Research And Design Of Real-time Wind Speed And Direction Measurement System Based On Ultrasound

Wind energy is a kinetic energy converted by solar energy as it flows through the air,characterized by large reserves,renewable energy,wide distribution,and low energy density.Due to the directionality of air flow,the wind speed experienced by the wind wheels of wind turbines varies in various wind directions.In order to maximize the capture of wind energy by wind turbines,it is necessary to provide wind speed and direction information to the pitch and yaw systems so that the system can make decisions about blade direction adjustment,thereby maximizing power generation efficiency.Therefore,the measurement of wind speed and direction plays an important role in wind power generation.The measurement methods of wind speed mainly include mechanical,hot-wire,pitot tube,and ultrasonic methods.Due to the fact that wind speed and wind direction indicators used for wind power generation need to be placed on the top of the unit and exposed to the air for a long time,the instruments are prone to corrosion and damage.The characteristics of ultrasonic non friction,non inertial measurement,and long service life can be well adapted to this environment.At the same time,ultrasonic measurement devices can measure the wind speed and obtain the magnitude of the wind direction.Therefore,ultrasonic type is more suitable for wind power generation applications.The traditional ultrasonic anemometer mainly adopts a reflective structure of two transmitters and two receivers.In order to avoid the interference between ultrasonic waves,this structure usually requires the design of a strobe circuit to measure in a time division manner,so the real-time performance is poor.Based on the demand of an ultrasonic product manufacturing enterprise in Fuzhou City,Fujian Province for improving the sampling rate and real-time performance of ultrasonic signals using time difference method,a direct beam two transmitter and four receiver structure is proposed to improve the real-time performance of measurement,and a set of ultrasonic wind speed and direction measurement system is designed based on this structure.The testing system mainly consists of ultrasonic transducers,transmitting and receiving circuits.The transmitting circuit is mainly composed of a driving circuit and a power amplifier circuit,and the STM32 controls the input of the driving signal.The receiving circuit mainly consists of an AD sampling circuit,an analog signal conditioning circuit,and an average filtering module composed of FPGA,FIFO module,MERGE module,FIR module,and SPI module.The data processed by FPGA is transmitted to STM32 through SPI module for data calculation and result display.Aiming at the problem of limited adjustable gain due to the small range of AD chips,a logarithmic amplifier is used to compress the signal envelope to improve it.However,logarithmic amplifiers increase the difficulty of peak detection of received wave signals while achieving gain adjustable range expansion and detection functions,thereby affecting the accuracy of measurement.To solve this problem,this paper proposes a method of breakpoint detection,which achieves accurate measurement of ultrasonic arrival time through Hampel filtering and changing detection feature points.Through analog and digital circuit simulations,this paper examines the filtering,detection,clock domain data processing,and transmission effects of the circuit.The wind speed and direction were tested in a wind tunnel environment.The test results show that the ultrasonic wind speed and direction measurement system designed in this paper can achieve the simultaneous reception of two receiving transducers under a single transmission signal,and has high measurement accuracy,achieving the expected goal of the project.