Research On Design Principle Of Differential Speed Regulating Transmission For Variable Speed And Constant Frequency Wind Turbine

Grid-connected wind turbine is one of the renewable energy production form which has mature technology and favorable development potential. At present, direct drive permanent magnet generator and doubly fed induction generator are mainly adopted in grid connected wind turbine. There are still some scabrous technical bottlenecks for this kind of variable speed and constant fequency system with electronic speed regulating technology. Such as the section of’rectification and contravariant’adding harmonic components in current, demanding additional equipment and increase of the control difficulty to accomplish high/low voltage ride through, increasing difficulty to design a cost effective and high reliability large capacity unit for the specially designed generator and frequency conversion device. Owing to excessive reliance on motor design and electronic speed regulating technology, those issue is difficult to get a substantial solution. It urgent needs satisfy the demands of the development of novel wind tubine.Under this circumstances, the novel wind turbine based on advanced speed regulating transmission become the hot topic in academia. This paper specific to the design principle of the its important branches witch is the wind turbine with differential speed regulating. This paper aims at providing theoretical support and scientific basis for new wind turbine with scheme design, principle verification, performance simulation. We studied the principle feasibility and operational effectiveness by means of the physical test and modeling simulation. The systematic analysis of the deficiency of the related research and the design method of overall transmission scheme is put forward. The main contents and innovative results are as follows.(1)The design method of transmission scheme for wind tubrine with differential speed regulating is put forward. Transmission scheme of arrangement and parameters configuration is a key link in the process of overall scheme design, but there is no pertinency design method. The method of overall transmission scheme formed by the determination of the differential gear train layout and optimize the transmission ratio. It is the theoretical basis for subsequent physics experiment and performance simulation. The arrangement of the differential gear train in the overall plan is determined based on differential drive principle and critical conditions of power delivery. The optimal value of transmission ratio and rated power of speed regulating motor can be got by the finite time process optimization method with the target of minimizing the peak power under multiple constraints. In addition, a derived scheme which is speed self-stabilizing scheme for the novel wind turbine is studied.(2)The first domestic testbed for the differential speed regulating wind turbine is setup to verify the feasibility of transmission principle by the way of the experimental study. The testbed consists of differential module, motor module and control module. The testbed can be built for differential speed regulating scheme and its derived scheme with adjusting the hardware and control program sothat a foundation for subsequent open experimental study is laid. The functional requirements of the textbed is that the synchronous generator on the output side has a constant speed, while the variable frequency motor simulate the variable speed of wind rotor and the servo motor speed is controlled by feedback program in upper computer, as the differential gearbox is the transmission with function of double input and single output. The measured data including speed and torque of key component is processed with analysis for speed error and power loss. The test results show the feasibility of the novel wind turbine with differential speed regulating scheme or its derived shceme.(3)The modeling and simulation for the differential speed regulating wind turbine is researched. The simulation tool is developed in the SIMULINK software environment. The technical support can be provided for the design and performance evaluation of the units in the future. A simulation model for megawatt differential speed regulating wind turbine is established based on the overall design before. The analysis of model performance under various wind conditions is made. We also made the dynamic characteristic analysis and comparison simulation betweent two speed regulating scheme and its derived scheme. The triaxial dynamic numerical model of the differential gear train whitch is the key part of overall transmission model is research and put forward. The power control method for differential speed reuglating wind turbine is get which includes the maximum power control below the rated wind speed and constant power control above the rated wind speed. The research on power regulation process is made under the input of a variety of wind speed. We obtain the performance curve of key parameters including the tip speed ratio, utilization rate of wind power, speed and power through the simulation and the trend of curve is explained. The running availability for design of differential speed regulating wind turbine is verified by the simulation results under the actual working conditions.