CN103296951A - Control method of birotor-structure variable-speed constant-frequency wind power generation system - Google Patents

Abstract

The invention relates to a control method of a variable-speed constant-frequency wind power generation system with a double-rotor structure, belonging to the control technology field of wind power generation systems. The invention aims to solve the problem that the existing dual-rotor wind power generation system can only operate efficiently at low wind speed. When the wind speed of the environment where the wind turbine is located reaches its cut-in wind speed, the wind turbine starts to rotate, drives the gear transmission mechanism to work, detects the wind speed of the environment where the wind turbine is located, and controls the adjustment when the wind speed of the environment where the wind turbine is located is lower than its rated wind speed. After the generator is connected to the grid, change the speed of the speed-regulating motor, and then change the speed of the output shaft of the wind turbine to achieve maximum power tracking control; when the wind speed in the environment where the wind turbine is located is greater than Or when it is equal to its rated wind speed, control the speed-regulating motor to the torque control state to make the generator run at rated speed, and the speed-regulating motor feeds the output power to the grid through the frequency converter. The invention is used for the control of the double-rotor structure wind power generation system.

Description

Control method of variable speed and constant frequency wind power generation system with double rotor structure

technical field

The invention relates to a control method of a variable-speed constant-frequency wind power generation system with a double-rotor structure, and belongs to the technical field of control of wind power generation systems.

Background technique

Due to their respective advantages, permanent magnet direct drive units and double-fed units occupy an important position in the global wind power industry. Especially double-fed units have become the core products of major wind power manufacturers due to their mature technology and high reliability of the whole machine. From the perspective of low wind speed operation, the direct-drive fan has no lower limit of operating speed, while the doubly-fed fan has low speed, large slip, high rotor voltage, and the inverter will be damaged, so there will be a 3-5m/s cut into the wind speed limit. However, the direct-drive fan needs to use a full-power inverter, and its capacity is about three times that of the double-fed unit inverter, which means that the direct-drive inverter itself and the power loss of cooling equipment are much larger. At the same time, the permanent magnet direct drive unit does not have a gearbox, which reduces the maintenance of the mechanical system, but reduces the reliability of the generator and frequency converter.

At present, more than 85% of the global wind turbines are models with gearboxes, especially in offshore units that require high reliability and stability. With the continuous development of gearbox technology and the continuous improvement of efficiency, a wind power generation system with a double-rotor structure with planetary gears has appeared. Its special electromechanical coupling structure and reasonable motor power matching have realized the high efficiency of the wind turbine at low wind speeds. Compared with the direct-drive structure, it has the advantages of reducing the capacity and power consumption of the motor and frequency converter, but this dual-rotor wind power generation system can only operate efficiently at low wind speeds.

Contents of the invention

The object of the present invention is to solve the problem that the existing dual-rotor wind power generation system can only operate efficiently at low wind speeds, and provides a control method for the variable-speed constant-frequency wind power generation system with a dual-rotor structure.

The control method of the double-rotor structure variable speed constant frequency wind power generation system of the present invention, the double rotor structure variable speed constant frequency wind power generation system includes a wind turbine, a gear transmission mechanism, a generator, a speed regulating motor and a frequency converter,

The wind turbine is respectively connected to the input shaft of the generator and the speed-regulating motor through the gear transmission mechanism, the electrical signal output terminal of the speed-regulating motor is connected to the electrical signal input terminal of the frequency converter, and the electrical signal output terminal of the frequency converter is used as the input terminal of the power grid; The electrical signal output terminal of the generator is used as the input terminal of the grid, the generator and the speed-regulating motor are coaxially arranged, and the stator of the generator and the stator of the speed-regulating motor are fixed on the housing.

The speed ratio range of the gear transmission mechanism is 2.8-13;

The gear transmission mechanism is divided into two forms:

The first type is: the gear transmission mechanism is composed of a sun gear, a planet carrier, a plurality of planetary gears and an inner ring gear, the plurality of planetary gears are located in the inner ring gear, and the planetary gears are distributed along the outer circumference of the sun gear,

The output shaft of the wind turbine is connected to the input shaft of the planet carrier. The planet carrier is used to support all the planetary gears. The planetary gears mesh with the sun gear and the ring gear at the same time. The central axes of the sun gear, the planet carrier and the ring gear coincide. The rotating shaft of the sun gear is connected to the rotating shaft of the rotor of the generator, and there is an air gap between the rotor of the generator and the stator of the generator; There is an air gap between the stators of the speed-regulating motor;

The second type is: the gear transmission mechanism is composed of a sun gear, a planet carrier, a plurality of planetary gears and an inner ring gear, the plurality of planetary gears are located in the inner ring gear, and the planetary gears are distributed along the outer circumference of the sun gear,

The output shaft of the wind turbine drives the ring gear to rotate synchronously. The planetary gear meshes with the sun gear and the ring gear at the same time. The planetary carrier is used to support all the planetary gears. The rotor of the motor is fixedly connected with the same axis, and there is an air gap between the rotor of the speed-regulating motor and the stator of the speed-regulating motor; the rotating shaft of the sun gear is connected to the rotating shaft of the rotor of the generator, and there is an air gap between the rotor of the generator and the stator of the generator. gap;

The central axes of the sun gear, ring gear and planet carrier coincide;

The control method is:

When the wind speed of the environment where the wind turbine is located reaches its cut-in wind speed, the wind turbine starts to rotate, drives the gear transmission mechanism to work, detects the wind speed of the environment where the wind turbine is located, and controls the speed regulation when the wind speed of the environment where the wind turbine is located is lower than its rated wind speed Motor speed, so that the generator reaches the grid-connected frequency. After the generator is connected to the grid, change the speed of the speed-regulating motor, and then change the speed of the wind turbine output shaft to achieve maximum power tracking control;

When the wind speed of the environment where the wind turbine is located is greater than or equal to its rated wind speed, the speed-regulating motor is controlled to the torque control state to make the generator run at rated speed, and the speed-regulating motor feeds the output power to the grid through the frequency converter.

The specific process of realizing maximum power tracking control in the control method is:

When the wind speed in the environment where the wind turbine is located reaches its cut-in wind speed, the output shaft of the wind turbine drives the generator and the speed-regulating motor to rotate through the gear transmission mechanism. Network speed n:

$\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 60</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; ;</span>$

According to the three-axis speed relationship of the sun gear, planet carrier and ring gear in the gear transmission mechanism, the relational formula is obtained:

w _a +pw _b -(1+p)w _c =0,

Where w _a is the angular frequency of the sun gear, p is the gear ratio of the inner ring gear to the sun gear, w _b is the angular frequency of the inner ring gear, w _c is the angular frequency of the planet carrier,

得到发电机达到并网转速时的调速电机转速值，该调速电机转速值即为内齿圈的角频率w_b：Depend on

Obtain the speed value of the speed-regulating motor when the generator reaches the grid-connected speed, and the speed value of the speed-regulating motor is the angular frequency w _b of the inner ring gear:

${\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 60</span>}\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 60</span>}}}{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; ,</span>$

SVPWM is used to control the speed of the speed-adjusting motor so that the generator reaches the grid-connected frequency;

After the generator is connected to the grid, the maximum power tracking control based on the optimal power given by the speed feedback is used to calculate the active power P _eG output by the generator and the active power P _eM output by the speed-regulating motor:

P _eG ＝u _Gd i _Gd +u _Gq i _Gq

P _eM =u _Md i _Md +u _Mq i _Mq ,

In the formula, u _Gd is the direct axis voltage of the generator, i _Gd is the direct axis current of the generator, u _Gq is the quadrature axis voltage of the generator, i _Gq is the quadrature axis current of the generator, u _Md is the direct axis voltage of the speed regulating motor, and i _Md is the direct-axis current of the speed-regulating motor, u _Mq is the quadrature-axis voltage of the speed-regulating motor, i _Mq is the quadrature-axis current of the speed-regulating motor,

The stator copper consumption P _Gcu of the generator and the stator copper consumption P _Mcu of the speed regulating motor are calculated from the active power P eG output by _the generator and the active power P _eM output by the speed regulating motor:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; Gcu</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; Q</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; Gd</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; Gs</span>}}$

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; Mcu</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; Q</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; Md</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; Mrs.</span>}}<span\; class="notranslate">\; ,</span>$

In the formula, R _Gs is the generator stator resistance, R _Ms is the speed regulating motor stator resistance,

Neglecting the iron loss and mechanical loss of the generator and the speed-regulating motor, the output power P _W of the wind turbine is calculated from the active power output by the generator and the speed-regulating motor and its stator copper consumption:

P _W ＝P _G -P _M ＝P _eG +P _Gcu -(P _eM -P _Mcu )

＝(u _Gd +i _Gd R _Gs )i _Gd +(u _Gq +i _Gq R _Gs )i _Gq -[(u _Md +i _Md R _Ms )i _Md

-(u _Mq +i _Mq R _Ms )i _Mq ]

_PG is the generator power, _PM is the speed regulating motor power;

The aerodynamic model of the wind turbine is:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&rho;\&pi;</span>}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; v</span>}}^{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; ,</span>$

ρ is the air density, C _P is the wind energy utilization coefficient, R is the impeller radius of the wind turbine, v is the wind speed of the environment where the wind turbine is located,

The tip speed ratio λ is: $\mathrm{\&lambda;}=\frac{w_{c}R}{v},$

The speed value w _b of the speed regulating motor in the maximum power tracking control is obtained by the above formula:

${\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span>{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; \&rho;\&pi;</span>}{\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 5</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 60</span>}\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 60</span>}}}{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; ,</span>$

Change the rotational speed value w _b of the speed regulating motor in the maximum power tracking control, and then change the rotational speed of the output shaft of the wind turbine, thereby realizing the maximum power tracking control.

In the control method, when the wind speed of the environment where the wind turbine is located is greater than or equal to its rated wind speed, the speed-regulating motor is controlled to be in the torque control state, so that the generator is operated at a rated speed, and the speed-regulating motor feeds the output power to the grid through the frequency converter The specific process is:

The specific process is divided into two power stages, namely the first power stage and the second power stage:

The first power stage is: P′ _G <P _W <P′ _G +P′ _M ,

The second power stage is: P _W >P′ _G +P′ _M ,

Among them, P' _G is the rated power of the generator, and P' _M is the rated power of the speed regulating motor;

In the first power stage, according to the three-axis torque relationship of the sun gear, the planet carrier and the ring gear, the torque T _M of the control speed regulating motor is:

${\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; \&times;</span>{{\mathrm{<span\; class="notranslate">\; T</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}}<span\; class="notranslate">\; ,</span>$

where T′ _G is the rated torque of the generator,

According to the above formula, control the torque T _M of the speed-regulating motor, even if the generator is running at a rated level, the speed-regulating motor will feed the output power to the grid through the frequency converter;

In the second power stage, pitch control is used to limit the output power of the wind turbine.

Advantages of the present invention: In the present invention, the double-rotor structure variable-speed constant-frequency wind power generation system forms an integrated wind turbine, generator and speed-regulating motor through planetary gears. In the control method, based on the sun gear, planet carrier and The three-axis speed and torque relationship characteristics of the inner ring gear control the speed of the speed-regulating motor at the rated wind speed to make the generator reach the grid-connected frequency. Changing the speed of the speed-regulating motor after grid-connecting changes the shaft speed of the wind turbine to achieve maximum power tracking Control; when the rated wind speed is above, the speed-regulating motor is switched to torque control to ensure the rated operation of the generator, and at the same time, part of the power is fed to the grid by the speed-regulating motor through the converter.

The control method of the present invention realizes the variable speed and constant frequency control through the electromechanical coupling mode, which realizes the high-efficiency control operation of the wind power generation system under full wind conditions, and the method is easy to implement. Capacity, broaden the range of speed regulation.

Description of drawings

Fig. 1 is a structural schematic diagram of the first form of the gear transmission mechanism in a variable-speed constant-frequency wind power generation system with a double-rotor structure;

Fig. 2 is a structural schematic diagram of the second form of the gear transmission mechanism in a variable-speed constant-frequency wind power generation system with a double-rotor structure;

为调速电机直轴电流参考输入量；

为调速电机交轴电流参考输入量；L_q为调速电机交轴电感；L_d为调速电机直轴电感；θ为调速电机转子位置角；u_α，u_β分别为调速电机两相静止坐标系下电压；u_dc为直流母线电压；

为MPPT计算出的调速电机参考转速；i_abc为调速电机三相电流；u_abc为调速电机三相电压；β为风力机桨距角；τ_β为执行机构时间常数。Fig. 3 is the schematic diagram of control method of the present invention; Among the figure, w _e is the angular frequency of the speed-regulating motor;

It is the reference input value of the direct axis current of the speed regulating motor;

is the quadrature-axis current reference input of the speed-regulating motor; L _q is the quadrature-axis inductance of the speed-regulating motor; L _d is the direct-axis inductance of _the speed-regulating motor; _θ is the rotor position angle of the speed-regulating motor; Voltage in the two-phase static coordinate system; u _dc is the DC bus voltage;

is the reference speed of the speed-regulating motor calculated by MPPT; i _abc is the three-phase current of the speed-regulating motor; u _abc is the three-phase voltage of the speed-regulating motor; β is the pitch angle of the wind turbine; τ _β is the time constant of the actuator.

Detailed ways

Specific Embodiment 1: The present embodiment will be described below with reference to FIGS. 1 to 3 . The control method of the dual-rotor variable-speed constant-frequency wind power generation system described in this embodiment includes a wind turbine 1 , gear transmission mechanism, generator 3, speed regulating motor 4 and frequency converter 5,

The wind turbine 1 is respectively connected to the input shafts of the generator 3 and the speed-regulating motor 4 through a gear transmission mechanism, the electrical signal output terminal of the speed-regulating motor 4 is connected to the electrical signal input terminal of the frequency converter 5, and the electrical signal output terminal of the frequency converter 5 serves as The input end of the grid; the electrical signal output end of the generator 3 is used as the input end of the grid, the generator 3 and the speed-regulating motor 4 are coaxially arranged, and the stator 3-2 of the generator and the stator 4-2 of the speed-regulating motor are all fixed on the on the shell,

The speed ratio range of the gear transmission mechanism is 2.8-13;

The gear transmission mechanism is divided into two forms:

The first is: the gear transmission mechanism is composed of a sun gear 2-1, a planetary carrier 2-2, a plurality of planetary gears 2-3 and an inner ring gear 2-4, and a plurality of planetary gears 2-3 are located on the inner ring gear 2-4, and the planetary gears 2-3 are distributed along the outer circumference of the sun gear 2-1,

The output shaft of the wind turbine 1 is connected to the input shaft of the planetary carrier 2-2, and the planetary carrier 2-2 is used to support all the planetary gears 2-3, and the planetary gears 2-3 are simultaneously connected with the sun gear 2-1 and the ring gear 2- 4-phase meshing, the central axes of the sun gear 2-1, the planetary carrier 2-2 and the ring gear 2-4 coincide, the rotation shaft of the sun gear 2-1 is connected to the rotation shaft of the rotor 3-1 of the generator, and the rotation shaft of the generator There is an air gap between the rotor 3-1 and the stator 3-2 of the generator; the inner ring gear 2-4 is fixedly connected with the inner circular surface of the rotor 4-1 of the speed-regulating motor, and the rotor 4-1 of the speed-regulating motor is connected with the speed-regulating motor There is an air gap between the stator 4-2 of the high-speed motor;

The second type is: the gear transmission mechanism is composed of a sun gear 2-1, a planet carrier 2-2, a plurality of planetary gears 2-3 and an inner ring gear 2-4, and a plurality of planetary gears 2-3 are located on the inner ring gear 2-4, and the planetary gears 2-3 are distributed along the outer circumference of the sun gear 2-1,

The output shaft of the wind turbine 1 drives the ring gear 2-4 to rotate synchronously, the planetary gear 2-3 meshes with the sun gear 2-1 and the ring gear 2-4 at the same time, and the planet carrier 2-2 is used to support all the planetary gears 2-3, the planet carrier 2-2 is located in the rotor 4-1 of the speed regulating motor, and is coaxially fixedly connected with the rotor 4-1 of the speed regulating motor, and the rotor 4-1 of the speed regulating motor is connected with the stator 4 of the speed regulating motor -2 is an air gap; the rotating shaft of the sun gear 2-1 is connected to the rotating shaft of the rotor 3-1 of the generator, and there is an air gap between the rotor 3-1 of the generator and the stator 3-2 of the generator;

The central axes of the sun gear 2-1, the ring gear 2-4 and the planet carrier 2-2 coincide;

The control method is:

When the wind speed of the environment where the wind turbine 1 is located reaches its cut-in wind speed, the wind turbine 1 starts to rotate, drives the gear transmission mechanism to work, and detects the wind speed of the environment where the wind turbine 1 is located. When the wind speed of the environment where the wind turbine 1 is located is lower than its rated wind speed , controlling the speed of the speed-regulating motor 4 so that the generator 3 reaches the grid-connected frequency, after the generator 3 is connected to the grid, changing the speed of the speed-regulating motor 4, and then changing the speed of the output shaft of the wind turbine 1, so as to realize maximum power tracking control;

When the wind speed in the environment where the wind turbine 1 is located is greater than or equal to its rated wind speed, the speed-regulating motor 4 is controlled to be in the torque control state, so that the generator 3 operates at a rated rate, and the speed-regulating motor 4 feeds the output power to the grid through the frequency converter 5 .

Specific embodiment two: the present embodiment will be described below in conjunction with FIG. 3 . This embodiment will further describe the embodiment one. The specific process of realizing the maximum power tracking control in the control method is as follows:

When the wind speed of the environment where the wind turbine 1 is located reaches its cut-in wind speed, the output shaft of the wind turbine 1 drives the generator 3 and the speed-regulating motor 4 to rotate through the gear transmission mechanism. According to the number of pole pairs P of the generator 3 and the grid frequency f, Synchronous grid-connected speed n of generator 3:

$\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 60</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; ;</span>$

According to the three-axis speed relationship of the sun gear 2-1, the planet carrier 2-2 and the ring gear 2-4 in the gear transmission mechanism, the relational formula is obtained:

w _a +pw _b -(1+p)w _c =0,

In the formula, w _a is the angular frequency of the sun gear 2-1, p is the gear ratio of the inner ring gear 2-4 to the sun gear 2-1, w _b is the angular frequency of the inner ring gear 2-4, and w _c is the planet carrier The angular frequency of 2-2,

得到发电机3达到并网转速时的调速电机转速值，该调速电机转速值即为内齿圈2-4的角频率w_b：Depend on

Obtain the speed value of the speed-regulating motor when the generator 3 reaches the grid-connected speed, and the speed value of the speed-regulating motor is the angular frequency w _b of the inner ring gear 2-4:

${\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 60</span>}\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 60</span>}}}{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; ,</span>$

Use SVPWM to control the speed of the speed-regulating motor, so that the generator 3 reaches the grid-connected frequency;

After the generator 3 is connected to the grid, the maximum power tracking control based on the optimal power given by the speed feedback is adopted to calculate the active power P _eG output by the generator 3 and the active power P _eM output by the speed-regulating motor 4:

P _eG ＝u _Gd i _Gd +u _Gq i _Gq

P _eM =u _Md i _Md +u _Mq i _Mq ,

In the formula, u _Gd is the direct axis voltage of the generator, i _Gd is the direct axis current of the generator, u _Gq is the quadrature axis voltage of the generator, i _Gq is the quadrature axis current of the generator, u _Md is the direct axis voltage of the speed regulating motor, and i _Md is the direct-axis current of the speed-regulating motor, u _Mq is the quadrature-axis voltage of the speed-regulating motor, i _Mq is the quadrature-axis current of the speed-regulating motor,

The stator copper consumption P _Gcu of the generator 3 and the stator copper consumption P _Mcu of the speed-regulating motor 4 are calculated from the active power P eG output by the generator 3 and the active power P _eM output by the speed-regulating motor ₄ :

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; Gcu</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; Q</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; Gd</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; Gs</span>}}$

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; Mcu</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; Q</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; Md</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; Mrs.</span>}}<span\; class="notranslate">\; ,</span>$

In the formula, R _Gs is the generator stator resistance, R _Ms is the speed regulating motor stator resistance,

Neglecting the iron loss and mechanical loss of the generator 3 and the speed-regulating motor 4, the output power P _W of the wind turbine 1 is calculated from the active power output by the generator 3 and the speed-regulating motor 4 and their stator copper consumption:

P _W ＝P _G -P _M ＝P _eG +P _Gcu -(P _eM -P _Mcu )

＝(u _Gd +i _Gd R _Gs )i _Gd +(u _Gq +i _Gq R _Gs )i _Gq -[(u _Md +i _Md R _Ms )i _Md

-(u _Mq +i _Mq R _Ms )i _Mq ]

_PG is the generator power, _PM is the speed regulating motor power;

The aerodynamic model of wind turbine 1 is:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&rho;\&pi;</span>}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="3"\; label="v"\; filenames="HDA00003269038900021.png"\; state="\{\{state\}\}">v</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; ,</span>$

ρ is the air density, C _P is the wind energy utilization coefficient, R is the impeller radius of the wind turbine 1, v is the wind speed of the environment where the wind turbine 1 is located,

The tip speed ratio λ is: $\mathrm{\&lambda;}=\frac{w_{c}R}{v},$

The rotational speed value w _b of the speed-regulating motor 4 in the maximum power tracking control is obtained by the above formula:

${\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span>{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; \&rho;\&pi;</span>}{\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 5</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 60</span>}\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 60</span>}}}{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; ,</span>$

The rotational speed value w _b of the speed regulating motor 4 in the maximum power tracking control is changed, and then the rotational speed of the output shaft of the wind turbine 1 is changed, thereby realizing the maximum power tracking control.

Specific Embodiment Three: The present embodiment will be described below in conjunction with FIG. 3 . This embodiment will further illustrate Embodiment 2. In the control method, when the wind speed of the environment where the wind turbine 1 is located is greater than or equal to its rated wind speed, the speed regulation is controlled. The motor 4 is in the torque control state, so that the generator 3 operates at a rated rate, and the specific process of the speed-regulating motor 4 feeding the output power to the grid through the frequency converter 5 is as follows:

The specific process is divided into two power stages, namely the first power stage and the second power stage:

The first power stage is: P′ _G <P _W <P′ _G +P′ _M ,

The second power stage is: P _W >P′ _G +P′ _M ,

Wherein _P'G is the rated power of generator 3, and _P'M is the rated power of speed-regulating motor 4;

In the first power stage, according to the three-axis torque relationship of the sun gear 2-1, the planet carrier 2-2 and the ring gear 2-4, the torque T _M of the control speed regulating motor 4 is:

${\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; \&times;</span>{{\mathrm{<span\; class="notranslate">\; T</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}}<span\; class="notranslate">\; ,</span>$

Where T′ _G is the rated torque of generator 3,

According to the above formula, the torque T _M of the speed-regulating motor 4 is controlled, even if the generator 3 is running at a rated rate, the speed-regulating motor 4 feeds the output power to the grid through the frequency converter 5;

In the second power stage, the output power of the wind turbine 1 is limited by pitch-variable operation.

在实际控制操作中，在等幅值坐标变换基础上，调速电机交轴电流i_Mq为：In vector control, the purpose of controlling its torque T _M can be achieved by controlling the quadrature axis current i _Mq of the speed-regulating motor; in order to achieve

In the actual control operation, on the basis of equal-amplitude coordinate transformation, the quadrature current i _Mq of the speed-regulating motor is:

${\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; Q</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; ,</span>$

Where φ _f is the flux linkage of the permanent magnet of the speed-regulating motor.

In the second power stage, the power of the wind turbine 1 is limited in conjunction with the pitch change operation.

In the control method of the present invention, the switching rules of the maximum power tracking control and the torque control of the speed-regulating motor:

给定。在P_M＜P′_G时，保持转矩控制方式，对比

与传感器检测到的w_b值，二者近似时调速电机切换为转速控制，按

给定。Introduce the rule reference quantity ΔP, when the condition P′ _G -ΔP<P _M <P′ _G +ΔP is satisfied, the ring gear 2-4 is locked, and the operation of the speed regulating motor 4 is stopped; when _PM ≥ P′ _G , Adjustable speed motor torque control, press

given. When P _M <P′ _G , keep the torque control mode, compare

When the value of w _b detected by the sensor is similar to that of the speed regulating motor, it switches to speed control, press

given.

The control method of the present invention is illustrated below in conjunction with Fig. 3:

1) When the wind speed is below the rated wind speed, the speed-regulating motor 4 is in an electric state, and the SVPWM speed-current double closed-loop method is used to control the speed through the frequency converter 5, so that the generator 3 can be closed and connected to the grid after reaching the grid-connected frequency.

2) After grid connection, the frequency of the generator 3 is consistent with the grid. At this time, the power of the generator and the speed-regulating motor is calculated in real time, and the reference speed of the speed-regulating motor is calculated by combining the power characteristic equation of the wind turbine to realize the maximum power tracking of wind energy.

3) When the wind speed is above the rated wind speed, the speed control is switched to torque control. The purpose is to realize the rated torque operation of the generator. Since the torque has a linear relationship with the quadrature axis current, this goal is achieved by controlling the quadrature axis current during specific operation. The speed-regulating motor is in the state of generating electricity under this wind condition.

4) When the rated wind speed is above and the output power of the wind turbine is less than the sum of the rated power of the generator and the rated power of the speed-regulating motor, the method described in 3) shall be adopted. When the output power of the wind turbine is greater than or equal to the rated power of the generator and the When the sum of the rated power is combined with the pitch control operation, the power of the wind turbine is limited.

The dual-rotor wind power generation system in the present invention uses the planetary gear as the core component to construct a three-port energy flow mode. The control method combines the characteristics of the direct drive type and the double-fed type variable speed constant frequency control idea, and has the following characteristics:

1) Since the power is distributed by dual motors, compared with the direct-drive wind power generation structure, the capacity of the generator body and the frequency converter are reduced, thereby reducing power loss.

2) The reasonable combination of generator and speed-regulating motor can effectively reduce the volume of a single motor under the same wind conditions.

3) In the present invention, when the system works in a sub-synchronous state, it needs to absorb energy from the grid, but this part of the energy plays an auxiliary role, and is finally fed back to the grid from the speed-regulating motor in the form of electrical energy-mechanical energy-electric energy.

In the control method of the present invention, when the input of the wind turbine exceeds the rated operating condition of the system, the dynamic effect of the system is improved by combining the pitch control to constrain the power, and through a smooth switching strategy.

Claims (3)

1. the control method of a dual-rotor structure variable-speed constant-frequency wind power generation system, described dual-rotor structure variable-speed constant-frequency wind power generation system comprises wind energy conversion system (1), gear drive, generator (3), buncher (4) and frequency converter (5),

Wind energy conversion system (1) is connected with the power shaft of generator (3) with buncher (4) respectively by gear drive, the electrical signal of buncher (4) connects the electric signal input end of frequency converter (5), and the electrical signal of frequency converter (5) is as the input of electrical network; The electrical signal of generator (3) is as the input of electrical network, generator (3) and the coaxial setting of buncher (4), and the stator (4-2) of the stator of generator (3-2) and buncher all is fixed on the housing,

The transmission velocity ratio scope of described gear drive is 2.8-13;

Described gear drive is divided into two kinds of forms:

First kind is: described gear drive is made up of sun gear (2-1), planet carrier (2-2), a plurality of planetary gear (2-3) and ring gear (2-4), a plurality of planetary gears (2-3) are positioned at ring gear (2-4), and planetary gear (2-3) distributes along the excircle direction of sun gear (2-1)

The output shaft of wind energy conversion system (1) connects the power shaft of planet carrier (2-2), planet carrier (2-2) is used for supporting all planetary gears (2-3), planetary gear (2-3) is meshed with sun gear (2-1) and ring gear (2-4) simultaneously, the axis of sun gear (2-1), planet carrier (2-2) and ring gear (2-4) coincides, the rotating shaft of sun gear (2-1) connects the rotating shaft of the rotor (3-1) of generator, is air gap between the stator (3-2) of the rotor of generator (3-1) and generator; Ring gear (2-4) is fixedlyed connected with the internal circular surfaces of the rotor (4-1) of buncher, is air gap between the stator (4-2) of the rotor of buncher (4-1) and buncher;

Second kind is: described gear drive is made up of sun gear (2-1), planet carrier (2-2), a plurality of planetary gear (2-3) and ring gear (2-4), a plurality of planetary gears (2-3) are positioned at ring gear (2-4), and planetary gear (2-3) distributes along the excircle direction of sun gear (2-1)

The output shaft of wind energy conversion system (1) drives ring gear (2-4) rotation synchronously, planetary gear (2-3) is meshed with sun gear (2-1) and ring gear (2-4) simultaneously, planet carrier (2-2) is used for supporting all planetary gears (2-3), planet carrier (2-2) is positioned at the rotor (4-1) of buncher, and with coaxial the fixedlying connected of rotor (4-1) of buncher, be air gap between the stator (4-2) of the rotor of buncher (4-1) and buncher; The rotating shaft of sun gear (2-1) connects the rotating shaft of the rotor (3-1) of generator, is air gap between the stator (3-2) of the rotor of generator (3-1) and generator;

The axis of sun gear (2-1), ring gear (2-4) and planet carrier (2-2) coincides;

It is characterized in that described control method is:

Wind energy conversion system (1) begins rotation when the wind speed of wind energy conversion system (1) environment of living in reaches its incision wind speed, the work of driven gear transmission mechanism, detect the wind speed of wind energy conversion system (1) environment of living in, when the wind speed of wind energy conversion system (1) environment of living in during less than its rated wind speed, control buncher (4) rotating speed makes generator (3) reach the frequency that is incorporated into the power networks, after generator (3) is incorporated into the power networks, change the rotating speed of buncher (4), and then change the rotating speed of wind energy conversion system (1) output shaft, to realize maximal power tracing control;

When the wind speed of wind energy conversion system (1) environment of living in during more than or equal to its rated wind speed, control buncher (4) is the torque state of a control, make the specified operation of generator (3), and buncher (4) is presented power output to electrical network by frequency converter (5).

2. the control method of dual-rotor structure variable-speed constant-frequency wind power generation system according to claim 1 is characterized in that, realizes in the described control method that the detailed process of maximal power tracing control is:

When the wind speed of wind energy conversion system (1) environment of living in reaches its incision wind speed, the output shaft of wind energy conversion system (1) drives generator (3) by gear drive and buncher (4) rotates, according to generator (3) number of pole-pairs P and mains frequency f, obtain the rotation speed n that is incorporated into the power networks synchronously of generator (3):

$n=\frac{60\&times;f}{P};$

Three rotation speed relation according to sun gear in the gear drive (2-1), planet carrier (2-2) and ring gear (2-4) obtain relational expression:

w _a+pw _b-(1+p)w _c＝0，

W in the formula _aBe the angular frequency of sun gear (2-1), p is the gear ratio of ring gear (2-4) and sun gear (2-1), w _bBe the angular frequency of ring gear (2-4), w _cBe the angular frequency of planet carrier (2-2),

By Obtain generator (3) and reach buncher tachometer value when being incorporated into the power networks rotating speed, this buncher tachometer value is the angular frequency w of ring gear (2-4) _b:

$w_b=\frac{(1+p)w_c-\frac{60f}{P}\&times;\frac{2\mathrm{\&pi;}}{60}}{p},$

Adopt SVPWM control buncher rotating speed, make generator (3) reach the frequency that is incorporated into the power networks;

After generator (3) is incorporated into the power networks, adopt based on the given maximal power tracing control of speed feedback best power, the active power P of calculating generator (3) output _EGAnd the active power P of buncher (4) output _EM:

P _eG＝u _Gdi _Gd+u _Gqi _Gq

P _eM＝u _Mdi _Md+u _Mqi _Mq，

U in the formula _GdBe generator direct-axis voltage, i _GdBe generator direct-axis current, u _GqBe generator quadrature-axis voltage, i _GqFor generator is handed over shaft current, u _MdBe buncher direct-axis voltage, i _MdBe buncher direct-axis current, u _MqBe buncher quadrature-axis voltage, i _MqFor buncher is handed over shaft current,

Active power P by generator (3) output _EGAnd the active power P of buncher (4) output _EMThe stator copper loss P of calculating generator (3) _GcuAnd the stator copper loss P of buncher (4) _Mcu:

$P_{\mathrm{Gcu}}=(i_{\mathrm{Gq}}^2+i_{\mathrm{Gd}}^2)R_{\mathrm{Gs}}$

$P_{\mathrm{Mcu}}=(i_{\mathrm{Mq}}^2+i_{\mathrm{Md}}^2)R_{\mathrm{Ms}},$

R in the formula _GsBe generator unit stator resistance, R _MsBe the buncher stator resistance,

Iron loss and the mechanical loss of ignoring generator (3) and buncher (4) are by generator (3) and the active power of buncher (4) output and the power output P of its stator copper loss calculating wind energy conversion system (1) _W:

P _W＝P _G-P _M＝P _eG+P _Gcu-(P _eM-P _Mcu)

＝(u _Gd+i _GdR _Gs)i _Gd+(u _Gq+i _GqR _Gs)i _Gq-[(u _Md+i _MdR _Ms)i _Md

-(u _Mq+i _MqR _Ms)i _Mq]

P _GBe generator power, P _MBe buncher power;

Wind energy conversion system (1) gas dynamic mode pattern is:

$P_W=\frac{1}{2}\mathrm{\&rho;\&pi;}{C}_P{R}^2{v}^3,$

ρ is atmospheric density, C _PBe power coefficient, R is the impeller radius of wind energy conversion system (1), and v is the wind speed of wind energy conversion system (1) environment of living in,

Tip speed ratio λ is: $\mathrm{\&lambda;}=\frac{w_{c}R}{v},$

Obtain the tachometer value w of buncher (4) in maximal power tracing control by above-mentioned formula _b:

$w_b=\frac{(1+p){(2P_W{\mathrm{\&lambda;}}^3/\mathrm{\&rho;\&pi;}{R}^5{C}_P)}^{1/3}-\frac{60f}{P}\&times;\frac{2\mathrm{\&pi;}}{60}}{p},$

Change the tachometer value w of buncher (4) in maximal power tracing control _b, and then the rotating speed of change wind energy conversion system (1) output shaft, realize maximal power tracing control thus.

3. the control method of dual-rotor structure variable-speed constant-frequency wind power generation system according to claim 2, it is characterized in that, in the described control method when the wind speed of wind energy conversion system (1) environment of living in during more than or equal to its rated wind speed, control buncher (4) is the torque state of a control, make the specified operation of generator (3), and the detailed process that buncher (4) is presented power output to electrical network by frequency converter (5) is:

This detailed process is divided into two power phase, i.e. first power phase and second power phase:

First power phase is: P ' _G＜P _W＜P ' _G+ P ' _M,

Second power phase is: P _W＞P ' _G+ P ' _M,

P ' wherein _GBe the rated power of generator (3), P ' _MRated power for buncher (4);

In first power phase, according to the three shaft torques relation of sun gear (2-1), planet carrier (2-2) and ring gear (2-4), control buncher (4) torque T _MFor:

$T_M=\frac{1}{p}\&times;{T^{\&prime;}}_G,$

T ' wherein _GBe the nominal torque of generator (3),

According to following formula, control buncher (4) torque T _MEven, the specified operation of generator (3), buncher (4) is presented power output to electrical network by frequency converter (5);

Second power phase adopts the power output of variable pitch performance constraint wind energy conversion system (1).

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