The domestic sensor market still needs to be developed, especially the technology of high current sensor, which is far behind the international level. However, with the development of economy, the development demand of new energy industries, such as rail transit or wind power, will drive the development of domestic sensor technology. More and more sensor manufacturers will focus on rail transit, new energy and other industries. The wind power industry promotes the development of traditional sensor technology. Since the early days of human development, wind energy has been used as an energy source. With the development of science and technology, people began to use wind energy more accurately.
Schleswig Holstein state in Germany is located between the North Sea and the Baltic Sea. Even in the case of small wind, the wind turbine generator units produced by Rexroth can still operate. If the wind direction changes 8 degrees from northwest to north, the anemometer will transmit the sensed signal to the control system, and control the yaw drive device to position the engine room to a proper position. The anemometer, including wind speed sensor and wind direction sensor, is developed with the development of wind power industry. Generally speaking, the wind speed sensor shall meet the measurement range of 0~60m/s, the error range is within 0.5m/s, and the working environment temperature shall meet the local air temperature conditions. The wind direction sensor shall meet the measurement range of 0~360 degrees, the accuracy of 2.5 degrees, and the working environment temperature shall meet the local air temperature conditions.
Li Jianlin, associate researcher of the New Energy Group of the Institute of Electrical Engineering of the Chinese Academy of Sciences, said, "The wind power industry will promote the application of high voltage and large current sensors, vibration sensors, temperature, humidity, wind measurement, pressure sensors and other products." Among them, as the current sensor is an essential component of the converter in the wind turbine, its application in the wind power industry is particularly important. In some inverters, small and PCB mounted current sensors are widely used. These sensors are part of the converter's closed-loop control and can ensure the inverter's rapid response.
When the inverter and intelligent power control of the generator are used at the same time, it can ensure that the wind turbine can provide continuous power to the grid within a wide wind speed range after starting, until the turbine stops at the upper wind speed. In order to position the driver optimally, the sensors in each converter will continuously measure the current. The quality and response time of the circuit controller are ultimately determined by the design and performance of the current sensor. This is why closed-loop current sensors with low current ratings are widely used in the wind power industry. In addition to its excellent linearity and accuracy, the closed-loop current sensor itself has the advantages of high bandwidth and fast response time.
Li Jianlin pointed out that the domestic current sensor market still needs to be developed, especially the large current sensor technology, which is far behind the international level. Due to the relatively immature technology of large current sensors in China, most domestic wind turbine manufacturers choose imported products when purchasing large current sensors. As the price of imported products is often higher than that of domestic products, this increases the pressure on production costs to a certain extent. In terms of small current sensor technology, there is no gap between the domestic technology level and the international level.
As most domestic wind power stations are located in the "Three North" (North China, Northeast, Northwest) and coastal areas, the climate is relatively harsh, so the requirements of wind turbine generators on sensor performance are high, especially the requirements on heating function, seismic resistance, anti high-frequency electromagnetic interference, anti polarity connection (connection), and anti shock and vibration of wind direction indicators are far higher than the performance indicators of general sensors, The units of tidal power stations also require that the sensors have good seawater corrosion resistance.
The application of sensors in the wind power industry is not only limited to the wind power industry. As far as China's power industry is concerned, there are many occasions to use sensors. Pressure sensors, temperature sensors and flow sensors are mainly used in power plants and power stations, and voltage sensors and current sensors are mainly used in the field of power transmission and transformation. Most of them belong to general sensors with low technical level but high requirements for reliability and stability, while optical sensors with high technical level requirements are still rarely used in the power industry.
As the sensors of power plants are generally selected by the unit equipment manufacturers, there are relatively many sensors used in China. The field of power transmission and transformation is different. Compared with the field of power generation, the one-time input of sensors is relatively small, and each power grid region is not very sensitive to the price when choosing a brand, and the use of some relatively new technologies can improve the level of power transmission and transformation. Therefore, foreign brand sensors are used more frequently. "
Rail transit drives the development of new sensor technology
With the rapid development of semiconductor technology, VVVF voltage regulation and frequency modulation traction inverter and CVCF auxiliary inverter are used in the traction control system and auxiliary power supply system of modern and advanced urban subway and light rail vehicles. Like the main line AC-DC-AC transmission locomotive, current sensors and voltage sensors are also widely used in the DC and AC circuits of the above systems to achieve closed-loop control of the entire system.
However, the biggest impetus of urban rail transit to sensor technology lies in wireless sensor network technology, infrared sensor technology stress sensor, gas sensor, speed sensor, photoelectric sensor technology and other new sensor fields, not just traditional sensor fields such as current sensor and voltage sensor. Wang Shuhe, deputy chief engineer, senior engineer and international project management expert of China Railway Electrification Survey, Design and Research Institute Co., Ltd., pointed out that "in the subway field, the demand and technical content of some toxic gas sensors related to ventilation and air conditioning, such as temperature, humidity and CO2 sensors, and anti-terrorism are very high.
In the field of high-speed multiple units, there is a very high demand for sensors related to oxygen monitoring and supply, earthquake, speed monitoring, axle temperature detection, connection looseness monitoring, foreign matter monitoring, etc. in the closed compartment, and these technologies are still developing and improving. The anti-theft and robbery sensors, such as the broken glass in the high-voltage chamber, the wrong entry, and the cable theft and robbery sensors, are very important. " Wang Shuhe further pointed out that these sensors are closely related to system equipment and personal safety.
In the air conditioning system of urban rail transit vehicles, sensors and electronic temperature controllers are often used for temperature control. The temperature controller mostly uses an electronic regulator, and the sensor is used for temperature detection. Generally, thermocouples or thermistors are used as sensors. In the passenger compartment, due to human respiration, the content of carbon dioxide (CO2) will increase. When it increases to a certain concentration, it will affect human health. The harmful gases generated in the articles carried by passengers in the vehicle will also make the air in the vehicle dirty. At this time, fresh air needs to be generated from the outside to replace the air in the vehicle. Therefore, the accurate detection of gas by sensors is particularly important.
Since January 2005, two subway stations in Washington, USA started to use a sensor that can detect chemical toxic gas, more and more subway stations began to use sensor detection technology to ensure the safe operation of rail transit. After the 2008 Beijing Olympic Games, many cities in China have stipulated that all rail transit stations should be compulsorily equipped with sensors to detect explosives and toxic and harmful chemicals. Because wireless sensor network includes many types of sensors that can detect, including earthquake, electromagnetic, temperature, humidity, noise, light intensity, pressure, soil composition, size, speed and direction of moving objects, it has become the main sensor technology in rail transit safety assurance system.
Wireless sensor network is one of the hot spots and difficult points of contemporary science and technology. Wireless sensor network is composed of a large number of sensor nodes randomly deployed. It can quickly form an adaptive network topology, and can co perceive and process distributed dynamic information to form an incomplete and limited autonomous integrated information system. It is the remote nerve endings of human beings. Shanghai Institute of Microsystems has conquered a number of key technologies and prototypes in MEMS sensors, chips, nodes, networks, collaborative processing and other aspects of wireless sensor networks, and has made significant progress in random deployment and networking, multiple clustering and networking, network architecture, multiple communication systems, virtual MIMO and other aspects. Some key technologies in the fields of blind source separation, multi-target collaborative identification, tracking and positioning of sensor networks are advanced in the world, and have been applied in a certain scale to meet the major national needs.
Another important application of the sensor of the 10000 material testing machine in ensuring the safety of rail transit is the screen door. In the past, there have been many accidents in which passengers were caught between the screen door and the train door. Now more and more rail transit stations are installing or planning to install infrared sensors or optical sensors to prevent passengers from becoming "sandwich cookies".
The country's strong investment in rail transit construction will further drive the development of the sensor market. In addition to the above sensors, it also includes machine vision sensors, shield machine sensors as the highest equipment for underground construction in rail construction.
With the further development of the sensor market, more and more sensor manufacturers have joined in the market competition. As a sensor manufacturer, whether it can keep up with the market demand, continuously expand its business blue ocean, and improve its technical strength, Kejian Instrument will become the key to breakthrough in development in the future.