Research On Characteristics And Structural Improvement Of High-Power Turbine Permanent Magnet Generator In Oil And Gas Well

With the continuous progress of petroleum exploration and development technology,drilling technology and drilling equipment are developing towards the direction of automation,integration,intelligentization and informatization.Correspondingly,the demand of power supply for downhole instruments is improved rapidly,that make the turbine permanent magnet generator gradually become one of the main power supplies for downhole instruments.However,there are some technical problems in downhole turbine permanent magnet generator,such as the magnetic performance of permanent magnet materials affected by high temperature,the coil become invalid easily because of scouring and corroding caused by drilling fluid,high-power demand in a restrictive space,etc.Around these questions,theoretical analysis,model simulation and experimental research are combined to research characteristic and improve structure about the downhole turbine permanent magnet generator.The main contents and phased achievements are as follows:1^st.The requirements for the permanent magnet used in downhole turbine generator of the high-temperature working environment are analyzed.The performances of several different permanent magnet materials in high temperature environment are investigated and compared,and suitable type and brand of permanent magnet materials used in downhole is selected,in order to provide a stable and high-density magnetomotive force source for turbine generator under high temperature downhole environments.2^nd.Aiming at the problem that coil failure of downhole turbine permanent magnet generator which is caused by scouring and corroding of drilling fluid,a structural improvement measure of adding a metal protective sleeve outside the stator coil is proposed.By establishing an equivalent magnetic circuit model with protective sleeve,the influence of protective sleeve on the magnetic circuit of the generator is analyzed.Then,the influence law of the permeability of the sleeve material and the thickness of sleeve on the output performance is deduced.According to the engineering design index and strength requirements,the material and thickness of the protective sleeve are determined.The calculation of magnetic circuit shows that the output voltage of the generator is decreased by 14.1 percent when the non-magnetic stainless steel protective sleeve with thickness of 1 millimeter is added.3^rd.The two-dimensional simulation model of the downhole turbine permanent magnet generator is established.In order to improve the power density of the generator,the numerical simulation method is adopted to optimize the parameters of the generator,such as permanent magnet thickness,polar arc coefficient,rotor inner diameter,generator length,etc.Furthermore,the electromagnetic design parameters of high-power turbine permanent magnet generator meeting the requirements in a restrictive space are determined.Numerical calculation shows that the optimized generator power density can be increased by 31.1percent.4^th.The test machine is made after the design,processing and assembly of the stator and rotor of the downhole turbine permanent magnet generator.Then experiment test is implemented,the test results indicate the feasibility and rationality of the generator structure improvement and parameter optimization design.These research results of this paper can provide theoretical reference and design basis for the development of downhole high-power turbine permanent magnet generator.