Synchronous phase locking control method and device for double-fed gravity energy storage system under unbalanced power grid voltage

Abstract

The invention provides a double-fed gravity energy storage system synchronous phase locking control method and device under unbalanced power grid voltage, and the method comprises the steps: obtaining related parameters of a double-fed motor, carrying out the band-pass filtering, Clarke transformation and dynamic filtering, generating a positive sequence component, generating a synchronous rotation angle through a phase-locked loop, and carrying out the dynamic filtering of the positive sequence component, thereby achieving the synchronous phase locking control of the double-fed gravity energy storage system. A rotor excitation voltage is generated through coordinate transformation, PI control and a composite regulator, and a switching signal is generated through space vector modulation after superposition excitation compensation, so that the rotating speed and reactive power stable control of the double-fed motor is realized, and the stable operation of the system when the power grid voltage is unbalanced is guaranteed.

Description

Technical Field

[0001] The present application belongs to the field of synchronous phase-locking, and in particular relates to a synchronous phase-locking control method and device for a double-fed gravity energy storage system under unbalanced grid voltage. Background Art

[0002] In a doubly-fed gravity energy storage system, grid voltage imbalance is a common and complex problem, which can cause a negative sequence component in the motor stator current, leading to adverse effects such as torque pulsation, power fluctuation, and efficiency reduction.

[0003] Traditional phase-locked loop (PLL) technology can accurately track the grid phase when the grid voltage is balanced, but its performance will degrade significantly under unbalanced conditions, and it cannot provide accurate synchronous rotation angle, affecting the control accuracy and stability of the doubly fed generator.

[0004] Although existing technologies attempt to improve through methods such as filtering and coordinate transformation, it is often difficult to simultaneously take into account filtering effect, response speed and control accuracy. Especially in the context of intensified grid fluctuations caused by the access of new energy sources, the limitations of traditional methods are becoming increasingly prominent. Summary of the Invention

[0005] The purpose of this application is to overcome the defects in the above-mentioned prior art and provide a synchronous phase-locked control method and device for a double-fed gravity energy storage system under unbalanced grid voltage.

[0006] The present application provides a synchronous phase-locked control method for a doubly-fed gravity energy storage system under unbalanced grid voltage, comprising:

[0007] Obtain the stator three-phase voltage, stator current and rotor current of the doubly-fed generator;

[0008] Converting the stator three-phase voltage, stator current and rotor current to the αβ stationary coordinate system to generate an αβ axis voltage component, an αβ axis stator current component and an αβ axis rotor current component;

[0009] Extracting a positive sequence voltage component, a positive sequence stator current component and a positive sequence rotor current component from the αβ axis voltage component, the αβ axis stator current component and the αβ axis rotor current component respectively;

[0010] Based on the positive sequence voltage component, generating a synchronous rotation angle through a phase locked loop;

[0011] Converting the positive sequence stator current component and the positive sequence rotor current component to a dq rotating coordinate system to generate a stator dq current and a rotor dq current;

[0012] Calculating the error of reactive power reference value by the stator dq current and positive sequence voltage component;

[0013] Generate a stator voltage reference value according to an error between a preset rotor speed reference value and an actual rotor speed, and generate a rotor dq axis current reference value according to an error between the stator voltage reference value and the reactive power reference value;

[0014] Inputting the rotor dq axis current reference value and the rotor dq current into a proportional integral-complex resonant composite regulator to generate a rotor excitation voltage;

[0015] The rotor excitation voltage is superimposed on the excitation compensation component based on the dynamic decoupling of the stator flux and the grid frequency to generate a rotor voltage modulation wave, which is used to generate a converter switching signal for synchronous phase-locked control.

[0016] Optionally, converting the stator three-phase voltage, stator current, and rotor current to an αβ stationary coordinate system to generate an αβ axis voltage component, an αβ axis stator current component, and an αβ axis rotor current component includes:

[0017] Processing the stator three-phase voltage through a bandpass filter having a center frequency equal to the grid fundamental frequency to generate a filtered stator voltage;

[0018] Converting the filtered stator voltage to an αβ stationary coordinate system through Clarke transformation to generate an αβ axis voltage component;

[0019] The stator current is converted to the αβ stationary coordinate system through Clarke transformation to generate an αβ-axis stator current component, and the rotor current is converted to the αβ stationary coordinate system based on the rotor position angle to generate an αβ-axis rotor current component.

[0020] Optionally, the positive-sequence stator current component and the positive-sequence rotor current component are respectively converted into a dq rotating coordinate system to generate a stator dq current and a rotor dq current; comprising:

[0021] Converting the positive sequence stator current component to a dq rotating coordinate system based on a synchronous rotation angle to generate a stator dq current;

[0022] The positive sequence rotor current component is converted into a dq rotating coordinate system based on the difference between the synchronous rotation angle and the rotor position angle to generate a rotor dq current.

[0023] Optionally, the rotor excitation voltage is superimposed on an excitation compensation component based on dynamic decoupling of the stator flux and the grid frequency to generate a rotor voltage modulation wave for generating a converter switching signal for synchronous phase-locked control, including:

[0024] The rotor voltage modulation wave is modulated by space vector to generate a converter switching signal, thereby realizing the speed and reactive power control of the doubly-fed generator.

[0025] Optionally, generating a stator voltage reference value according to an error between a preset rotor speed reference value and an actual rotor speed, and generating a rotor dq axis current reference value according to an error between the stator voltage reference value and the reactive power reference value, includes:

[0026] The error between the preset rotor speed reference value and the actual speed is input into the first PI controller to generate a stator voltage reference value, and the error between the stator voltage reference value and the reactive power reference value is input into the second PI controller to generate a rotor d-axis current reference value and a rotor q-axis current reference value.

[0027] The present application also provides a synchronous phase-locked control device for a double-fed gravity energy storage system under unbalanced grid voltage, comprising:

[0028] An acquisition module is used to obtain the stator three-phase voltage, stator current and rotor current of the doubly-fed generator;

[0029] A component module converts the stator three-phase voltage, stator current and rotor current into an αβ stationary coordinate system to generate an αβ axis voltage component, an αβ axis stator current component and an αβ axis rotor current component;

[0030] A positive sequence module extracts a positive sequence voltage component, a positive sequence stator current component and a positive sequence rotor current component from the αβ axis voltage component, the αβ axis stator current component and the αβ axis rotor current component respectively;

[0031] An angle module, which generates a synchronous rotation angle through a phase-locked loop based on the positive sequence voltage component;

[0032] a conversion module, converting the positive sequence stator current component and the positive sequence rotor current component into a dq rotating coordinate system to generate a stator dq current and a rotor dq current;

[0033] an error module, calculating an error of a reactive power reference value through the stator dq current and the positive sequence voltage component;

[0034] a reference module, generating a stator voltage reference value according to an error between a preset rotor speed reference value and an actual rotor speed, and generating a rotor dq axis current reference value according to an error between the stator voltage reference value and the reactive power reference value;

[0035] An excitation module inputs the rotor dq axis current reference value and the rotor dq current into a proportional integral-complex resonant composite regulator to generate a rotor excitation voltage;

[0036] The control module superimposes the rotor excitation voltage onto the excitation compensation component based on the dynamic decoupling of the stator flux and the grid frequency to generate a rotor voltage modulation wave for generating a converter switching signal for synchronous phase-locked control.

[0037] Optionally, the component module converts the stator three-phase voltage, stator current and rotor current to an αβ stationary coordinate system to generate an αβ axis voltage component, an αβ axis stator current component and an αβ axis rotor current component, including:

[0038] Processing the stator three-phase voltage through a bandpass filter having a center frequency equal to the grid fundamental frequency to generate a filtered stator voltage;

[0039] Converting the filtered stator voltage to an αβ stationary coordinate system through Clarke transformation to generate an αβ axis voltage component;

[0040] The stator current is converted to the αβ stationary coordinate system through Clarke transformation to generate an αβ-axis stator current component, and the rotor current is converted to the αβ stationary coordinate system based on the rotor position angle to generate an αβ-axis rotor current component.

[0041] Optionally, the conversion module converts the positive-sequence stator current component and the positive-sequence rotor current component into a dq rotating coordinate system to generate a stator dq current and a rotor dq current; comprising:

[0042] Converting the positive sequence stator current component to a dq rotating coordinate system based on a synchronous rotation angle to generate a stator dq current;

[0043] The positive sequence rotor current component is converted into a dq rotating coordinate system based on the difference between the synchronous rotation angle and the rotor position angle to generate a rotor dq current.

[0044] Optionally, the excitation module superimposes the rotor excitation voltage on an excitation compensation component based on dynamic decoupling of the stator flux and the grid frequency to generate a rotor voltage modulation wave for generating a converter switching signal for synchronous phase-locked control, including:

[0045] The rotor voltage modulation wave is modulated by space vector to generate a converter switching signal, thereby realizing the speed and reactive power control of the doubly-fed generator.

[0046] Optionally, the reference module generates a stator voltage reference value according to an error between a preset rotor speed reference value and an actual rotor speed, and generates a rotor dq axis current reference value according to an error between the stator voltage reference value and the reactive power reference value, including:

[0047] The error between the preset rotor speed reference value and the actual speed is input into the first PI controller to generate a stator voltage reference value, and the error between the stator voltage reference value and the reactive power reference value is input into the second PI controller to generate a rotor d-axis current reference value and a rotor q-axis current reference value.

[0048] The beneficial effects of this application are:

[0049] The present application provides a synchronous phase-locked control method for a doubly-fed gravity energy storage system under an unbalanced grid voltage, comprising: obtaining a stator three-phase voltage, a stator current, and a rotor current of a doubly-fed motor; converting the stator three-phase voltage, the stator current, and the rotor current to an αβ stationary coordinate system to generate an αβ axis voltage component, an αβ axis stator current component, and an αβ axis rotor current component; extracting a positive sequence voltage component, a positive sequence stator current component, and a positive sequence rotor current component from the αβ axis voltage component, the αβ axis stator current component, and the αβ axis rotor current component, respectively; generating a synchronous rotation angle based on the positive sequence voltage component through a phase-locked loop; converting the positive sequence stator current component and the positive sequence rotor current component to a dq Rotating coordinate system, generating stator dq current and rotor dq current; calculating the error of reactive power reference value through the stator dq current and positive sequence voltage component; generating stator voltage reference value according to the error between preset rotor speed reference value and actual rotor speed, generating rotor dq axis current reference value according to the error between the stator voltage reference value and the reactive power reference value; inputting the rotor dq axis current reference value and rotor dq current into proportional integral-complex resonance composite regulator to generate rotor excitation voltage; superimposing the rotor excitation voltage on the excitation compensation component based on the dynamic decoupling of stator flux and grid frequency to generate rotor voltage modulation wave, which is used to generate converter switching signal and perform synchronous phase-locked control. This application extracts positive sequence components through filtering, coordinate transformation, and dynamic filtering, combines phase-locked loop and composite regulator to achieve precise synchronous rotation angle and rotor excitation voltage control, thereby ensuring stable control of speed and reactive power of doubly fed motor when grid voltage is unbalanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a schematic diagram of the synchronous phase-locked control process of the double-fed gravity energy storage system in this application;

[0051] Figure 2 It is a schematic diagram of the control structure in this application. DETAILED DESCRIPTION

[0052] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it is understood that various forms of implementing the present disclosure are not limited by the embodiments set forth herein. Rather, the embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0053] Please refer to Figure 1 and Figure 2 As shown, the present application provides a synchronous phase-locked control method for a double-fed gravity energy storage system under unbalanced grid voltage, comprising:

[0054] S101, obtaining a stator three-phase voltage, a stator current, and a rotor current of a doubly-fed generator;

[0055] Specifically, obtaining the stator three-phase voltage, stator current, and rotor current of the doubly-fed motor includes:

[0056] The stator three-phase voltage (u) of the doubly fed generator is collected in real time by sensors. sa_mea 、u sb_mea 、u sc_mea ), stator three-phase current (i sa_mea 、i sb_mea 、i sc_mea ) and rotor three-phase current (i ra_mea 、i b_mea r、i c_mea r), and obtain the rotor position angle θ through the optical encoder r .

[0057] S102, converting the stator three-phase voltage, stator current and rotor current to the αβ stationary coordinate system to generate an αβ axis voltage component, an αβ axis stator current component and an αβ axis rotor current component;

[0058] The collected stator three-phase voltage is input into the power frequency bandpass filter to filter out high-frequency noise and output the filtered voltage u sa_mea1 、u sb_mea1 、u sc_mea1 .

[0059] Transfer function definition:

[0060]

[0061] The voltage expression after filtering is:

[0062]

[0063] Where s is the Laplace operator and ω1 = 100πrad / s is the rated frequency. Using the above formula, high-frequency interference is filtered out, retaining the 50 Hz power frequency signal. The damping ratio ξ is in the range of 0.5 ≤ ξ ≤ 1.5.

[0064] The bandpass filter removes high-frequency noise and harmonic interference from the stator voltage, preserving the power frequency signal and ensuring a pure voltage signal at the phase-locked loop input. The filter transfer function is designed as a second-order bandpass (center frequency ω1 = 100πrad / s). Adjusting the damping ratio ξ balances the filter's bandwidth and steepness to avoid phase distortion.

[0065] The filtered three-phase stator voltage is converted into the αβ axis component in the two-phase stationary coordinate system through Clarke transformation. The expression is as follows:

[0066]

[0067] Simplify the three-phase voltage into two-phase orthogonal components, 0≤k mea1 ≤1 is used to smooth the transition of the signals before and after filtering, and finally generate the αβ axis voltage component u sα 、u sβ .

[0068] The Clarke transform converts the three-phase voltages into orthogonal components in a two-phase stationary coordinate system, simplifying the three-phase system into a two-dimensional orthogonal signal. This transform eliminates redundant information in the three-phase voltages, providing a suitable input form for phase extraction in the phase-locked loop (PLL), while also preventing the impact of three-phase imbalance on synchronization accuracy.

[0069] Clarke transformation is performed on the stator current and rotor current to generate the αβ axis current components. The transformation formula is as follows:

[0070] Stator current conversion:

[0071]

[0072] Rotor current conversion:

[0073]

[0074] Finally, θ r The rotor electrical position angle obtained by the encoder generates the αβ axis stator and rotor current components i sα 、i sβ andi rα 、i rβ .

[0075] Clarke transforms are performed on the stator and rotor currents to generate the corresponding α and β axis current components. The current signals are then normalized to the same coordinate system as the voltage, providing standardized input for subsequent rotating coordinate system transformations and current closed-loop control.

[0076] S103, extracting a positive-sequence voltage component, a positive-sequence stator current component, and a positive-sequence rotor current component from the αβ-axis voltage component, the αβ-axis stator current component, and the αβ-axis rotor current component, respectively;

[0077] Using a first-order bandpass filter, the positive sequence voltage and current are obtained:

[0078]

[0079] Where, the subscript p represents the positive sequence component, the subscript n represents the negative sequence component, and G1(s) is a first-order bandpass filter. The expression is:

[0080]

[0081] S104, generating a synchronous rotation angle through a phase-locked loop based on the positive-sequence voltage component;

[0082] Based on the αβ axis positive sequence voltage component, a synchronous rotation angle is generated by synchronizing the grid phase through a phase-locked loop (PLL), and the αβ axis positive sequence voltage component is input into a phase-locked loop (PLL) to extract the grid voltage synchronous phase θ1.

[0083] The PLL tracks u sα,p 、u sβ,p The phase difference is used to generate the synchronous rotation angle θ1 and angular frequency ω1, ensuring that the control system coordinate phase angle is strictly synchronized with the grid voltage vector phase angle.

[0084] The phase-locked loop (PLL) tracks the phase difference of the positive sequence voltage components of the αβ axes and dynamically adjusts the synchronous rotation angle θ1 and the electrical angular frequency ω1, so that the control system coordinate phase angle is strictly synchronized with the grid voltage.

[0085] S105, converting the positive-sequence stator current component and the positive-sequence rotor current component into a dq rotating coordinate system to generate a stator dq current and a rotor dq current;

[0086] The αβ-axis positive sequence current components are converted into a dq rotating coordinate system based on the synchronous rotation angle and the rotor position angle to generate a stator dq current and a rotor dq current.

[0087] Stator voltage dq conversion:

[0088]

[0089] Stator current dq conversion:

[0090]

[0091] Rotor current dq conversion:

[0092]

[0093] The current is decomposed into active (d-axis) and reactive (q-axis) components that are synchronized with the grid.

[0094] Based on the synchronous rotation angle θ1 and the rotor electrical position angle θ r The α and β axis current components are converted into stator and rotor currents in the dq rotating coordinate system through Park transformation. The current is decomposed into active (d-axis) and reactive (q-axis) components synchronized with the grid, directly associated with the power control target, and provides standardized input for current reference value generation and closed-loop regulation.

[0095] S106. Calculating an error in a reactive power reference value using the stator dq current and the positive sequence voltage component;

[0096] According to the grid demand, set the reactive power reference value Q s_ref , the error of reactive power reference value:

[0097] Q s =1.5(u sq,p i sd,p -u sd,p i sq,p )

[0098] S107, generating a stator voltage reference value according to an error between a preset rotor speed reference value and an actual rotor speed, and generating a rotor dq axis current reference value according to an error between the stator voltage reference value and the reactive power reference value;

[0099] The rotor d-axis current reference value and the q-axis current reference value are generated according to the error between the preset rotor speed reference value and the actual speed and the voltage requirement.

[0100] D-axis current reference value generation:

[0101] First level: electrical speed speed error (ω r_ref -ω r ) Input speed proportional integral controller, output stator voltage d-axis component reference value U sd_ref :

[0102] u sd_ref =G w (s)(ω r_ref -ω r )

[0103] Level 2: stator voltage d-axis component error (U sd_ref -U sd,p ) Input the d-axis PI controller to generate i rd_ref :

[0104] i * rd =k udp (u sd_ref -u sd,p )+k udi ∫(u sd_ref -u sd,p )dt

[0105] Q-axis current reference value generation:

[0106] According to the grid demand, set the reactive power reference value Q s_ref , and then the reactive power error (Q s_ref -Q s ) is input to the reactive power proportional integral controller, and outputs the stator q-axis current component reference value I sq_ref :

[0107] i sq_ref =G Q (s)(Q s_ref -Q s )

[0108] Q s =1.5(u sq,p i sd,p -u sd,p i sq,p )

[0109] The rotor q-axis current compensation term is superimposed, that is:

[0110]

[0111] Then, the reference value of the rotor q-axis current component can be written as:

[0112]

[0113] Therefore, the DFIG rotor q-axis current reference value can be expressed as:

[0114]

[0115] The rotor speed error (ω r_ref -ω r ) is converted into a stator d-axis voltage reference value, and then further generates a rotor d-axis current reference value i rd_ref ;q-axis current reference value i rd_ref It is directly generated by the stator q-axis current reference value and the superimposed compensation component.

[0116] S108, inputting the rotor dq axis current reference value and the rotor dq current into a proportional integral-complex resonant composite regulator to generate a rotor excitation voltage;

[0117] Based on the rotor d-axis current reference value and q-axis current reference value, the rotor excitation voltage is directly obtained through a composite rotor current regulator composed of "proportional integral + first-order bandpass filter":

[0118]

[0119] Based on the error between the reference and actual rotor current values, the composite rotor current controller dynamically calculates the d-axis and q-axis excitation voltages. The proportional-integral and resonance coefficients are dynamically adjusted based on the grid frequency and rotor current harmonics to adapt to control requirements under different operating conditions, ensuring rapid current tracking and steady-state accuracy.

[0120] S109, superimposing the rotor excitation voltage onto an excitation compensation component based on dynamic decoupling of the stator flux and the grid frequency to generate a rotor voltage modulation wave for generating a converter switching signal for synchronous phase-locked control;

[0121] On the basis of the excitation voltage, the excitation compensation component u is superimposed md _c om 、u mq _c om , then:

[0122]

[0123] Used to eliminate the impact of grid disturbances on rotor voltage and improve dynamic response.

[0124] The excitation voltage is superimposed on the excitation compensation component to generate the final rotor voltage modulation wave's d- and q-axis components. The stator excitation compensation term corrects the coupling effect caused by grid disturbances through the flux linkage equation, enhancing the system's anti-interference capability.

[0125] The rotor voltage modulation wave reference value u md 、u mq Through space vector modulation, the converter switching signal is generated to achieve speed and reactive power control of the doubly fed generator.

[0126] Space vector modulation (SVPWM) converts the rotor voltage reference into the converter's PWM switching signal, driving the IGBT power devices to reconstruct the voltage waveform. High-frequency switching accurately tracks the voltage command, ultimately achieving decoupled active and reactive power control of the doubly-fed generator, meeting the charging and discharging requirements of gravity energy storage and the power quality requirements of the grid.

[0127] The present application also provides a synchronous phase-locked control device for a double-fed gravity energy storage system under unbalanced grid voltage, comprising:

[0128] An acquisition module is used to obtain the stator three-phase voltage, stator current and rotor current of the doubly-fed generator;

[0129] A component module converts the stator three-phase voltage, stator current and rotor current into an αβ stationary coordinate system to generate an αβ axis voltage component, an αβ axis stator current component and an αβ axis rotor current component;

[0130] A positive sequence module extracts a positive sequence voltage component, a positive sequence stator current component and a positive sequence rotor current component from the αβ axis voltage component, the αβ axis stator current component and the αβ axis rotor current component respectively;

[0131] An angle module, which generates a synchronous rotation angle through a phase-locked loop based on the positive sequence voltage component;

[0132] a conversion module, converting the positive sequence stator current component and the positive sequence rotor current component into a dq rotating coordinate system to generate a stator dq current and a rotor dq current;

[0133] an error module, calculating an error of a reactive power reference value through the stator dq current and the positive sequence voltage component;

[0134] a reference module, generating a stator voltage reference value according to an error between a preset rotor speed reference value and an actual rotor speed, and generating a rotor dq axis current reference value according to an error between the stator voltage reference value and the reactive power reference value;

[0135] An excitation module inputs the rotor dq axis current reference value and the rotor dq current into a proportional integral-complex resonant composite regulator to generate a rotor excitation voltage;

[0136] The control module superimposes the rotor excitation voltage onto the excitation compensation component based on the dynamic decoupling of the stator flux and the grid frequency to generate a rotor voltage modulation wave for generating a converter switching signal for synchronous phase-locked control.

[0137] Furthermore, the component module converts the stator three-phase voltage, stator current and rotor current to the αβ stationary coordinate system to generate the αβ axis voltage component, the αβ axis stator current component and the αβ axis rotor current component, including:

[0138] Processing the stator three-phase voltage through a bandpass filter having a center frequency equal to the grid fundamental frequency to generate a filtered stator voltage;

[0139] Converting the filtered stator voltage to an αβ stationary coordinate system through Clarke transformation to generate an αβ axis voltage component;

[0140] The stator current is converted to the αβ stationary coordinate system through Clarke transformation to generate an αβ-axis stator current component, and the rotor current is converted to the αβ stationary coordinate system based on the rotor position angle to generate an αβ-axis rotor current component.

[0141] Furthermore, the conversion module converts the positive sequence stator current component and the positive sequence rotor current component into a dq rotating coordinate system to generate a stator dq current and a rotor dq current; including:

[0142] Converting the positive sequence stator current component to a dq rotating coordinate system based on a synchronous rotation angle to generate a stator dq current;

[0143] The positive sequence rotor current component is converted into a dq rotating coordinate system based on the difference between the synchronous rotation angle and the rotor position angle to generate a rotor dq current.

[0144] Furthermore, the excitation module superimposes the rotor excitation voltage onto an excitation compensation component based on dynamic decoupling of the stator flux and the grid frequency to generate a rotor voltage modulation wave for generating a converter switching signal for synchronous phase-locked control, including:

[0145] The rotor voltage modulation wave is modulated by space vector to generate a converter switching signal, thereby realizing the speed and reactive power control of the doubly-fed generator.

[0146] Furthermore, the reference module generates a stator voltage reference value according to an error between a preset rotor speed reference value and an actual rotor speed, and generates a rotor dq axis current reference value according to an error between the stator voltage reference value and the reactive power reference value, including:

[0147] The error between the preset rotor speed reference value and the actual speed is input into the first PI controller to generate a stator voltage reference value, and the error between the stator voltage reference value and the reactive power reference value is input into the second PI controller to generate a rotor d-axis current reference value and a rotor q-axis current reference value.

[0148] The above description of the embodiments is intended to facilitate understanding and application of this application by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to the above embodiments can be made, and the general principles described herein can be applied to other embodiments without requiring creative effort. Therefore, this application is not limited to the above embodiments. Any improvements or modifications made to this application by those skilled in the art based on the disclosure of this application should fall within the scope of protection of this application.

Claims

1. A synchronous phase-locked control method for a double-fed gravity energy storage system under unbalanced grid voltage, characterized in that: include: Obtain the stator three-phase voltage, stator current and rotor current of the doubly-fed generator; Converting the stator three-phase voltage, stator current and rotor current to the αβ stationary coordinate system to generate an αβ axis voltage component, an αβ axis stator current component and an αβ axis rotor current component; Extracting a positive sequence voltage component, a positive sequence stator current component and a positive sequence rotor current component from the αβ axis voltage component, the αβ axis stator current component and the αβ axis rotor current component respectively; Based on the positive sequence voltage component, generating a synchronous rotation angle through a phase locked loop; Converting the positive sequence stator current component and the positive sequence rotor current component to a dq rotating coordinate system to generate a stator dq current and a rotor dq current; Calculating the error of reactive power reference value by the stator dq current and positive sequence voltage component; Generate a stator voltage reference value according to an error between a preset rotor speed reference value and an actual rotor speed, and generate a rotor dq axis current reference value according to an error between the stator voltage reference value and the reactive power reference value; Inputting the rotor dq axis current reference value and the rotor dq current into a proportional integral-complex resonant composite regulator to generate a rotor excitation voltage; The rotor excitation voltage is superimposed on the excitation compensation component based on the dynamic decoupling of the stator flux and the grid frequency to generate a rotor voltage modulation wave, which is used to generate a converter switching signal for synchronous phase-locked control.

2. The synchronous phase-locked control method for a double-fed gravity energy storage system under unbalanced grid voltage according to claim 1, characterized in that: The stator three-phase voltage, stator current and rotor current are converted to the αβ stationary coordinate system to generate the αβ axis voltage component, the αβ axis stator current component and the αβ axis rotor current component, including: Processing the stator three-phase voltage through a bandpass filter having a center frequency equal to the grid fundamental frequency to generate a filtered stator voltage; Converting the filtered stator voltage to an αβ stationary coordinate system through Clarke transformation to generate an αβ axis voltage component; The stator current is converted to the αβ stationary coordinate system through Clarke transformation to generate an αβ-axis stator current component, and the rotor current is converted to the αβ stationary coordinate system based on the rotor position angle to generate an αβ-axis rotor current component.

3. The synchronous phase-locked control method for a double-fed gravity energy storage system under unbalanced grid voltage according to claim 1, characterized in that: Converting the positive sequence stator current component and the positive sequence rotor current component to a dq rotating coordinate system to generate a stator dq current and a rotor dq current; comprising: Converting the positive sequence stator current component to a dq rotating coordinate system based on a synchronous rotation angle to generate a stator dq current; The positive sequence rotor current component is converted into a dq rotating coordinate system based on the difference between the synchronous rotation angle and the rotor position angle to generate a rotor dq current.

4. The synchronous phase-locked control method for a double-fed gravity energy storage system under unbalanced grid voltage according to claim 1, characterized in that: The rotor excitation voltage is superimposed on the excitation compensation component based on the dynamic decoupling of the stator flux and the grid frequency to generate a rotor voltage modulation wave for generating a converter switching signal to perform synchronous phase-locked control, including: The rotor voltage modulation wave is modulated by space vector to generate a converter switching signal, thereby realizing the speed and reactive power control of the doubly-fed generator.

5. The synchronous phase-locked control method for a double-fed gravity energy storage system under unbalanced grid voltage according to claim 1, characterized in that: Generating a stator voltage reference value according to an error between a preset rotor speed reference value and an actual rotor speed, and generating a rotor dq axis current reference value according to an error between the stator voltage reference value and the reactive power reference value, including: The error between the preset rotor speed reference value and the actual speed is input into the first PI controller to generate a stator voltage reference value, and the error between the stator voltage reference value and the reactive power reference value is input into the second PI controller to generate a rotor d-axis current reference value and a rotor q-axis current reference value.

6. A synchronous phase-locked control device for a double-fed gravity energy storage system under unbalanced grid voltage, characterized in that: include: An acquisition module is used to obtain the stator three-phase voltage, stator current and rotor current of the doubly-fed generator; A component module converts the stator three-phase voltage, stator current and rotor current into an αβ stationary coordinate system to generate an αβ axis voltage component, an αβ axis stator current component and an αβ axis rotor current component; A positive sequence module extracts a positive sequence voltage component, a positive sequence stator current component and a positive sequence rotor current component from the αβ axis voltage component, the αβ axis stator current component and the αβ axis rotor current component respectively; An angle module, which generates a synchronous rotation angle through a phase-locked loop based on the positive sequence voltage component; a conversion module, converting the positive sequence stator current component and the positive sequence rotor current component into a dq rotating coordinate system to generate a stator dq current and a rotor dq current; an error module, calculating an error of a reactive power reference value through the stator dq current and the positive sequence voltage component; a reference module, generating a stator voltage reference value according to an error between a preset rotor speed reference value and an actual rotor speed, and generating a rotor dq axis current reference value according to an error between the stator voltage reference value and the reactive power reference value; An excitation module inputs the rotor dq axis current reference value and the rotor dq current into a proportional integral-complex resonant composite regulator to generate a rotor excitation voltage; The control module superimposes the rotor excitation voltage onto the excitation compensation component based on the dynamic decoupling of the stator flux and the grid frequency to generate a rotor voltage modulation wave for generating a converter switching signal for synchronous phase-locked control.

7. The synchronous phase-locked control device for a double-fed gravity energy storage system under unbalanced grid voltage according to claim 6, characterized in that: The component module converts the stator three-phase voltage, stator current and rotor current into the αβ stationary coordinate system to generate the αβ axis voltage component, the αβ axis stator current component and the αβ axis rotor current component, including: Processing the stator three-phase voltage through a bandpass filter having a center frequency equal to the grid fundamental frequency to generate a filtered stator voltage; Converting the filtered stator voltage to an αβ stationary coordinate system through Clarke transformation to generate an αβ axis voltage component; The stator current is converted to the αβ stationary coordinate system through Clarke transformation to generate an αβ-axis stator current component, and the rotor current is converted to the αβ stationary coordinate system based on the rotor position angle to generate an αβ-axis rotor current component.

8. The synchronous phase-locked control device for a double-fed gravity energy storage system under unbalanced grid voltage according to claim 6, characterized in that: The conversion module converts the positive sequence stator current component and the positive sequence rotor current component into a dq rotating coordinate system to generate a stator dq current and a rotor dq current; including: Converting the positive sequence stator current component to a dq rotating coordinate system based on a synchronous rotation angle to generate a stator dq current; The positive sequence rotor current component is converted into a dq rotating coordinate system based on the difference between the synchronous rotation angle and the rotor position angle to generate a rotor dq current.

9. The synchronous phase-locked control device for a double-fed gravity energy storage system under unbalanced grid voltage according to claim 6, characterized in that: The excitation module superimposes the rotor excitation voltage on the excitation compensation component based on the dynamic decoupling of the stator flux and the grid frequency to generate a rotor voltage modulation wave for generating a converter switching signal to perform synchronous phase-locked control, including: The rotor voltage modulation wave is modulated by space vector to generate a converter switching signal, thereby realizing the speed and reactive power control of the doubly-fed generator.

10. The synchronous phase-locked control device for a double-fed gravity energy storage system under unbalanced grid voltage according to claim 6, characterized in that: The reference module generates a stator voltage reference value according to an error between a preset rotor speed reference value and an actual rotor speed, and generates a rotor dq axis current reference value according to an error between the stator voltage reference value and the reactive power reference value, including: The error between the preset rotor speed reference value and the actual speed is input into the first PI controller to generate a stator voltage reference value, and the error between the stator voltage reference value and the reactive power reference value is input into the second PI controller to generate a rotor d-axis current reference value and a rotor q-axis current reference value.

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