Research On Measuring Method Of Shaft Power For Marine Power Plant

Diesel engine, as the "heart" of the ship, its working state directly reflects the behavior of the power plant in service. By means of real-time condition monitoring and fault diagnosis for the marine diesel engine, we can effectively know the operating condition of the ship so as to extend the ship's service life and reduce the operating cost. Shaft power, which is one of the most important performance parameters, can be measured to assess the working condition of the power system overally. Therefore, study on the method for torque measurement of the power system, has important application value in the project. This paper mainly contains the following contents:1) Established a computational model on magnetic field for the measuring system, 2-D finite element method has been used to calculate the effect of the magnetic steels on magnetic field distribution and to analyze the characteristic of non-uniform distributed magnetic steels and the measuring principle of torque based on phase difference of magnetic sensor technology.2) Shafting alignment and reforming for torque simulating measuring of a long shaft power plant which has been built on the test-bed in semi-anechoic room is introduced. Based on the analysis of dynamics and mechanics of material for shafting and the using of appropriate shafting alignment technical method, the accuracy of centering for the shafting has been achieved.3) Manufactured a shaft power measuring instrument for the shafting of the large slow-speed ships based on phase difference of magnetoresistance effect, and the parts which were used to fix the measuring instrument and sensor were Designed and installed; In accordance with the feature of the magnetoresistive sensor, DC-DC power module and some electronic components were chosen for making the signal amplification and adjustable biased circuit, which was designed to realize the signal conditioning of the sensor; A simulated torque measurement system based on LabVIEW has been developed.4) Used torque simulating measurement system to test different phase difference on the test-bed and to study the method of signal analysis and processing, then the error on the experiment result were analysed.