CN102913399A - Plasma flow control method for reducing the wake loss of a wind turbine - Google Patents

Abstract

A plasma flow control method to reduce the wake loss of wind turbines: asymmetrically arrange two metal electrodes on both sides of the insulating material, one of which is exposed in the air, and the other metal electrode is embedded in the insulating material, forming a A set of plasma exciters, which are installed at the trailing edge of the suction surface of the wind turbine blades, in such a way that the induced flow direction of the plasma is the same as the main flow direction; plasma exciters are applied to the two metal electrodes of the plasma exciter The excitation voltage generates a weakly ionized low-temperature plasma above the metal electrode embedded in the insulating material, and transmits energy to the boundary layer through the collision of ions and neutral gas molecules, so that the surrounding air forms a horizontal jet with a static flow of zero and accelerates the surrounding air. Air flow within the facing. The invention can reduce the wake loss of the wind turbine, reduce the interference of the wake to the downstream wind turbine, and improve the total output power of the whole wind farm.

Description

A Plasma Flow Control Method to Reduce Wind Turbine Wake Loss

technical field

The invention relates to the field of energy technology and is used in the wind power generation industry, in particular to a new method for reducing the wake loss of a wind turbine and improving the power generation efficiency of a wind turbine, and more specifically to a plasma flow for reducing the wake loss of a wind turbine Control Method.

technical background

Energy is an important material foundation of the national economy and a basic condition for human survival. The speed of national economic development and the improvement of people's living standards all depend on the amount of energy provided. The gradual depletion of traditional fossil energy and the pollution of the environment have made the energy crisis approaching. my country has become a major energy producer and consumer in the world. With the continuous development of economy and society, my country's energy demand will continue to grow, and energy shortage has become a key issue restricting economic development. The development of renewable green energy is the only way for the sustainable development of society. Therefore, the development and utilization of renewable new energy has attracted more and more attention. Renewable energy includes water energy, biomass energy, wind energy, solar energy, geothermal energy and ocean energy. These resources have great potential, low environmental pollution, sustainable utilization, and are important energy sources that are conducive to the harmonious development of man and nature. Since the 1970s, the idea of sustainable development has gradually become the consensus of the international community. The development and utilization of renewable energy has been highly valued by countries all over the world. Many countries regard the development and utilization of renewable energy as an important part of their energy strategy and put forward a clear The goal of energy development has formulated laws and policies to encourage the development of renewable energy, and renewable energy has developed rapidly. In recent years, among the green energy developed and researched, wind energy has become one of the fastest-growing energy sources in the world, and its annual growth rate is expected to reach 20% in the next 10 years. Wind energy is called "the energy of the future". Unlike traditional energy sources such as coal, oil and atomic energy, it will neither pollute the environment nor be exhausted. In developing countries where living standards are rising, wind energy is an easily installed and efficient source of energy, and is often the only means of delivering electricity to remote areas. In industrialized countries, wind energy is a new type of energy that takes both energy capacity expansion and environmental protection into consideration.

Unlike the rising cost of most energy sources, the cost of wind energy has fallen as technology has improved, and the economics of wind energy have continued to improve. For example, the cost of electricity generated by a large wind power station in Denmark has been reduced by about two-thirds over the past 10 years. The invention is proposed aiming at reducing the cost of wind power and improving the economy of wind power. Many wind turbines are arranged together in a wind farm, and some wind turbines will be in the wake of other wind turbines, which will affect the performance of the wind turbines, reduce the power output, and affect the total power output of the entire wind farm. The invention can improve the total output power of the whole wind farm by improving the wake of the wind turbine.

Contents of the invention

The purpose of the present invention is to propose a plasma flow control method that reduces the wake loss of a wind turbine. The method of the present invention can reduce the wake loss of the wind turbine on the one hand, and can reduce the interference of the wake to the downstream wind turbine on the other hand. , which in turn can increase the total output power of the entire wind farm.

In order to achieve the above object, the plasma flow control method for reducing the wake loss of the wind turbine provided by the present invention is:

Two metal electrodes are arranged asymmetrically on both sides of the insulating material, one of the metal electrodes is exposed in the air, and the other metal electrode is embedded in the insulating material to form a set of plasma exciter, which is installed in the wind turbine At the trailing edge of the suction surface of the blade, the installation method must make the plasma-induced flow direction the same as the main flow direction; the plasma excitation voltage is applied to the two metal electrodes of the plasma actuator, and weak ionization is generated above the metal electrodes embedded in the insulating material. The low-temperature plasma transmits energy to the boundary layer through the collision of ions and neutral gas molecules, so that the surrounding air forms a horizontal jet with zero static flow, and accelerates the air flow in the boundary layer.

The plasma flow control method for reducing the wake loss of the wind turbine, wherein the plasma actuator is 1-1000mm away from the trailing edge of the blade.

The plasma flow control method for reducing the wake loss of the wind turbine, wherein, the plasma excitation voltage is 1-100kV, and the frequency of the plasma excitation voltage is an alternating current of 1-1000kHz.

The plasma flow control method for reducing the wake loss of the wind turbine, wherein, the insulating material of the plasma actuator is polytetrafluoroethylene, ceramics or quartz glass.

The plasma flow control method for reducing the wake loss of the wind turbine, wherein, the thickness of the insulating material of the plasma actuator is 0.01-100mm.

The plasma flow control method for reducing the wake loss of the wind turbine, wherein, the material of the metal electrode of the plasma actuator is tungsten, molybdenum, steel or copper.

The plasma flow control method for reducing the wake loss of the wind turbine, wherein, the shape of the metal electrode of the plasma actuator is rectangular.

The plasma flow control method for reducing the wake loss of the wind turbine, wherein, the metal electrode width of the plasma actuator is 0.1-100mm.

The present invention is very different from the known technology in reducing the wake loss of wind turbines: plasma flow control is a flow control technology based on plasma aerodynamic excitation, and plasma excitation uses plasma as a carrier to apply a a controllable disturbance. The innovation of the present invention is reflected in:

1) Apply plasma flow control method to reduce wind turbine wake loss;

2) Plasma excitation is electrical excitation without moving parts;

3) Simple structure, low power consumption, and easy adjustment of excitation parameters;

4) The excitation frequency is wide and the response is quick.

Description of drawings

Fig. 1 is the structural representation of the plasma exciter that the present invention adopts;

Fig. 2 is a structural schematic diagram for realizing the method of the present invention.

Fig. 3 is a schematic diagram of known wind turbine blade wake;

Fig. 4 is a schematic diagram of reducing the wake of a wind turbine by plasma excitation according to the present invention.

Detailed ways

The plasma flow control method for reducing the wake loss of the wind turbine provided by the invention is used in a wind power generation system. The method of the invention includes the following parts:

The blades of the wind turbine play the role of driving the generator to generate electricity, and are also the carrier of the plasma exciter;

Plasma exciter, which generates plasma after being connected to high-voltage electricity, and accelerates the nearby air;

Plasma excitation voltage (high voltage AC power supply), which provides power for the plasma exciter.

From the perspectives of fluid mechanical aerodynamic thermodynamics and plasma physics, the invention adopts a plasma excitation method suitable for flow control of the wind turbine wake, so that the wind turbine wake loss is kept at a low level.

The present invention arranges the plasma exciter at the fixed position of the blade of the wind turbine, and applies the plasma excitation of appropriate intensity and frequency. On the one hand, it can reduce the wake loss of the wind turbine, and on the other hand, it can reduce the impact of the wake on the downstream wind turbine. interference.

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

Fig. 1 is the schematic structural view of the plasma exciter 1 of the present invention, two metal electrodes 11, 12 are arranged asymmetrically (staggered) on both sides of the insulating material 10, and a metal electrode 11 is exposed in the surrounding air (hereinafter referred to as bare electrode 11), another metal electrode 12 is embedded in insulating material 10 (hereinafter referred to as buried electrode 12) to form a group of plasma actuators 1, and the width of metal electrodes 11, 12 can be 0.1-100mm. In fact, there may be multiple pairs of exposed electrodes 11 and buried electrodes 12 in a group of plasma exciters, all of which are arranged in a staggered manner. The staggered distance between the two metal electrodes of the exposed electrodes 11 and the buried electrodes 12 may be 0-5mm. The present invention can use, but not limited to, rectangular metal electrodes made of copper material, and the insulating material can be used, but not limited to, such as polytetrafluoroethylene or quartz glass, and the thickness of the insulating material is 0.01-100mm. Under the action of excitation voltage 13 (voltage 1-100kV, frequency 1-1000kHz high-voltage alternating current), weakly ionized low-temperature plasma 20 can be generated above the buried electrode 12, and transported to the boundary layer through the collision of ions and neutral gas molecules The energy makes the surrounding air form a horizontal jet flow with zero static flow rate, accelerates the flow of air in the boundary layer, and produces the induced flow as shown in Figure 1.

Fig. 2 is a structural representation of the present invention, and the plasma exciter 1 is arranged on the trailing edge of the suction surface 15 of the wind turbine blade 14, and the plasma exciter 1 (the edge of the buried electrode 12) is reserved 1- 1000mm distance. The exposed electrode 11 of the plasma exciter is connected to the high-voltage end of the excitation voltage 13, and the buried electrode 12 of the plasma exciter is connected to the ground end of the excitation voltage 13. The excitation voltage 13 is always turned on during the operation of the wind turbine, and the plasma excitation is applied. The wake loss of the blades of the wind turbine can be reduced, and the interference to the downstream wind turbine can be reduced at the same time.

Figure 3 shows a schematic diagram of the flow around the blades of a known wind turbine. It can be seen from the figure that the incoming flow forms a wake after passing through the blades of the wind turbine. The wake is filled with irregular vortices, which continuously consumes the energy of the airflow, and forms pressure resistance and aerodynamic noise.

Fig. 4 has provided the present invention and utilizes the plasma excitation to reduce the wake width schematic diagram, as seen from the figure under the action of the plasma excitation, compared with not applying the plasma excitation in Fig. 3, the wake width behind the wind turbine blade decreases, like this The wake loss can be reduced, and the disturbance to the downstream wind turbine can be reduced at the same time.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (8)

1. A plasma flow control method for reducing wind turbine wake loss: Two metal electrodes are arranged asymmetrically on both sides of the insulating material, one of the metal electrodes is exposed in the air, and the other metal electrode is embedded in the insulating material to form a set of plasma exciter, which is installed in the wind turbine At the trailing edge of the suction surface of the blade, the installation method must make the plasma-induced flow direction the same as the mainstream direction; The plasma excitation voltage is applied to the two metal electrodes of the plasma exciter, and a weakly ionized low-temperature plasma is generated above the metal electrodes embedded in the insulating material, and the energy is transmitted to the boundary layer through the collision of ions and neutral gas molecules, making the surrounding The air forms a horizontal jet with zero static flow, which accelerates the flow of air in the boundary layer. 2. The plasma flow control method for reducing the wake loss of the wind turbine according to claim 1, wherein the plasma actuator is 1-1000mm away from the trailing edge of the wind turbine blade. 3. The plasma flow control method for reducing the wake loss of the wind turbine according to claim 1, wherein the plasma excitation voltage is 1-100kV, and the frequency of the plasma excitation voltage is an alternating current of 1-1000kHz. 4. The plasma flow control method for reducing the wake loss of the wind turbine according to claim 1, wherein the insulating material of the plasma actuator is polytetrafluoroethylene, ceramics or quartz glass. 5. The plasma flow control method for suppressing flow separation on the suction surface of a wind turbine blade according to claim 1, wherein the thickness of the insulating material of the plasma actuator is 0.01-100 mm. 6. The plasma flow control method for reducing the wake loss of a wind turbine according to claim 1, wherein the metal electrode of the plasma actuator is made of tungsten, molybdenum, steel or copper. 7. The plasma flow control method for reducing the wake loss of a wind turbine according to claim 1, wherein the shape of the metal electrode of the plasma actuator is rectangular. 8. The plasma flow control method for reducing the wake loss of the wind turbine according to claim 1, wherein the metal electrode width of the plasma actuator is 0.1-100mm.

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