CN201045750Y - Outer rotor brushless doubly-fed generator and its control device - Google Patents

Abstract

An external rotor brushless double-fed generator and a control device thereof relate to a wind power generator. The utility model includes a generator main body, a stator, a rotor, fan blades, and a hub. The main body is provided with an outer rotor generator and an exciter. The rotors of the generator and the exciter are coaxially installed, and the generator and the exciter are arranged in an axial series structure; The control device is equipped with unit centralized control device, exciter AC excitation device, generator excitation device, generator speed sensor and fan brake controller; unit centralized control device is equipped with signal input port for sensor measurement; exciter AC excitation device The input side of the main circuit is connected to the output end of the generator stator, and the main circuit on the output side is connected to the stator winding of the exciter; the main circuit of the generator magnetic aid device is connected to the output end of the generator, and the output end of the generator is connected to the power grid. The utility model has the advantages of light weight, brushless, direct drive, no gear box, convenient adjustment of reactive power, low control cost, high safety, reliability and operating efficiency of the unit.

Description

Outer rotor brushless doubly-fed generator and its control device

technical field

The utility model relates to a wind power generator, in particular to a brushless double-fed generator with a variable-speed constant-frequency winding outer rotor and a control device thereof.

Background technique

Known technology doubly-fed induction generators, as variable-speed constant-frequency units, are widely used in hydropower stations, pumped storage power stations, especially in large-scale wind power generating units, because of the characteristics of variable-speed and constant-frequency operation of the units, the The energy conversion efficiency is greatly improved; and because the active power and reactive power of the generator set are regulated through the small power converter on the rotor side, the control characteristics and control cost of the unit are very satisfactory. Because the speed of large-scale MW-level wind turbines is very low, generally 15-35rpm, such a low speed will increase the number of pole pairs of the motor, and the geometric size and weight of the motor will greatly increase. The current method is to increase the speed through the speed-increasing gearbox, and the efficiency of the gearbox can reach 97%. Although the failure rate is relatively high, this method can choose a high-speed double-fed induction generator, generally a 4/6-pole motor, thereby reducing the need for motor manufacturing. and cost hassles. As the capacity of offshore wind farms increases, such as 3-5MW units, or even 10MW capacity units are under development. The reliability of this type of unit, mainly due to the downtime caused by slip ring and gearbox failure, has become a prominent problem. In consideration of the reliability of the wind turbine unit, the system conversion efficiency and the overall cost of the unit, the permanent magnet direct drive synchronous wind turbine The generator set came into being. Chinese patent CN200410003089.3 discloses a MW level direct drive permanent magnet external rotor synchronous wind generator, which adopts a multi-pole external rotor structure. The generator includes a fixed shaft, a rotating shaft, a coil winding, a permanent magnetic steel, an iron core, a stator and an outer rotor, wherein the rotating shaft is mounted on the fixed shaft through a bearing, the stator is mounted on the fixed shaft through a stator bracket, and the outer rotor passes through The rotor support is installed on the rotating shaft, and an axial cooling ventilation passage may be provided between the winding coil and the stator support; a protective cover is provided on the windward surface between the outer rotor and the stator. This unit removes the speed-up gearbox that loses system efficiency and frequent failures, does not have slip ring brushes that transmit large currents, uses permanent magnet materials for excitation, and reduces excitation losses. network, so as to realize the variable-speed and constant-frequency power generation of wind turbines. Due to its good reliability and high system efficiency, the permanent magnet direct-drive synchronous wind turbine has many advantages, such as low maintenance cost, although the unit cost is higher than the former. This model has technical defects such as large motor diameter, inconvenient installation and transportation, high cost of generator and full power converter, and inconvenient operation of generator for reactive power adjustment.

Contents of the invention

The problem to be solved by the utility model is to provide an outer rotor brushless doubly-fed generator and its control device by overcoming the above-mentioned defects in the patented technology.

One of the purposes of the utility model is to provide an outer rotor brushless double-fed generator;

The second purpose of this case is to provide a control device for an outer rotor brushless doubly-fed generator.

This case solves the technical problem of the external rotor brushless doubly-fed generator by adopting the following technical solutions:

According to the utility model, an outer rotor brushless double-fed generator is provided, which includes a generator main body, a stator, a rotor, fan blades, and a hub. The fan blades are installed on the hub, and in the generator main body, the rotor rotates relative to the stator. The fan blades drive the hub to drive the rotor to rotate, wherein the main body is equipped with an outer rotor generator and an exciter, the rotors of the generator and the exciter are installed coaxially, and the generator and the exciter are axially connected in series; the generator and the exciter Independent magnetic circuits, the number of pole pairs of the generator rotor winding is the same as the number of pole pairs of the generator stator winding, the number of pole pairs of the exciter rotor winding is the same as the number of pole pairs of the exciter stator winding; the generator stator winding is connected in parallel to the generator magnetic device .

In this case, the solution to the technical problems of the external rotor brushless doubly-fed generator can be further realized by the following technical measures:

The aforementioned outer rotor brushless double-fed generator, wherein the generator consists of a generator stator core, a generator stator winding installed in the iron core slot, a generator rotor iron core, and a power generator installed in the iron core slot. Composed of generator rotor windings, the generator rotor rotates around the generator stator outside the generator stator, and a generator air gap is set between the generator stator core and the generator rotor core; the generator magnetic assist device is installed on the inner stator output shaft in a cylindrical space.

The aforementioned outer rotor brushless double-fed generator, wherein the exciter consists of the exciter stator core, the exciter stator winding installed in the iron core slot, the exciter rotor iron core, the exciter installed in the iron core slot The exciter rotor is composed of the exciter rotor winding. The exciter rotor rotates around the exciter stator outside the exciter stator. An exciter air gap is set between the exciter stator core and the exciter rotor iron core. The exciter stator winding is connected with an excitation device; the excitation device Installed in the cylindrical space of the output shaft of the inner stator;

The stator core of the exciter and the stator core of the generator are installed on the outside of the stator shell of the exciter and the stator shell of the generator respectively, and the two shells are connected with the motor support plate to form a whole;

The exciter rotor core and the generator rotor core are installed in the same motor casing, and the two rotors are supported by the motor left bearing and the motor right bearing to rotate around the stator.

The aforementioned external rotor brushless doubly-fed generator, wherein, the generator rotor winding and the exciter rotor winding have a wire-wound wave winding structure and a star connection mode, and the exciter rotor winding is connected to the generator rotor winding through the rotor winding connecting wire. Phase sequence connection.

In the aforementioned external rotor brushless double-fed generator, the hub on which the fan blades are installed is equipped with a general-purpose pitch-variable mechanism. The adjustment of the wheel speed, the hub mounting plate is used to connect the hub with the output shaft of the motor.

The aforementioned outer rotor brushless double-fed generator, wherein the generator is provided with a motor tilting installation mechanism, the bottom of the motor casing is connected to the motor support plate, so that the motor is tilted by 5-10 degrees, so as to prevent the blades from scraping against the tower during operation, A yaw mechanism is installed between the base of the motor and the top of the tower.

The utility model solves the technical problem of the control device of the outer rotor brushless doubly-fed generator by adopting the following technical solutions:

A control device for an outer rotor brushless doubly-fed generator provided according to the utility model includes a unit centralized control device, the centralized control device is connected to a signal sensor, and is provided with a control signal output port, wherein: the control device is provided with a unit centralized control device , Exciter AC excitation device, generator magnetic assist device connected in parallel with generator stator winding, generator speed sensor and fan brake controller;

The centralized control device of the unit is provided with a signal input port for wind speed sensor measurement, a signal input port for wind direction sensor measurement, and an output signal port for remote communication with the host computer; the centralized control device of the unit is connected to the generator terminal voltage transformer to measure Get the generator terminal voltage value, connect with the generator output current transformer to measure the generator output current value; the unit centralized control device is connected with the excitation voltage transformer to measure the exciter excitation voltage value, and the excitation current mutual inductance connected to the generator to measure the excitation current value of the exciter; the centralized control device of the unit is connected to the generator speed sensor and the fan brake controller;

The input side of the main circuit of the AC excitation device of the exciter is connected to the inner side of the grid-connected switch at the output end of the generator stator through the excitation switch. The AC excitation device receives the control command of the centralized control device of the unit, and the main circuit of the output side is connected to the stator winding of the exciter;

The main circuit of the generator magnetic assisting device is connected to the output terminal of the generator, and accepts the control command of the centralized control device of the unit, and the output terminal of the generator is connected to the grid through a grid-connected switch and a step-up transformer.

In this case, the solution to the technical problem of the control device of the external rotor brushless doubly-fed generator can be further realized by the following technical measures:

The control device of the aforementioned outer rotor brushless doubly-fed generator, wherein the centralized control device of the unit is connected to control the yaw mechanism to make the wind rotor rotate in the upwind direction, and the centralized control device of the unit controls the pitch mechanism through a closed loop to maintain the rated wind speed of the wind rotor Operate at the best wind energy utilization rate below, and operate with the rated output power of the generator above the rated wind speed; the pitch change mechanism is connected with the speed measuring device, the pitch angle measuring device, the pitch servo mechanism, the servo motor, and the pitch control device.

The control device of the aforementioned outer rotor brushless doubly-fed generator, wherein the main circuit of the excitation device is composed of two sets of bidirectional rectification-inversion units; Part of the active energy, when the generator is running above the synchronous speed, the excitation device provides excitation current to the exciter stator, and part of the active energy is fed to the grid; the excitation device communicates with the centralized control device of the unit through the control loop.

The control device of the aforementioned outer rotor brushless doubly-fed generator, wherein the unit centralized control device is provided with a motor temperature rise monitoring port and a wind wheel braking signal output port; the generator magnetic assist device is provided with a capacitor, and the capacitor passes through Thyristor controls its input quantity, and the conduction control of the thyristor is completed by the centralized control device of the unit.

Compared with the prior art, the utility model has obvious advantages and beneficial effects. It can be seen from the above technical solutions that the utility model has at least the following advantages under the excellent structural configuration:

The utility model adopts the winding type external rotor brushless double-fed power generation technical scheme, and realizes the variable-speed and constant-frequency operation of the unit in the field of large-scale wind power generation. The variable current excitation device with rated capacity can conveniently adjust reactive power and other technical advantages. The utility model effectively simplifies the structure of the unit, reduces the diameter of the generator, reduces the weight of the unit, facilitates equipment transportation, reduces the cost of the control system, and improves the safety, reliability and operating efficiency of the unit. Compared with the prior art, the utility model has remarkable contribution and progress, and is indeed a good technology with novelty, creativity and practicality.

The specific embodiment of the utility model is given in detail by the following examples and accompanying drawings.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of the utility model;

Fig. 2 is a schematic block diagram of the structure of the working principle of the utility model;

Fig. 3 is a schematic block diagram of the hardware structure of the unit centralized control device of the utility model.

Detailed ways

Below in conjunction with the accompanying drawings and preferred embodiments, the specific implementation, structure, features and effects provided by the present utility model will be described in detail as follows.

As shown in Figure 1-3.

An external rotor brushless double-fed generator, including a generator main body, a stator, a rotor, a fan blade 2, and a hub 1, the fan blade 2 is installed on the hub 1, and in the generator main body, the rotor is configured to rotate relative to the stator, The fan blades 2 drive the hub 1 to drive the rotor to rotate. The outer rotor generator and exciter are installed in the main body. The generator and exciter rotors are installed axially. Independent magnetic circuit, the number of 15 pole pairs of the generator rotor winding is the same as the number of 14 pole pairs of the generator stator winding, and the number of 16 pole pairs of the exciter rotor winding is the same as the number of 7 pole pairs of the exciter stator winding.

Wound outer rotor brushless doubly-fed motor (WBDFG) structure:

WBDFG is compounded by two multi-pair-pole wound rotor motors. The P _P opposite-pole motor is a generator, and the P _C opposite-pole motor is an exciter. The pole-to-pole relationship between the two motors satisfies: P _P ≥ P _C . The generator and the exciter have independent iron core magnetic circuits and are installed in a shell. The rotors of the two motors are coaxially installed, and the windings are of a wire-wound wave winding structure. The wires are made of copper or aluminum. The rotors are multi-phase, preferably three-phase. The windings are all star-connected, and the outlet ends of the two rotor windings are connected in reverse phase sequence.

Outer rotor brushless double-fed generator outer rotor structure:

In order to utilize the internal space of the motor cylindrical motor output shaft 6, an outer rotor structure is adopted. As shown in the figure: the fan blade 2 is installed on the hub 1, and the hub 1 is provided with a general-purpose variable pitch mechanism 29. The pitch variable mechanism 29, under the control of the unit centralized control device 24, realizes Wind wheel speed adjustment. The hub mounting plate 3 is used to connect the hub 1 with the motor output shaft 6 .

The outer rotor WBDFG consists of an exciter and a generator axially connected in series. The exciter that doubles as power generation is composed of the exciter stator core 9, the exciter stator winding 7 installed in the iron core slot, the exciter rotor iron core 8, and the exciter rotor winding 16 installed in the iron core slot. The rotor of the exciter rotates around the exciter stator on the outside of the exciter stator. An exciter air gap 12 is set between the exciter stator core 9 and the exciter rotor iron core 8. The exciter stator winding 7 is connected with the excitation device 23. The exciter rotor The winding 16 is connected with the rotor winding 15 of the generator in anti-phase sequence through the connecting wire 13 of the rotor winding. The generator consists of a generator stator core 11, a generator stator winding 14 installed in the core slot, a generator rotor core 10, and a generator rotor winding 15 installed in the iron core slot. The outside of the generator stator rotates around the generator stator. A generator air gap 17 is provided between the generator stator iron core 11 and the generator rotor iron core 10 . The generator stator winding 14 is connected in parallel with the generator magnetic assisting device 22 .

The exciter stator core 9 and the generator stator core 11 are respectively installed on the outer sides of the exciter stator casing 32 and the generator stator casing 33 with different diameters. The right shaft end support plate 30 of the motor is connected as a whole, and is annularly connected with the nacelle rear cover 20 and the motor installation support plate 27 .

The exciter rotor core 8 and the generator rotor core 10 are installed in the same motor casing 28, the motor casing 28 is respectively connected with the motor left end cover 18 and the motor right end cover 5, and the two end covers pass through the motor left bearing 19 and the motor right bearing 4 Support the two rotors to rotate around the stator.

The bottom of the motor casing 28 is connected with the motor support plate 27 to make the motor tilt 5-10 degrees, so as to prevent the blade from scraping against the tower tube 26 during operation, and a yaw mechanism 25 is installed between the motor base and the tower tube top.

The generator magnetic assisting device 22 is installed in the cylindrical space of the inner stator output shaft, and connected in parallel with the generator stator winding 14, and the excitation device 23 is installed in the cylindrical space of the inner stator output shaft, and is connected with the exciter stator winding 7, The unit centralized control device 24 is installed in the cylindrical space of the output shaft of the inner stator, and is connected with relevant components inside and outside the unit.

A control device for an outer rotor brushless doubly-fed generator, comprising a unit centralized control device connected to a signal sensor and provided with a control signal output port, wherein the control device is provided with a unit integrated control device 24, an exciter AC excitation Device 23, generator magnetic aid device 22, wind speed and wind direction measuring device, generator speed sensor and fan brake controller;

The unit centralized control device 24 is provided with a signal input port D1 for wind speed sensor measurement, a signal input port D2 for wind direction sensor measurement, and an output signal port D3 for remote communication with the host computer; the unit centralized control device 24 and the generator terminal voltage mutual induction connected to the generator T2 to measure the generator terminal voltage value, and connected to the generator output current transformer T3 to measure the generator output current value; the unit centralized control device 24 is connected to the excitation voltage transformer T5 to measure the excitation voltage Machine excitation voltage value is connected with excitation current transformer T4 to measure the excitation current value of exciter; unit centralized control device 24 is connected with generator speed sensor and fan brake controller;

The input side of the main circuit of the AC excitation device 23 of the exciter is connected to the inner side of the grid-connected switch at the output end of the generator stator through the excitation switch K2. winding connection;

The main circuit of the generator magnetic aid device 22 is connected to the output end of the generator, and receives the control command of the unit centralized control device 24, and the output end of the generator is connected to the grid through the grid-connected switch K1 and the step-up transformer T1.

Structure of WBDFG control device for WBDFG external rotor brushless doubly-fed motor:

The WBDFG control device includes unit centralized control device, exciter AC excitation device, generator magnetic assist device, yaw controller, pitch controller, wind speed and direction measurement device, generator speed sensor, fan brake controller, etc.

The unit centralized control device 24 is equipped with a control unit 24-1, a touch screen 24-2, an upper remote central control computer 24-3, an automatic synchronization device 24-4, an adapter unit 24-5 at the generator side, and an adapter unit at the exciter side. Unit 24-6, protection control unit 24-7. The control unit 24-1 is provided with signal input ports of wind speed, wind direction, rotational speed, and motor temperature rise, and signal output ports of switch K1, switch K2, yaw control, pitch adjustment, uncable output, and wind wheel brake switch.

The unit centralized control device 24 is provided with a signal input port D1 for wind speed sensor measurement, a signal input port D2 for wind direction sensor measurement, an output signal port D3 for remote communication with the host computer, a motor temperature rise monitoring port, and a wind wheel Brake signal output port.

The unit centralized control device 24 is connected to the voltage transformer T2 to measure the generator terminal voltage value, and is connected to the current transformer T3 to measure the generator output current value.

The unit centralized control device 24 is connected with the voltage transformer T5 to measure the excitation voltage value of the exciter, and connected with the current transformer T4 to measure the excitation current value of the exciter. The input side of the main circuit of the AC excitation device 23 is connected to the inner side of the grid-connected switch at the output end of the generator stator through the excitation switch K2. connection, the main circuit of the excitation device 23 is composed of two sets of bidirectional PWM rectifier-inverter units Q1 and Q2. When WBDFG runs below the synchronous speed, Q1PWM rectifies and Q2PWM inverts, and the excitation device 23 provides excitation current and part of active energy to the exciter stator. While the exciter stator provides excitation current, some active energy is fed to the grid. The excitation device 23 communicates with the unit centralized control device 24 through a control loop.

The main circuit of the generator magnetic assisting device 22 is connected to the output end of the generator, and receives control instructions from the unit centralized control device 24 . The generator magnetic aid device 22 is composed of n+1 capacitors, and its input quantity is controlled by the thyristor. The conduction control of the thyristor is completed by the centralized control device 24 of the generator set. The voltage transformer 690/110000V TI is connected to the power grid.

The unit centralized control device 24 controls the WBDFG through the yaw mechanism 25 to rotate the wind rotor in the upwind direction. The unit centralized control device 24 controls the pitch mechanism 29 through the idle loop to keep the wind rotor running at the best wind energy utilization rate below the rated wind speed. The above operates at the rated output power of the generator. The pitch change mechanism 29 is composed of a rotational speed measurement mechanism G1, a pitch angle measurement mechanism G2, a pitch change servo mechanism G3, a servo motor M1, and a pitch change control device G4.

The electrical control method of the wire-wound brushless doubly-fed motor WBDFG is as follows:

The excitation system of WBDFG is composed of the AC excitation device 23 and the generator excitation device 22. Under the control of the unit centralized control device 24, the excitation and boosting of the generator, grid-connected power generation and reactive power regulation are completed.

Excitation control: When the wind turbine is below the rated speed, the WBDFG is driven to rotate at a certain speed, the generator is in a state of disconnection from the power grid, the exciter is ready to start excitation, and the generator magnetic assist device 22 is adjusted by the centralized control device 24 of the generator to make The voltage of the generator gradually builds up, and the output voltage of the generator is measured by the unit centralized control device 24 through T2. When the no-load output voltage of the generator reaches 30%-60% of the rated output voltage, the unit centralized control device 24 makes K2 close, and the exciter The AC excitation device 23 is activated, and the unit centralized control device 24 adjusts the AC excitation device 23 so that the voltage of the generator reaches the rated output value and the frequency of the generator meets the requirements for grid connection, and prepares for grid connection.

Grid-connected control: the unit centralized control device 24 measures the voltage, phase sequence, and frequency on both sides of K1 through T2 and T6, and the wind turbine speed through G. The control device 24 adjusts the amplitude and frequency of the voltage of the AC excitation device 23, and tracks the data measured on the power grid side and the wind turbine speed. After consistency, the synchronous device built in the unit centralized control device 24 sends out a signal to make the generator grid-connected switch K1 automatically close to complete the grid-connected.

Variable speed and constant frequency characteristic control: The current national standard stipulates that the output voltage frequency range of wind turbines is: 47.5Hz-51Hz. No matter how the generator speed changes, if the stator voltage frequency meets the frequency range specified by the national standard and is the same as the grid frequency, the wind turbine will realize variable speed and constant frequency operation. The specific control process is as follows:

As the wind speed changes, the unit centralized control device 24 adjusts the pitch angle of the wind turbine blades 2 by controlling the pitch mechanism 29 in a well-known manner, thereby adjusting the mechanical speed ω _r of the generator. The AC excitation device 23 feeds the AC excitation current frequency f _C through the exciter stator winding 7, and the rotating magnetic field at this frequency generates an induced current in the exciter rotor winding 16 with a frequency S _C f _C , and the rotor current passes through the exciter rotor The generator rotor winding 15 connected with the winding 16 in anti-phase sequence forms the excitation field of the generator stator winding 14, and the mechanical rotation speed of the excitation field relative to the generator rotor is ${\mathrm{\ω}}_2=\frac{2\mathrm{\π}60S_C{f}_C}{P_P},$ The generator stator voltage frequency is the grid frequency f ₁ , and the rotation speed of the magnetic field at this frequency is ${\mathrm{\ω}}_1=\frac{2\mathrm{\π}60f_1}{P_P}.$ When working synchronously, the sum or difference of the mechanical angular velocity of the generator rotor and the angular velocity of the synchronous rotation of the excitation field relative to it is always synchronous with the angular velocity of the stator magnetic field synchronous rotation. The relationship between the three is expressed by the following formula.

ω ₁ = ω _r ± ω ₂ or ${\mathrm{\ω}}_1=\frac{2\mathrm{\π}60f_1}{P_P}={\mathrm{\ω}}_r\±\frac{2\mathrm{\π}60S_C{f}_C}{P_P}$

In the formula: when the generator speed is lower than the synchronous speed of WBDFG, take the "+" sign

When the generator speed is higher than the synchronous speed of WBDFG, take "-" sign

Therefore, with the generator stator output voltage frequency f ₁ as the target, the variable speed constant frequency characteristic control of WBDFG can be realized by adjusting the wind turbine speed, that is, the generator speed ω _r and the exciter stator excitation current frequency f _C to form a closed-loop control.

Active power control:

The speed of WBDFG can also be expressed as:

general representation $N=\frac{60(50\±f_C)}{P_P+P_C}$ synchronous speed $N_0=\frac{60\×50}{P_P+P_C}$ f _C =0

Among them, N: wind turbine speed, that is, generator speed f _C : exciter stator excitation current frequency

In this relationship, when N<N ₀ , the AC excitation device 23 provides the excitation current to the stator winding 7 of the exciter, and at the same time feeds in the active power of the slip capacity, which feeds in the phase sequence of the excitation current to make the exciter rotor The steering is opposite to that of the generator, and the above expression takes the sign "-". When N>N ₀ , the AC excitation device 23 supplies the excitation current to the stator winding 7 of the exciter, and also feeds the active power of the slip capacity to the grid , which feeds the phase sequence of the excitation current to make the exciter rotor turn the same as the generator turn, and the above expression takes the "+" sign. In the above-mentioned variable speed constant frequency characteristic control method, the generator speed is adjusted in stages according to different laws to realize the active power control of the unit. After the WBDFG is connected to the grid, when the wind turbine is running below the rated wind speed, the unit centralized control device 24 adjusts the pitch angle of the wind turbine blade 2 in a well-known manner by controlling the pitch change mechanism 29 so that the speed of the wind turbine is maximized by the wind energy utilization coefficient Mode operation, this stage is the stage of maximizing the utilization rate of wind energy. At this stage, when the generator speed is lower than the synchronous speed, the "-" range is taken. In this speed range, the exciter provides excitation and also needs to absorb active power from the grid with a capacity equal to the slip power of the generator. This part of active power is passed through The exciter stator winding 7, the exciter rotor winding 16, the generator rotor winding 15 and the generator stator winding 14 are output. This part of the active power does not contribute to the grid and has a certain internal loss. The efficiency of the WBDFG generator in this range is the lowest. When the generator works at synchronous speed, that is, f _C =0 state, the exciter only inputs the excitation power, and the generator outputs active power alone. At this moment, the efficiency of the WBDFG generator is relatively high. When the generator speed is higher than the synchronous speed, take the "+" interval. In this interval, while the exciter provides excitation, there is also active power equal to the slip power of the generator from the generator rotor winding 15, exciter rotor winding 16, Feed into the grid through the stator winding 7 of the exciter, and both sides of the generator and the exciter contribute active power to the grid at the same time in this section, which is the so-called double-fed power generation. The efficiency of the WBDFG generator in this section is very high. When the wind turbine is running at the rated wind speed and above, the unit centralized control device 24 adjusts the pitch angle of the wind turbine blade 2 in a well-known manner by controlling the pitch change mechanism 29 to make the speed of the wind turbine basically constant, and the WBDFG operates in the rated power output mode. This stage is the constant power output stage. In the constant power output stage, WBDFG is double-fed power generation, and the efficiency of the generator is the highest.

Voltage and reactive power control: WBDFG can be connected to the grid at different speeds. Before grid connection, when the frequency and phase sequence meet the requirements, the generator magnetic assist device 22 is adjusted by the unit centralized control device 24 to gradually build up the voltage of the generator , the unit centralized control device 24 measures the output voltage of the generator through T2, when the no-load output voltage of the generator reaches 30%-60% of the rated output voltage, the unit centralized control device 24 adjusts the magnitude of the excitation device 23 AC excitation current, Thereby adjusting the level of generator output voltage. After the generator is connected to the grid, the unit centralized control device 24 adjusts the excitation device 23 and the generator magnetic assist device 22 to make the power factor of the WBDFG feeding power to the grid meet the national standard, cos=±0.975. The utility model utilizes the organic combination of the AC excitation device on the exciter side and the auxiliary excitation device on the generator side, and completes the reactive power control meeting the national standard requirements under the adjustment of the unit centralized control device according to the operation requirements of the wind farm.

The above is only a preferred embodiment of the utility model, and does not limit the utility model in any form. Any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the utility model, All still belong to within the scope of the technical solution of the utility model.

Claims (10)

1. A brushless doubly-fed generator with an outer rotor, comprising a generator main body, a stator, a rotor, fan blades (2), and a hub (1), where the fan blades (2) are installed on the hub (1), and on the generator main body Inside, the structure of the rotor rotating relative to the stator is set, and the fan blades (2) drive the hub (1) to drive the rotor to rotate. It is characterized in that: an outer rotor generator and an exciter are arranged in the main body, and the rotor of the generator and the exciter is installed coaxially. The generator and the exciter are axially connected in series; the generator and the exciter have independent magnetic circuits, the number of pole pairs of the generator rotor winding (15) is the same as that of the generator stator winding (14), and the number of pole pairs of the exciter rotor winding (16 ) pole pair number is the same as the exciter stator winding (7) pole pair number; the generator stator winding (14) is connected in parallel with the generator magnetic assisting device (22). 2. The outer rotor brushless doubly-fed generator as claimed in claim 1, characterized in that: the generator consists of a generator stator iron core (11), a generator stator winding (14) contained in the iron core slot, Generator rotor iron core (10), generator rotor winding (15) installed in the iron core slot, the generator rotor rotates around the generator stator outside the generator stator, generator stator iron core (11) and power generation A generator air gap (17) is arranged between the rotor iron cores (10) of the generator; the generator magnetic assisting device (22) is installed in the cylindrical space of the output shaft of the inner stator. 3. The outer rotor brushless doubly-fed generator as claimed in claim 1 or 2, characterized in that: the exciter consists of an exciter stator core (9), an exciter stator winding (7) contained in the iron core slot ), the exciter rotor core (8), and the exciter rotor winding (16) installed in the iron core slot, the exciter rotor rotates around the exciter stator outside the exciter stator, and the exciter stator core (9) An exciter air gap (12) is provided between the exciter rotor core (8), and an excitation device (23) is connected to the exciter stator winding (7); the excitation device (23) is installed on the cylindrical output shaft of the inner stator in space; The exciter stator core (9) and the generator stator core (11) are installed on the outside of the exciter stator shell (32) and the generator stator shell (33) respectively, and the two shells are connected with the motor support plate to form a whole; The exciter rotor iron core (8) and the generator rotor iron core (10) are installed in the same motor casing (28), and the two rotors are supported to rotate around the stator by the motor left bearing (19) and the motor right bearing (4). 4. The outer rotor brushless doubly-fed generator as claimed in claim 3, characterized in that: generator rotor winding (15) and exciter rotor winding (16) are wire-wound wave winding structure, star connection mode, The exciter rotor winding (16) is connected to the generator rotor winding (15) in anti-phase sequence through the rotor winding connection line (13). 5. The outer rotor brushless doubly-fed generator as claimed in claim 4, characterized in that: the hub (1) on which the fan blade (2) is installed is provided with a general pitch-changing mechanism (29), and the pitch-changing mechanism ( 29) Under the control of the unit centralized control device (24), by changing the pitch angle of the blade (2), the adjustment of the wind rotor speed is realized, and the hub mounting plate (3) is used to connect the hub (1) to the motor output shaft ( 6) Connect. 6. The outer rotor brushless doubly-fed generator as claimed in claim 1, characterized in that: the generator is provided with a tilting installation mechanism, and the bottom of the motor casing (28) is connected with the motor support plate (27), so that the motor is tilted 5- 10 degrees, a yaw mechanism (25) is installed between the motor base and the tower top. 7. A control device for an external rotor brushless doubly-fed generator, comprising a unit centralized control device connected to a signal sensor and provided with a control signal output port, characterized in that the control device is provided with a unit centralized control device (24 ), an exciter AC excitation device (23), a generator magnetic assist device (22) connected in parallel with the generator stator winding (14), a generator speed sensor and a fan brake controller; The unit centralized control device (24) is provided with a signal input port (D1) for wind speed sensor measurement, a signal input port (D2) for wind direction sensor measurement, and an output signal port (D3) for remote communication with the host computer; the unit centralized control device (24) Connect with generator terminal voltage transformer (T2) to measure generator terminal voltage value, connect with generator output current transformer (T3) to measure generator output current value; unit centralized control The device (24) is connected with the excitation voltage transformer (T5) to measure the value of the excitation voltage of the exciter, and connected with the excitation current transformer (T4) to measure the value of the excitation current of the exciter; the unit centralized control device (24) is connected to Generator speed sensor and fan brake controller; The input side of the main circuit of the AC excitation device (23) of the exciter is connected to the inner side of the grid-connected switch at the output end of the generator stator through the excitation switch (K2). The main circuit on the output side is connected to the stator winding of the exciter; The main circuit of the generator magnetic aid device (22) is connected to the output end of the generator, and accepts the control command of the unit centralized control device (24), and the output end of the generator is connected to the power grid connect. 8. The control device of the outer rotor brushless doubly-fed generator as claimed in claim 7, characterized in that: the unit centralized control device (24) is connected to control the yaw mechanism (25), so that the wind rotor rotates in the upwind direction, and the unit gathers The control device (24) maintains the operation of the wind rotor with the best wind energy utilization rate below the rated wind speed and the rated output power of the generator above the rated wind speed through the closed-loop control of the pitch mechanism (29); the pitch mechanism (29) is connected to the rotating speed Measuring device (G1), pitch angle measuring device (G2), pitch servo mechanism (G3), servo motor (M1), and pitch control device (G4). 9. The control device of the outer rotor brushless doubly-fed generator as claimed in claim 7 or 8, characterized in that: the main circuit of the excitation device (23) is made up of two groups of bidirectional rectification-inverting units; During the following operation, the excitation device (23) provides excitation current and part of the active energy to the exciter stator. The quantity is fed to the grid; the excitation device (23) communicates with the unit centralized control device (24) through a control loop. 10. The control device of the outer rotor brushless doubly-fed generator as claimed in claim 9, characterized in that: the unit centralized control device (24) is provided with a motor temperature rise monitoring port and a wind wheel brake signal output port The generator magnetic aiding device (22) is provided with a capacitor, and the capacitor controls its input quantity through the thyristor, and the conduction control of the thyristor is completed by the unit centralized control device (24).

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