Doubly-fed wind turbine generator control method and system and storage medium

Abstract

The invention belongs to the field of new energy power generation equipment, and particularly relates to a doubly-fed wind turbine generator control method and system and a storage medium, and the method comprises the steps: obtaining a real-time angular frequency deviation signal of a power grid, and adjusting the bandwidth of a phase-locked loop when the system frequency deviation is greater than a specified value; a final d-axis rotor current reference instruction is obtained through calculation; calculating a reactive power reference instruction according to the q-axis current reference instruction, introducing a reactive power control link, and calculating a q-axis rotor current reference instruction through a reactive power controller; the doubly-fed wind turbine generator generates a new control signal by an upper-layer control loop based on the new current reference signal, so that the doubly-fed wind turbine generator outputs corresponding active power and reactive power, and rapid active support for the power grid frequency is realized; compared with an existing method for achieving frequency control in a phase-locked loop, the method has the advantages that a differential operator does not need to be introduced, frequency response is fast, the control structure is simple, the bandwidth of the phase-locked loop does not need to be adjusted to a low value, and the accuracy of phase angle tracking of the phase-locked loop is kept.

Description

Technical Field

[0001] The present invention belongs to the field of new energy power generation equipment, and particularly relates to a control method, system and storage medium for a doubly-fed wind turbine generator set. Background Art

[0002] China is gradually transforming from a traditional power system dominated by thermal power to a new power system with new energy as the main body. However, with the continuous increase in the new energy penetration rate, the stability of China's power system has been significantly reduced, the active support ability of power generation equipment has been significantly weakened, and system voltage and frequency problems have become prominent. To cope with the increasingly deteriorating system dynamics, grid guidelines have put forward clear requirements for new energy power generation equipment in terms of grid active support, that is, new energy power generation equipment should be able to have voltage and frequency support capabilities similar to synchronous machines during grid disturbances.

[0003] Inertia control, as the initial stage of frequency control, determines the maximum frequency change rate and maximum frequency deviation in the initial stage of the system. The existing inertia control strategies of doubly-fed wind turbine generator sets mainly add quantities related to the frequency change rate to the active power reference command. However, this method usually requires introducing the differential component of the frequency, which is then prone to bring high-frequency noise and thus affect the stability of the system. At the same time, the inertia response speed of such methods is generally relatively slow, and the phase-locked loop generally has higher rapidity compared to the active control loop. Therefore, theoretically, using the phase-locked loop to achieve inertia control has a faster response speed. Some scholars have achieved virtual inertia control of doubly-fed wind turbine generator sets by reducing the bandwidth of the phase-locked loop. However, in this way, the bandwidth of the phase-locked loop generally needs to be adjusted below 1 Hz, and the response speed is still relatively slow, and the increase in active power during inertia response is small. Research has achieved inertia response by introducing terms related to the frequency differential term or step term into the output phase angle of the phase-locked loop. However, this control method will also bring stability problems due to introducing an additional control loop.

[0004] How to achieve the inertia response of a doubly-fed wind turbine generator set, taking into account the rapidity of inertia response, avoiding the stability problems brought by the differential operator, and at the same time minimizing the modification of the existing control loop has become a key technical problem to be solved urgently at present. Summary of the Invention

[0005] The present invention provides a control method, system and storage medium for a doubly-fed wind turbine generator set, mainly solving the problems of slow power response speed and poor stability in the current grid frequency active support control process.

[0006] To achieve the above object, the present invention provides a fast frequency response control method for a doubly-fed wind turbine generator set, including the following steps: Obtain the real-time angular frequency deviation signal of the power grid through a phase-locked loop, and adjust the bandwidth of the phase-locked loop when it is detected that the frequency deviation is greater than a specified value; Remove the active power control loop, calculate the d-axis rotor current reference command according to the active power reference command given by the power tracking curve, and at the same time introduce the frequency deviation droop additional current reference command into the d-axis rotor current reference command to obtain the final d-axis rotor current reference command; Calculate the reactive power reference command according to the q-axis current reference command, introduce the reactive power control link, and calculate the q-axis rotor current reference command through the reactive power controller; Based on the new current reference signal, the doubly-fed wind turbine generates a new control signal by the upper control loop, so that the doubly-fed wind turbine outputs the corresponding active power and reactive power, realizing the fast and active support for the power grid frequency.

[0007] Furthermore, when the detected frequency deviation is greater than 0.2 Hz, adjust the bandwidth of the phase-locked loop to 1 Hz - 3 Hz.

[0008] Furthermore, the real-time angular frequency deviation signal of the power grid is ω err， Its calculation expression includes: ; In the formula: ω is the real-time angular frequency of the system; ω 0 is the rated angular frequency of the system; The system angular frequency deviation signal ω err and the frequency deviation signal f err The relationship between them includes: ; The adjustment of the bandwidth of the phase-locked loop is realized by adjusting the parameters of the phase-locked loop PI controller, and the specific calculation expression includes: The proportional parameter k ppll of the phase-locked loop is expressed as: ; The integral parameter k ipll of the phase-locked loop is expressed as: ; In the formula: ω -3dB is the angular frequency corresponding to the bandwidth of the phase-locked loop; ζ pll is the damping ratio of the phase-locked loop.

[0009] Furthermore, the calculation expression of the final d-axis rotor current reference command includes: ; In the formula:L s is the stator inductance, L m is the excitation inductance, V s is the stator voltage, D P is the damping coefficient of the grid angular frequency deviation, P ref is the active power reference command, f err is the system frequency deviation detected by the phase-locked loop.

[0010] Furthermore, the calculation expression between the reactive power reference command and the rotor q-axis current reference command includes: ; In the formula: Q ref is the reactive power reference command, I rqref is the rotor q axis current reference command; L s is the stator inductance, L m is the excitation inductance, V s is the stator voltage; ω 0 is the rated angular frequency of the system.

[0011] The present invention also provides a control system for a phase-locked loop electronic power device, using the above-mentioned double-fed wind turbine fast frequency response control method, including: Sampling and processing unit: used to collect stator and rotor voltage and current signals, motor rotor angle signals, and rotor angular velocity signals; Phase-locked loop: calculates the phase reference signal of the system based on the stator voltage measurement; Coordinate transformation unit: used to transform the three-phase voltage and current AC signals in the three-phase stationary coordinate system into two-phase voltage and current DC signals in the two-phase rotating coordinate system; Output power control loop: calculates the d-axis and q-axis current reference commands input to the rotor current control loop through closed-loop regulation using the above-mentioned reference commands and feedback measurements; Rotor current control loop: calculates the modulation voltage signal through closed-loop regulation using the rotor current command and rotor measurement; Space vector modulator: used to generate the PWM control signal for controlling the switch tubes of the rotor-side converter through space vector modulation; Rotor-side converter: The switch signal input end is connected to the output end of the space vector modulator.

[0012] Further, the sampling and processing unit includes: Sampling unit: for collecting the stator AC voltage signal of the doubly-fed motor V sabc , rotor current signal I rabc； Encoder unit: for obtaining the rotor angle θ r and rotor angular velocity ω r ; The phase-locked loop includes: Park coordinate transformation unit: for transforming the stator voltage signal in the three-phase stationary coordinate system V sabc into the stator d-axis voltage V sd , q-axis voltage V sq ; Controller unit: for calculating the system angular frequency deviation signal according to the q-axis voltage; Feedforward unit: for obtaining the phase angle compensation signal according to the system frequency deviation degree; Adder unit: for superimposing the system rated angular frequency signal to obtain the system real-time angular frequency signal; Subtractor unit: for subtracting the phase angle output by the phase-locked loop from the compensation angle; Integrator unit: for obtaining the phase angle of the grid-connected point voltage by integrating the system real-time angular frequency signal θ pll ; The coordinate transformation unit includes: Park coordinate transformation unit: for transforming the stator voltage signal V sabc and rotor current signal I rabc in the three-phase stationary coordinate system into the stator d-axis voltage V sd , q-axis voltage V sq , rotor d-axis current I rd , q-axis current I rq ; The output power control loop includes: Subtractor unit: for subtracting the reference signal from the feedback signal to obtain the error signal; Controller unit: The active power controller is used to perform closed-loop processing on the active power to obtain the rotor d-axis current reference signal, and the reactive power controller is used to perform closed-loop processing on the reactive power to obtain the rotor q-axis current reference signal; Output limiter unit: used to ensure that the output current reference command does not exceed the current limit that the equipment can withstand; The rotor current control loop includes: Feedforward unit: Calculate and obtain the feedforward compensation signal I rd through the rotor d-axis current I rq and the q-axis current V rdc ; V rqc ; Controller unit: According to the rotor d-axis current command I rdref and the q-axis current command I rqref and the actual rotor d-axis current I rd and the q-axis current I rq , calculate to obtain the d-axis error signal I errd and the q-axis error signal I errq ; The controller unit includes a first controller and a second controller. The first controller is used to perform closed-loop regulation on the d-axis error signal I errd to obtain the converter d-axis voltage demand signal U rd , and the second controller is used to perform closed-loop regulation on the q-axis error signal I errq to obtain the converter q-axis voltage demand signal U rq ; Modulation signal generation unit: includes a first adder and a second adder. The first adder is used to add the d-axis error signal I errd and the d-axis feedforward compensation signal V rdc to obtain the d-axis modulation signal V rd * ; The second adder is used to add the q-axis error signal I errq and the q-axis feedforward compensation signal V rqc to obtain the q-axis modulation signal V rq *; The space vector modulator is used for the modulation signal U rd , U rq to perform SVPWM modulation to obtain the PWM control signal of the switching tubes of the rotor-side converter U rabc , and this signal is used to control the conduction and cutoff of the switching tubes in the rotor-side converter, so as to regulate the output voltage signal of the rotor-side converter.

[0013] The present invention also provides a control method for a doubly-fed wind turbine, including the following steps: Collect the real-time angular frequency deviation signal of the power grid. When the detected frequency deviation is greater than 0.2 Hz, immediately adjust the bandwidth of the phase-locked loop to 1 Hz to 3 Hz; Adopt the above-mentioned fast frequency response control method for the doubly-fed wind turbine to obtain a new d-axis rotor current reference command and a q-axis rotor current reference command; Based on the new d-axis rotor current reference command and q-axis rotor current reference command, adopt vector control to control the doubly-fed wind turbine to quickly output power to the power grid, so as to achieve fast active support for the power grid frequency.

[0014] The present invention also provides a storage medium, on which a computer program is stored. When the computer program is executed by a processor, the above-mentioned fast frequency response control of the doubly-fed wind turbine and / or the control method of the doubly-fed wind turbine are realized.

[0015] The technical solution provided by the present invention at least has the following technical effects: The fast frequency response control method for the doubly-fed wind turbine disclosed by the present invention obtains a new d-axis rotor current reference command, a q-axis rotor current reference command and a reactive power reference signal Q ref ; Based on the new current reference command signal, the doubly-fed wind turbine generates a new control signal by the upper control loop, so that the doubly-fed wind turbine has corresponding active power and reactive power, and then realizes active support for the power grid frequency. Since the coupling of the active and reactive power control loops during frequency support is more prominent for the dynamic response of frequency support, therefore, the method of the present invention can achieve the control goal of fast active support for the power grid frequency, with fast response speed, simple and easy to implement. Compared with the existing frequency control method in the phase-locked loop, it has the advantages of not needing to introduce a differential operator, fast frequency response, simple control structure, and not needing to adjust the phase-locked loop bandwidth to a lower value, and maintains the accuracy of the phase angle tracking of the phase-locked loop. Description of the Drawings

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0017] Figure 1 It is a flowchart of a fast frequency response control method for a doubly-fed wind turbine provided in Embodiment 1 of the present invention; Figure 2 It is the main circuit topology structure of the doubly-fed wind turbine provided in Embodiment 1 of the present invention; Figure 3 It is a schematic diagram of the phase-locked loop structure and a modified schematic diagram of the fast frequency response control method in the phase-locked loop in Embodiment 1 of the present invention; Figure 4 It is a schematic diagram of the upper-layer control of the doubly-fed wind turbine and a schematic diagram of active power and reactive power control in Embodiment 1 of the present invention; Figure 5 It is an experimental result diagram corresponding to Steps 110 and 120 of the method in this embodiment after the grid frequency drops suddenly provided in Embodiment 1 of the present invention; Among them, (a) is an experimental result diagram of the wind turbine output power change and the system frequency change rate without using active control by using the method of the present invention; (b) is an experimental result diagram of the wind turbine output power change and the system frequency change rate when using active control by using the method of the present invention; Figure 6 It is an experimental result diagram corresponding to Steps 110 and 130 of the method in this embodiment after the grid frequency drops suddenly provided in Embodiment 1 of the present invention; Among them, (a) is an experimental result diagram of the wind turbine output power change and the system frequency change rate under reactive power control by using the method of the present invention; (b) is an experimental result diagram of the wind turbine output power change and the system frequency change rate when using active and reactive power control by using the method of the present invention; Figure 7 It is an experimental result diagram corresponding to all steps of this embodiment after the grid frequency drops suddenly provided in Embodiment 1 of the present invention; Among them, (a) is the experimental result diagram corresponding to the phase-locked loop bandwidth set to 1 Hz and the droop coefficient D p = 0.01; (b) is the experimental result diagram corresponding to the phase-locked loop bandwidth set to 1 Hz and the droop coefficient D p = 0.005; (c) is the experimental result diagram corresponding to the phase-locked loop bandwidth set to 2 Hz and the droop coefficient D p = 0.01.

[0018] In all the drawings, the same reference numerals are used to denote the same elements or structures, where: 1. Sampling and processing unit; 2. Phase-locked loop; 3. Coordinate transformation unit; 4. Output power control loop; 5. Rotor current control loop; 6. Space vector modulator; 7. Rotor-side converter. Detailed implementation manners

[0019] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below by referring to the drawings are exemplary and are intended to explain the embodiments of the present invention, and should not be construed as a limitation to the present invention.

[0020] Embodiment 1: This embodiment discloses a fast frequency response control method for a doubly-fed wind turbine generator set, as Figure 1 shown, which includes the following steps: Step 110: Obtain the real-time angular frequency deviation signal of the power grid through a phase-locked loop.

[0021] Among them, the method for judging that the power grid frequency deviates from the rated value is specifically as follows: as Figure 2 shown, the main circuit topology structure of the doubly-fed wind turbine, Figure 2 where DFIG represents the doubly-fed wind turbine, U rabc Inverter drive signal; RSC represents the rotor-side converter; U dc represents the DC bus voltage; I sabc represents the three-phase stator output current, ω r represents the rotor angular velocity, θ r represents the rotor rotation angle. As Figure 3 shown, the phase-locked loop adopted in this article, its working process is specifically as follows: collect the port voltage signal of the doubly-fed wind turbine generator set connected to the power grid V sabc ; through coordinate transformation, transform the port voltage signal in the three-phase stationary coordinate system V sabc into the port voltage in the two-phase stationary coordinate system V αβ ; through coordinate transformation, transform the port voltage signal in the two-phase stationary coordinate system V αβ into the port voltage in the two-phase rotating coordinate system V sd and V sq , where the coordinate transformation angle signal θpll Provided by the phase signal output from the phase-locked loop; and q shaft voltage signal V sq is input to a PI 0 controller to obtain the real-time angular frequency of the system ω and the rated angular frequency ω 0 of the angular frequency deviation signal ω err = ω - ω 0 , the system angular frequency deviation signal ω err and the frequency deviation signal f err are related as follows: ω err = 2π f err , the frequency deviation signal f err = f - f 0 , where: f is the real-time frequency of the system, f 0 is the rated frequency of the system. Thus, the angular frequency deviation signal ω err can be used to indirectly judge the degree to which the system frequency deviates from the rated value. The angular frequency deviation signal ω err and the rated angular frequency signal ω 0 are added to obtain the real-time angular frequency signal ω ; the real-time angular frequency signal ω passes through an integration link to obtain the phase angle signal reference θ pll of the entire system.

[0022] When it is detected that the grid frequency deviation from the rated value is greater than 0.2 Hz, the system switches to the frequency support mode. By switching the PI controller of the PLL from mode 0 to mode 1, the bandwidth of the PLL is adjusted to 1 Hz to 3 Hz. In this embodiment, the bandwidth is adjusted to about 2 Hz, and the PLL bandwidth adjustment is flexibly realized to quickly respond to the frequency drop. The specific calculation expression is as follows: The proportional parameter k ppll of the phase-locked loop is expressed as: ; The integral parameter k ipll of the phase-locked loop is expressed as: ; Wherein: ω -3dB is the angular frequency corresponding to the PLL bandwidth, ζ pll is the damping ratio of the PLL, usually taken as 0.707.

[0023] Step 120: Cut off the active power control loop, calculate the d-axis rotor current reference command according to the active power reference command given by the power tracking curve, and at the same time introduce a frequency deviation droop additional current reference command into the d-axis rotor current reference command to obtain the final d-axis rotor current reference command; Step 130: Calculate the reactive power reference command according to the q-axis current reference command, introduce a reactive power control link, and calculate the q-axis rotor current reference command through a reactive power controller; As Figure 4 shown, steps 120 and 130 are specifically: First, collect the terminal voltage signal of the doubly-fed wind turbine V sabc , the rotor current signal I rabc and the rotor position angle signal θ r : Use the θ pll obtained above to perform a coordinate transformation to transform the terminal voltage signal in the three-phase stationary coordinate system V sabc to the voltage amplitude signal in the two-phase rotating coordinate system; Use the phase information θ pll and the rotor position angle signal θ r obtained above to perform a coordinate transformation to transform the rotor current signal in the three-phase stationary coordinate system I rabc to the current signals I rd and I rq in the two-phase rotating coordinate system.

[0024] When it is detected that the grid frequency deviates from the rated value by 0.2 Hz, the active power and reactive power control loops simultaneously switch from mode 0 to mode 1, i.e., the frequency support mode. At this time, the active reference value of the rotor current is no longer obtained by the active power closed-loop control, but the d-axis rotor current reference command is calculated according to the active power reference command calculated from the power tracking curve, and a frequency deviation droop additional current reference command I rd * is introduced into the d-axis rotor current reference command I P , and the specific expression is: ; Wherein: L s is the stator inductance, L m is the field inductance, V s is the stator voltage, D P is the grid angular frequency deviation damping coefficient, P ref is the active power reference command, f err is the system frequency deviation detected by the phase-locked loop.

[0025] Subtract the deviation signal of the two I rdref = I rd * - I P to obtain the rotor d axis current reference signal I rdref . Secondly, calculate the reactive power reference command through the q axis current reference command, introduce the reactive power control link, and the obtained reactive power reference value Q ref and Q e are subtracted. The deviation signal of the two Q err = Q ref - Q e is input to the reactive power controller PI Q and the output result is limited to obtain the rotor q axis current reference signal I rqref .

[0026] The calculation expression between the reactive power reference command and the rotor q axis current reference command includes: ; Wherein: Q ref is the reactive power reference command, I rqref is the rotor q axis current reference command; L s is the stator inductance, L m is the field inductance, Vs is the stator voltage, ω 0 is the system rated angular frequency.

[0027] Finally, after obtaining the rotor current d, q axis reference current command I rdref and I rqref after that, according to the rotor d axis current command I rdref and the rotor q axis current command I rqref respectively compare with the actual rotor d axis current I rd and q axis current I rq to obtain the d axis error signal I errd and q axis error signal I errq , where I errd = I rdref - I rd , I errq = I rqref - I rq ; For the d axis error signal I errd and q axis error signal I errq respectively adopt PI controllers for closed-loop control to obtain the converter d axis voltage demand signal U rd and the converter q axis voltage demand signal U rq ; According to the rotor d axis current I rd and q axis current I rq generate the d axis feedforward signal V rdc and q axis feedforward signal V rqc; where, V rdc =- ω 2 σL r L rq + E rd , V rqc = ω 2 σL r L rd + E rq The feedforward signal V rdc 、 V rqc is composed of the decoupling feedforward term - ω 2 σL r L rq 、 ω 2 σL r L rd and the induced electromotive force feedforward term E rd 、 E rq and consists of two parts. ω 2 is the slip angle, σ is the leakage inductance coefficient, L r is the rotor self-inductance, E rd is the d axis component of the induced electromotive force on the rotor side, E rq is the q axis component of the induced electromotive force on the rotor side; According to the feedforward signal V rdc 、 V rqc and the converter d axis voltage demand signal V rd 、the converter q axis voltage demand signal V rq the modulation signal V rd * 、 V rq * ; where,V rd * = V rdc + V rd , V rq * = V rqc + V rq ; For the rotor modulation signal V rd * 、 V rq * According to the phase information θ pll and the rotor position angle θ r Perform inverse coordinate transformation to obtain the rotor modulation voltage in the two-phase stationary coordinate system V rα * 、 V rβ * ; Input the modulation signals V rα * 、 V rβ * into the SVPWM module for processing to obtain the drive signals of the power tubes of the rotor-side converter U rabc 。

[0028] Step 140: Based on the new current reference signal, the doubly-fed wind turbine generates a new control signal by the upper control loop, so that the doubly-fed wind turbine outputs the corresponding active power and reactive power, realizing fast active support for the grid frequency.

[0029] To better illustrate the effect of the method of this embodiment, a wind farm composed of 80 1.5MW typical doubly-fed wind turbines is taken as an example for simulation research. Before the fault occurs, the system frequency is the rated frequency, and the doubly-fed unit stably outputs at a power of 0.7 p.u. At 6 s, the system suddenly increases the load. The experimental result diagrams of the output power and the system frequency obtained by using Steps 110 and 120 in the control method proposed in this embodiment are as Figure 5 shown, Figure 5 in which (a) shows the changes in the active power output of the grid-connected wind turbine and the system frequency change rate without using active control and reactive control in this embodiment. Compared with Figure 5 in (b) which adopts the control scheme with active control and without reactive control, the increase in the active power of the wind turbine is significantly improved, and the system frequency change rate is significantly reduced.

[0030] Figure 6 In (a), the active power output of the grid-connected fan and the change rate of the system frequency under the condition of not adopting active power control and adopting reactive power control in this embodiment are compared with Figure 6 In (b), under the control scheme of adopting active power control and no reactive power control, the increase in the active power of the wind turbine is significantly improved, and the change rate of the system frequency is significantly reduced.

[0031] Figure 7 For the active power output of the grid-connected fan and the change of the system frequency under the complete control scheme in this embodiment, except for the inertial response, an obvious primary frequency modulation response is also presented.

[0032] Embodiment 2: Based on the method of Embodiment 1, this embodiment discloses a control system of a phase-locked loop power electronic device, including: a sampling and processing unit 1, a phase-locked loop 2, a coordinate transformation unit 3, an output power control loop 4, a rotor current control loop 5, a space vector modulator 6, and a rotor-side converter 7 in the main circuit of a doubly-fed wind turbine.

[0033] Among them, the input end of the sampling and processing unit 1 is connected to the stator and rotor sides of the doubly-fed motor, and is used to collect stator and rotor voltage and current signals, motor rotor angle signals, and rotor angular velocity signals. The stator voltage measurement in its output end is connected to the input ends of the phase-locked loop 2 and the coordinate transformation unit 3; the rotor current measurement in its output end is connected to the input end of the coordinate transformation unit 3.

[0034] The phase-locked loop 2 calculates the phase reference signal of the system according to the stator voltage measurement, and its output end is connected to the input ends of the coordinate transformation unit 3 and the space vector modulator 6.

[0035] The coordinate transformation unit 3 changes the three-phase voltage and current AC signals in the three-phase stationary coordinate system into two-phase voltage and current DC signals in the two-phase rotating coordinate system. The power measurement in its output end is connected to the feedback end of the output power control loop 4, and the rotor current signal in its output end is connected to the feedback end of the rotor current control loop 5.

[0036] The output power control loop 4 performs closed-loop regulation through the reference instruction and feedback measurement to calculate the d , q axis current reference instruction input to the rotor current control loop 5.

[0037] The rotor current control loop 5 performs closed-loop regulation through the rotor current instruction and rotor measurement to calculate the modulation voltage signal, and its output end is connected to the modulation input end of the space vector modulator 6.

[0038] The space vector modulator 6 is used to generate a PWM control signal for controlling the switching tubes of the rotor-side converter through space vector modulation, and its output terminal is connected to the switching signal input terminal of the rotor-side converter 7.

[0039] In the embodiment of the present invention, the sampling and processing unit 1 includes: a sampling unit for collecting the stator AC voltage signal of the doubly-fed motor V sabc , the rotor current signal I rabc ; an encoder unit for obtaining the rotor angle θ r and the rotor angular velocity ω r .

[0040] The phase-locked loop 2 includes: a Park coordinate transformation unit for transforming the stator voltage signal in the three-phase stationary coordinate system V sabc into the stator d axis voltage V sd , q axis voltage V sq ; a controller unit for calculating the system angular frequency deviation signal according to the q axis voltage; a feed-forward unit for obtaining a phase angle compensation signal according to the system frequency deviation degree; an adder unit for superimposing the system rated angular frequency signal to obtain the system real-time angular frequency signal; a subtractor unit for subtracting the phase angle output by the phase-locked loop and the compensation angle; an integrator unit for obtaining the phase angle of the grid-connected voltage by integrating the system real-time angular frequency signal θ pll .

[0041] The coordinate transformation unit 3 includes: a Park coordinate transformation unit for transforming the stator voltage signal in the three-phase stationary coordinate system V sabc and the rotor current signal I rabc into the stator d axis voltage V sd , q axis voltage V sq , the rotor d axis current I rd , q axis current I rq .

[0042] The power control loop 4 includes: a subtractor unit for subtracting the feedback signal from the reference signal to obtain an error signal; a controller unit, where the active power controller is used to perform closed-loop processing on the active power to obtain the rotor d shaft current reference signal, and the reactive power controller is used to perform closed-loop processing on the reactive power to obtain the rotor q shaft current reference signal; an output limiter unit for ensuring that the output current reference command does not exceed the current limit that the equipment can withstand.

[0043] The rotor current control loop 5 includes: a feedforward unit that calculates and obtains a feedforward compensation signal through the rotor d shaft current I rd 、 q shaft current I rq ; a controller unit that calculates and obtains a V rdc 、 V rqc shaft error signal based on the rotor d shaft current command I rdref 、 q shaft current command I rqref and the actual rotor d shaft current I rd 、 q shaft current I rq . Among them, the first controller is used to perform closed-loop regulation on the d shaft error signal I errd 、 q shaft error I errq to obtain the converter d shaft voltage demand signal I errd , and the second controller is used to perform closed-loop regulation on the d shaft error signal U rd to obtain the converter q shaft voltage demand signal I errq ; a modulation signal generation unit, where the first adder is used to add the q shaft error signal U rq and the d shaft error signal I errd and d shaft feedforward compensation signal V rdc to obtain the d shaft modulation signalV rd * , the second adder is used to q axis error signal I errq and q axis feedforward compensation signal V rqc add them to obtain q axis modulation signal V rq * .

[0044] The space vector modulator 6 is used to perform SVPWM modulation on the modulation signal U rd , U rq to obtain the PWM control signal of the switching tubes of the rotor-side converter U rabc , and this signal is used to control the conduction and cutoff of the switching tubes in the rotor-side converter, so as to regulate the output voltage signal of the rotor-side converter.

[0045] In this embodiment, the power control loop of the doubly-fed wind turbine is improved. The grid angular frequency deviation signal is obtained in real time through the phase-locked loop. When the detected frequency deviation is greater than 0.2 Hz, the bandwidth of the phase-locked loop is immediately adjusted to about 2 Hz; the active power control loop is removed, and the rotor d axis current reference value is calculated according to the active power reference command. At the same time, in the d axis rotor current, a frequency deviation droop additional current reference command is introduced to obtain the final d axis rotor current reference command; the reactive power reference command is calculated according to the rotor q axis current reference command, and a reactive power control link is introduced. The rotor q axis current reference command is calculated through the reactive power controller; the upper-layer control of the doubly-fed wind turbine obtains a new control signal according to the new current reference signal, so that the doubly-fed wind turbine can actively provide fast frequency support.

[0046] Specifically, it includes: first, obtaining the grid angular frequency deviation signal through the phase-locked loop; secondly, switching the power control, and calculating the d axis rotor current reference command according to the active power reference command given by the power tracking curve. At the same time, a frequency deviation droop additional current reference command is introduced into the d-axis rotor current reference command, and this output is the d axis rotor current reference command described in step 120 I rdref . According to the q axis current reference command, calculate the reactive power reference command, and introduce a reactive power control link. This output is the qAxis rotor current reference command I rqref 。

[0047] The upper - layer control of the doubly - fed wind turbine generates new control signals through coordinate transformation based on a new current reference signal, enabling the doubly - fed wind turbine to generate active power that meets the grid demand. Therefore, the method of the present invention can achieve the control objective of quickly and actively supporting the grid frequency, with a fast response speed, being simple and easy to implement. It can effectively provide fast and active frequency support when frequency disturbances occur. It can not only quickly slow down the change of the system frequency without investing in any hardware devices, but also maintain the accuracy of the phase - locked loop phase - locking. Among them, it should be noted that the frequency response of conventional wind turbines requires reducing the PLL bandwidth to 1 Hz or even lower, while the present invention only needs to reduce the PLL bandwidth to about 2 Hz.

[0048] Active current damping link, specifically: Obtain the real - time grid angular frequency deviation signal based on the phase - locked loop. The angular frequency deviation signal undergoes grid angular frequency deviation damping control to obtain a damping signal I P ; Preferably, during the frequency disturbance, the rotor current reference signal is the sum of the droop term and the original rotor current term, and the specific expression is: ; Where: L s is the stator inductance, L m is the excitation inductance, V s is the stator voltage, D P is the grid angular frequency deviation damping coefficient, P ref is the active power reference command, f err is the system frequency deviation detected by the phase - locked loop.

[0049] Compared with other frequency support methods, the frequency response speed is significantly improved, the structure is simple, the portability is strong, greatly enhancing the active frequency support ability of new - energy power generation equipment, and maintaining the accuracy of the steady - state tracking of the original phase - locked loop.

[0050] Embodiment 3: This embodiment discloses a control method for a doubly - fed wind turbine, including: Collect the real - time grid angular frequency deviation signal. When the detected frequency deviation is greater than 0.2 Hz, immediately adjust the bandwidth of the phase - locked loop to 1 Hz - 3 Hz. In this embodiment, the bandwidth of the phase - locked loop is adjusted to about 2 Hz; A new d-axis rotor current reference command and q-axis rotor current reference command are obtained by using the fast frequency response control method for a doubly-fed wind turbine set described in Embodiment 1; the related technical solutions are the same as those in Embodiment 1 and will not be elaborated here.

[0051] Based on the new d-axis rotor current reference command and q-axis rotor current reference command, vector control is adopted. Vector control is a common control method in this field, mainly by independently controlling the d-axis and q-axis components to achieve decoupling control, controlling the doubly-fed wind turbine set to quickly output power to the power grid, and realizing fast active support for the power grid frequency.

[0052] Adopt the power grid frequency support control strategy as described above, adjust the phase-locked loop bandwidth, calculate the d-axis rotor current reference command according to the active power reference command given by the power tracking curve, introduce a frequency deviation droop additional current reference command into the d-axis rotor current reference command, and introduce a reactive power control link. Calculate the q-axis rotor current reference command through a reactive power controller to obtain a new active current reference signal I rdref and I rqref and is used in the vector control of equipment power transmission. This way of bottom-layer control, on the one hand, enables the power generation equipment to actively and quickly support the power grid frequency and maintains the accuracy of the phase-locked loop phase-locking, and on the other hand, can achieve stable and reliable power generation tasks, and is applicable to direct-drive wind turbines, photovoltaic systems and other similar new energy power generation equipment and is simple and feasible.

[0053] Embodiment 4: This embodiment discloses a storage medium. Instructions are stored in the storage medium. When a computer reads the instructions, the computer is made to execute the fast frequency response control method for a wind turbine set described in Embodiment 1 above or the control method for a doubly-fed wind turbine set described in Embodiment 3.

[0054] The related technical solutions are the same as those in Embodiment 1 and Embodiment 3 and will not be elaborated here.

[0055] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A fast frequency response control method for a doubly-fed wind turbine generator system, characterized in that: The steps include: The real-time angular frequency deviation signal of the power grid is obtained through a phase-locked loop, and when the frequency deviation is detected to be greater than a specified value, the bandwidth of the phase-locked loop is adjusted; The active control loop is removed, and the d-axis rotor current reference instruction is calculated according to the active power reference instruction given by the power tracking curve. At the same time, a frequency deviation droop additional current reference instruction is introduced into the d-axis rotor current reference instruction to obtain the final d-axis rotor current reference instruction. The reactive power reference command is calculated according to the q-axis current reference command, a reactive power control link is introduced, and the q-axis rotor current reference command is calculated by the reactive power controller; Based on the new current reference signal, the upper control loop generates a new control signal for the doubly-fed wind turbine generator set, so that the doubly-fed wind turbine generator set outputs corresponding active power and reactive power, thereby achieving rapid and active support for the grid frequency.

2. The fast frequency response control method of a doubly-fed wind turbine generator set according to claim 1, characterized in that: When the frequency deviation is detected to be greater than 0.2 Hz, the bandwidth of the phase-locked loop is adjusted to 1 Hz to 3 Hz.

3. The fast frequency response control method of a doubly-fed wind turbine generator system according to claim 1, characterized in that: The real-time angular frequency deviation signal of the power grid is: ω err , whose calculation expressions include: ； Where: ω is the real-time angular frequency of the system; ω 0 is the rated angular frequency of the system; System angular frequency deviation signal ω err and frequency deviation signal f err The expressions between include: ； The bandwidth of the phase-locked loop is adjusted by adjusting the parameters of the phase-locked loop PI controller. The specific calculation expressions include: Phase-locked loop ratio parameters k ppll The expression is: ； Phase-locked loop integral parameters k ipll The expression is: ； Where: ω -3dB is the angular frequency corresponding to the phase-locked loop bandwidth; ζ pll is the phase-locked loop damping ratio.

4. The fast frequency response control method of a doubly-fed wind turbine generator set according to claim 1, characterized in that: The calculation expression of the final d-axis rotor current reference command includes: ； Where: L s is the stator inductance, L m is the magnetizing inductance, V s is the stator voltage, D P is the grid angular frequency deviation damping coefficient, P ref is the active power reference command, f err It is the system frequency deviation detected by the phase-locked loop.

5. The fast frequency response control method of a doubly-fed wind turbine generator set according to claim 1, characterized in that: The reactive power reference command and the rotor q The calculation expressions between the axis current reference instructions include: ； Where: Q ref is the reactive power reference command, I rqref For the rotor q Axis current reference command; L s is the stator inductance, L m is the magnetizing inductance, V s is the stator voltage, ω 0 is the rated angular frequency of the system.

6. A control system for a phase-locked loop electronic power device, characterized in that: The method for fast frequency response control of a doubly-fed wind turbine generator system as claimed in any one of claims 1 to 5 comprises: Sampling and processing unit (1): used to collect stator and rotor voltage and current signals, motor rotor angle signals and rotor angular velocity signals; Phase-locked loop (2): Calculates the system phase reference signal based on the stator voltage measurement; Coordinate transformation unit (3): used to transform the three-phase voltage and current AC signals in the three-phase stationary coordinate system into two-phase voltage and current DC signals in the two-phase rotating coordinate system; Output power control loop (4): closed loop regulation is performed through the reference command and feedback measurement to calculate the d and q axis current reference commands for the input rotor current control loop; Rotor current control loop (5): The modulated voltage signal is calculated by closed-loop regulation through rotor current command and rotor measurement; Space vector modulator (6): used to generate a PWM control signal for controlling the switch tube of the rotor-side converter through space vector modulation; Rotor-side converter (7): a switch signal input terminal is connected to an output terminal of a space vector modulator.

7. The control system of the phase-locked loop electronic power device according to claim 6, characterized in that: The sampling processing unit (1) comprises: Sampling unit: used to collect the stator AC voltage signal of the double-fed motor V sabc , rotor current signal I rabc； Encoder unit: used to obtain the rotor angle of the doubly-fed motor θ r and the rotor angular velocity ω r ; The phase-locked loop (2) comprises: Park coordinate transformation unit: used to transform the stator voltage signal in the three-phase stationary coordinate system V sabc Transformed into the stator d-axis voltage in the two-phase rotating coordinate system V sd , q-axis voltage V sq ; Controller unit: used to calculate the system angular frequency deviation signal according to the q-axis voltage; Feedforward unit: used to obtain phase compensation signal according to the degree of system frequency deviation; Adder unit: used to superimpose the system rated angular frequency signal to obtain the system real-time angular frequency signal; Subtractor unit: used to make a difference between the phase angle output by the phase-locked loop and the compensation angle; Integrator unit: used to obtain the phase angle of the grid-connected point voltage by integrating the real-time angular frequency signal of the system θ pll ; The coordinate transformation unit (3) comprises: Park coordinate transformation unit: used to transform the stator voltage signal in the three-phase stationary coordinate system V sabc and rotor current signal I rabc Transformed into the stator d-axis voltage in the two-phase rotating coordinate system V sd , q-axis voltage V sq , rotor d-axis current I rd , q-axis current I rq ; The output power control loop (4) comprises: Subtractor unit: used to obtain an error signal by subtracting the reference signal from the feedback signal; Controller unit: The active power controller is used to perform closed-loop processing on the active power to obtain a rotor d-axis current reference signal, and the reactive power controller is used to perform closed-loop processing on the reactive power to obtain a rotor q-axis current reference signal; Output limiter unit: used to ensure that the output current reference instruction does not exceed the current limit that the equipment can withstand; The rotor current control loop (5) comprises: Feedforward unit: through the rotor d-axis current I rd , q-axis current I rq To calculate the feedforward compensation signal V rdc , V rqc ; Controller unit: According to the rotor d-axis current command I rdref ,q-axis current command I rqref and the actual rotor d-axis current I rd , q-axis current I rq , calculate the d-axis error signal I errd , q-axis error signal I errq The controller unit includes a first controller and a second controller, wherein the first controller is used to convert the d-axis error signal I errd Perform closed-loop regulation to obtain the converter d-axis voltage demand signal U rd The second controller is used to convert the q-axis error signal I errq Perform closed-loop regulation to obtain the converter q-axis voltage demand signal U rq ; The modulation signal generating unit includes a first adder and a second adder, wherein the first adder is used to add the d-axis error signal I errd and d-axis feedforward compensation signal V rdc Add to get the d-axis modulation signal V rd * The second adder is used to convert the q-axis error signal I errq and q-axis feedforward compensation signal V rqc Add to obtain the q-axis modulation signal V rq * ; The space vector modulator (6) is used to modulate the signal U rd , U rq Perform SVPWM modulation to obtain the PWM control signal of the switch tube of the rotor side converter (7) U rabc The signal is used to control the on and off of the switch tube in the rotor-side converter (7), thereby regulating the output voltage signal of the rotor-side converter (7).

8. A control method for a doubly-fed wind turbine generator system, characterized in that: The steps include: Collect the real-time angular frequency deviation signal of the power grid. When the frequency deviation is detected to be greater than 0.2 Hz, immediately adjust the bandwidth of the phase-locked loop to 1 Hz to 3 Hz. A new d-axis rotor current reference instruction and a q-axis rotor current reference instruction are obtained by using the fast frequency response control method of the doubly-fed wind turbine set as described in any one of claims 1 to 5; Based on the new d-axis rotor current reference instruction and q-axis rotor current reference instruction, vector control is adopted to control the doubly-fed wind turbine to quickly output power to the grid, thereby realizing rapid and active support for the grid frequency.

9. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method as claimed in any one of claims 1 to 5 and / or claim 8 is implemented.

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