Fundamentals of a power splitting driving chain for large wind turbines

The current tendency of the development of wind power technology is that the variable wind turbines adjust the speed of wind rotor at real time in accordance with wind speed to absorb wind energy more effectively and improve the operating condition of power chain. A critical point of the design of variable wind turbines is to settle the influence of wind speed changes on the smooth electric power output and power driving chain. Based on the differential planet gear system, this paper gives a research on a kind of power splitting driving chain (PSDC), with the basic thought as follow: The wind rotor linked by planet gear frame axis functions as the main power input terminal; Both a main generator and an auxiliary one are adopted in the double degree of freedom planet gear mechanism; The main generator is driven by gear ring of the planet gear mechanism to realize most of energy conversion in the power driving chain and the electric-energy output to the power grid; the auxiliary generator linked by the sun gear serves as the servo element of PSDC. Meanwhile, the servomotor links the supply grid with bi-efficacy of generator and motor under the control of small electronic power devices, achieving the control of electromagnetic torque and the constant-speed operating function of main generator. The analysis in this paper shows that the large variable wind turbines consisting of this kind of power splitting driving chain (PSDC) could provide new solutions for those problems with which variable wind turbines are confronted, such as difficulties in the design and manufacture of special large generator, its extortionate cost, the high price of electronic power system for high power conversion and control, as well as the mutual influence between wind turbine unit and supply grid.