Research Of Error Compensation For V-cone Flow Measurement System

With the energy crsis and the degree of industrial automation deepening, the demand of the flowmeter is growing. Therefore, it is of great significance to compensate the system error to improve the precision and the versatility of V-cone flowmeter. A V-cone flow measurement system with high precision and high versatilily is designed.The overall system frame, compensation algorithms, hardware, software and application testing of the V-cone flowmeter were studied in this paper. The system design was solved as follows:(1) The error compensation algorithm of the system is designed. The Genetic Algorithm-BP Neural Network (GA-BP) algorithm is improved, which combining the control gene and simulated annealing algorithm to optimize the structure and the weight of BP network, thus, a Hierarchical Genetic Simulated Annealing algorithm to optimize BP neural network(HGSA-BP) is designed, which is used to compensate the error of pressure sensor A contrastive study dealt with the compensation models for the density or the compression coeffcient of the different fluid media is designed.(2) The hardware designing of the system is completed, which included sensor collection, the conditioning circuit of differential pressure sensor, pressure sensor and temperature sensor, the minimum system and the peripheral circuits of MSP430F4794 MCU. Each sensor signal conditioning circuits contains a corresponding hardware compensation circuits,which calibrate the differential pressure signal, absolute pressure signal and temperature signal initially.(3) The software designing of the system is completed. A high accuracy flow measurement and compensation program is completed in the software designing which using the modular programming method. There are two parts in software designing:design of MCU software and design of PC software. The MCU software including initalization routines, data collection routines, flow measurement and compensation routines, display and key moduale routines, serial communication routines. Online compensation and real-time monitoring are the main function of PC software, which including the software designing of control interface, the design of VC++ and Matlab Access database, the mixed programming between VC++ and Matlab. The mixed programming between VC++, Matlab and Access database is designed to apply for the HGSA-BP network.(4) The online compensation for differential pressure sensor and pressure sensor are completed, the precision of compensated sensor can reach 0.07%. The mass flow measurements are completed with water and air respectively, the precision of mass flow measurement can reach 0.3%.The characteristic of this paper is that using the HGSA-BP algorithm to compensate the differential pressure sensor and pressure sensor, and using the mixed programming between VC++, Matlab and Access database to apply for the algorithm. According to different characteristics of the fluids, The different compensation models are used respectively to improve the precision of the system.