CN201213248Y - Continuously variable speed constant frequency operation wind turbine - Google Patents

Abstract

The continuously variable speed and constant frequency operation of the wind turbine can realize the real variable speed and constant frequency operation, which can significantly improve the reliability of the system, the operating efficiency and the utilization efficiency of wind energy. The speed regulation part of the hybrid continuously variable speed wind power generation system; the electric transmission includes a stator (3.1), an outer rotor (3.2), an inner rotor (3.3), and a slip ring (3.4). The ring (3.4) and brushes are connected to the first power converter (5); multi-phase windings are also arranged on the stator (3.1) and connected to the second power converter (6); the electric transmission (3) has two shafts , the shaft on one side is the input shaft, which connects the mechanical speed increaser (2) and the outer rotor (3.2) of the electric transmission; the other side shaft is the output shaft, which connects the inner rotor of the transmission and the generator (4); the first power converter ( 5). The second power converter (6) is connected to the same DC power supply (E).

Description

Continuously variable speed constant frequency operation wind turbine

technical field

The utility model is a device for wind power generation, which belongs to the technical field of wind power generator manufacturing.

Background technique

As the whole society continues to pay attention to energy and environmental issues, the development and utilization of renewable energy is showing a trend of accelerated development. Wind energy exists widely on the earth and is currently one of the most mature renewable energy sources that people have mastered. A wind turbine is a device that converts mechanical energy into electrical energy in a wind power generation system. It is a tool that connects the prime mover with the output electrical energy. It not only directly affects the quality and efficiency of the output electrical energy, but also affects the performance and system of the entire wind power conversion system. Structure. Since wind energy is an energy source with low energy density, wind turbines driven by wind energy work at relatively low rotational speeds (tens of revolutions per minute). Looking at the wind power generation systems that have been put into operation and are being developed at home and abroad, they can basically be classified into two categories. The first type of wind power generation system uses a mechanical speed-up gear between the wind turbine and the generator, but the multi-stage speed-up gear is not only bulky and heavy, but also has poor reliability and requires frequent maintenance. It is the weakest link in the wind power generation system; The second type is a direct drive wind turbine, which eliminates the speed-up gear, so it has the advantages of high efficiency, fast dynamic response, and low maintenance costs. However, since the direct drive generator works at a low speed of tens of revolutions per minute, in order to ensure that its output voltage is within the normal frequency range (30-80Hz), the generator needs to adopt a larger diameter of the stator and rotor and more poles. The logarithm increases the difficulty in the design and manufacture of the generator. On the other hand, wind energy has randomness, fluctuating from big to small. In the current wind power generation system, when the wind speed is lower than the rated wind speed, the wind rotor can absorb wind energy to the maximum extent, and when the wind speed is higher than a certain limit, in order to maintain power generation The output frequency of the machine is basically constant, and the wind wheel is stalled by adjusting the pitch of the blades, so that the wind energy cannot be fully utilized. In order to solve the above problems, in 2007, a new type of wind power generation system with electric continuously variable transmission as the intermediate link - electric continuously variable speed dual power flow wind power generation system was proposed, and patents for invention and utility model were applied for. This system not only cancels the multi-stage speed-up gear, but also adopts the conventional electric excitation generator, and makes the generator work at a constant speed to realize the real variable-speed and constant-frequency operation. However, when the wind speed is low and the variable speed is large, the efficiency of the electrical transmission is significantly reduced, resulting in a reduction in the utilization efficiency of the entire wind power generation system. Therefore, it has been a long-term pursuit of technicians in this field to develop new power generation systems suitable for efficient conversion of wind energy, reliable operation, high efficiency, convenient control and good power supply performance.

Contents of the invention

Technical problem: The purpose of this utility model is to propose a continuously variable speed and constant frequency operation wind power generator on the basis of the electric stepless variable speed dual power flow wind power generation system, so as to realize the real variable speed and constant frequency operation, which can significantly improve the reliability of the system Performance, operating efficiency and utilization efficiency of wind energy can significantly improve the working point of the electric transmission, operating efficiency and the efficiency of the entire system.

Technical solution: The wind power generator with stepless variable speed and constant frequency operation of the utility model, a mechanical speed increaser, an electrical transmission, a generator, a first power converter, and a second power converter; wherein: the mechanical speed increaser and the electrical transmission constitute The speed regulation part of the electromechanical hybrid continuously variable speed wind power generation system; the electric transmission includes a stator, an outer rotor, an inner rotor, and a slip ring, and a multi-phase winding is arranged on the inner rotor, which is connected to the first power conversion through a slip ring and a brush. Multi-phase windings are also set on the stator and connected to the second power converter; the electric transmission has two shafts, one shaft is the input shaft, which connects the mechanical speed increaser and the outer rotor of the electric transmission; the other shaft is the output The shaft connects the inner rotor of the transmission and the generator; the first power converter and the second power converter are connected to the same DC power supply. Depending on the type of motor used, the outer rotor structure is a cage rotor, permanent magnet rotor or other types. The DC power supply is composed of batteries or capacitors.

When working, the wind turbine drives the low-speed end of the mechanical speed increaser to rotate at an angular velocity ω _w , and drives the outer rotor of the electric transmission to rotate at an angular velocity ω _o after being accelerated by the first-stage mechanical speed increaser. When current is passed into the inner rotor winding and the stator winding, electromagnetic torque will be generated on the inner rotor through electromagnetic coupling, which will drive the inner rotor to rotate at an angular velocity ω _g , thereby driving the generator rotor to rotate and generate electricity. The mechanical power converted from the wind turbine will be divided into two parts, one part is in the form of mechanical power, which is directly transmitted from the outer rotor to the inner rotor through the medium of electromagnetic field, which is called mechanical power flow; the other part is in the form of electrical power, From the stator winding, power converter 6, power converter 5, slip rings and brushes, to the inner rotor winding, it is called electric power flow. The ratio of the two power flows is determined by the speed ratio of the inner and outer rotors. If various losses are ignored, the input power of the transmission (wind turbine power) should be equal to the output power (namely, the input power of the generator).

If the DC power supply is composed of an energy storage unit (battery, capacitor, etc.), part of the input power can be stored in the form of electric energy, or the energy in the energy storage unit can be released to the output shaft. When the power of the wind turbine is greater than the power of the generator, the excess energy can be converted into electrical energy and stored; on the contrary, when the power of the wind turbine is less than the power of the generator, the energy in the energy storage unit can be released to supplement the lack of input power .

By controlling the magnitude and frequency of the current applied to the stator winding and inner rotor winding of the electric transmission, the speed of the generator can be adjusted steplessly, so that the speed of the generator does not change with the change of the wind speed, and the variable wind speed and constant frequency output can be realized.

Beneficial effects: the utility model proposes a stepless variable speed constant frequency operating wind power generator on the basis of the electrical stepless variable speed dual power flow wind power generation system. It not only increases the reliability of the system, improves the working point of the electric transmission, but also retains the advantages of the electric stepless variable speed dual power flow wind power generation system, realizes the real variable speed and constant frequency operation, and can significantly improve the reliability and operating efficiency of the system and wind energy efficiency. Due to the one-stage mechanical speed increase, the speed increase ratio of the electric transmission does not need to be too large, which can significantly improve the working point, operating efficiency and the efficiency of the entire system of the electric transmission. details as follows:

1. The input speed of the electric transmission is increased by adopting the first-stage mechanical speed increaser to increase the speed ratio, and the speed ratio of the inner and outer rotors of the electric transmission is reduced, and the working point and operating efficiency of the electric transmission are improved.

2. Due to the existence of the mechanical speed increaser, the wind energy is buffered, the electrical transmission is protected, and the reliability of the system is improved. At the same time, the one-stage mechanical speed increaser has higher mechanical strength, good reliability and high efficiency than the multi-stage mechanical speed increaser.

3. No matter how the wind speed changes, through the electromechanical hybrid variable speed system, the generator can work at the rated speed to achieve variable speed and constant frequency operation.

4. Electric energy can be generated by a conventional electric excitation generator without power electronic devices, no harmonics, and good power quality.

5. It has dual power flow of mechanical power and electric power, which can store excess wind energy and release it to drive the generator when necessary, with high wind energy utilization efficiency.

6. The electromechanical hybrid transmission system can be used as a starter motor, and can also brake the wind wheel.

Description of drawings

Figure 1 is a schematic diagram of the composition of the power generation system, which includes: wind turbine 1, mechanical speed increaser 2, electrical transmission 3, stator 3.1, outer rotor 3.2, inner rotor 3.3, slip ring 3.4, main generator 4, the first A power converter 5 , a second power converter 6 , and a third power converter 7 .

Fig. 2 is a specific implementation scheme of a wind power generator with continuously variable speed and constant frequency operation based on a mechanical speed increaser and a permanent magnet electric transmission.

Detailed ways

The wind power generator with stepless variable speed and constant frequency operation of the utility model includes a wind turbine 1, a mechanical speed increaser 2, an electric transmission 3, a generator 4, a first power converter 5, and a second power converter 6; wherein: the mechanical speed booster The transmission 2 and the electric transmission 3 constitute the speed regulation part of the electromechanical hybrid continuously variable speed wind power generation system; the electric transmission 3 includes a stator 3.1, an outer rotor 3.2, an inner rotor 3.3, and a slip ring 3.4, and the inner rotor 3.3 is provided with multi-phase The winding is connected to the first power converter 5 through the slip ring 3.4 and the brush; the stator 3.1 is also provided with a multi-phase winding, and is connected to the second power converter 6; the electric transmission 3 has two shafts, and one shaft is the input The shaft is connected to the mechanical speed increaser 2 and the outer rotor 3.2 of the electric transmission; the other side shaft is the output shaft, connected to the inner rotor 3.3 of the transmission and the generator 4; the first power converter 5 and the second power converter 6 are connected to the same DC power supply E. The structure of the outer rotor 3.2 is cage-type rotor, permanent magnet rotor or other types according to the type of motor used. The DC power supply E is constituted by a storage battery or a capacitor.

Take an electromechanical hybrid wind power generation system based on a mechanical speed increaser and a permanent magnet electric transmission as an example, as shown in Figure 2. The speed of the wind turbine is increased through a first-stage mechanical speed increaser, and the outer rotor of the electric transmission is connected with the mechanical speed increaser. The outer rotor is installed on a hollow skeleton, and the hollow skeleton is installed on the input shaft through bearings. The inner and outer surfaces of the outer rotor are respectively embedded with permanent magnets, and the stator is embedded with three-phase symmetrical windings, which are connected to the power converter 1. The inner rotor is installed on the output shaft, and its surface is embedded with three-phase symmetrical windings. It is connected with the brush and the power converter 2, and the output shaft is directly connected with the generator shaft. The main generator adopts a conventional three-phase synchronous electric excitation generator, and the excitation current is supplied by a DC chopper circuit.

The utility model is characterized in that a mechanical speed increaser and an electric speed changer are used for speed regulation. First, the first-level mechanical speed increaser is used to increase the speed, buffer the wind energy, protect the electric continuously variable transmission, improve the reliability of the system and the working efficiency of the electric transmission; second, use the electric transmission to realize stepless speed regulation, so that the power generation Third, because the electric transmission has two power flows, it can store the excess wind energy in energy storage components such as capacitors or batteries, and release it when necessary to supplement the insufficient wind energy. , which can significantly improve the utilization efficiency of wind energy.

Claims (3)

1. A continuously variable speed constant frequency running wind generator is characterized in that the device comprises a wind turbine (1), a mechanical speed increaser (2), an electric transmission (3), a generator (4), a first power conversion (5), the second power converter (6), and the third power converter (7); wherein: the mechanical speed increaser (2) and the electrical transmission (3) constitute the electromechanical hybrid continuously variable speed wind power generation system The speed regulating part; the electric transmission (3) includes a stator (3.1), an outer rotor (3.2), an inner rotor (3.3), and a slip ring (3.4). ) and brushes are connected to the first power converter (5); multi-phase windings are also set on the stator (3.1) and connected to the second power converter (6); the electric transmission (3) has two shafts, one side The shaft is an input shaft, which is connected to the mechanical speed increaser (2) and the outer rotor (3.2) of the electric transmission; the other side shaft is an output shaft, which is connected to the inner rotor (3.3) of the transmission and the generator (4); the first power converter ( 5). The second power converter (6) is connected to the same DC power supply (E). 2. The continuously variable speed constant frequency wind power generator according to claim 1, characterized in that the structure of the outer rotor (3.2) is a cage rotor or a permanent magnet rotor according to the type of motor used. 3. The wind power generator with continuously variable speed and constant frequency operation according to claim 1, characterized in that the DC power supply (E) is formed by a storage battery or a capacitor.

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