CN109193773B - Method and device for controlling predicted power of double feeders - Google Patents

Abstract

The invention discloses a method and a device for controlling the predicted power of a double feeder, comprising the following steps: generating a traditional active power differential expression and an extended reactive power differential expression by combining a traditional active power expression and an extended reactive power expression with a double-fed motor mathematical model; discretizing the obtained differential expression by using a first-order Euler discrete method, and calculating a power value at the next moment according to the power value at the current moment; calculating a target rotor voltage vector reference value according to the obtained power value at the next moment by utilizing a dead-beat prediction power control method; and obtaining three voltage vectors required by the reference value of the target rotor voltage vector and action time thereof by utilizing a Space Vector Pulse Width Modulation (SVPWM) technology, and finally obtaining a driving signal for driving a switching tube of the inverter.

Description

A method and device for predictive power control of a doubly-fed machine

technical field

The invention relates to the field of wind power generation of doubly-fed electric machines, in particular to a method and device for predicting power of doubly-fed electric machines.

Background technique

The traditional DFIG control is usually based on an ideal power grid. When an unbalanced fault occurs, the power grid will generate negative sequence components, resulting in negative sequence components in the stator voltage, stator current and rotor current, and the electromagnetic torque will appear larger. Pulsation, where the power delivered to the grid oscillates. Therefore, it is necessary to study the high-performance control strategy of DFIG under unbalanced power grid to eliminate the negative sequence current in the stator and rotor windings or suppress the double-frequency fluctuation of active power and reactive power.

At present, there are many literatures concerning the control strategy of DFIG under unbalanced grid, such as "Direct Power Control of Doubly-Fed-Induction-Generator-Based Wind Turbines Under Unbalanced" in "IEEE Transactions on Power Electronics" Vol. 25, No. 2, 2010 Grid voltage" proposes a direct power control (DPC) method for doubly-fed generators in unbalanced power grids. By deriving the power compensation value under various control objectives, it is directly superimposed with the original power reference value to achieve The control objective of eliminating torque ripple and maintaining the stator current sinusoidal, but the steady-state performance of this method is limited by the switching vector table and hysteresis comparator, power fluctuation and current distortion are large.

Most of the methods in the existing literature solve the problem based on the traditional power theory, but the control method using the traditional power definition increases the complexity of the system when achieving the control target, which is not conducive to implementation and application. The extended instantaneous reactive power theory is proposed in "Modeling and Analysis of Instantaneous Active and Reactive Power for PWM AC/DC Converter UnderGeneralized Unbalanced Network" in "IEEE Transactions on Power Delivery", Vol. 21, No. 3, 2006. Power is specifically expressed as the dot product of current and voltage delay signals, which is more suitable for power control in unbalanced grids than the traditional definition of reactive power. However, there is still a lack of application of this new power definition in the field of predictive control of DFIGs to simplify the control strategy of DFIGs in unbalanced grids to improve their steady-state performance.

SUMMARY OF THE INVENTION

In view of this, the purpose of the present invention is to provide a method and device for predictive power control of a doubly-fed machine that simplifies the structure of the control system, so as to improve the steady-state performance of the control.

Based on the above purpose, the method for predictive power control of a doubly-fed machine provided by the present invention includes:

For the expression of traditional active power and the expression of extended reactive power, the traditional active power differential expression and the extended reactive power differential expression are generated by using the mathematical model of the doubly-fed machine;

Using the first-order Euler discretization method, the obtained differential expression is discretized, and the power value at the next moment is calculated from the power value at the current moment;

Using the deadbeat predictive power control method, calculate the target rotor voltage vector reference value according to the obtained power value at the next moment;

Using the space vector pulse width modulation technology SVPWM, the three voltage vectors and their action time required for the target rotor voltage vector reference value are obtained, and finally the drive signal for driving the inverter switch tube is obtained.

Further, the traditional active power differential expression and the extended reactive power differential expression are generated by using the mathematical model of the doubly-fed machine to the expression of the traditional active power and the expression of the extended reactive power, and the steps include:

Set the sub- _voltage as us and the _stator current as is;

Let the traditional active power be expressed as P _s and the extended reactive power as

扩展无功功率表达式为

其中u′_s为延时1/4T后的定子电压，“*”表示该变量的共轭值；According to the mathematical model of DFIG, the traditional active power expression is defined as

The extended reactive power expression is

where u' _s is the stator voltage after a delay of 1/4T, "*" represents the conjugate value of the variable;

和扩展无功功率微分表达式为

其中，

L_m，L_s，L_r分别为互感、定子自感和转子自感，R_s，R_r为定子电阻和转子电阻，u_r为转子侧电压，i_r为转子电流值，ω_s,ω_r,ω_sl,为当前时刻的双馈电机同步速、转速和转差速，ψ_s为定子磁链值，r、s、m分别表示转子侧变量、定子侧变量和互感变量。Combined with the doubly-fed machine equation, the traditional active power differential expression is generated as

and the extended reactive power differential expression is

in,

L _m , L _s , L _r are mutual inductance, stator self-inductance and rotor self-inductance, R _s , R _r are stator resistance and rotor resistance, ur _r is rotor side voltage, _ir is rotor current value, ω _s , ω _r , ω _sl , are the synchronous speed, rotational speed and differential speed of the DFIG at the current moment, ψ _s is the stator flux linkage value, and r, s, and m represent the rotor-side variable, stator-side variable and mutual inductance variable, respectively.

Further, the first-order Euler discretization method is used to discretize the obtained differential expression, and the step of calculating the power value at the next moment from the power value at the current moment includes:

和

其中上标“k”为变量在当前时刻的值，上标“k+1”为变量在下一时刻的值，T_s为系统控制周期；Using the first-order Euler discretization method to discretize the obtained traditional active power differential expression and extended reactive power differential expression, the expression of the discrete method is obtained

and

The superscript "k" is the value of the variable at the current moment, the superscript "k+1" is the value of the variable at the next moment, and T _s is the system control period;

Via the formula:

Using the obtained traditional active power differential expression, extended reactive power differential expression and the power value calculated at time k, the power value at time k+1 is calculated.

Further, in the method for predicting power control using deadbeat, the step of calculating the target rotor voltage vector reference value according to the obtained power value at the next moment includes:

扩展无功功率参考值表示为

目标转子电压矢量参考值表示为

Let the traditional active power reference value be expressed as

The extended reactive power reference value is expressed as

The target rotor voltage vector reference value is expressed as

将下一时刻的功率值定义为功率参考值；Via the formula:

Define the power value at the next moment as the power reference value;

计算转子侧参考电压矢量，其中，

下标“dq”表示转子坐标系中的dq轴，下标“sd”表示定子侧变量在转子坐标系d轴上的值，下标“sq”表示定子侧变量在转子坐标系q轴上的值，下标“rd”表示转子侧变量在转子坐标系d轴上的值，下标“rq”表示转子侧变量在转子坐标系q轴上的值；According to the obtained expression of the discrete method, using the power deadbeat predictive control method, the formula is:

Calculate the rotor-side reference voltage vector, where,

The subscript "dq" represents the dq axis in the rotor coordinate system, the subscript "sd" represents the value of the stator side variable on the d axis of the rotor coordinate system, and the subscript "sq" represents the stator side variable on the q axis of the rotor coordinate system. value, the subscript "rd" represents the value of the rotor-side variable on the d-axis of the rotor coordinate system, and the subscript "rq" represents the value of the rotor-side variable on the q-axis of the rotor coordinate system;

计算目标转子电压矢量参考值。Via the formula:

Calculates the target rotor voltage vector reference.

的三个电压矢量v₀,v₁,v₂及其作用时间t₀,t₁,t₂，最终得到驱动逆变器开关管的驱动信号。Further, the target rotor voltage vector reference value obtained by using the space vector pulse width modulation technology SVPWM synthesis

The three voltage vectors v ₀ , v ₁ , v ₂ and their action times t ₀ , t ₁ , t ₂ finally obtain the drive signal for driving the switch tube of the inverter.

On the other hand, the present invention also provides a doubly-fed machine predictive power control device, comprising:

Bidirectional DC source, doubly-fed motor, recyclable grid simulator, voltage and current sampling circuit, DSP controller and drive circuit;

Among them, the voltage and current sampling circuit uses the voltage Hall sensor and the current Hall sensor to collect the DC bus voltage, the two-phase voltage on the stator side of the DFIG, the two-phase current on the stator side and the two-phase current on the rotor side of the DFIG respectively. After conditioning the circuit, it enters the DSP controller and converts it into a digital signal;

The DSP controller completes the flexible power control method of the doubly-fed motor, outputs six switching pulses, and then obtains the driving signals of the six switching tubes of the inverter after passing through the driving circuit.

As can be seen from the above, the method and device for predictive power control of a doubly-fed motor provided by the present invention can eliminate active power and extend reactive power without calculating additional power compensation values by adopting the control method of extending the definition of reactive power. The power fluctuates at twice the frequency, and the stator current is not distorted, which simplifies the control system structure and significantly improves the steady-state performance of the control. The proposed DFIG predictive power control method is completely suitable for the control under the balanced grid; by using the space vector pulse width modulation technology, the steady-state performance of the control is further improved.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

1 is a flowchart of an embodiment of a method for predicting power of a doubly-fed machine provided by the present invention;

Fig. 2 is the principle block diagram based on the predictive power control method of DFIG provided by the present invention;

3 is a schematic diagram of the hardware structure of the doubly-fed machine predictive power control device provided by the present invention;

4 is a steady-state simulation waveform of an embodiment of the predicted power control of a doubly-fed motor based on extended reactive power under an unbalanced power grid;

5 is a steady-state experimental waveform of an embodiment of the predicted power control of a doubly-fed machine based on extended reactive power under an unbalanced power grid;

FIG. 6 is the THD of the stator one-phase current in the steady state experimental waveform shown in FIG. 5 .

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

As shown in FIG. 1, it is a flowchart of an embodiment of a method for predicting power of a doubly-fed machine provided by the present invention, including:

In step 101, the traditional active power differential expression and the extended reactive power differential expression are generated by using the mathematical model of the doubly-fed machine for the expression of the traditional active power and the expression of the extended reactive power, and the steps include:

Set the sub- _voltage as us and the _stator current as is;

Let the traditional active power be expressed as P _s and the extended reactive power as

扩展无功功率表达式为

其中“*”表示该变量的共轭值，u′_s为延时1/4T后的定子电压；According to the mathematical model of DFIG, the traditional active power expression is defined as

The extended reactive power expression is

Among them, "*" represents the conjugate value of the variable, and u' _s is the stator voltage after a delay of 1/4T;

Based on the above formula, combined with the doubly-fed machine equation, the traditional differential expression of active power is generated as:

生成扩展无功功率微分表达式为：

The generated extended reactive power differential expression is:

L_m，L_s，L_r为互感、定子自感和转子自感，R_s，R_r为定子电阻和转子电阻，u_r为转子侧电压，i_r为转子电流值，ω_s,ω_r,ω_sl,为当前时刻的双馈电机同步速、转速和转差速，ψ_s为定子磁链值，r、s、m分别表示转子侧变量，定子侧变量和互感变量。in,

L _m , L _s , L _r are mutual inductance, stator self-inductance and rotor self-inductance, R _s , R _r are stator resistance and rotor resistance, ur _r is rotor side voltage, _ir is rotor current value, ω _s , ω _r ,ω _sl , is the synchronous speed, rotational speed and differential speed of the doubly-fed motor at the current moment, ψ _s is the stator flux linkage value, r, s, m represent the rotor side variable, the stator side variable and the mutual inductance variable, respectively.

In step 102, the first-order Euler discretization method is used to discretize the differential expression obtained in step 101, and the power value at the next moment K+1 is calculated from the power value at the current moment K, and the steps include:

Using the first-order Euler discretization method to discretize the obtained traditional differential expression of active power and extended differential expression of reactive power, the expression obtained by the discrete method is:

和

and

The superscript "k" is the value of the variable at the current moment, the superscript "k+1" is the value of the variable at the next moment, and T _s is the system control period;

Using the obtained differential expression and the power value calculated at time k, the expression for calculating the power value at time k+1 is:

In step 103, using the deadbeat predictive power control method, the step of calculating the reference value of the target rotor voltage vector according to the power value at the next moment obtained in step 102 includes:

扩展无功功率参考值表示为

目标转子电压矢量参考值表示为

Let the traditional active power reference value be expressed as

The extended reactive power reference value is expressed as

The target rotor voltage vector reference value is expressed as

Using the obtained power expression after first-order Euler discretization, and using the power deadbeat predictive control method, the power value at time K+1 is directly defined as the power reference value, and the rotor side reference voltage vector is obtained. The formulas are: :

下标“dq”表示转子坐标系中的dq轴，下标“sd”表示定子侧变量在转子坐标系d轴上的值，下标“sq”表示定子侧变量在转子坐标系q轴上的值，下标“rd”表示转子侧变量在转子坐标系d轴上的值，下标“rq”表示转子侧变量在转子坐标系q轴上的值；in,

The subscript "dq" represents the dq axis in the rotor coordinate system, the subscript "sd" represents the value of the stator side variable on the d axis of the rotor coordinate system, and the subscript "sq" represents the stator side variable on the q axis of the rotor coordinate system. value, the subscript "rd" represents the value of the rotor-side variable on the d-axis of the rotor coordinate system, and the subscript "rq" represents the value of the rotor-side variable on the q-axis of the rotor coordinate system;

计算目标转子电压矢量参考值。Via the formula:

Calculates the target rotor voltage vector reference.

采用空间矢量脉宽调制技术(SVPWM)，得到合成目标转子电压矢量参考值

所需要的三个电压矢量v₀,v₁,v₂以及它们的作用时间t₀,t₁,t₂；Step 104, according to the target rotor voltage vector reference value obtained in step 103

Using Space Vector Pulse Width Modulation (SVPWM) to obtain the synthetic target rotor voltage vector reference value

The three required voltage vectors v ₀ , v ₁ , v ₂ and their action times t ₀ , t ₁ , t ₂ ;

According to the three voltage vectors obtained in step 104 and their action time, the driving signal for driving the switching tube of the inverter is obtained.

The method and device for predicting power of a doubly-fed motor provided by the present invention can eliminate the active power and extend the double-frequency fluctuation of the reactive power without calculating the extra power compensation value by adopting the control method of extending the definition of reactive power, and realize The sinusoidal current of the stator is not distorted, which simplifies the structure of the control system and significantly improves the steady-state performance of the control.

Under the balanced power grid, the extended reactive power adopted by the present invention has the same effect as the traditional active power, and the predictive power control method of the doubly-fed motor proposed by the present invention is completely suitable for the control under the balanced power grid; by using the space vector pulse width modulation technology, further Improve the steady state performance of the control.

As shown in FIG. 2 , it is a principle block diagram of a DFIG predictive power control method provided by the present invention, including a DFIG 201 , a delay unit 202 , a power calculation unit 203 , a voltage calculation unit 204 , and a space vector modulation module 205 .

The delay unit is responsible for delaying the stator voltage by 1/4 cycle, the power calculation unit performs the power value calculation in the above step 102, and the voltage calculation unit performs the target rotor voltage vector reference value calculation in the above step 103.

On the other hand, the predictive power control device for a doubly-fed machine provided by the present invention, as shown in FIG. 3 , includes:

Recyclable power grid simulator 301, bidirectional DC source 303, doubly fed motor 201, voltage and current sampling circuit 304, DSP controller 305 and drive circuit 306;

Among them, the voltage and current sampling circuit uses the voltage Hall sensor and the current Hall sensor to collect the DC bus voltage, the two-phase voltage on the stator side of the DFIG, the two-phase current on the stator side of the DFIG, and the two-phase current on the rotor side, and the sampling signal passes through the signal. After conditioning the circuit, it enters the DSP controller and converts it into a digital signal;

The DSP controller is used to complete the control method proposed in the above steps 101 to 104, output six switching pulses, and then obtain the driving signals of the six switching tubes of the inverter after passing through the driving circuit.

The effectiveness of the predictive power control method of the DFIG provided by the present invention is obtained by analyzing the simulation waveform shown in FIG. 4 , the experimental waveform shown in FIG. 5 and the current THD results in the experimental waveform shown in FIG. 6 . Among them, the simulation waveforms shown in Fig. 4 are the steady state of the doubly-fed machine predictive power control (DPC-SVM) based on the space vector modulation method and the improvement of the extended instantaneous power theory (DPC-SVM) method under the condition of the unbalanced grid. The simulation waveform, the sampling frequency of both methods in the simulation is 10kHz. The simulated waveforms are, from top to bottom, the active power on the stator side, the reactive power on the stator side, the stator current, the rotor current and the grid voltage. The control objective in Fig. 4(a) is to eliminate the double frequency fluctuation of the traditional active power and the traditional reactive power. The reactive power channel of Fig. 4(a) shows two kinds of reactive powers at the same time. The active power eliminates the double-frequency fluctuation, and under this control objective, the new reactive power still has a double-frequency waveform. The control objective in Fig. 4(b) is to eliminate the double frequency fluctuation of the traditional active power and the new type of reactive power. In the reactive power channel in Fig. 4(b), the double frequency fluctuation of the new type of reactive power is eliminated. , the traditional reactive power has double frequency fluctuation. As shown in Fig. 4(a) and Fig. 4(b), when the grid is balanced, the reactive power under both power theories remains constant. When the grid voltage drops asymmetrically, the DPC-SVM based on the new reactive power A sinusoidal but asymmetrical stator current, constant active power and extended reactive power are guaranteed. In traditional DPC-SVM, although the traditional active power and traditional reactive power can also be kept constant, the stator current will be seriously distorted, which will cause pollution to the power grid.

Figure 5 shows the steady-state experimental waveforms of the traditional DPC-SVM and the improved DPC-SVM method using the extended instantaneous power theory under unbalanced grid conditions. The waveforms from top to bottom are traditional active power, traditional reactive power, new reactive power, stator current waveform and rotor current waveform. Similar to the simulation figure, the double frequency fluctuation of the conventional active power in the reactive power channel in Fig. 5(a) is eliminated, and the novel active power double frequency fluctuation in Fig. 5(b) is eliminated and the stator current is sinusoidal. The sampling frequency of the control algorithm in the experiment is 10kHz. Within 0-0.1s, the grid voltage remains balanced, and at 0.1s, the phase A voltage drops to 70% of the original voltage amplitude. Through analysis and comparison, the experimental results and the simulation results can be in a one-to-one correspondence. The sinusoidal but asymmetrical stator current, constant active power and extended reactive power can be obtained by using the extended reactive power.

Figure 6 shows two DPC-SVM current harmonic analysis based on different power theories under unbalanced power grid, Figure 6(a) is the one-phase stator current spectrum of the traditional DPC-SVM method, and Figure 6(b) is based on One-phase stator current spectrum of the improved DPC-SVM method with extended reactive power definition. It can be seen that the stator current using DPC-SVM is seriously distorted, and the current THD is high, especially the 3rd harmonic, which leads to the A-phase stator current that is similar to the triangular wave in Figure 6(a). After introducing the extended reactive power definition, the stator current harmonics are suppressed, the overall THD is significantly reduced, and the three-phase stator currents in Figure 6(b) can all maintain sinusoidal.

Through the analysis of the above simulation waveforms, experimental waveforms and experimental results, the method of extended instantaneous power theory can realize the sine of the stator current and the constant power without superimposing any power compensation value, which is more suitable for the unbalanced power grid. High-performance control of doubly-fed machines.

It can be seen that the method and device for predictive power control of a doubly-fed machine provided by the present invention can eliminate active power and extend reactive power double frequency without calculating additional power compensation values by adopting the control method of extending the definition of reactive power. Fluctuation of the stator current is realized, and the sinusoidal current of the stator is not distorted, which simplifies the structure of the control system and significantly improves the steady-state performance of the control; under the balanced power grid, the extended reactive power used in the present invention has the same effect as the traditional active power. The motor predictive power control method is completely suitable for the control under the balanced grid; by using the space vector pulse width modulation technology, the steady-state performance of the control is further improved.

The apparatuses in the foregoing embodiments are used to implement the corresponding methods in the foregoing embodiments, and have the beneficial effects of the corresponding method embodiments, which will not be repeated here.

Those of ordinary skill in the art should understand that the discussion of any of the above embodiments is only exemplary, and is not intended to imply that the scope of the present disclosure (including the claims) is limited to these examples; under the spirit of the present invention, the above embodiments or There may also be combinations between technical features in different embodiments, steps may be carried out in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Additionally, well known power/ground connections to integrated circuit (IC) chips and other components may or may not be shown in the figures provided in order to simplify illustration and discussion, and in order not to obscure the present invention. . Furthermore, devices may be shown in block diagram form in order to avoid obscuring the present invention, and this also takes into account the fact that the details regarding the implementation of these block diagram devices are highly dependent on the platform on which the invention will be implemented (i.e. , these details should be fully within the understanding of those skilled in the art). Where specific details (eg, circuits) are set forth to describe exemplary embodiments of the invention, it will be apparent to those skilled in the art that these specific details may be used without or with changes The present invention is carried out below. Accordingly, these descriptions are to be considered illustrative rather than restrictive.

Although the present invention has been described in conjunction with specific embodiments thereof, many alternatives, modifications, and variations to these embodiments will be apparent to those of ordinary skill in the art from the foregoing description. For example, other memory architectures (eg, dynamic RAM (DRAM)) may use the discussed embodiments.

Embodiments of the present invention are intended to cover all such alternatives, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omission, modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (5)

1. A dual feeder prediction power control method is characterized by comprising the following steps:

generating a traditional active power differential expression and an extended reactive power differential expression by combining a traditional active power expression and an extended reactive power expression with a double-fed motor mathematical model;

discretizing the obtained differential expression by using a first-order Euler discrete method, and calculating a power value at the next moment according to the power value at the current moment;

calculating a target rotor voltage vector reference value according to the obtained power value at the next moment by utilizing a dead-beat prediction power control method;

obtaining three voltage vectors required by the reference value of the target rotor voltage vector and action time thereof by using a Space Vector Pulse Width Modulation (SVPWM) technology, and finally obtaining a driving signal for driving a switching tube of the inverter;

the expression of the traditional active power and the expression of the extended reactive power are used for generating a traditional active power differential expression and an extended reactive power differential expression by utilizing a double-fed motor mathematical model, and the steps comprise:

setting the sub-voltage to u_sStator current is i_s；

Let conventional active power be denoted as P_sExtended reactive power is expressed as

According to a double-fed motor mathematical model, a traditional active power expression is defined as

The extended reactive power is expressed as

Wherein u'_sFor the stator voltage after time delay 1/4T, "+" indicates the conjugate value of the variable;

combining a double-fed motor equation, and generating the traditional active power differential expression as

And the extended reactive power differential expression is

Wherein,

L_m，L_s，L_rare respectively mutual inductance, stator self-inductance and rotor self-inductance, R_s，R_rAs stator and rotor resistances u_rIs the rotor side voltage, i_rIs the rotor current value; omega_s,ω_r,ω_slSynchronous speed, rotational speed and slip speed of the dual-feeder at the current moment, psi_sFor the stator flux linkage values, r, s, m represent the rotor-side variables, the stator-side variables and the mutual inductance variables, respectively.

2. The dual-feeder prediction power control method according to claim 1, wherein the discretizing the obtained differential expression by a first-order euler discretization method, and the calculating the next-time power value from the current-time power value comprises:

discretizing the obtained traditional active power differential expression and the obtained expanded reactive power differential expression by using a first-order Euler discrete method to obtain an expression of a discrete method

And

where the superscript "k" is the value of the variable at the current time, the superscript "k + 1" is the value of the variable at the next time, T_sFor system controlA period;

by the formula:

and calculating the power value at the k +1 moment by using the obtained traditional active power differential expression, the obtained extended reactive power differential expression and the power value calculated at the k moment.

3. The dual-feeder prediction power control method according to claim 2, wherein the step of calculating the reference value of the target rotor voltage vector according to the next-time power value obtained by the method of power control using dead-beat prediction comprises:

let the conventional active power reference value be expressed as

The extended reactive power reference value is expressed as

The target rotor voltage vector reference value is expressed as

By the formula:

defining the power value of the next moment as a power reference value;

according to the obtained discrete method expression, a power dead beat prediction control method is utilized, and the following formula is adopted:

a rotor-side reference voltage vector is calculated, wherein,

the subscript "dq" denotes the dq axis in the rotor coordinate system;

by the formula:

a target rotor voltage vector reference value is calculated.

4. The dual-feeder predicted power control method according to claim 3, wherein the target rotor voltage vector reference value synthesized by Space Vector Pulse Width Modulation (SVPWM) is used

Three voltage vectors v of₀,v₁,v₂And time of action t thereof₀,t₁,t₂And finally obtaining a driving signal for driving the inverter switching tube.

5. A dual feeder predictive power control apparatus, comprising:

the system comprises a bidirectional direct current source, a double-fed motor, a recyclable power grid simulator, a voltage and current sampling circuit, a DSP controller and a driving circuit;

the voltage and current sampling circuit respectively collects direct-current bus voltage, double-phase voltage at the stator side of the double-fed motor, double-phase current at the stator side of the double-fed motor and double-phase current at the rotor side by using a voltage Hall sensor and a current Hall sensor, and a sampling signal enters the DSP controller after passing through the signal conditioning circuit and is converted into a digital signal;

the DSP controller completes the double-fed motor flexible power control method of any one of claims 1 to 4, outputs six switching pulses, and then obtains driving signals of six switching tubes of the inverter after passing through a driving circuit.

Images