Power and current prediction control method and system for grid-side converter of double-fed motor

Abstract

The application discloses a power and current prediction control method and system of a doubly-fed motor grid-side converter, relates to the technical field of converter monitoring, and comprises the following steps: predicting the current value and active power and reactive power value of the doubly-fed motor grid-side converter in the next control period according to a power prediction model and a current prediction model; considering the active power, the reactive power and the current component of the axis in the coordinate system, designing an improved value function, and obtaining the length of time during which a voltage vector acts in the next control period by minimizing the value function; and performing power switch control of the doubly-fed motor grid-side converter based on the length of time during which the voltage vector acts in the next control period. dq Coordinate system dq The axis current component, design an improved value function, and obtain the length of time during which a voltage vector acts in the next control period by minimizing the value function; and perform power switch control of the doubly-fed motor grid-side converter based on the length of time during which the voltage vector acts in the next control period. The application considers the power and current parameter control of the doubly-fed motor grid-side converter under three-phase balanced conditions, and realizes efficient control of the doubly-fed motor grid-side converter under three-phase grid voltage balanced conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of converter monitoring technology, in particular to a power and current predictive control method and system for a grid-side converter of a doubly-fed motor. BACKGROUND

[0002] With the continuous growth of the proportion of new energy in the energy structure, the traditional coal industry is facing new challenges in transformation and upgrading. In the operation of coal-fired generating units, more than 80% of the energy consumption is consumed by rotating auxiliary equipment such as fans and pumps. Therefore, optimizing the energy efficiency of these auxiliary equipment is the core link to improve the performance of coal-fired generating units. Compared with the traditional method of adjusting the damper or gate valve to control the flow, the rapid development of modern variable frequency speed regulation technology enables the energy saving of fan, pump and other auxiliary equipment by more than 50%, effectively improving energy utilization and power quality.

[0003] When the fan and pump and other equipment are speed-regulated, the doubly-fed motor speed-regulation system plays a key role, which realizes the speed regulation of the motor and the conversion of energy through a two-stage power conversion circuit, which helps to adapt to different loads and improve system conversion efficiency. However, even if the power grid is in a relatively ideal three-phase voltage balance state, improper control mode will cause the input current of the rectifier in the power conversion circuit to be distorted, making the output DC voltage unstable, and thus leading to poor power quality transmitted to the power grid, serious harmonic interference, and reducing the operation efficiency and performance of the whole system. SUMMARY

[0004] The present application aims at the deficiencies of the prior art, and provides a power and current predictive control method and system for a grid-side converter of a doubly-fed motor, to solve the problems of the prior art.

[0005] The present application specifically provides the following technical solutions: a power and current predictive control method for a grid-side converter of a doubly-fed motor, comprising the following steps:

[0006] establishing a power model and a current model of the grid-side converter of the doubly-fed motor under a three-phase power grid voltage balance state;

[0007] constructing a power prediction model and a current prediction model based on the voltage vector of the power model and the current model, and predicting the current value and the active power and reactive power values of the grid-side converter of the doubly-fed motor in the next control period according to the power prediction model and the current prediction model;

[0008] considering the active power, the reactive power and dq under the coordinate system dq the current component of the axis, designing an improved value function, and obtaining the duration of the voltage vector in the next control period by minimizing the value function;

[0009] Based on the voltage vector action time of next control cycle, the space vector pulse width modulation technology is used to generate the switch state of the grid-side converter of the doubly-fed motor in the next control cycle, and the power and current prediction control is performed.

[0010] Preferably, the design improves the value function, and the voltage vector action time of the next control cycle is obtained by minimizing the value function, specifically:

[0011] Considering the active power, the reactive power and dq The active and reactive current components of the axis in the coordinate system dq The value function about power and current is constructed J The value function J As shown in the following formula:

[0012] ;

[0013] Wherein P r 、Q r 、I dr 、I qr The reference values of the active power, the reactive power and dq The active and reactive current components of the axis in the coordinate system dq P, Q, I d 、I q The current sampling period, k 1 represents the next sampling period; k+

[0014] The partial derivative of the value function about the voltage action time is calculated to obtain the voltage vector action time which makes the value function minimum T 0 、T 1 and T 2, wherein, T 0 represents the zero vector action time, T 1 and T 2 represent the effective vector action time, and the sum of T 0 、T 1 and T 2 is the whole sampling period.

[0015] Preferably, the power model and the current model of the grid-side converter of the doubly-fed motor in the balanced state of the three-phase power grid are established, specifically:

[0016] The current model is constructed according to the relationship between the active and reactive voltage components in the dq coordinate system and the current components of the axis, and the specific expression is: dq

[0017] ​​​ ;

[0018] in, This represents the angular frequency of the input sinusoidal voltage. U d and U q These represent the active and reactive voltage components in the dq coordinate system, respectively. I d and I q These represent the active and reactive current components in the dq coordinate system, respectively. R This is the estimated equivalent resistance value of the grid-side converter circuit for the doubly-fed motor. L The estimated value of the input filter inductance for the grid-side converter of the doubly-fed induction generator; S d , S q These represent the three-phase bridge arm switching states of the doubly-fed induction generator grid-side converter. S a , S b , S c Switching components in the dq coordinate system U dc Indicates the DC bus output voltage;

[0019] In grid voltage When oriented towards the d-axis, Through grid voltage Calculate active power P and reactive power Q The specific expression is:

[0020] ;

[0021] Active power P and reactive power Q This indicates that, in conjunction with the current model, the power model of the doubly-fed induction generator (DFIG) grid-side converter is obtained, and the specific expression is as follows:

[0022] .

[0023] Preferably, the step of predicting the current value, active power, and reactive power value of the doubly-fed induction generator grid-side converter for the next control cycle based on the power prediction model and the current prediction model specifically involves:

[0024] by U rd = S d U dc , Urq =S q U dc As the dq axis control quantity, the prediction model equation of current and power is obtained, and the dq axis current change rate and power change rate are obtained;

[0025] Based on the prediction model equation of current and power, the initial value of current and power in the current sampling period is obtained, and the initial value, the dq axis current change rate and the power change rate are used to calculate the voltage vector U m After the action of T 1 and T 2 time, the current value and active power and reactive power value of the grid-side converter of the doubly-fed motor are obtained.

[0026] Preferably, the space vector pulse width modulation technology is used to generate the switching state of the grid-side converter of the doubly-fed motor in the next control period, and the power and current prediction control is performed, specifically:

[0027] In one sampling period T s Three consecutive voltage vectors are selected in one sampling period, different three-phase bridge arm switching states of the grid-side converter of the doubly-fed motor are defined, and the voltage vectors of the three-phase bridge arm switching states of the grid-side converter of the doubly-fed motor under different combination conditions are obtained. V n ;

[0028] One three-phase voltage period input from the AC side of the grid-side converter of the doubly-fed motor is divided into six sectors according to 60-degree intervals, the sector to which the three-phase AC voltage input from the grid-side converter of the doubly-fed motor at the current time belongs is determined, and the voltage vector operated in the current sector is obtained.

[0029] Based on the voltage vector action time length of the next control period, based on the obtained voltage vector, the switching state of the grid-side converter of the doubly-fed motor in the next control period is generated through the vector pulse width modulation technology, and the power and current prediction control of the grid-side converter of the doubly-fed motor is performed.

[0030] The application provides a power and current prediction control system of a grid-side converter of a doubly-fed motor, comprising:

[0031] A model construction module is used to establish a power model and a current model of the grid-side converter of the doubly-fed motor under balanced state of three-phase grid voltage;

[0032] A power prediction module is used to construct a power prediction model and a current prediction model based on the voltage vector of the power model and the current model, and predict the current value and active power and reactive power value of the grid-side converter of the doubly-fed motor in the next control period according to the power prediction model and the current prediction model;

[0033] an action duration acquisition module, configured to consider active power, reactive power and dq in a coordinate system dq a current component of the axis, design an improved value function, and acquire the voltage vector action duration of the next control period by minimizing the value function;

[0034] a control module, configured to generate a switching state of the grid-side converter of the doubly-fed motor in the next control period based on the voltage vector action duration of the next control period, and perform power and current predictive control by using a space vector pulse width modulation technique.

[0035] The application provides a computer device, comprising a memory and a processor, the memory stores a program, and the program is executed by the processor to make the processor execute the steps of the power and current predictive control method of the grid-side converter of the doubly-fed motor.

[0036] The application provides a storage medium, which stores a computer program, and the computer program is executed by a processor to realize the steps of the power and current predictive control method of the grid-side converter of the doubly-fed motor.

[0037] Compared with the prior art, the application has the following remarkable advantages:

[0038] The application respectively establishes a power model and a current model, predicts the current value and the active power and reactive power value of the grid-side converter of the doubly-fed motor in the next control period, and acquires the voltage vector action duration of the next control period in combination with the current value and the active power and reactive power value, thereby realizing accurate description of the working state of the grid-side converter of the doubly-fed motor, and performing power switch control of the grid-side converter of the doubly-fed motor by using a space vector pulse width modulation technique, so that the switching state of the grid-side converter of the doubly-fed motor in the next control period can be controlled, the power quality transmitted to the power grid is improved, and the overall operation efficiency of the system is improved. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 The figure is a control structure diagram of the grid-side converter of the doubly-fed motor in the control structure of the doubly-fed motor mentioned in the embodiments of the application;

[0040] Figure 2 The figure is a sector division diagram obtained by the three-phase alternating current voltage input into the grid-side converter of the doubly-fed motor mentioned in the embodiments of the application;

[0041] Figure 3 The figure is a three-phase input alternating current voltage simulation waveform of the grid-side converter of the doubly-fed motor under the balanced working condition of the three-phase power grid voltage and by using the method of the application mentioned in the embodiments of the application;

[0042] Figure 4The simulation waveform of three-phase input alternating current of the double-fed motor grid-side converter under the balanced three-phase grid voltage condition and using the method of the present application is mentioned in the embodiments of the present application.

[0043] Figure 5 The simulation waveform of active power and reactive power of the double-fed motor grid-side converter under the balanced three-phase grid voltage condition and using the method of the present application is mentioned in the embodiments of the present application.

[0044] Figure 6 The simulation waveform of d-axis current and q-axis current of the double-fed motor grid-side converter under the balanced three-phase grid voltage condition and using the method of the present application is mentioned in the embodiments of the present application.

[0045] Figure 7 The simulation waveform of DC bus voltage of the double-fed motor grid-side converter under the balanced three-phase grid voltage condition and using the method of the present application is mentioned in the embodiments of the present application.

[0046] Figure 8 The FFT analysis result graph of the A-phase current of the three-phase input alternating current of the double-fed motor grid-side converter under the balanced three-phase grid voltage condition and using the method of the present application is mentioned in the embodiments of the present application.

[0047] Figure 9 The flow chart of the power and current prediction control method of the double-fed motor grid-side converter is provided by the present application. DETAILED DESCRIPTION

[0048] The technical solutions of the embodiments of the present application will be described clearly and completely in combination with the drawings in the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor should belong to the protection scope of the present application.

[0049] As shown in Figure 9 The present application provides a power and current prediction control method of a double-fed motor grid-side converter, which specifically includes the following steps:

[0050] Step S1: establishing the power model and the current model of the double-fed motor grid-side converter under the balanced three-phase grid voltage condition.

[0051] The current model of the double-fed motor grid-side converter under the balanced three-phase grid voltage condition is established as follows, which is expressed as:

[0052] (1);

[0053] wherein, ω ω represents the angular frequency of the input sinusoidal voltage; Ud and U q They represent dq Active and reactive voltage components in the coordinate system; I d and I q They represent dq Active and reactive current components in the coordinate system; R This is the estimated equivalent resistance value of the grid-side converter circuit for the doubly-fed motor. L The estimated value of the input filter inductance for the grid-side converter of the doubly-fed induction generator; S d ，S q These represent the three-phase bridge arm switching states of the doubly-fed induction generator grid-side converter. S a , S b , S c In two-phase rotation ( dq Switching components in the coordinate system.

[0054] Doubly fed motor grid-side converter topology as follows Figure 1 As shown, its three-phase AC input voltage is U a , U b , U c The three-phase AC input current is I a , I b , I c ; R This is the estimated equivalent resistance value of the grid-side converter circuit for the doubly-fed motor. L The estimated value of the input filter inductance for the grid-side converter of the doubly-fed induction generator; U dc This is the DC bus output voltage.

[0055] When the grid voltage is oriented d In the case of shaft ( Active power P and reactive power Q It can be represented as:

[0056] (2);

[0057] Based on the current model established by equation (1), the power model of the doubly-fed induction generator grid-side converter can be obtained as follows:

[0058] (3);

[0059] Step S2: Constructing power prediction model and current prediction model based on power model and current model, and predicting current value and active power, reactive power value of grid-side converter of double-fed motor in next control period according to power prediction model and current prediction model.

[0060] According to the change rule of current and power under the action of different voltage vectors, in a certain time interval, select several continuous voltage vectors as action vectors. Therefore, combined with the traditional SVPWM modulation method, select 3 voltage vectors in one sampling period T s , respectively one zero vector and two effective vectors, and the selection method is selected according to different sectors.

[0061] Define the three-phase bridge arm switch state as S a , S b , S c , when S i =1( i = a , b , c ), it means i the upper switch tube of the bridge arm is turned on, and the lower switch tube is turned off, and when S i =0( i = a , b , c ), it means i the upper switch tube of the bridge arm is turned off, and the lower switch tube is turned on. Get the three-phase bridge arm switch state S a , S b , S c of the grid-side converter of the double-fed motor under different combination conditions V n , which can be defined as V n =[ S a S b S c ] (n=1,2,…,8), then V 1=[0 0 0], V 2=[0 0 1], V 3=[0 1 0], V 4=[0 1 1], V5=[1 00], V 6=[1 0 1], V 7=[1 1 0], V 8 =[1 1 1], wherein V 2 to V 7 represent non-zero voltage vectors, V 1 and V 8 represent zero voltage vectors.

[0062] Table 1 Voltage vector table of grid-side converter of doubly-fed motor

[0063]

[0064] One three-phase voltage cycle of the AC side input of the grid-side converter of the doubly-fed motor is divided into six sectors according to 60-degree intervals, which are defined as shown in Table 2, and a sector division diagram is shown in Figure 2 a， U b， U c is the three-phase input voltage of the AC side. U Table 2 Sector division and corresponding voltage vector table

[0065]

[0066] According to the current and power models established according to formulas (1) and (3), the current and power prediction model equations are obtained as

[0067] rd U d =S dc , U rq U q =S dc As the dq-axis control quantity, the current and power prediction model equations, and the dq-axis current change rate and power change rate are obtained; wherein the current and power prediction model equations are: U

[0068] (4). Suppose that the voltage vector

[0069] is applied, then the dq-axis current change rate and power change rate of the motor are U m dq e dm 、e qm 、e ppm and e ​​qqm may be written as:

[0070] (5) ;

[0071] where different voltage vectors U j (j=0,1,2) can be obtained by dividing sectors of the input three-phase AC voltage of the grid-side converter of the doubly-fed motor and selecting from 8 voltage vectors V n (n=1,2,…,8). In equation (6) , are control quantities U rd , U rq under different voltage vectors U j , are described in detail as follows:

[0072] where U rα and U rβ The values under different voltage vectors are shown in Table 3.

[0073] Table 3 U rα and U rβ The corresponding table of values under different voltage vectors

[0074]

[0075] According to the above correspondence, the values under voltage vectors U m , dq the rate of change of the axis current and the rate of change of power e dm 、e qm 、e ppm and e qqm .

[0076] Under the condition that the grid-side converter of the doubly-fed motor is balanced with the three-phase grid voltage, based on the prediction model equation of the current and power, it is assumed that at the beginning of the K th sampling period, the current and power initial values of the current sampling period are obtained as I d 、I q , P, QAnd the initial values, dq-axis current change rate, and power change rate are plotted in the voltage vector. U m (in the six non-zero voltage vectors of the corresponding sector) V 2~ V (Select from 7) After the action T 1 and T 2. During this time period, obtain the current, active power, and reactive power values ​​of the doubly-fed induction generator (DFIG) grid-side converter. The d-axis and q-axis current and power values ​​are shown below. P, Q It will become:

[0077] (6);

[0078] Similarly, the voltage vector can be calculated. U n (in the six non-zero voltage vectors of the corresponding sector) V 2~ V Select from 7) under the action dq Shaft current change rate and power change rate e dn ，e qn ，e ppn ，e qqn ; and voltage vector U 0 (by zero voltage vector) V 1 and V 8 Select (under the action) dq Shaft current change rate and power change rate e d0 ，e q0 ，e pp0 ，e qq0 .

[0079] Let the current sampling period be K Then the next sampling period dq The shaft current and power can be expressed as, where T s = T 0 +T 1 +T 2 To control the cycle.

[0080] (7);

[0081] Step S3: Consider active power, reactive power, anddq in the coordinate system dq the current components of the axes, a value function is designed and minimized to obtain the length of the voltage vector in the next control period.

[0082] The value function is defined considering the active power, the reactive power and dq in the coordinate system dq the value function of the current components of the axes J as shown in the following formula:

[0083] (8);

[0084] wherein P r ，Q r ，I dr ，I qr are the active power, the reactive power and dq in the coordinate system dq the active and reactive current components of the axes P, Q, I d ，I q reference values.

[0085] The value function J is calculated to minimize it, i.e. the partial derivative of the value function with respect to the voltage action time is calculated to obtain the voltage vector action time T 0 ，T 1 and T 2 is expressed as:

[0086] (9);

[0087] wherein denotes the partial derivative of the value function with respect to the voltage vector action time T 1, denotes the partial derivative of the value function with respect to the voltage vector action time T 2,

[0088] Based on the formulas (7), (8), (9), it is solved that:

[0089] (10);

[0090] wherein:

[0091]

[0092]

[0093]

[0094]

[0095]

[0096]

[0097] Step S4: Based on the next control cycle voltage vector action duration, the space vector pulse width modulation technique is used to generate the next control cycle double-fed motor grid-side converter switch state, and the power and current prediction control is performed.

[0098] According to the three-phase alternating current voltage state input by the double-fed motor grid-side converter at the current moment, the sector to which the double-fed motor grid-side converter belongs is determined, and the operation voltage vector of the current sector is obtained U 0 ，U 1 ，U 2 The sector determination process is: the three-phase input voltage on the alternating current side is U a > U b >0> U c The state is sector 1; the three-phase input voltage on the alternating current side is U b > U a >0> U c The state is sector 2; the three-phase input voltage on the alternating current side is U b > U c >0> U a The state is sector 3; the three-phase input voltage on the alternating current side is U c > U b >0> U a The state is sector 4; the three-phase input voltage on the alternating current side is U c > U a >0> U b The state is sector 5; the three-phase input voltage on the alternating current side is U a > U c >0> U bThe state is sector 6.

[0099] Briefly, according to the input three-phase AC value of the grid-side converter of the doubly-fed motor at the current moment, the current sector can be determined N , and the operating voltage vector corresponding to the current sector is obtained therefrom U 0, U m and U n The specific sector determination process is as follows:

[0100] Take , if , then , otherwise , if , then , otherwise , if , then , otherwise , so the sector is: .

[0101] Wherein U ab , U bc , U ca , respectively, represent the line voltages between the AC sides of the grid-side converter of the doubly-fed motor a and b , b and c , and c and a ; A, B, C are intermediate parameters required in the calculation process and have no actual physical meaning; N is the sector number obtained by calculation.

[0102] According to the next control cycle voltage vector action time obtained in step 3 T 0 ，T 1 ，T 2 , based on the obtained voltage vector, the switch state of the next control cycle of the grid-side converter of the doubly-fed motor is generated through the space vector pulse width modulation technology, and the power and current prediction control of the grid-side converter of the doubly-fed motor is carried out. The present application comprehensively considers the power and current parameter control of the grid-side converter of the doubly-fed motor under three-phase balanced working condition, and realizes the efficient control of the grid-side converter of the doubly-fed motor under three-phase grid voltage balanced condition.

[0103] Simulation verification:

[0104] A Matlab / Simulink simulation model and a 1200W experimental prototype are built to simulate the control method adopted in the application. The topological current parameters of the grid-side converter of the doubly-fed motor are as follows: the effective value of three-phase input voltage is 220V, the angular frequency of input sinusoidal voltage is , the input filter inductance is L = 0.0015 H , the inductance and the equivalent resistance value of the circuit are 3 ohms, the DC bus output filter capacitance is R , and the DC bus output load is C = 1500 uF R L =300 ohms. The simulation and simulation experiment parameters of the grid-side converter of the doubly-fed motor are as follows: the control period is T s =0.0001 seconds, the active power PI control parameter of the outer loop voltage loop is K p =0.0365, K i =0.04.

[0105] Figure 3 is the three-phase input AC voltage of the grid-side converter of the doubly-fed motor adopting the method of the application under the balanced working condition of three-phase grid voltage.

[0106] Figure 4 is the three-phase input AC current simulation waveform of the grid-side converter of the doubly-fed motor adopting the method of the application under the balanced working condition of three-phase grid voltage. As shown in Figure 4 , the input three-phase current of the grid-side converter of the doubly-fed motor adopting the method of the application can follow the control of the three-phase input voltage, the input three-phase AC current waveform presents sinusoidal variation and balanced amplitude without distortion.

[0107] Figure 5 is the active power and reactive power simulation waveform of the grid-side converter of the doubly-fed motor adopting the method of the application under the balanced working condition of three-phase grid voltage. As shown in the figure, the active power and reactive power fluctuate little and the waveform is stable.

[0108] Figure 6 is the d-axis current and q-axis current simulation waveform of the grid-side converter of the doubly-fed motor adopting the method of the application under the balanced working condition of three-phase grid voltage in the dq coordinate system. As shown in the figure, the current waveform has small ripple and is stable. d q

[0109] Figure 7 is the DC side bus voltage simulation waveform of the grid-side converter of the doubly-fed motor adopting the method of the application under the balanced working condition of three-phase grid voltage. As shown in the figure, the system can output stable 600V DC voltage in a short time, and the rectification effect is good. ​​​

[0110] Figure 8 The image shows the FFT analysis results of the A-phase current of the three-phase input AC current of the doubly-fed induction generator grid-side converter using the method of this invention under three-phase grid voltage balance conditions. It can be seen that the total harmonic content of the A-phase input current is 1.63%, which meets the requirement of the "Power Quality Public Grid Harmonics" standard that the total harmonic content should not exceed 5%.

[0111] The above experimental results verify the feasibility and effectiveness of the power and current prediction control method for a doubly fed motor grid-side converter mentioned in this invention.

[0112] Based on the same inventive concept, this invention provides a power and current prediction control system for a doubly fed motor grid-side converter, comprising: a model building module, a power prediction module, an operation duration acquisition module, and a control module.

[0113] The model building module is used to establish the power and current models of the doubly-fed induction generator (DFIG) grid-side converter under three-phase grid voltage balance conditions. The power prediction module is used to construct power and current prediction models based on the voltage vectors of the power and current models, and to predict the current, active power, and reactive power values ​​of the DFIG grid-side converter in the next control cycle based on these models. The duration acquisition module considers active power, reactive power, and... dq coordinate system dq The current component of the shaft is used to design an improved value function, and the duration of the voltage vector action in the next control cycle is obtained by minimizing the value function. The control module is used to generate the switching state of the doubly-fed motor grid-side converter in the next control cycle based on the duration of the voltage vector action in the next control cycle, using space vector pulse width modulation technology, and to perform power and current predictive control.

[0114] The present invention also provides a computer device, including a memory and a processor. The memory stores a program, and when the program is executed by the processor, the processor performs the steps of a power and current prediction control method for a doubly-fed motor grid-side converter.

[0115] According to the disclosed embodiments, the computer device can communicate with one or more external devices (e.g., keyboard, pointing device, Bluetooth communication, etc.) or with any device that enables the computing device to communicate with one or more other computing devices (e.g., router, demodulator, etc.).

[0116] The present invention also provides a storage medium storing a computer program thereon, wherein the computer program, when executed by a processor, implements the steps of a power and current prediction control method for a doubly-fed induction generator grid-side converter.

[0117] According to disclosed embodiments, storage media can be non-transitory computer-readable storage media, for example, can include but are not limited to: a portable computer diskette, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or Flash memory), a portable compact disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing. In the present disclosure, storage media can be any tangible medium that includes or stores programs for use by or in connection with an instruction execution system, apparatus, or device.

[0118] The above description is further detailed in conjunction with specific preferred embodiments of the present application, and for those skilled in the art, without departing from the concept of the present application, a number of simple deductions or replacements can also be made, which should be considered as falling within the scope of protection of the present application.

Claims

1. A power and current prediction control method for a doubly-fed induction generator grid-side converter, characterized in that, include: Establish the power and current models of the grid-side converter of the doubly-fed induction generator under the voltage balance state of a three-phase power grid; Based on the voltage vector of the power model and the current model, a power prediction model and a current prediction model are constructed, and the current value, active power and reactive power value of the grid-side converter of the doubly-fed motor in the next control cycle are predicted according to the power prediction model and the current prediction model. Considering active power, reactive power and dq coordinate system dq The current component of the shaft is used to design an improved value function, and the duration of the voltage vector action in the next control cycle is obtained by minimizing the value function. Based on the duration of the voltage vector action in the next control cycle, space vector pulse width modulation technology is used to generate the switching state of the doubly fed motor grid-side converter in the next control cycle, and power and current predictive control is performed. The design improves the value function, and obtains the duration of the voltage vector action in the next control cycle by minimizing the value function, specifically as follows: Considering active power, reactive power and dq coordinate system dq The current components of the axis are used to construct a value function of power and current. J value function J As shown in the following formula: ； in P r 、Q r 、I dr 、I qr They are active power, reactive power and dq coordinate system dq Active and reactive current components of the shaft P, Q, I d 、I q Reference value, k Indicates the current sampling period. k+ 1 indicates the next sampling period; By calculating the partial derivative of the value function with respect to the voltage application time, the voltage vector application time that minimizes the value function is obtained. T 0 、T 1 and T 2, of which, T 0 indicates zero vector action time. T 1 and T 2 represents the effective vector action time, in order to T 0 、T 1 and T The sum of 2 is used as the entire sampling period.

2. The power and current prediction control method for a doubly-fed induction generator grid-side converter as described in claim 1, characterized in that, The establishment of the power model and current model of the doubly-fed induction generator grid-side converter under the three-phase power grid voltage balance state is specifically as follows: The active and reactive voltage components in the dq coordinate system and dq The relationship between the current components of the shaft is used to construct a current model, the specific expression of which is: ； in, This represents the angular frequency of the input sinusoidal voltage. U d and U q These represent the active and reactive voltage components in the dq coordinate system, respectively. I d and I q These represent the active and reactive current components in the dq coordinate system, respectively. R This is the estimated equivalent resistance value of the grid-side converter circuit for the doubly-fed motor. L The estimated value of the input filter inductance for the grid-side converter of the doubly-fed induction generator; S d , S q These represent the three-phase bridge arm switching states of the doubly-fed induction generator grid-side converter. S a , S b , S c Switching components in the dq coordinate system U dc Indicates the DC bus output voltage; In grid voltage When oriented towards the d-axis, Through grid voltage Calculate active power P and reactive power Q The specific expression is: ； Active power P and reactive power Q This indicates that, in conjunction with the current model, the power model of the doubly-fed induction generator (DFIG) grid-side converter is obtained, and the specific expression is as follows: 。 3. The power and current prediction control method for a doubly-fed induction generator grid-side converter as described in claim 2, characterized in that, The prediction of the current, active power, and reactive power values ​​of the doubly-fed induction generator grid-side converter for the next control cycle based on the power prediction model and the current prediction model is as follows: by U rd = S d U dc , U rq =S q U dc As the control variables of the dq axis, the predictive model equations for current and power are obtained, as well as the rate of change of current and power of the dq axis; Based on the prediction model equations for current and power, the initial values ​​of current and power in the current sampling period are obtained, and the initial values, the dq-axis current change rate, and the power change rate are plotted in the voltage vector. U m After action T 1 and T 2. During this time, the current value, active power, and reactive power values ​​of the grid-side converter of the doubly fed motor are obtained.

4. The power and current prediction control method for a doubly-fed induction generator grid-side converter as described in claim 3, characterized in that, The method of using space vector pulse width modulation technology to generate the switching state of the doubly-fed induction generator grid-side converter for the next control cycle, and performing power and current predictive control, specifically involves: In a sampling period T s Three consecutive voltage vectors are selected to define different three-phase arm switching states of the doubly-fed induction generator (DFIG) grid-side converter, and the voltage vectors of the three-phase arm switching states of the DFIG grid-side converter under different combinations of conditions are obtained. V n ; One three-phase voltage cycle input to the AC side of the doubly-fed motor grid-side converter is divided into six sectors at 60-degree intervals. The sector to which the current sector belongs is determined based on the current state of the three-phase AC voltage input to the doubly-fed motor grid-side converter, and the voltage vector of the current sector operation is obtained. Based on the voltage vector duration of the next control cycle, and using the obtained voltage vector, the switching state of the doubly-fed motor grid-side converter for the next control cycle is generated through vector pulse width modulation (VPWM) technology, enabling predictive control of the power and current of the doubly-fed motor grid-side converter.

5. A power and current prediction control system for a doubly-fed induction generator grid-side converter, characterized in that, include: The model building module is used to establish the power and current models of the doubly fed motor grid-side converter under the three-phase grid voltage balance state. The power prediction module is used to construct power prediction models and current prediction models based on voltage vectors of power and current models, and predict the current value, active power and reactive power value of the grid-side converter of the doubly-fed motor in the next control cycle according to the power prediction model and current prediction model. The duration acquisition module is used to consider active power, reactive power, and dq coordinate system dq The current component of the shaft is used to design an improved value function, and the duration of the voltage vector action in the next control cycle is obtained by minimizing the value function. The control module is used to generate the switching state of the doubly-fed motor grid-side converter in the next control cycle based on the duration of the voltage vector action in the next control cycle, using space vector pulse width modulation technology, and to perform power and current predictive control. The design improves the value function, and obtains the duration of the voltage vector action in the next control cycle by minimizing the value function, specifically as follows: Considering active power, reactive power and dq coordinate system dq The current components of the axis are used to construct a value function of power and current. J value function J As shown in the following formula: ； in P r 、Q r 、I dr 、I qr They are active power, reactive power and dq coordinate system dq Active and reactive current components of the shaft P, Q, I d 、I q Reference value, k Indicates the current sampling period. k+ 1 indicates the next sampling period; By calculating the partial derivative of the value function with respect to the voltage application time, the voltage vector application time that minimizes the value function is obtained. T 0 、T 1 and T 2, of which, T 0 indicates zero vector action time. T 1 and T 2 represents the effective vector action time, in order to T 0 、T 1 and T The sum of 2 is used as the entire sampling period.

6. A computer device, characterized in that, The device includes a memory and a processor, wherein the memory stores a program that, when executed by the processor, causes the processor to perform the steps of a power and current prediction control method for a doubly fed motor grid-side converter as described in any one of claims 1 to 4.

7. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the power and current prediction control method for a doubly fed motor grid-side converter according to any one of claims 1 to 4.

Images