields the stator-side active power reference value f. s_ref (i.e., the reference value in S106).

[0134] According to formulas 25-28 above, the stator electromagnetic power P fed into the power grid from the stator side and rotor side... e With electromagnetic torque T e It is directly proportional, so the electromagnetic torque T can be changed by adjusting the mechanical torque (i.e., the load torque of the weight). e This allows for the regulation of the power fed into the grid, while the rotor speed ω r It only affects the electromagnetic power fed into the grid on the rotor side, which can be controlled by adjusting the rotor speed ω. r (i.e., the speed of the weight block, i.e., the control of the rotor-side converter state in 10864) Adjustable stator-side active power reference value f s_ref This allows for the control of the proportion of active power fed into the grid from the stator side in the total active power, thereby enabling active support for the grid connection point.

[0135] The beneficial effects of the embodiments of the present invention are as follows:

[0136] 1) Formulas 4 and 5 implement frequency and voltage regulation, which is not present in grid-fed control. This is similar to feedforward in grid-connected control, but there is a fundamental difference. In grid-connected control, the frequency fs and voltage Us being compared are constructed through a control algorithm, while in Formulas 4 and 5, the frequency fs and voltage Us are compared using actual values ​​sampled by a phase-locked loop. Applying feedforward with grid-connected characteristics to grid-fed control is one of the innovations of this invention.

[0137] 2) While doubly-fed induction generators (DFIGs) enhance control flexibility, they also alter the system's inertia characteristics. Compared to synchronous motors, DFIGs significantly reduce rotational inertia and damping coefficients. While this improves response speed, it weakens their natural ability to suppress grid frequency fluctuations. To compensate for this deficiency, this invention incorporates a targeted design in its grid-connected control strategy: utilizing the inductive characteristics of the line, the active power at the feed-in node is dynamically adjusted to support the grid connection point frequency (i.e., Equations 4 and 5), while real-time adjustment of reactive power is used to maintain the grid connection point voltage level.

[0138] 3) The present invention can adjust the power output by changing the mechanical torque of the heavy object through S202-S210, and optimize the energy conversion efficiency by adjusting the rotor speed (i.e. the speed of the heavy object), which significantly enriches the means of power control.

[0139] Example 3

[0140] This embodiment provides an experimental illustration of the methods described in the above embodiments, such as... Figures 4-10 As shown.

[0141] A doubly-fed gravity energy storage system was built in Simulink, employing the control strategy proposed in this invention that combines feedforward control with grid-following control. Its control block diagram is shown below. Figure 4 As shown. Verification of grid connection point frequency support: The grid frequency was set to abruptly change from 50Hz to 49.5Hz at 0.5s and then from 49.5Hz to 50Hz at 1s. The frequency change waveform under grid control is shown below. Figure 5 As shown, the frequency variation waveform under feedforward cooperative network control with network characteristics is as follows: Figure 6 As shown, comparison Figure 5 and Figure 6 As can be seen from the rise time, grid-following control cannot buffer sudden changes in grid frequency; the rate of change of frequency at the grid connection end is consistent with the rate of change of frequency at the grid end. However, a control strategy that combines grid-connected characteristic feedforward with grid-following control can effectively buffer sudden changes in grid frequency, such as... Figure 7 As shown, by changing the active power flowing through the grid connection point to support the grid connection point frequency, the frequency change rate at the grid connection end is significantly smaller than that at the grid end. Verification of the grid connection point voltage amplitude support: The grid voltage amplitude per unit value is set to abruptly change from 1 to 0.8 at 0.8s, from 0.8 to 0.9 at 1s, and from 0.9 to 1 at 1.2s. The d-axis voltage change waveform under grid control is shown below. Figure 8 As shown, the waveform of d-axis voltage change under feedforward coordinated grid control with grid characteristics is as follows: Figure 9 As shown, comparison Figure 8 and Figure 6 As can be seen from the voltage amplitude, grid-following control cannot mitigate sudden changes in grid voltage amplitude; the d-axis voltage at the grid connection end is essentially the same as the d-axis voltage at the grid end. However, a control strategy that combines grid characteristic feedforward with grid-following control can effectively mitigate changes in the grid's d-axis voltage, such as... Figure 10 As shown, by changing the reactive power flowing through the grid connection point, the voltage amplitude at the grid connection point can be supported. When the grid voltage suddenly drops to 0.8pu, the voltage amplitude at the grid connection point can be increased to 0.826pu, and when the grid voltage suddenly drops to 0.9pu, the voltage amplitude at the grid connection point can be increased to 0.915pu.

[0142] This technology enables proactive support for grid connection points.

[0143] Example 4

[0144] This invention provides a cooperative control device for a doubly-fed gravity energy storage system with grid-connected characteristics. The device includes: a first control module, used to control the stator-side voltage frequency f obtained by a phase-locked loop. s_pll The first module determines the voltage phase θ of the stator-side output; the second module is used to adjust the pre-acquired stator-side stationary two-phase voltage U based on the voltage phase θ. sαβ Perform coordinate transformation to obtain the d-axis voltage U in the rotating coordinate system.sd_pll The third control module is used to control the stator-side output voltage frequency reference value f based on a pre-set value. s_ref and the voltage frequency f on the stator side s_pll Determine the feedforward ΔP for the stator-side electromagnetic active power. s Based on the stator-side output voltage amplitude reference value U sd_ref The d-axis voltage U in the rotating coordinate system sd_pll Determine the feedforward ΔQ of the stator-side electromagnetic reactive power. s The fourth control module is used to feed forward ΔP based on the stator-side electromagnetic active power. s Feedforward ΔQ of stator-side electromagnetic reactive power s Determine the status of the rotor-side converter.

[0145] The doubly-fed gravity energy storage system collaborative control device with grid-building characteristics provided in this embodiment of the invention has the same beneficial effects as the aforementioned doubly-fed gravity energy storage system collaborative control method with grid-building characteristics, and will not be repeated in this embodiment.

[0146] Example 5

[0147] This invention also provides an electronic device 130, such as... Figure 11 The diagram shown is a structural schematic of an electronic device 130 provided in an embodiment of the present invention, including a processor 131, a memory 132, and a bus 133. The memory 132 stores machine-readable instructions executable by the processor 131. When the electronic device 130 is running, the processor 131 communicates with the memory 132 via the bus 133, and the machine-readable instructions are executed by the processor 131 using the methods described in the above-described method embodiments.

[0148] This invention also provides a computer-readable storage medium storing a computer program, which is executed by a processor. Those skilled in the art will understand that, for convenience and brevity, the specific working processes of the systems and devices described above can be referred to the corresponding processes in the method embodiments, and will not be repeated here. In the several embodiments provided by this invention, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of modules is only a logical functional division; in actual implementation, there may be other division methods. For example, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Furthermore, the displayed or discussed mutual coupling or direct coupling or communication connection can be through some communication interfaces; the indirect coupling or communication connection of devices or modules can be electrical, mechanical, or other forms. Additionally, the functional units in the various embodiments of this invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0149] The above embodiments are merely illustrative examples and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A collaborative control method for a doubly-fed gravity energy storage system with grid-connected characteristics, characterized in that, The method includes: S102: The stator-side voltage frequency obtained from the phase-locked loop. Determine the phase of the output voltage on the stator side. ; S104: According to the voltage phase The pre-acquired stator-side stationary two-phase voltage Perform coordinate transformation to obtain the d-axis voltage in the rotating coordinate system. ; S106: Based on a pre-set stator-side output voltage frequency reference value and the voltage frequency on the stator side Feedforward for determining stator-side electromagnetic active power Based on the reference value of the stator-side output voltage amplitude d-axis voltage in the rotating coordinate system Feedforward for determining stator-side electromagnetic reactive power ; S108: Feedforward based on stator-side electromagnetic active power Feedforward of stator-side electromagnetic reactive power Determine the status of the rotor-side converter; S108 includes: S1082: Feedforward based on stator-side electromagnetic active power Feedforward of stator-side electromagnetic reactive power Determine the current reference value in the rotating coordinate system on the rotor side. ; S1084: Determine the dual closed-loop feedforward for voltage and current. ; S1086: Based on the current reference value in the rotating coordinate system on the rotor side. and dual closed-loop feedforward Determine the conduction state of the rotor-side converter; S1082 includes: ； ； in, For a preset proportional-integral controller, For the pre-acquired active power error, For the pre-acquired reactive power error, The voltage along the d-axis in a rotating coordinate system. The voltage frequency on the stator side The corresponding rotational speed, The mutual inductance between the coaxial equivalent windings of the stator and rotor in a rotating coordinate system; S1084 includes: ； in, , , , , , respectively represent the rotor resistance, speed slip, leakage inductance coefficient, and stator flux linkage along the d-axis in a two-phase rotating coordinate system; , , , , These represent the mutual inductance between the coaxial equivalent windings of the stator and rotor in the rotating coordinate system, the self-inductance of the equivalent two-phase winding of the stator in the rotating coordinate system, the self-inductance of the equivalent two-phase winding of the rotor in the rotating coordinate system, the q-axis current on the rotor side in the rotating coordinate system, and the d-axis current on the rotor side in the rotating coordinate system, respectively.

2. The collaborative control method for a doubly-fed gravity energy storage system with grid-like characteristics according to claim 1, characterized in that, S106 includes: ； in, These are pre-acquired frequency coefficient constants; ； in, This is a pre-acquired amplitude coefficient constant.

3. The collaborative control method for a doubly-fed gravity energy storage system with grid-like characteristics according to claim 2, characterized in that, S102 includes: ； Where s is the differential operator.

4. The collaborative control method for a doubly-fed gravity energy storage system with grid-like characteristics according to claim 3, characterized in that, S104 includes: ； in, Overall, this represents the d-axis voltage in a rotating coordinate system. and q-axis voltage .

5. The collaborative control method for a doubly-fed gravity energy storage system with grid-like characteristics according to claim 1, characterized in that, S102 also includes: information from the phase-locked loop based on closed-loop acquisition.

6. A cooperative control device for a doubly-fed gravity energy storage system with grid-connected characteristics, characterized in that, The device includes: The first control module is used to determine the stator-side voltage frequency obtained from the phase-locked loop. Determine the phase of the output voltage on the stator side. ; The second control module is used to determine the voltage phase. The pre-acquired stator-side stationary two-phase voltage Perform coordinate transformation to obtain the d-axis voltage in the rotating coordinate system. ; The third control module is used to base the stator-side output voltage frequency reference value on a pre-set value. and the voltage frequency on the stator side Feedforward for determining stator-side electromagnetic active power Based on the reference value of the stator-side output voltage amplitude d-axis voltage in the rotating coordinate system Feedforward for determining stator-side electromagnetic reactive power ; The fourth control module is used to feed forward the electromagnetic active power on the stator side. Feedforward of stator-side electromagnetic reactive power Determine the status of the rotor-side converter; The fourth control module is also used for feedforward based on the electromagnetic active power on the stator side. Feedforward of stator-side electromagnetic reactive power Determine the current reference value in the rotating coordinate system on the rotor side. Determine the dual closed-loop feedforward for voltage and current. According to the current reference value in the rotating coordinate system on the rotor side. and dual closed-loop feedforward Determine the conduction state of the rotor-side converter; The fourth control module is also used for: ； ； in, For a preset proportional-integral controller, For the pre-acquired active power error, For the pre-acquired reactive power error, The voltage along the d-axis in a rotating coordinate system. The voltage frequency on the stator side The corresponding rotational speed, The mutual inductance between the coaxial equivalent windings of the stator and rotor in a rotating coordinate system; The fourth control module is also used for: ； in, , , , , , respectively represent the rotor resistance, speed slip, leakage inductance coefficient, and stator flux linkage along the d-axis in a two-phase rotating coordinate system; , , , , These represent the mutual inductance between the coaxial equivalent windings of the stator and rotor in the rotating coordinate system, the self-inductance of the equivalent two-phase winding of the stator in the rotating coordinate system, the self-inductance of the equivalent two-phase winding of the rotor in the rotating coordinate system, the q-axis current on the rotor side in the rotating coordinate system, and the d-axis current on the rotor side in the rotating coordinate system, respectively.

7. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the cooperative control method for a doubly-fed gravity energy storage system with grid-forming characteristics as described in any one of claims 1 to 5.

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