Error Control Of Ultrasonic Flow Measurement And Its LabVIEW Application

The efficiency of hydraulic turbine is an important index for the economic operation of hydropower.Even if its value is increased by 0.1%,the economic benefit can be greatly improved.The efficiency test of hydraulic turbine can not only grasp the operation of the unit,but also make adjustments to the operation in time to ensure that it works in the high efficiency area as far as possible.Flow measurement is the key content in the efficiency test,and it is also the most difficult project to carry out.Its accuracy plays a decisive role in the efficiency test results,and there is no effective method to verify the measurement accuracy and error composition.Starting with the basic principle and method of efficiency test of hydraulic uni ts,this paper focuses on the flow measurement,and finally chooses the method of time difference ultrasonic flow measurement to study.By deducing the flow formula under this method,it is found that the error is related to the inner diameter D of pipeline,the angle of sound path ?,the velocity c of ultrasonic wave in water and the flow coefficient K.Based on the influencing factors,the flow measurement error description model is established.A quantitative method for error analysis based on ideal flow measurement system is proposed,and the influence of various parameters measurement errors on the comprehensive error of the system is analyzed.The relevant control methods are proposed for the dominant factors with great influence,and the control of the system comprehensive error is analyzed.On the basis of defining the whole process of unit efficiency test,the virtual instrument which combines the test system with computer calculation is used to provide a platform for the efficiency test of hydraulic units.On this basis,a set of turbine efficiency testing system based on ultrasonic flow measurement method is established with the help of LabVIEW related platform.Finally,the error control of the proposed ultrasonic flow measurement method is verified according to the results of the efficiency test,and its feasibility is preliminarily proved.This provides a certain guiding role for the research and design of the ultrasonic flowmeter.The development and application of efficiency testing has a good reference value for the utilization of water resources,the improvement of the economic benefits of hydropower plants and the better operation of generator sets and power grids.