CN112003318A - Wind power grid-connected inverter direct-current bus voltage control method - Google Patents

Wind power grid-connected inverter direct-current bus voltage control method Download PDF

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CN112003318A
CN112003318A CN202010504620.4A CN202010504620A CN112003318A CN 112003318 A CN112003318 A CN 112003318A CN 202010504620 A CN202010504620 A CN 202010504620A CN 112003318 A CN112003318 A CN 112003318A
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loop
current
voltage
wind power
power grid
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马幼捷
杨霞
周雪松
杨路勇
刘茂
陶龙
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Tianjin University of Technology
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/28—The renewable source being wind energy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/76—Power conversion electric or electronic aspects

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Abstract

The invention discloses a method for controlling the voltage of a direct-current bus of a wind power grid-connected inverter, which comprises the following steps: establishing a wind power grid-connected inverter system model; constructing a LADRC double closed-loop structure based on a wind power grid-connected inverter system model to realize direct-current bus voltage control; the LADRC double closed-loop structure takes a first-order LADRC current loop as an inner loop and a first-order LADRC voltage loop as an outer loop. The novel double-closed-loop structure does not depend on an accurate mathematical model of a controlled system, is simple in design and convenient to realize, the current loop applies the LADRC technology to solve the coupling problem among dq-axis currents, the influence of dq-axis current fluctuation on the voltage of a direct-current bus is avoided, and the voltage loop applies the LADRC technology to improve the anti-interference performance of the direct-current bus voltage under the power grid fault.

Description

Wind power grid-connected inverter direct-current bus voltage control method
Technical Field
The invention relates to the field of wind power generation control, in particular to a method for controlling the voltage of a direct-current bus of a wind power grid-connected inverter.
Background
With the continuous improvement of the permeability of wind power in a power grid, the mutual influence between the wind power generator set and a power system is more and more obvious. The wind power grid-connected inverter connects a wind turbine generator and a large power grid into an organic whole, is one of important links in the whole wind power industry, and plays an important role in stabilizing direct-current bus voltage and controlling power factors. The working performance of the wind power grid-connected inverter directly influences the safe, stable and efficient operation of a wind power system, and the research on the control strategy of the wind power grid-connected inverter has important value.
At present, a voltage and current double closed loop structure is mostly adopted for controlling the wind power grid-connected inverter. The voltage loop controls the voltage of the direct current bus to be maintained at a preset value, and the output value of the voltage loop is used as the input of the current loop. The current loop adjusts the reference value of the reactive power according to the requirement of the wind turbine generator on the reactive power, and then the control effect of the voltage loop is improved. The current loop plays an important role in the control of the wind power grid-connected inverter. However, the current of the dq axis of the current loop has a coupling problem, and the control effect of the wind power grid-connected inverter is influenced. In addition, the voltage and current double-closed-loop structures all adopt a classical PI control mode. The PI control strategy for eliminating the error based on the process error can generate certain time delay, and the contradiction between rapidity and overshoot in system response is difficult to solve. The addition of the integral link can generate phase lag to a certain extent, easily generate integral saturation phenomenon, and is unfavorable to system stability, and PI control has poor anti-interference capability to the system, is sensitive to control parameter change and has poor robustness. The development of scientific technology has higher and higher requirements on control precision and speed and adaptability to environmental changes, so that the traditional voltage and current double closed-loop control effect is not ideal. An improved PI control or a novel control strategy is searched for to replace the classical PI double closed-loop control to be a mode for improving the control effect of the wind power grid-connected inverter.
Disclosure of Invention
The invention aims to provide a method for controlling the voltage of a direct-current bus of a wind power grid-connected inverter, which aims to solve the problems in the prior art, and the problem of coupling between dq-axis currents is solved by applying an LADRC (linear active disturbance control) technology to a current loop, so that the influence of the dq-axis current fluctuation on the voltage of the direct-current bus is avoided; the voltage ring adopts the LADRC technology to greatly improve the anti-interference performance of the direct-current bus voltage under the power grid fault.
In order to achieve the purpose, the invention provides the following scheme: the invention provides a method for controlling the voltage of a direct-current bus of a wind power grid-connected inverter, which comprises the following steps:
establishing a wind power grid-connected inverter system model;
constructing a LADRC double closed-loop structure based on a wind power grid-connected inverter system model to realize direct-current bus voltage control;
the LADRC double closed-loop structure takes a first-order LADRC current loop as an inner loop and a first-order LADRC voltage loop as an outer loop.
Preferably, the voltage relationship of the wind power grid-connected inverter in the dq rotation coordinate system is as follows:
Figure BDA0002526079100000021
the current relationship is as follows:
Figure BDA0002526079100000031
in the formula ud、uqFor the components of the output voltage of the grid-side inverter on the d and q axes, ugd、ugqFor the components of the voltage of the three-phase network on the d and q axes, igd、igqThe components of the output current of the grid-side inverter on d and q axes, omega is the fundamental angular velocity of the grid voltage, SkAre the components of the switching function in the d and q axes.
Preferably, the voltage on the direct current side of the wind power grid-connected inverter is realized by controlling active power.
Preferably, the first-order LADRC includes a second-order linear extended state observer LESO, a linear state error feedback control law LSEF, and a dynamic compensation link.
Preferably, the second-order linear extended state observer LESO corresponding to the current loop of the first-order labrc is:
Figure BDA0002526079100000032
in the formula, z1iIs a tracking signal for the d-axis reference current,
Figure BDA0002526079100000033
is z1iA differential signal of z2iIs a tracking signal of the total disturbance of the current loop,
Figure BDA0002526079100000034
is z2iDifferential signal of udComponent of output voltage on d-axis for grid-side inverter, igdComponent, ω, of the grid-side inverter output current on the d-axis0iObserver bandwidth as current loop, b0iIs a compensation factor for the current loop;
the linear state error feedback control law LESF and the dynamic compensation link are as follows:
Figure BDA0002526079100000035
in the formula u0iIs the output of the current loop controller, uiAs input to the controlled object of the current loop, ωciController bandwidth for current loop id_refIs a d-axis reference current.
Preferably, the voltage loop of the first-order LADRC and the second-order linear extended state observer LESO are:
Figure BDA0002526079100000041
in the formula, z1uA tracking signal for the dc bus voltage reference,
Figure BDA0002526079100000042
is z1uA differential signal of z2uIs a tracking signal of the total disturbance of the voltage loop,
Figure BDA0002526079100000043
is z2uDifferential signal of id_refIs d-axis reference current, udcIs the actual value of the DC bus voltage, omega0uObserver bandwidth as voltage loop, b0uIs a compensation factor for the voltage loop.
The linear state error feedback control law LESF and the dynamic compensation link are as follows:
Figure BDA0002526079100000044
in the formula u0uIs the output of the voltage loop controller, uuAs input to the controlled object of the voltage loop, ωcuIs the controller bandwidth of the voltage loop, udc_refIs the reference value of the DC bus voltage.
The invention discloses the following technical effects:
(1) the novel double closed-loop structure does not depend on an accurate mathematical model of a controlled system, and is simple in design and convenient to implement;
(2) the current loop solves the coupling problem among the dq axis currents by applying the LADRC technology, and avoids the influence of the dq axis current fluctuation on the voltage of a direct current bus;
(3) the voltage ring improves the anti-interference performance of the direct-current bus voltage under the grid fault by applying the LADRC technology.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a circuit structure of a wind power grid-connected inverter;
FIG. 2 is a structure of a first order LADRC;
FIG. 3 is a structure diagram of LADRC double closed-loop control of a wind power grid-connected inverter;
FIG. 4 is a comparison of DC bus voltage waveforms in two control modes of a wind power grid-connected inverter in the process of connecting a fan and a power grid;
FIG. 5 is a comparison of voltage waveforms of the DC bus under two control modes when the d-axis reference current suddenly changes;
FIG. 6 is a comparison of voltage waveforms of the DC bus under two control modes when the q-axis reference current suddenly changes;
fig. 7 is a comparison of dc bus voltage waveforms in two control modes when the grid voltage symmetrically drops by 60%.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
The invention provides a method for controlling the voltage of a direct-current bus of a wind power grid-connected inverter, which comprises the following steps:
step S1, establishing a wind power grid-connected inverter system model, where fig. 1 is a circuit structure of a wind power grid-connected inverter, and six bridge arms of the inverter are composed of fully-controlled switching devices, i.e., IGBTs and freewheeling diodes. The model of the voltage source type PWM inverter under the three-phase static coordinate system is as follows:
Figure BDA0002526079100000061
wherein C is DC bus capacitor, RgIs a grid-side equivalent resistance, LgIs a.c. or the likeEffective filter inductance, isFor the current flowing out of the fan-side rectifier, idcFor the current flowing into C, igFor the current flowing into the grid-side inverter, iga、igb、igcAnd ua、ub、ucRespectively the output current of the AC side of the inverter and the voltage to the N point, uga、ugb、ugcFor three-phase mains voltage, udcIs the voltage across C.
As shown in the formula (1), the abc three-phase circuits are independent of each other, and the output voltage u of the inverter is adjusteda、ub、ucThe AC side current i can be changedga、igb、igcAnd the control of the grid-connected inverter is realized. However, the model contains time-varying electric quantity, which increases the difficulty of designing the control system. Obtaining a voltage relation of the wind power grid-connected inverter under a two-phase rotating coordinate system through Park conversion, wherein the voltage relation is as follows:
Figure BDA0002526079100000062
in the formula ud、uqFor the components of the output voltage of the grid-side inverter on the d and q axes, ugd、ugqFor the components of the voltage of the three-phase network on the d and q axes, igd、igqThe components of the output current of the grid-side inverter on d and q axes are shown, and omega is the fundamental wave angular velocity of the grid voltage;
the current relationship is as follows:
Figure BDA0002526079100000071
in the formula, SkAre the components of the switching function in the d and q axes.
Step S2: based on a wind power grid-connected inverter system model, the LADRC double closed-loop control of the wind power grid-connected inverter realizes the voltage control of a direct-current bus:
in the rotating dq synchronous coordinate system, the grid voltage vector is oriented according to the d axis, and then u isgd＝E，u gq0. According to the instantaneous power theory, the active power and the reactive power in the three-phase grid-connected inverter under the steady state are expressed as follows:
Figure BDA0002526079100000072
the instantaneous value of the input power at the direct current side of the wind power grid-connected inverter is expressed as follows:
P＝udcidc (5)
neglecting the power loss of the power electronic device, there are
P＝udcidc＝ugdigd (6)
From the above analysis, the DC side voltage u of the inverterdcWith the d-axis component i of the inverter output currentgdIs in direct proportion. To the DC side voltage udcCan be realized by controlling the active power, i.e. by controlling igdTo be implemented.
Step S2.1: constructing a first-order LADRC:
regardless of the tracking differentiator, the first-order LADRC consists of a second-order linear extended state observer LESO, a linear state error feedback control law LSEF and a dynamic compensation link, which is referred to fig. 2.
Assuming u and y as input and output, respectively, of a first order system, b0For the estimated value of the input control gain, f is all uncertain factors and unknown external disturbance in the system, the differential signal of the estimated value is represented by h, and the state variable is taken as follows: x is the number of1＝y，x2The expanded state space of the first order system is described as:
Figure BDA0002526079100000081
(6) the second-order LESO for formula is:
Figure BDA0002526079100000082
in the formula (I), the compound is shown in the specification,z1a tracking signal of y, z2To track the total disturbance signal, beta1、β2Are the coefficients of the observer. And appropriate parameters are selected, so that the state variable of the observer can track the state variable of the system in real time.
Taking the control law of the system as follows:
Figure BDA0002526079100000083
since only for the state variable x1The observations were made so the LSEF was controlled using the following ratios:
u0＝kp(v-z1) (10)
in the formula, kpThe gain is controlled proportionally.
Through parameterization, gain coefficients of the observer and the controller can be obtained:
β1＝2ω0，β2＝ω0 2 (11)
kp＝ωc (12)
the first order LADRC can be simplified to the bandwidth omega to the observer0And bandwidth ω of the controllercThe two parameters are reasonably adjusted to obtain a better control effect.
Step S2.2: constructing a current loop of the first-order LADRC based on the first-order LADRC structure:
coupling among the dq axis currents, power grid voltage, parameter uncertainty and the like are regarded as sum disturbance, estimation and compensation are carried out through an LESO and dynamic compensation link, and the dq axis currents are decoupled. Taking d-axis current as an example for design, the state space expression corresponding to the current loop control system obtained according to the formula (2) is as follows:
Figure BDA0002526079100000091
the state space expression corresponding to the current loop is as follows:
Figure BDA0002526079100000092
in the formula, the current loop compensation factor b0i＝1/Lg。x1iIs the actual value of d-axis current, uiFor the component of the output voltage of the grid-side inverter on the d-axis, uiInput for d-axis current loop, x2iNew state variable, x, expanded for LESO2iIs used to describe the total disturbance of the current loop, denoted as x2i＝fi＝-Rgigd/Lg+ωigq-ugd/LgAnd is and
Figure BDA0002526079100000093
relating the q-axis component to the d-axis component ω igqThe decoupling of the dq-axis current is achieved as part of the total disturbance.
The second-order LESO corresponding to the current loop obtained from equations (8) and (11) is:
Figure BDA0002526079100000094
in the formula, z1iIs a tracking signal for the d-axis reference current,
Figure BDA0002526079100000095
is z1iA differential signal of z2iIs a tracking signal of the total disturbance of the current loop,
Figure BDA0002526079100000096
is z2iDifferential signal of udComponent of output voltage on d-axis for grid-side inverter, igdComponent, ω, of the grid-side inverter output current on the d-axis0iObserver bandwidth as current loop, b0iIs a compensation factor for the current loop;
selecting a suitable observer bandwidth omega0iCan make z be1i、z2iFast tracking d-axis reference current id_refAnd the total perturbation of the current loop.
The LESF and dynamic compensation links of the proportion control are as follows:
Figure BDA0002526079100000101
in the formula u0iIs the output of the current loop controller, uiAs input to the controlled object of the current loop, ωciController bandwidth for current loop id_refIs a d-axis reference current.
Step S2.3: constructing a voltage ring of the first-order LADRC based on the first-order LADRC structure:
when the voltage outer ring adopts LADRC, firstly establishing a corresponding LESO, and obtaining a state space expression corresponding to the voltage outer ring according to the formula (3):
Figure BDA0002526079100000102
in the formula, the voltage loop compensation factor b0u＝3/2C。x1uIs the actual value of the bus voltage, uuRepresenting d-axis current reference value, uuInput for voltage loop controlled object, x2uNew state variable, x, expanded for LESO2uTo describe the total disturbance of the voltage loop, denoted x2u＝fu＝is/C-3SqigqC,/2C, and
Figure BDA0002526079100000103
the second order LESO of the voltage ring is:
Figure BDA0002526079100000104
in the formula, z1uA tracking signal for the dc bus voltage reference,
Figure BDA0002526079100000105
is z1uA differential signal of z2uIs a tracking signal of the total disturbance of the voltage loop,
Figure BDA0002526079100000106
is z2uDifferential signal of id_refIs d-axis reference current, udcIs the actual value of the DC bus voltage, omega0uObserver bandwidth as voltage loop, b0uA compensation factor for the voltage loop;
selecting a suitable observer bandwidth omega0uCan make z be1u、z2uFast tracking DC bus voltage udcAnd total perturbation of the voltage loop.
The LESF and dynamic compensation links are as follows:
Figure BDA0002526079100000111
in the formula u0uIs the output of the voltage loop controller, uuFor input of a voltage ring controlled object, udc_refIs a reference voltage value, omega, of the voltage loopcuIs the controller bandwidth of the voltage loop.
Step S2.4: constructing a LADRC double closed-loop structure based on a current loop of a first-order LADRC and a voltage loop of the first-order LADRC, and realizing direct-current bus voltage control:
a structural block diagram of the dual closed-loop control of the wind power grid-connected inverter LADRC is shown in fig. 3:
(1) in the voltage ring, the reference value of the direct current bus voltage is used as the input end of the voltage ring LADRC and is compared with the bus voltage value estimated by the LESO; the output value of the voltage ring and the measured value of the direct-current bus voltage are used as two input ends of the voltage ring LESO; taking the voltage feedback of the DC bus to obtain the proportional control law of the state error, b0uA compensation factor for the voltage loop; compensating a disturbance estimation value obtained by the LESO through a feedforward link so as to obtain a given value of the d-axis current;
(2) in the current loop, the symmetry of the dq-axis current loop is considered, and the design is performed by taking the d-axis current loop as an example: the given value of d-axis current is used as the input end of the current loop LADRC and is estimated by LESOComparing the d-axis current values; the output value of the current loop and the measured value of the d-axis current are used as two input ends of a current loop LESO; taking d-axis current feedback to obtain state error to form a proportional control law, b0iIs a compensation factor for the current loop; and compensating the disturbance estimation value obtained by the LESO through a feedforward link, and further obtaining the d-axis output voltage of the wind power grid-connected inverter. The difference between the design of the q-axis current loop and the design of the d-axis current loop is the selection of a q-axis reference current value, and when the current reference value selected by the input end of the q-axis current loop LADRC is 0, unit power factor grid connection can be realized through a space voltage vector modulation technology.
To further verify the effect of the present invention, the control effect based on the dual closed-loop structure of LADRC and the dual closed-loop structure of PI is compared: firstly, establishing a simulation model of the wind power grid-connected system by using SIMULINK, and comparing waveforms of direct-current bus voltage under two control modes. Fig. 4 is a comparison of dc bus voltage waveforms of the wind power grid-connected inverter under two control modes in the process of connecting the wind turbine and the power grid, and referring to fig. 4, the time for the dc bus voltage waveform adopting the LADRC double closed loop to reach a steady state is shorter. Referring to fig. 5, the d-axis reference current increases by 1000A at 0.6s and decreases by 500A at 1s, and the dc bus voltage waveforms under the two control modes are compared, so that the fluctuation range of the dc bus voltage adopting the LADRC double closed loop is smaller when the d-axis reference current changes, and a shorter transition process time is generated, while the dc bus voltage under the PI double closed loop control generates a larger fluctuation range and a longer transition process time. Referring to fig. 6, the q-axis reference current increases by 1000A at 0.6s and decreases by 1000A at 1s, and the dc bus voltage waveforms are compared in the two control modes. When the q-axis reference current is changed, the same can be obtained, and the fluctuation range and the transition process time of the direct-current bus voltage when the LADRC double closed loop is adopted are obviously smaller than those of PI double closed loop control. As can be seen from fig. 5 and 6, when the wind power grid-connected inverter adopts a dual closed loop structure based on the LADRC, the influence of the change of the d-axis reference current and the q-axis reference current on the voltage of the direct-current bus is small, which indicates that the decoupling effect of the dq-axis current is obvious. Referring to fig. 7, the grid voltage symmetrically drops by 60% at 0.6s-1s, the dc bus voltage waveforms are compared in the two control modes, and when the grid voltage suddenly changes, the fluctuation range and the transition process time of the dc bus voltage adopting the double closed-loop LADRC are both smaller than those of the PI double closed-loop control, which indicates that the anti-interference performance based on the double closed-loop LADRC structure under the grid fault is better.
The LADRC technology takes a part (including system uncertain factors and external unknown disturbance) of a controlled system, which is different from an integral series connection type, as a sum disturbance, compensates the system into the integral series connection type system through a dynamic compensation link, and controls the controlled system by using a certain error feedback control law. The decoupling performance and the anti-interference performance are obviously superior to those of the classical PI control. The larcd ac technology has been applied to control of motor speed control systems, photovoltaic systems, wind power systems, and the like.
The LADRC technology is independent of an accurate mathematical model of a controlled system, does not need to measure the disturbance of the system, takes an LESO as a core, observes the actual motion of the system through input and output, compensates the system into a linear integral series structure by using a dynamic compensation link, and then uses an LSEF to enable the closed-loop system to obtain better control performance. The LADRC technology has obvious effects on decoupling performance and anti-interference performance. A classical PI controller is adopted in a voltage and current double-closed-loop control system of the wind power grid-connected inverter, and the effects on decoupling performance and anti-interference performance are not ideal. The LADRC technology is used for replacing the classical PI control to improve the control performance of the wind power grid-connected inverter. The current loop applies the LADRC technology to solve the coupling problem among dq axis currents, the voltage loop applies the LADRC technology to improve the anti-interference performance under the voltage fault of a power grid, finally the voltage stabilization control of the direct current bus voltage of the wind power grid-connected inverter is achieved, and the anti-interference performance of the whole wind power system is improved.
In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, are merely for convenience of description of the present invention, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.
The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.

Claims (6)

1. A wind power grid-connected inverter direct-current bus voltage control method is characterized by comprising the following steps: the method comprises the following steps:
establishing a wind power grid-connected inverter system model;
constructing a LADRC double closed-loop structure based on a wind power grid-connected inverter system model to realize direct-current bus voltage control;
the LADRC double closed-loop structure takes a first-order LADRC current loop as an inner loop and a first-order LADRC voltage loop as an outer loop.
2. The wind power grid-connected inverter direct-current bus voltage control method according to claim 1, characterized in that: the voltage relation of the wind power grid-connected inverter under the dq rotation coordinate system is as follows:
Figure FDA0002526079090000011
the current relationship is as follows:
Figure FDA0002526079090000012
in the formula ud、uqFor the components of the output voltage of the grid-side inverter on the d and q axes, ugd、ugqFor the components of the voltage of the three-phase network on the d and q axes, igd、igqThe components of the output current of the grid-side inverter on d and q axes, omega is the fundamental angular velocity of the grid voltage, SkFor the components of the switching function in the d, q axes, LgIs an alternating current equivalent filter inductor.
3. The wind power grid-connected inverter direct-current bus voltage control method according to claim 1, characterized in that: the direct-current side voltage of the wind power grid-connected inverter is realized by controlling active power.
4. The wind power grid-connected inverter direct-current bus voltage control method according to claim 1, characterized in that: the first-order LADRC comprises a second-order linear extended state observer LESO, a linear state error feedback control law LSEF and a dynamic compensation link.
5. The wind power grid-connected inverter direct-current bus voltage control method according to claim 1, characterized in that: the second-order linear extended state observer LESO corresponding to the d-axis current loop of the first-order LADRC is:
Figure FDA0002526079090000021
in the formula, z1iIs a tracking signal for the d-axis reference current,
Figure FDA0002526079090000022
is z1iA differential signal of z2iIs a tracking signal of the total disturbance of the current loop,
Figure FDA0002526079090000023
is z2iDifferential signal of udComponent of output voltage on d-axis for grid-side inverter, igdComponent, ω, of the grid-side inverter output current on the d-axis0iObserver bandwidth as current loop, b0iIs a compensation factor for the current loop;
the linear state error feedback control law LESF and the dynamic compensation link are as follows:
Figure FDA0002526079090000024
in the formula u0iIs the output of the current loop controller, uiAs input to the controlled object of the current loop, ωciController bandwidth for current loop id_refIs a d-axis reference current.
6. The wind power grid-connected inverter direct-current bus voltage control method according to claim 1, characterized in that: the voltage loop of the first-order LADRC and the second-order linear extended state observer LESO are as follows:
Figure FDA0002526079090000025
in the formula, z1uA tracking signal for the dc bus voltage reference,
Figure FDA0002526079090000026
is z1uA differential signal of z2uIs a tracking signal of the total disturbance of the voltage loop,
Figure FDA0002526079090000027
is z2uDifferential signal of id_refIs d-axis reference current, udcIs the actual value of the DC bus voltage, omega0uObserver bandwidth as voltage loop, b0uA compensation factor for the voltage loop;
the linear state error feedback control law LESF and the dynamic compensation link are as follows:
Figure FDA0002526079090000031
in the formula u0uIs the output of the voltage loop controller, uuAs input to the controlled object of the voltage loop, ωcuIs the controller bandwidth of the voltage loop, udc_refIs the reference value of the DC bus voltage.
CN202010504620.4A 2020-06-05 2020-06-05 Wind power grid-connected inverter direct-current bus voltage control method Pending CN112003318A (en)

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